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[227] COMPUTERIZED ADAPTIVE METHODS FOR SELECTING HEARING AIDS
Donald D. Dirks, PhD
VA Medical Center, West Los Angeles, CA 90073
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C432-4RA)
PURPOSE--The objectives of this project were to evaluate the relative merits of selected nonlinear signal processing strategies for use in hearing aid design and to explore the use of subjective judgments for measuring speech intelligibility and quality for application in hearing aid evaluations.
METHODOLOGY--The overall research plan for this area of study included the comparative assessment of three signal processing strategies: 1) linear amplification; 2) output compression (compression ratio 8:1, fast attack time); and 3) symmetrical peak clipping. Compression and clipping have been advocated for use in limiting the output of a hearing aid while linear amplification was used as a reference condition. A digital master hearing aid was developed and used to process the speech signals, set the compression and clipping parameters, and provide the prescribed frequency-gain response for groups of individuals with moderate-to-severe sensorineural hearing loss. Both speech intelligibility and speech quality performance for sentence material was used to assess the differences in perceptual performance among the experimental strategies. Stimuli were presented at sound pressure levels below and above the threshold for clipping and compression.
Although the assessment of subjective sound quality has been recognized as essential for determining patients satisfaction with a hearing aid, its measurement has received only modest systematic investigation and no clinical protocol has been widely accepted. In one experiment, subjective judgments of speech clarity and intelligibility were examined for both nonimpaired and hearing-impaired listeners using the psycho-physical methods of paired comparison and category ratings. In a second experiment, judgments of clarity and intelligibility were rated for several conditions in which frequency response and/or signal-to-noise ratio was varied while intelligibility was equated based on articulation index (AI) theory.
PROGRESS--The investigations revealed that speech intelligibility was only modestly affected by peak clipping or compression while listening in a quiet environment. Speech quality, however, became progressively poorer as speech was delivered at increasingly higher levels above the threshold for clipping. In backgrounds of noise, both intelligibility and quality were more adversely affected by peak clipping than by compression or linear amplification. The results from these experiments were presented at several scientific meetings cited later in the publication and presentation list. Currently we are completing analysis of the results and preparing it for publication.
RESULTS--These results indicated that the output of a hearing aid should be limited with compression rather than peak clipping. While assessing processing strategies in a digital master hearing aid can provide important comparative results for making decisions about the relative merits of various circuitry options, future investigations should also include clinical trials so that the comparative effects of peak clipping and output compression can be assessed in more naturalistic settings.
In the initial experiments on subjective sound quality, speech clarity judgments obtained by paired comparisons and category rating were highly related to the AI estimates both for control and hearing-impaired subjects. When the performance range was wide, both methods provided similar judgments for the control subjects. For the hearing-impaired subjects, paired comparisons were more sensitive than category rating. When the performance range was narrow, paired comparisons were more sensitive than category rating in differentiating between filters for both groups of subjects. This difference was less obvious for the controls when paired comparison data were converted to the category ratings. Large between-subject variability was evident for the hearing-impaired subjects on the psychophysical scaling procedures, most notably for category rating.
When judging the clarity among stimulus items where performance varied over a wide range, both category rating and paired comparisons provided comparable judgments for controls. For conditions in which perceptual differences between stimulus items were restricted either by the choice of conditions or by the effects of sensorineural hearing loss, the method of paired comparisons was the more sensitive procedure.
The purpose of the second investigation was to determine whether subjective judgments of clarity or intelligibility would be rated equally among conditions in which speech was equated for predicted intelligibility (using the Speech Intelligibility Index, SII) but varied in bandwidth. Twenty control listeners rated clarity and intelligibility for sentence material (Hearing In Noise Test) in speech-shaped noise at six paired-low and high-pass filtered conditions in which SII was equated for each pair. For three paired conditions, predicted intelligibility increased as SII was increased monotonically (0.3, 0.4, 0.5). In the remaining paired conditions, SII continued to increase monotonically (0.6, 0.7, 0.8) but predicted intelligibility was held at a maximal level (>95 percent). Predicted intelligibility was estimated from the transfer function relating SII to speech recognition scores determined in preliminary experiments. Differences in ratings between paired low- and high-pass filtered sentences did not reach statistical significance for either clarity or intelligibility, indicating that the spectral differences at equivalent SIIs did not influence the judgments for either of the two dimensions. For conditions in which predicted intelligibility increased, both clarity and intelligibility ratings increased in a similar manner. For conditions in which predicted intelligibility was maximized, intelligibility ratings remained the same statistically across conditions while clarity ratings changed modestly. Although high correlations were observed between clarity and intelligibility ratings, intelligibility ratings were consistently higher than clarity ratings for comparable conditions. The results suggested that controls produced clarity or intelligibility ratings for the same speech material and experimental conditions that were highly rated but differed in magnitude. Caution is required when substituting clarity for intelligibility.
IMPLICATIONS--Future investigations should be directed toward establishing the factors associated with sensorineural hearing loss which produce large between-subject variability and reduced sensitivity when using category ratings as compared to paired comparisons. Further consideration should be given to methods in which subjects make an assessment of a preferred condition or processing scheme based on a paired comparison paradigm which incorporates a rating scale to indicate the strength of their preference.
[228] CHANGES IN AUDITORY ABILITIES WITH HEARING AID USE
Lenore Holte, PhD; George Haskell, PhD; Janette Rogers,
MA; Cynthia Hogan, PhD
Iowa City VA Medical Center, Iowa City, Iowa 52246;
University of Rochester, Rochester, New York 14642; email:
holte.lenore@iowa-city.va.gov
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C847-2RA)
PURPOSE--Recent investigations suggest that the benefit of amplification for speech understanding increases over the first few weeks or months of hearing aid use for some listeners. The purpose of this project is to determine the effects of daily hearing aid use on speech recognition abilities and to test one hypothesis regarding an explanation for any changes in these abilities. Specifically, we are exploring whether increases in hearing aid benefit occur over a 6-mo period in novice hearing aid users, and, if so, whether these increases in benefit are accompanied by an increased reliance on high-frequency information in speech. We are also investigating changes in preference for various frequency responses over time.
METHODOLOGY--Three groups of hearing-impaired subjects are being evaluated using the Nonsense Syllable Test (NST) at a signal-to-noise ratio of +20 dB. One control group is composed of experienced hearing aid users who wear their hearing aids daily. Another control group is made up of novice hearing aid users who do not wear their hearing aids outside the laboratory during the study and only wear them during their monthly study visits. The experimental group participants are novice users who wear their hearing aids daily. All hearing aids have been fit binaurally according to the NAL-R prescriptive formula for a moderate-level input with output limiting set to avoid exceeding loudness discomfort. These groups are followed over a period of 6 mo and tested at monthly intervals. At each visit the following measures are performed: 1) the NST in the unaided condition, in an aided condition with the NAL-R frequency response, and in an aided condition with a flatter frequency response (hearing aid benefit is defined as aided minus unaided performance); 2) crossover frequency for NST syllables (this is a measure of the contributions of various frequency regions of speech to speech intelligibility and is the frequency that divides the speech spectrum in half with regard to information used by the listener); 3) subjectively preferred frequency response (NAL-R vs. a flatter response) while listening to a sample of running speech and a sample of music.
Changes in benefit of amplification to nonsense syllable recognition is compared for the three subject groups. If daily use of binaural amplification results in an increase in hearing aid benefit, it is expected that an increase in benefit will be demonstrated only for the experimental group using their prescribed frequency response. If increased reliance on high frequency speech cues is responsible for this change in benefit, it is anticipated that crossover frequency will increase for the experimental group over the study period, but not for the two control groups.
PROGRESS--To date, 14 subjects have been recruited into the control group of experienced users (5 have completed the study), 8 have been recruited into the control group of novice users (3 have completed the study), and 15 have been recruited into the experimental group (4 have completed the study). Software has been developed to play NST stimuli, record responses from a touch screen, and score responses.
RESULTS--Results to date from subjects who have completed at least 3 monthly follow-up visits (11 experienced controls, 4 novice controls, and 8 novice experimental) indicate no consistent group acclimatization effect on speech recognition in any of these groups. This has also been recently reported in other studies of acclimatization with binaural amplification. Interestingly, both groups of novice users are experiencing an increasing preference over time for the high-frequency emphasis response for both speech and music. This occurs whether they wear this response on a daily basis or only once per month in the laboratory. There is also a small trend toward increasing reliance on high frequency cues in speech in both novice groups, although this is not reflected in increased aided speech recognition scores. It remains to be seen whether this will be significant.
FUTURE PLANS--Subject recruitment will continue and data collection completed on 20 subjects in each group for 6 mo following hearing aid fitting. We will also begin to explore the notion of listeners' changing preferences for amplification parameters and try to determine whether they can be influenced, by experience, to prefer those amplification characteristics that optimize speech intelligibility.
[229] IS THERE AN "ACCLIMATIZATION EFFECT" WITH HEARING AIDS?
Carol A. Sammeth, PhD; Julie Patterson, MA; Maureen P.
Coughlin, MA
Roudebush VA Medical Center, Audiology Section,
Indianapolis, IN 46202; email:
Sammeth@indianapolis.va.gov
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C840-RA)
PURPOSE--In 1992, Gatehouse coined the term "acclimatization effect" to refer to improvement in speech recognition scores seen over time in a small sample of users following the fitting of hearing aids. He believed that the improvements were due to their learning to use the amplified speech cues now available to them, rather than simply to stimulation of auditorily deprived ears. Since that time, however, conflicting data have been reported as to whether or not such a phenomenon exists. The present study will examine this effect with a carefully designed study that attempts to control for test-retest variability of the speech recognition tasks, evaluates the effects of changes in preferred volume wheel setting over time, and uses both linear and nonlinear amplifiers.
METHODOLOGY--Data will be obtained on adults with bilaterally symmetrical sensorineural hearing loss who have and have not previously used amplification. New users will be fitted with binaural sets of both linear and nonlinear hearing aids using probe microphone measurements. Aided speech recognition will be evaluated using the adaptive Hearing-In-Noise-Test (HINT) to determine signal-to-noise ratio (SNR) for 50 percent correct sentence intelligibility and with the Speech-Perception-In-Noise (SPIN) test at a fixed, individually determined SNR. One-half of the subjects will wear the linear hearing aid set home and one-half will wear the nonlinear set home. A unique aspect of this study is that each subject will serve as his/her own control. There will be several repeat sessions measuring binaurally aided speech recognition during a 2-week period prior to the subjects taking the hearing aids home, in order to assess across-session test/retest reliability. Subsequently, repeat measurements will be made at intervals over a 4-mo period, during which subjects will wear the aids on a daily basis. At each of these sessions, testing will be accomplished both with the volume wheel at user-preferred setting and at the original prescribed gain setting. APHAB questionnaire data also will be collected repeatedly to examine any change in subjective impressions of hearing aid satisfaction. Experienced users will be evaluated on the speech recognition tasks with their own hearing aids at a user-selected volume wheel setting fixed across sessions, and also will complete repeat APHABs in order to explore variability.
PROGRESS--To date, data collection has been completed or is underway on 26 subjects (19 new users and 7 experienced users). The early data do not appear to show an acclimatization effect for most of the subjects on the speech recognition tasks; notably, however, the new users have shown relatively high test-retest variability during pre-wearing time and fairly high variability has also been seen for experienced users. Because acclimatization may be greatest for subjects with more severe losses, in whom audibility of speech energy is insufficient without amplification, we are attempting to enroll some subjects in the study who have more severe hearing losses. The questionnaire data are now being analyzed.
IMPLICATIONS--Determination of the existance of an acclimatization effect with hearing aids is crucial because such an effect has significant implications for both clinical practice and research protocols. If there is a period of acclimatization to new amplification, longer trial periods may be necessary prior to measurement of user benefit and decision making regarding changes in electroacoustic parameters.
[230] ACCLIMATIZATION IN MONAURALLY-FITTED ADULTS
Shlomo Silman, PhD; Carol A. Silverman, PhD; Michele B.
Emmer, MS; John Lutolf, PhD
VA Medical Center, East Orange, New Jersey 07019,
Brooklyn College, CUNY, Brooklyn, NY 11210, Hunter College,
CUNY New York, NY 10010; Brooklyn College, CUNY, Brooklyn,
NY 11210; VA Medical Center, East Orange, New Jersey
07019
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C845-RA)
PURPOSE--The purpose of this study is to investigate the aided soundfield performance at each of the four discrete volume control settings on the hearing aid. This will be done periodically over a 2-year period in experienced and inexperienced monaurally-fitted adults on the two behavioral measures: the low-predictability (LP) sentences of the Speech Perception in Noise (SPIN) test and the nonsense syllable test (NST).
METHODOLOGY--The first 3-4 months of the study were devoted to subject recruitment from several VA and Speech and Hearing centers, stimulus recording and calibration, and staff recruitment and training. For the last 9 months, we were able to recruit 59 subjects, 23 of whom were excluded from the study on the basis of attrition, change in hearing, or withdrawal. At this time, we have 36 subjects (so far) who remain in the study, of whom 22 were seen for their 3-mo re-evaluation, and 11 for their 6-mo re-evaluation.
PROGRESS--Because the sample size has not, as yet, met the minimum power of statistics, we have not performed a statistical analysis. We are hoping, for the next report, to have culled enough data to enable us to perform a statistical analysis.
FUTURE PLANS--We shall continue recruiting subjects until we meet the minimum statistical-power requirement in order to perform statistical analysis.
[231] EVALUATION OF NONAUDITORY FACTORS THAT AFFECT HEARING AID USE IN ELDERLY VETERANS
Bruce Z. Rappaport, PhD; Stephen A. Fausti, PhD
VA Medical Center, Albuquerque, NM 87120; VA Medical
Center, Portland, OR 97207
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C570-2RA)
PURPOSE--To date there has been no rigorous investigation of the predictive value of assessing various nonauditory factors when considering amplification for the elderly. Limited study with a small sample size, as well as much anecdotal evidence suggests that a large scale, well-controlled study is warranted.
There are no known estimates of successful hearing aid use in the VA population. Numerous authors have acknowledged the influence of visual acuity, manual dexterity, cognition, motivation, and family support on the hearing aid evaluation, selection, and rehabilitation processes with elderly patients.
The key questions of this study are: how do the nonauditory factors affect the use of hearing aids in an elderly veteran population? and do auditory factors relate to predicting hearing aid success in this sample?
METHODOLOGY--Specific aims of this investigation are to evaluate several auditory and nonauditory factors in a group of elderly veterans who are to receive hearing aids through the VHA. Each veteran will receive an initial evaluation which will include the following:
At 4 mo following fitting and dispensing of the selected hearing aids, subjects will be reevaluated on items 1-4 above as well as a Hearing Aid Satistaction Survey, and a Hearing Aid Benefit Inventory.
PROGRESS--To date, 210 subjects have completed the study. Results are encouraging in that they demonstrate the contribution of nonauditory factors to changes in perceived benefit from hearing aid use and to perceived satisfaction from hearing aid use.
[232] DEVELOPMENT OF AN AUTOMATED TECHNIQUE FOR CLINICAL TINNITUS EVALUATION: A PILOT STUDY
Stephen A. Fausti, PhD; James A. Henry, PhD; Curtin R.
Mitchell, PhD
VA Medical Center, Portland, OR 97207; Department of
Otolaryngology, Oregon Health Sciences University, Portland,
OR
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Pilot Project #C1693-PA)
No report was received for this issue.
[233] EVALUATION OF WORD-RECOGNITION PERFORMANCE WITH SENTENCE MATERIALS
Richard H. Wilson, PhD; Ted S. Bell, PhD
Audiology, VA Medical Center, Mountain Home, TN 37684;
Human Auditory Research Lab, Head & Neck Surgery, UCLA, Los
Angeles, CA 90024-1794; email:
wilson.richard@mtn-home.va.gov;
tbell@ucla.edu
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C690-RA)
PURPOSE--Evaluation of speech recognition is a complex problem involving many interacting factors from both acoustic and nonacoustic sources. Our task has been to develop a clinical test for assessing speech understanding that is ecologically valid, statistically reliable, and efficient in terms of ease and time of administration. To accomplish this task, we controlled the acoustical properties as well as the psycho-linguistic properties of the speech itself. Our goal was to develop a word recognition measure that uses sentence materials, and isolates linguistic (lexical) sources of variability, and equates psychometric characteristics for individual sentences, providing homogeneous lists suitable for clinical testing using an adaptive procedure. The work of the past year has focused on speech stimuli in a noise background.
METHODOLOGY--The sentence materials we developed combine aspects from several traditional approaches to speech audiometry. Individual word constituents vary with respect to word frequency of usage and phonetic confusibility. In each sentence, three target words are embedded that vary with respect to word frequency and word confusibility. We have isolated several linguistic sources of variability that have never been considered in routine clinical testing, concepts borrowed from the neighborhood activation model of spoken word recognition. Word usage is undoubtedly the single most significant factor biasing word recognition. After each sentence was scaled to produce a common RMS level across the entire set of sentences, the psychometric function relating the intelligibility of each word of each sentence to presentation level across the full perceptual dynamic range of each sentence in a background of speech-shaped noise was determined.
Forty-two nonimpaired controls were tested at five signal-to-noise ratios to determine the psychometric function. Then the following criteria were employed to select a subset of sentences that were homogeneous with respect to their perceptual characteristics. The sentences had to be monotonic in mid-range of the psychometric function; increasing the audibility should always lead to greater intelligibility. Further, any sentence that exhibited extreme properties, either too easy or too difficult, was removed as well. The remaining sentences were then individually adjusted to equate them in terms of intelligibility. The sentences, initially scaled to equal RMS levels, are scaled to equal intelligibility. This process involved determination of the 50 percent point on the function for each sentence, then computing the adjustment in dB to equate the midpoints. This final manipulation produced a sentence test in which each sentence was equally intelligible in the midrange of the psychometric function. This property makes them ideal for adaptive testing methods, since extraneous variation has been largely removed from the sentences through selection and rescaling.
PROGRESS--Studies in the last year have replicated earlier results obtained in quiet with controls and hearing-impaired listeners. Our studies have shown that the difference in intelligibility between often-used words and rarely-used words is as large as 20 percentage points (in the midrange of the psychometric function) when the RMS levels of the stimuli were equated. It is important to note that usage and familiarity are not the same concept. There are many words that we seldom use, yet we know them very well; for example, the word "violin" is understood commonly, but in ordinary conversation, it is not a likely word. Another significant variable that we have included in our speech testing materials is the phonetic confusibility of the individual words. We used a metric based on the number of other words in the language that are phonetically similar to a given target word; that is, the number of words that differ by a single phoneme. Words that are phonetically similar to many other words in the language are said to be in dense lexical neighborhoods, and words that are phonetically unique, that is, sound like very few words in the lexicon, are said to be in sparse neighborhoods. Our research has shown that words in sparse neighborhoods are more intelligible than words in dense neighborhoods when overall RMS levels are equated, especially among low-usage words. Remaining work includes the task of rescaling individual words within each sentence to further reduce variability. The data collected thus far have allowed us to calculate the degree to which individual masking patterns will be modified to reduce word-to-word variability.
These sentences will be distributed as a clinical speech test on standard audio media with statistical norms for interpretation stratified by audiometric characteristics and age. The test will: a) identify individuals who have a specific deficit understanding speech when listening in noise; b) be suitable for evaluation of patients with peripheral or central speech deficits; c) provide a means of monitoring progressive disorders or for evaluating rehabilitative interventions; and d) provide a simple, reliable, and efficient screening procedure that could be used in nonclinical environments. The corpus of sentences have been shown to be valid, reliable, and efficient in preliminary clinical trials.
[234] FEASIBILITY OF PRIMING TO PREDICT CUING-RESPONSIVENESS IN APHASIA TREATMENT: A PILOT STUDY
Camille M. Bushell, PhD
Research Service, VA Medical Center, New York, NY
10010
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Pilot Project #C1851-PA)
PURPOSE--Aphasia, a language disorder resulting from stroke or head trauma, may prevent communication of even the simplest messages and is devastating to the individual and his/her family. The central language dysfunction is a word-finding deficit. Any scientifically grounded rehabilitation intervention is desperately needed for these individuals. The purpose of the present study is to develop a quick, inexpensive prognostic instrument that would save clinicians' time in identifying which aphasic patients will benefit from a semantic facilitation therapy program designed for word-finding deficits. Presently there is no standard method for identifying who might succeed in such a treatment program.
The prognostic instrument involves the semantic priming procedure, which has been studied extensively in normal adults and is grounded in a model of normal word retrieval. Thus, results from this procedure provide insights into the damaged processes and mechanisms underlying word-finding deficits as defined and measured in the normal model. Utilizing such a theoretically motivated procedure to direct the choice of therapy plan is preferable over the trial-and-error approach clinicians currently use.
METHODOLOGY--The prognostic procedure consists of a computerized task and requires approximately 1 hour for administration and scoring. Patients see related and unrelated pairs of words (e.g., lion-tiger; oven-tiger) in addition to word-nonword pairs; their task is to decide if the second word is a real word or a nonword. Reaction times are measured to the millisecond. The list of word pairs is loaded with related word pairs in a high relatedness proportion (RP) condition, but loaded with unrelated word pairs in a low RP condition. In the normal population, RTs are much faster in the high RP condition than in the low RP condition, due to the usage of an expectancy strategy. This strategy is similar to the mental operations necessary for success in semantic cuing therapy, described next.
Treatment consists of a program developed to reinforce the link between semantic representations and their corresponding phonologic codes. Subjects match a picture of an object (used in daily activities) to its name embedded in an array of words containing several related foils, after which they read aloud the correct picture name. A post-test, identical to the pre-test baseline measure, is given upon completion of therapy to measure the cumulative effects of therapy and generalization to untrained, semantically related words. In several reports, semantic facilitation treatment has been shown to be effective in improving word finding, at time intervals up to 1 year post-therapy. Because of the overlap in underlying cognitive operations involved in the semantic priming procedure and in the semantic facilitation therapy program, performance in the priming procedure was examined to determine whether it predicted success in treatment.
PROGRESS--Six fluent persons with aphasia were tested in the pilot study. Positive semantic priming effects were obtained using a procedure that motivated participants to engage in expectancy-based semantic processing. These subjects also showed benefit from semantic facilitation techniques in therapy. In sum, results from the semantic priming procedure predicted that these suubjects would benefit from treatment utilizing semantic cues. Thus, these preliminary results suggest that semantic priming procedure is a useful prognostic instrument to aid clinicians in choosing appropriate therapy for aphasic individuals.
FUTURE PLANS--Based on the promising pilot data, additional subjects with a variety of aphasia types will be tested to determine which individuals will benefit from treatment interventions involving semantic facilitation and cuing techniques.
[235] PROBLEM-SOLVING STRATEGIES OF BRAIN-INJURED AND NORMAL SUBJECTS
Robert C. Marshall, PhD
Department of Communicative Disorders, University of
Rhode Island, Kingston, RI 02881; email:
rcmarsh@uriacc.uri.edu
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C837-3RA)
PURPOSE--The objectives of this study are to examine and compare the problem-solving strategies of brain-injured (TBI) subjects and nonimpaired controls and to determine the effects of Strategy Modeling Training (SMT) on the problem-solving efforts of the TBI subjects.
METHODOLOGY--The experimental task in this study is a modification of Mosher and Hornsby's Twenty Questions Task (20Q). In this task the subject sees an array of pictures representing items in common categories (e.g., animals). He is asked to identify the item in the array that the examiner is thinking of by asking "yes" and "no" questions: the object of the game is to identify the item asking as few questions as possible. Subjects meeting selection criteria are administered a battery of cognitive and language tests. Following introduction to the 20Q task, each subject plays three 20Q games to establish a pre-training performance level. Subjects then receive a period of SMT using stimuli that are similar to (e.g., words), but different from those used in the 20Q task (e.g., pictures). SMT teaches the subject to use efficient strategies in solving 200 problems in role-playing situations with the examiner. Following a 1-wk period of no training, three more 20Q games are played by the subject (post-training); a month later, three final games are played (Maintenance).
PROGRESS--So far, our research team has concentrated on the 20Q task performance of two groups, TBI subjects and age-matched controls. Twelve TBI subjects have completed the pre-training, post-training, and maintenance phases of the study. We have developed a means of quantifying the efficiency of subjects' performance on the 20Q task. This uses a 100 mm visual analog scale with anchor points, "not at all efficient" and "highly efficient." Parameters considered include: 1) the use of constraint-seeking (e.g., Is it a form of transportation?) rather than hypothesis-scanning questions (e.g., Is it the airplane?); 2) demonstration of an obvious strategy by the subject in playing 20Q (e.g., Is it in the top two rows?); 3) use of "narrowing" questions after identifying the category containing the target item; and 4) clarity and absence of ambiguity in questions asked. Recently, 20Q performances of 12 TBI and 12 controls were rated for efficiency. The data have not been analyzed.
FUTURE PLANS--We will complete analysis on the data we have as we continue to put more subjects into the project. Initial analyses will assess inter- and intra-judge reliability on the rating procedure. Using a series of Analysis of Variance (ANOVA), we plan to compare the pre-training performances of the TBI and normal subjects. Our expectation is that there will be marked differences among the groups. Next we will attempt to identify those specific aspects of 20Q problem-solving that distinguish TBI and control performance. Next, we will compare the post-treatment and maintenance performances of the TBI subjects with the pre-treatment maintenance performance of the normal performance control. Our hope here is than TBI subjects will improve their 20Q performance secondary to SMT and will therefore no longer differ significantly from that of normal subjects. Initial observations lead us to believe that some TBI subjects improve following SMT and some do not. Individual analyses will then be carried to explain performances of TBI subjects. We plan to analyze individual performances in relation to performance on cognitive and language tests administered to each subject.
[236] QUANTIFYING SPOKEN LANGUAGE HANDICAP IN APHASIA
Patrick J. Doyle, PhD
Audiology & Speech Pathology, Research Service (151R),
Highland Drive VA Medical Center, Pittsburgh, PA 15206;
email: pdoyle@vms.cis.pitt.edu
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C894-2RA)
No report was received for this issue.
[237] ANALYSIS AND TREATMENT OF APRAXIC SOUND ERRORS
Julie L. Wambaugh, PhD; Patrick J. Doyle, PhD
Research Service, Salt Lake City VA Medical Center Salt
Lake City, UT 84148; Audiology and Speech Pathology Service,
VA Pittsburgh Healthcare System, Pittsburgh, PA 15206;
email: kfunk@utah.uswest.net
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C692-4RA)
PURPOSE--Treatment for apraxia of speech frequently focuses on training correct production of incorrectly produced sounds. At the current time, little is known about the generalization effects of such training. That is, it is not clear whether training of specific sounds will result in increases in correct productions of untrained sounds or whether trained sounds will be used correctly in untrained contexts. Therefore, the primary objectives of this investigation are to: 1) determine the stimulus generalization effects of a minimal contrast treatment for apraxia of speech; 2) evaluate the effects of sequential modification of treatment in terms of promoting additional stimulus generalization; 3) study the effects of treatment on general measures of verbal production; and 4) perform acoustic comparisons of correctly and incorrectly articulated sounds, as produced by apraxic patients pre- and post-treatment, in order to examine the relation among such sounds.
METHODOLOGY--Combined single subject and group experimental designs are being used to examine the effects of treatment. Multiple baseline designs across subjects, behaviors, and conditions are being used to evaluate the effects of treatment on production of specific sounds in treated and untreated words across several stimulus conditions within individual subjects. Concurrently, a repeated measures group design is being employed to evaluate the effects of treatment on additional aspects of speech production.
Sixteen apraxic/aphasic subjects will receive treatment, applied individually in a manner consistent with a multiple baseline design. Continuous baseline, treatment, and maintenance probes will be conducted for each individual subject to evaluate production of specific sounds. Additional measures of speech production (e.g., percent consonants correct on consonant inventory, PICA verbal score) will be obtained from each subject prior to and following treatment in order to determine group effects of treatment.
In addition to the preceding pre- and post-treatment measures, samples of incorrectly and correctly produced sounds will be collected and analyzed acoustically. Pre-treatment word lists are prepared for each subject on the basis of performance on a consonant inventory probe. These lists are designed to elicit incorrect productions of sounds that individual subjects misarticulate. Following acquisition of incorrectly produced sounds, word lists are prepared to elicit correct productions of homonymous words. Non-brain-damaged speakers are being matched for age, sex, and regional dialect to each apraxic subject. Correct productions of each of the words utilized in the apraxic speaker's sample are being elicited from the normal speakers for purposes of comparison. Acoustic analyses will be specific to selected sounds and the Computerized Speech Lab is being utilized for the measurements.
PROGRESS--Ten apraxic/aphasic subjects have been entered into treatment to date. An additional two subjects are currently in the baseline phase of the investigation.
PRELIMINARY RESULTS--Acquisition effects of treatment have been positive for all subjects, with the exception of one subject who presented with a combination of apraxia of speech and severe phonemic paraphasia. Generalization to nontraining stimulus conditions has been limited for the majority of subjects, however, treatment instituted in those conditions has resulted in increased correct sound productions.
Acoustic analyses of incorrect and correct sound productions have been completed for five subjects. Results indicate that sound errors produced by these subjects appear to be more like distortions than sound substitutions. Analyses comparing pre- and post-treatment speech samples have revealed positive spectral and temporal changes in sound productions.
[238] IMPROVING RESONANCE AND ARTICULATION THROUGH VIDEONASOPHARYNGOSCOPIC FEEDBACK
Ava-Lee Kotler, MS; Cathy McCann, MClSc; Lisa Roske, MA;
Mary Anne Witzel, PhD
Bloorview MacMillan Centre, Toronto, ON Canada M4G
1R8
Sponsor: Dental Department, Bloorview MacMillan Centre, Toronto, ON Canada M4G 1R8
PURPOSE--The purpose of this study is to examine the amount of change in speech that results from the use biofeedback therapy using nasendoscopy. Reevaluation after several months will occur to see if changes in speech remain.
METHODOLOGY--Participants were outpatients registered with the Cleft Lip and Palate Facial Program at Bloorview MacMillan Centre. Up to six adolescents and adults scheduled to undergo biofeedback therapy using nasopharyngoscopy were asked to participate. Each participant was seen for six sessions. The first and last session were approximately 2 hrs in length. At the start of the first session each subject underwent the following protocol: hearing screening, completion of a questionnaire to rate his/her speech and understanding of the speech problem, resonance, articulation, and nasometry (i.e., nasalance) assessments, and orientation to the use of nasopharyngoscopic biofeedback. Immediately following insertion of the nasendoscope and just prior to its removal in all sessions, participants were asked to repeat sounds, words and sentences (i.e., probes) without viewing the monitor. These speech samples constituted the baseline, training probe, and post-treatment probes. During the biofeedback portion of the session, the participants viewed the monitor and attempted to respond to the examiner's directions to change the movement of the velopharynx. Biofeedback sessions focused on specific goals based on each person's speech pattern and potential for change. The biofeedback portion of the session lasted up to 30 min. If the subject demonstrated sufficient improvement toward a goal, as determined by clinical judgment, he or she was provided with a home program to complete on a daily basis before the next session. At the end of the last session, each participant provided feedback regarding the biofeedback sessions and received recommendations for future treatment. Each is seen for a follow-up session within 6 mo of the last session. During the follow-up, the protocol completed in the sixth session will be repeated.
PROGRESS--Four participants between the ages of 16 and 55, with diagnoses of cleft lip and palate, took part in the study; three completed it and the fourth decided not to continue after the second session. Data collection has been completed recently; analysis is in progress.
[239] DEVELOPMENT OF A DATABASE OF CANE TECHNIQUES
Bruce B. Blasch, PhD; William R. De l'Aune, PhD
VA Rehabilitation Research and Development Center, VA
Medical Center, Decatur, GA 30033; email: bearcon@aol.com;
delaune.william_r@atlanta.va.gov
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C813-2RA)
PURPOSE--The goal of the 3-yr study is to construct a database of cane techniques used by blind individuals to establish norms and to evaluate cane techniques over time. This information will be applied to problems of evaluation, development, and design of mobility techniques, accessibility standards, and Electronic Travel Aids (ETAs).
METHODOLOGY--A mobility client profile has been developed in conjunction with the orientation and mobility staffs of five of the VA Blind Rehabilitation Centers (BRCs). Data in the profile is obtained from the mobility instructor, the client, and from visits to the home of the client. Information about travel patterns and use or disuse of cane techniques is recorded before, during, and after training at the BRCs and through follow-up with the client after discharge. Included in this profile is information contained in the RoboCane;tm software package.
RESULTS--The profile was successfully developed in the first year of the project. However, due to clinical staff cutbacks at the BRCs, gathering of information on the full mobility profile has proved to be very problematic. In order to facilitate data gathering, the investigators have expanded the scope of the project to include data gathering and analysis of national Blind Rehabilitation Service information on all rehabilitation programs, not simply mobility. By doing this, we have broadened our scope to include mobility information in the context of the full rehabilitation experience. We have also expanded our sample size to include data from clients seen at all of the 10 BRCs. Data is being gathered on the client's physical status, travel environment, and history of vision rehabilitation services in the Blind Rehabilitation Service Data Base. Information on functional performance of common tasks is being recorded in terms of frequency, need, interest, independence, and satisfaction through the use of the Blind Rehabilitation Service Functional Outcome Survey (on a pre-rehabilitation, post-rehabilitation, and 6-month follow-up basis). Information on satisfaction with programmatic aspects of Blind Rehabilitation is also being gathered. Data on over 700 blinded veterans has been gathered.
FUTURE PLANS/IMPLICATIONS--The data gathered in this study can be used to generate demographic norms for visually impaired individuals in different environments. This data set will be invaluable as a university learning tool for mobility students, practicing mobility specialists, clients, and their families. Perhaps most importantly, these objective measures provide documentation for increased accountability, which results in improved quality assurance, increased capacity for training and monitoring of professional staff, and diminished threat of liability.
[240] A STUDY OF ILLUMINATION SOURCES FOR LOW VISION INDIVIDUALS
Gale R. Watson, MD
Rehabilitation Research and Development Center, VA
Medical Center, Decatur, GA 30033; email:
GW1@delphi.com
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C815-2RA)
PURPOSE--The objectives of this 2-yr project were to determine whether specific recommendations for appropriate illumination sources and levels of illumination could be derived for individuals with low vision who read. We studied illumination sources in order to provide professionals with an objective decision-making rationale for lighting recommendations, based on type of visual impairment, type of lighting, and amount of light. We sought to answer four questions: 1) Is there a difference in performance associated with different illumination sources? 2) Are differences in performance associated with different illumination sources also associated with specific visual pathologies? 3) Is there a difference in optimum and preferred illumination? 4) Are differences in optimum and preferred illumination associated with specific visual pathologies?
METHODOLOGY--Seventy-eight subjects with low vision were recruited from in the following categories: 19 with macular loss, 23 with restricted fields, 15 with cataract or other media opacity, and 21 with general amblyopia with no field loss. Each subject who agreed to participate was tested without low vision devices for acuities, field of view, and contrast sensitivity.
The participants were then evaluated by reading a shortened version of the Pepper Visual Skills for Reading Test with a 5× spectacle magnifier under each of the following lighting sources:
After reading the Pepper Test under each lighting condition, participants completed a visual fatigue dairy to indicate a variety of physiological reactions to the type of lighting, and to indicate their subjective preference for each lighting device.
FINAL RESULTS--The data were analyzed to ascertain whether individuals with some pathologies require certain types of lighting for best performance, and to determine whether any relationship exists between specific pathologies and illumination preference. A traditional repeated measures design using various types of illumination was used. There was no relationship between accuracy or rate of reading and the type of illumination used for these subjects. There was no relationship between performance under different illumination conditions and pathology groupings. Variables of age, acuity, field, and contrast sensitivity function had no relationship with pathology group, reading scores, or type of illumination. While there were differences between the illumination type preferred by individual subjects, there was no link between pathology or clinical data.
IMPLICATIONS--We conclude from these results that for a short-term reading task, such as reading bills or mail, readers with low vision must have access to a wide variety of lighting devices in order to find a device that gives best performance, but that no rule base can be ascertained to help professionals to make specific recommendations. Further research is required to discover whether this is true for reading tasks of long duration, such as reading the newspaper.
[241] MEASURING LOW VISION READING ASSESSMENTS USING A SCANNING LASER OPHTHALMOSCOPE
Gale R. Watson, MD; Ronald Schuchard, PhD
Rehabilitation Research and Development Center, VA
Medical Center, Decatur, GA 30033; University of Missouri,
Kansas City School of Medicine, Department of Ophthalmology,
Kansas City, MO 64108; email: GW1@delphi.com;
RSCHUCHARD@vax1.umkc.edu
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C849-2RA)
PURPOSE--We seek to evaluate the efficiency and efficacy of available low vision reading rehabilitation assessment tools using the scanning laser ophthalmoscope (SLO) with the following questions: 1) Do rate, accuracy and error scores on a visual skills for reading test relate to preferred retinal locus (PRL) ability and characteristics as measured by the SLO? 2) Do reading training techniques efficiently and effectively assist readers with macular loss in improving their visual skills for reading? 3) Can the effectiveness of reading training be measured by the improvement in visual skills such as PRL ability/characteristics and/or improvements in reading assessment scores? 4) Are improvements in reading performance related to improvements in different PRL abilities/characteristics or improvements in reading assessment scores which might allow the prediction of the type of reading training that is most appropriate for individuals with low vision?
METHODOLOGY--Software for the SLO has been developed for low vision reading rehabilitation and assessment, so that the Pepper VSRT, the Morgan LVRCA, and the MNRead acuity charts can be presented. This capability allows the investigators to see the visual stimuli (letters and words) on the retina that the patients see when viewing into the instrument and thus determine the interaction between the macular scotoma and PRL. Eighty subjects who have macular degeneration and are interested in reading with low vision devices are being recruited from the Eye Clinic of the Atlanta VA Medical Center. Before rehabilitation intervention, subjects are being assessed with standard clinical testing instruments (e.g., acuity, contrast sensitivity, glare, etc.) and specialized clinical testing, (e.g., SLO macular perimetry, binocular retinal correspondence, and preferred retinal locus testing, including fixation stability, pursuit ability, saccade ability, and word retinal location). Reading performance will be assessed by the Pepper VSRT, the Morgan LVRCA, and the MNRead Acuity charts. These three reading tests will be performed both in their standard method of presentation and in the SLO. Reading rehabilitation is being provided at the Atlanta VA Medical Center using normal accepted training strategies that assist the subjects in maximizing their visual skills for reading. After the reading rehabilitation is complete, the standard clinical testing, specialized clinical testing, and reading performance assessment is being repeated.
PROGRESS--Programming for the input of the reading tests on the SLO has been completed. The MNRead test, the Morgan Low Vision Reading Comprehension Test, and the Pepper Visual Skills for Reading Tests are being administered via SLO. Subject testing has begun, and 15 subjects have completed the sequence.
FUTURE PLANS/IMPLICATIONS--Following the methods described above will provide this research project with a database of reading performance information as it relates to visual function characteristics of patients. We will be able to determine whether any of the visual function characteristics have an influence on reading performance, training strategies, or outcomes. For example, the error patterns within the Pepper test can be related to macular scotoma and PRL characteristics. This database of reading performance information will also allow the investigators to propose detailed clinical procedures for the optimal training strategies and outcome assessment tools for each individual low vision patient's reading capabilities. The final results of this project will lead to a better understanding of the reading skills and abilities of individuals with macular loss.
[242] DESIGN AND EVALUATION OF LIQUID CRYSTAL (LC) DARK-ADAPTING EYEGLASSES FOR PERSONS WITH LOW VISION
David A. Ross, MSEE, MEd; Gary L. Mancil, OD
Atlanta VA Medical Center, Rehabilitation R&D, Decatur,
Georgia 30033; Salisbury VA Medical Center, Surgical
Service, Salisbury, NC 28144; email:
DavidRoss1@mindspring.com;
MANCIL.GARY_L@FORUM.VA.GOV
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C776-RA)
PURPOSE--The purpose of this three-year project was to develop and evaluate liquid crystal (LC) light/dark-adapting eyewear for individuals with low vision. Many such persons function best under restricted lighting conditions. The purpose of this project was to develop LC sunglasses that very quickly and precisely control the amount of illumination reaching the users eyes and to test the usefulness and practicality of LC sunglasses in actual use by people with low vision.
METHODOLOGY--Initial prototypes were constructed based on an evaluation of LC materials for optical clarity and dynamic light/dark range. Initial prototypes were then tested by a small, diverse, population of 22 people with low vision. Results of these initial tests were employed to re-design the LC sunglasses to make them better match the needs of that population. New prototypes were then constructed for subject testing.
More rigorous testing began in September 1996 of 107 subjects: 23 with central vision loss from ARMD, 32 with cloudy ocular media, 14 with pseudoaphakia, 8 with retinitis pigmentosa, and 30 controls with nonimpaired vision. Measures of acuity, contrast sensitivity, and mobility performance were recorded under varied lighting and glare conditions for all subjects while wearing either no sunwear, their personal choice of the best available sunwear, or the LC prototype. Data included quantified measures of performance, Likert scale subject ratings, and freeform subject comments. All quantitative results (including Likert scale subject responses) were referenced to a "no sunwear" baseline of performance (or response). Verbal comments were grouped by category and counted. Paired t-tests at the 95 percent confidence level were employed to reveal significant performance differences between the prototype and the "best" alternative. Multivariate analyses and least squares means graphs were used to indicate significant differences among the subpopulations. Finally, regression analyses were performed for mobility as a function of acuity and contrast sensitivity. Subject comments formed the basis for specific case studies which complemented the objective findings.
PROGRESS--This project was successfully completed March 1997.
RESULTS--The final prototype employed a flip-up polarizer which provided the LC sunglasses with two light-dark ranges: one range for indoors (68 to 35 percent), and one for outdoors (23 to 2 percent). In general, when subjects wore the LC prototype, their performance on acuity tests, contrast sensitivity tests, and in mobility tests was significantly better than when they wore their choice of the best of alternate sunwear. Of the four population groups with visual disabilities, people with ARMD showed the most improvement in acuity and contrast sensitivity. People with pseudoaphakia showed the most improvement (54 percent) in mobility task performance, while people with ARMD were second with 34 percent improvement. Results also indicated that further improvement could be achieved in all populations by making the glasses become completely clear in darker environments, and by customizing the darkening response to meet the particular needs of the individual.
FUTURE PLANS--Based on the above results, a Small Business Innovative Research grant has been submitted by a company wishing to further develop fast-darkening sunglasses for people with ARMD.
[243] EVALUATION OF CENTRAL AND PERIPHERAL VISION ENHANCEMENT DEVICES FOR DRIVING
Janet P. Szlyk, PhD; Timothy McMahon, OD; William
Seiple, PhD; Joan Stelmack, OD
Research and Development, VA Medical Center (West Side),
Chicago, IL 60612; Department of Ophthalmology and Visual
Sciences, University of Illinois at Chicago Chicago, IL
60612; Department of Ophthalmology, New York University
Medical Center, New York, NY 10016; Blind Rehabilitation
Service, Hines VA Medical Center, Hines, IL 60141; email:
janeszly@uic.edu
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C754-2RA)
PURPOSE--In the current phase of the project, we tested the hypothesis that an amorphic lens system could be used effectively by persons with peripheral visual field loss. They would spend the majority of time viewing through a carrier lens, and the amorphic lens would be used for transiently spotting and localizing peripheral visual field information. We also tested whether the clients would benefit from a 12-week training curriculum in the use of the amorphic system for navigation, mobility, and automobile driving.
METHODOLOGY--We recruited 15 persons with peripheral visual field loss due to RP (14), choroideremia (1), or Usher's Syndrome Type II (1), ranging in age from 27 to 67 yrs (mean 45.2 yrs ±13.4). The median visual acuity for this group was 0.12 LogMar (Snellen equivalent approximately 20/25) as measured with the ETDRS charts and protocol. Amorphic lenses are available in minifying powers ranging from 1.2 to 2.0 in increments of 0.2. Lenses were prescribed based on the highest power that could be worn in a walking task without unreasonable side effects. The amorphic lenses were mounted inferiorly on both the left and right carrier lenses.
The Orientation and Mobility (O&M) training was accomplished in 4 weekly sessions, with each week focusing on specific areas of visual function. These areas included locating objects, tracking stimuli, scanning skills, and enhancing visual memory. Following the O&M training, clients began a driving training curriculum consisting of 8 weekly sessions within the grounds of the Hines VA Medical Center. Once again training focused on specific skills related to the use of the amorphic lens system for driving.
PROGRESS--Subjects were divided into two groups equivalent in age, visual acuity, mean horizontal field extent, and mean contrast sensitivity. The study utilized a cross-over design in which Group A received the training during the first 3 mo of the 6-mo study, and Group B received the training during the second 3 mo. All were administered clinical vision, psychophysical and laboratory, O&M, and driving assessment tests without the amorphic lenses on the first assessment day as a baseline measure (Test Day 1). Group A was then given their lenses and trained on the laboratory and driving curriculum. Group B did not receive the lenses nor the training during this period. At 3 mo, all subjects were again tested with the assessment battery (Test Day 2): Group A with the amorphic lenses, Group B without. During the next 3-mo, Group A kept the lenses, but received no further training; Group B received the lenses and were trained on the laboratory and driving curriculum. At 6 mo, all were tested with the assessment battery with the amorphic lenses (Test Day 3).
For the purpose of subsequent analyses, the 203 individual tasks within the assessment tests were coded according to the primary visual skill involved in the task. These visual skills included: recognition (43), peripheral detection (46), scanning (61), tracking (19), visual memory (19), and mobility (21).
RESULTS--Overall for both groups combined, the percentage of tests improved ranged from 46.4 percent in the mobility category to 27.0 percent in the scanning category, with an overall improvement of 37.3 percent. Those subjects with initially smaller visual field extents showed a greater percentage of peripheral detection tests showing improvement following training with the lenses (r(14)=-0.54, p<0.05). In addition, those with initially smaller visual field extent showed a greater percentage of scanning tests showing improvement following training with the lenses (r(14)=-0.62, p< 0.02).
We found improvement in visual functioning within all the broad skills categories with training in the use of a bioptic amorphic lens system. There was greater improvement for those with smaller visual field extents in peripheral field-related tasks.
FUTURE PLANS--We are presently conducting Phase 2 of this project, in which we are investigating the effectiveness of bioptic telescopic lenses for driving and other functional tasks in persons with central vision loss.
[244] MICROPHOTODIODE TILES AS PROSTHESES FOR THE RESTORATION OF VISUAL FUNCTION
Neal S. Peachey, PhD; Alan Y. Chow, MD; Machelle T.
Pardue, PhD; Jay I. Perlman, PhD, MD; Evan B. Stubbs Jr.,
PhD
Hines VA Medical Center, Hines, IL 60141; Departments of
Neurology, Ophthalmology, and Molecular and Cellular
Biochemistry, Loyola University Medical Center, Maywood, IL
60153; Optobionics Corporation, Wheaton, IL 60187
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C1569-RA)
PURPOSE--In many blinding conditions, the photoreceptor cells are primarily affected while other layers of the neural retina are spared. In these cases, restoration of photoreceptor function could lead to recovery of lost vision. The overall purpose of this project is to determine whether this can be accomplished using semiconductor-based photodiodes placed in the subretinal space. In the report period, we have evaluated whether tunicamycin treatment of the cat eye provides a suitable model of photoreceptor degeneration and placed implants into the subretinal space of normal untreated cats.
METHODOLOGY--To evaluate its effectiveness, 1 mg of tunicamycin was dissolved in 10 ml DMSO and injected into the vitreous chamber of one eye of three adult cats; the fellow eye received vehicle alone. Retinal function was evaluated by electroretinography in sedated cats (11 mg/kg ketamine; 2 mg/kg xylazine). Retinal architecture was evaluated by light microscopy and immunocytochemistry using a polyclonal antibody against the Na,K-ATPase catalytic subunit.
Photodiodes ;sl1.5 mm in diameter and 50 µm thick, that respond electrically to light from 500 to 1100 nm were implanted in adult cat eyes using sterile surgical techniques under halothane (0.8 percent) anesthesia. An incision made in the temporal sclera provided access to the vitreous chamber and retina. A retinotomy was made and a small amount of saline was injected to create a retinal bleb. A partial vitrectomy created a channel from the scleral incision to the retinotomy site that was filled with Healon. The implant was positioned near the retinotomy opening with a plastic carrier and then moved into the subretinal space. After the scleral incision was closed the cat was awakened and received postoperative antibiotic treatment. The appearance of the retina was evaluated by indirect ophthalmoscopy. In addition, electrical responses were recorded from sedated cats to infrared (IR) stimuli, which isolate implant-mediated responses from those of the native visual system.
PROGRESS--Tunicamycin induced a panretinal degeneration that affected all cellular layers. Successful implantations, defined by the maintenance of a stable subretinal implant position and the retina remaining attached over the implant site, have been made in four cats. Electrophysiological recordings have been made using IR stimuli to isolate implant-mediated activity. These indicate that the implant functions in the subretinal space.
RESULTS--The electroretinogram of tunicamycin-treated eyes was reduced to ;sl15 percent of that of the normal eye. Histological analysis indicated that all retinal layers were affected. Tunicamycin treatment induced marked alterations in the differential distribution of the Na,K-ATPase within the retina. The location of the implant has remained stable in all four animals. Animals have been evaluated electrophysiologically at monthly intervals using IR stimulation. These recordings establish that the implant functions electrically within the subretinal space. Over time, the implant response increases in amplitude.
FUTURE PLANS--We plan to follow these, and additional cats with subretinal implants, for extended periods of time. This will allow us to examine the long-term functionality of the implant and the stability of the electrical responses that have been seen. In addition, cortical recordings are being made to determine whether implant activity is sufficient to stimulate the visual pathway. Biocompatibility will be assessed histologically at designated time points. In addition, smaller scale implants are being fabricated that can be more easily introduced into the subretinal space. Finally, we are working to develop an animal model of photoreceptor degeneration that can be used to evaluate the possibility that the implant will restore visual function to a retina that suffers from a retinitis pigmentosa-like disorder.
[245] LOW VISION ENHANCEMENT SYSTEM (LVES)
Rex A. Ballinger, OD; Peter A. Lalle, OD; Joseph H.
Maino, OD; Joan Stelmack, OD; Kristen Tallman, OD; Richard
Wacker, OD; Brendal Waiss, OD
VA Medical Center, Baltimore, MD 21201; VA Medical
Center, Kansas City, MO 64128; VA Medical Center, Hines, IL
60141; VA Medical Center, West Haven, CT 06516; VA Medical
Center, Palo Alto, CA 94304; VA Medical Center, Northport,
NY 11768
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C638-2DA)
No report was received for this issue.
[246] DEVELOPMENT OF THE SCANNING LASER OPTHALMOSCOPE FOR LOW VISION REHABILITATION: PHASE 2
Joseph Maino, OD; Ronald Schuchard, PhD; George
Timberlake, PhD; Donald Fletcher, MD; Wen-Te Lin, MS; Rolf
Nygaard, PhD; Jamie Young, OTD; Kacie Thompson, BSRT
(R)
Kansas City VA Medical Center, Kansas City MO 64128;
University of Missouri-Kansas City, Kansas City MO 64108;
Kansas University Medical Center, Kansas City KS 66160;
email: rschuchard@cctr.umkc.edu
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C838-2RA)
PURPOSE--The vast majority of people with impaired vision retain some functional vision with which to perform everyday tasks and are characterized as persons with low vision. Currently there are no clinically practical means for accurately and precisely measuring their scotomas and preferred retinal loci for visual tasks. In addition, there is neither a reliable or efficient method for training eccentric viewing at optimal retinal areas nor for evaluating the effectiveness of the current training which require many man-hours to accomplish. Therefore, although low vision rehabilitation effectively incorporates compensation for impaired acuity (e.g., training and devices like magnifiers, CCTVs, and LVES), low vision rehabilitation specialists have no means for effectively compensating for impaired visual function due to macular scotomas, a condition affecting a significant proportion of the low-vision population. The project objective is to develop the scanning laser ophthalmoscope (SLO) as an effective and efficient low vision rehabilitation system.
METHODOLOGY--To accomplish this objective, evaluation/treatment procedures on the SLO have been developed with a Windows NT computer graphics/imaging system using the Targa 2000 Pro graphics/imaging board (TrueVision Inc), called the Scanning Laser Ophthalmoscope Low Vision Rehabilitation System (SLO LVRS). The specific clinical testing modules developed are: 1) software to measure precisely and accurately scotoma and preferred retinal locus (PRL) locations and PRL abilities, 2) algorithms to perform automated retinal image registration, 3) software for teaching and evaluating eccentric viewing training, and 4) software for low vision patient management. In addition to the software and hardware development, investigation into the intellectual problems has begun. For example, the parameters for computer automated image registration have been explored so that scotoma measurements and PRL abilities can be performed quickly and efficiently.
PRELIMINARY RESULTS--Beta testing of the modules is being done at the VICTORS program at the Kansas City VA Medical Center, the Visual Independence Program of the Eye Foundation of Kansas City, the Low Vision Service of the Retinal Consultants of Southwest Florida, and the Rehabilitation Research and Development Center at the Atlanta VA Medical Center. Extensive work into the laser power and spatial field characteristics of the SLO has been done both for short-term (daily) and long-term (monthly) reliability. The stability of the laser power as well as the homogeneity of the SLO display field requires monthly calibration protocols to assure the proper quality control in the clinical testing. However, the magnification changes in the SLO image due to emmetropia for most patients does not require special optical correction. Reliability (test-retest and inter-tester) of the methods for macular perimetry and PRL ability testing was evaluated and new methods have been developed and incorporated into SLO LVRS to increase the reliability. The characteristics of the PRL movement during fixation alone and while performing the fixation task during perimetry have been determined to indicate the range of retinal movements (direction and size) that must be monitored by the computer-automated registration. A Hough Transform image registration algorithm is being developed for computer automated registration of SLO images.
FUTURE PLANS--Validity evaluations of the methods for macular perimetry and PRL ability testing will be performed. Reliability and efficacy of eccentric viewing training with SLO LVRS will be evaluated at the beta test sites. The SLO LVRS will be installed at additional VA Medical Centers as funding from these individual centers allows.
[247] FACTORS LEADING TO DISUSE OF LOW VISION DEVICES BY VISUALLY IMPAIRED ELDERLY
Gary L. Mancil, OD, FAAO; Gale Watson, MEd; William de
l'Aune, PhD; Rickilyn M. Mancil, MA, COMS; Jim Boyette, MS;
Melissa Mitchell, BS
Vision Rehabilitation Research Laboratory, Salisbury VA
Medical Center, Salisbury, NC 28146; Atlanta Rehabilitation
Research and Development Center; Atlanta VA Medical Center;
Decatur, GA 30033; email: mancil.gary@forum.va.gov
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #C814-2RA)
PURPOSE--In this 3-yr study, the project team is evaluating long-term usage patterns of low vision devices by older veterans to identify causes of disuse of previously successful devices. In the past 2 yrs, we have established a representative sample of older adults who have low vision; provided comprehensive low vision care for each subject in order to prescribe the most appropriate low vision device to address that person's specific goals; collected base-line data on selected ocular, physical, and psycho-social characteristics of each subject (pretest); and implemented a monitoring system to document usage patterns over time. Currently, we are repeating low vision clinical and the base-line data set at any time a device is deemed no longer of use by a subject (post-test); and establishing correlations to identify factors which lead to disuse of the prescribed low vision devices. Late in the project, a panel of experts will be convened to evaluate the research results and make recommendations pertinent to the activities of manufacturers, clinicians, and funding agencies.
METHODOLOGY--Over 125 subjects, aged 65-95, with low vision enrolled in this project. Entry level data (baseline) was collected in four ways: a thorough patient interview, including the Adaptation to Vision Loss Scale, the Mini-Mental State Exam, the Health Status Questionnaire, the Geriatric Depression Scale, and the Functional Assessment Inventory); an eye health evaluation with photodocumentation (to determine the cause of low vision); a standardized low vision device evaluation (to determine personal goals and visual abilities, and evaluate devices to fulfill those goals); and a "criterion referenced" low vision device-training protocol. Subjects were then prescribed the devices found successful for their stated goals. Finally, subjects entered the monitoring portion of the study where they were mailed a large-print post card with a visual analog scale monthly for the duration of the project. Subjects indicated their level of satisfaction for each device. If their level varied from the initial post-training baseline by a significant amount, they were asked to return to the clinic for post-test assessment ("unsuccessful users"). Twenty five successful users were randomly chosen to undergo post-test assessment that would confirm no problems existed. Of those 25, 7 were also randomly selected to undergo a home visit where the low vision training specialist collected clinical data (by repeating many of the clinical tests in the home setting) and functional data (asking the subject to perform the tasks they commonly complete with the devices in their own way). In this way, the accuracy of the monitoring system was evaluated.
PROGRESS--A total of 131 subjects completed the project protocols including the interview, eye health evaluation, low vision device evaluation, extensive low vision device training, and entering the follow-up program. Of these, 13 have discontinued for a variety of reasons: 3 are deceased; 10 are too ill, have moved, or are not willing to continue. One hundred eighteen people are currently receiving monitoring cards, with an average of five devices per subject, (i.e., approximately 600 devices are being followed). Data are currently being input and coded for in-depth analysis.
FUTURE PLANS--Subjects will be monitored at least through 1997 and analysis will be completed thereafter. A panel of experts will then be convened to evaluate project findings and make recommendations regarding device design/modification, implications of service delivery models, and applications in clinical practice. Final data analysis and final reporting will then be completed.
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