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At least 253 records · Page 14Linked to original sources
PubMed1992

Quantitative evaluation of flicker ERG waveforms in low vision patients.

Flicker electroretinograms (FERGs) of 30Hz were recorded for 46 eyes (23 cases) of low vision, including 38 eyes with retinal diseases and 8 eyes with optic neuropathy, and for 39 normal eyes (33 cases). The recorded wave forms were analysed by two methods: (1) to measure the peak to peak amplitude and pseudophase directly, and (2) to measure the amplitude and phase of fundamental response component (30Hz) by discrete Fourier transform (DFT). The abnormality ratios between these two methods were compared in low vision patients. All the eyes with optic neuropathy showed normal flicker ERG, the abnormality ratios of directly measured amplitude and the amplitude by DFT were 60.9% in 28 eyes and 71.7% in 33 eyes with retinal diseases respectively, the difference being no statistically significant (P > 0.05), while the abnormality ratios of directly measured pseudo-phase and the phase by DFT were 60.9% in 28 eyes and 82.6% in 38 eyes with retinal diseases respectively, the difference being statistically significant (P < 0.05). These results suggest that FERGs are an objective way to test the retinal function, and DFT for flicker ERGs are more useful in quantitative evaluation of the retinal function.

Adolescent↗
PubMed1983

Recent advances in clinical low-vision care.

In the past decade there has been a growth in the awareness of the impact that low vision has on the individual and on society in general. The clinical eye-care professions have become more conscious of their responsibility to assist partially sighted patients and low-vision care is becoming a specialty area within optometry and ophthalmology. This paper reviews recent advances in the optical devices and prescribing procedures that have contributed to improving the care that is available to assist low-vision patients with distance-vision tasks, near-vision tasks and visual-field problems.

Distance Perception↗
PubMed1985

Computer low vision aids.

Computers are invading all facets of optometric practice including low vision care. This brief paper will discuss indications for prescribing computer low vision aids, hardware and software currently available, and provide several short case reports to illustrate how the visually impaired individual can utilize this new technology.

Adult↗
PubMed2005

[Low-vision rehabilitation of age-related macular degeneration patients with retrofoveal choroidal new-vessels treated with photodynamic therapy with verteporfin].

PURPOSE: To demonstrate the rehabilitation benefit and immediate optical magnification and electronic equipment advantage in an age-related macular degeneration population with retrofoveal choroidal new-vessels treated by photodynamic therapy using Visudyne. PATIENTS AND METHODS: Sixty seven consecutive patients with retrofoveal choroidal new-vessels treated by Photodynamic Therapy using Visudyne were referred to an orthoptist for low-vision rehabilitation. The criteria investigated for this study were: long distance visual acuity, reading ability, contrast sensitivity, (before treatment and during post-treatment examinations), and fixation localization and optical equipment model. RESULTS: This study showed and studied visual acuity variations, mostly for patients with good visual acuity at inclusion. Contrast sensitivity stayed more or less the same. Retinal fixation was foveolar most of the time (68.7%). Optical or electronic devices for low-vision patients are numerous and video systems were the most currently used among our population. 62.7% des patients had low-vision rehabilitation with optic aids. DISCUSSION AND CONCLUSION: This study threw light on patient optic aids which must be prescribed according to his needs and difficulties, without delay. This equipment will then be readapted at each stage of the patient evolution. PDT treatment gives an important role to low-vision rehabilitation associated with optic magnification aids.

Aged↗
PubMed1985

An itinerant model for delivery of clinical low vision services in a rural community.

In 1976, a premise was developed that resulted in the inception of a mobile low vision service in the State of New Hampshire. Today, the New Hampshire Association for the Blind continues to provide low vision service throughout the state using a mobile clinical van and a training staff who provide training in aid use within the home. The model has proved effective in dealing with the special needs of the low vision population in a rural area.

Community Health Services↗
PubMed1996

Blindness and low vision in southeast Turkey.

In preparation for the planning of a regional prevention of blindness programme, a population-based survey of blindness and eye disease was conducted in two provinces (Diyarbakir and Mardin) of southeast Turkey. A stratified cluster random sampling procedure was used to select 8,571 persons. The main objectives of the survey were to assess the population need for basic ophthalmic services, both in rural and in rapidly growing urban communities, and to secure baseline data for subsequent evaluation of the programme. The prevalence of visual impairment (best binocular vision poorer than 6/ 18) was estimated at 1.9% with 95% confidence limits of 1.6% and 2.1%, amounting to 29,400 +/- 4500 visually imparied persons in the regional population of 1.6 million. The prevalence of blindness (best vision poorer than 3/60) was 0.4%, and an estimated 1.5% had low vision (best vision poorer than 6/18, but not blind). Compared to the blindness prevalence of 0.2% in the European Economic Community (EEC), the age-standardised prevalence of blindness in southeast Turkey was 8 times as high. The main causes of blindness in the sample were cataract (50%), corneal opacity (15%), glaucoma (12%), phthisis (6%) and optic atrophy (6%). Cataract and refractive errors were responsible for 52% and 26% of the low vision, respectively. Acute inflammatory trachoma was prevalent in a number of rural and urban communities, affecting an estimated 25,900 people in the region. The need for basic ophthalmic services was estimated for the two provinces. Some 26,600 were in need of cataract surgery, 4,400 needed eyelid surgery for trachoma-induced entropion, and 28,600 required spectacles to improve their visual acuity to 6/18 or better. More than half of the current burden of severe visual loss in the two provinces of southeast Turkey is potentially remediable through the provision of cataract surgery and of spectacles to correct aphakia. The survey findings suggest that as the age structure of the regional population approaches that of the EEC through the "ageing trend', a four-fold increase in the burden of blindness might be expected, unless improvements are made in curative and preventive ophthalmic services in parallel with the general development that improves survival.

Adolescent↗
PubMed2006

Contrast sensitivity and visual hallucinations in patients referred to a low vision rehabilitation clinic.

AIM: To examine the association of reported visual hallucinations and measured visual parameters in adult patients referred for low vision rehabilitation. METHODS: All patients (N = 225) referred to a low vision rehabilitation clinic for a calendar year were asked a standardised question about symptoms of formed visual hallucinations. Best corrected visual acuity and contrast sensitivity using the Pelli-Robson chart were measured. We conducted multiple logistic regression analysis of the association between visual hallucinations and visual parameters. RESULTS: Of the total cohort, 78 (35%) reported visual hallucinations. Visual acuity and contrast sensitivity were considered in four quartiles. In multiple logistic regression controlling for contrast sensitivity, age, gender, report of depression and independence, measured acuity in each of the poorer three categories (compared to the best) was not associated with reported hallucinations. Contrast sensitivity in the three poorer quartiles (compared to the best) was strongly associated with the report of hallucinations (OR 4.1, CI 1.1, 15.9; OR 10.5, CI 2.6, 42.1; OR 28.1, CI 5.6, 140.9) after controlling for acuity, age, sex, depression and independence. CONCLUSIONS: Lowest contrast sensitivity was the strongest predictor of reported hallucinations after adjusting for visual acuity.

Aged↗
PubMed2006

Low vision rehabilitation services: the Saskatchewan experience.

From a suitcase carrying various magnifiers in 1955, the Saskatchewan Low Vision Clinic has enlarged -- and the affiliated Canadian National Institute for the Blind (CNIB) has slimmed down through provincial amalgamation and budgetary cutbacks. Now, aids range from magnifiers to closed-circuit televisions, new technologies can be obtained on loan from the CNIB, and some financial assistance is available. Because Saskatchewan is still comparatively rural, with 60% of the population distributed throughout the province outside the two major urban areas, access to low vision services can be a problem. Increasing use of specialized counsellors, however, is helping deal with specific needs, and we hope to add psychologists, occupational therapists, and social workers as money is available.

Health Services Accessibility↗
PubMed1999

Development and sensitivity to visual impairment of the Low Vision Functional Status Evaluation (LVFSE).

BACKGROUND: Functional limitation because of visual impairment is one of the most important measures of low vision rehabilitation outcome because it represents the true impact of visual impairment upon the daily lives of individuals. The Low Vision Functional Status Evaluation (LVFSE) was designed to evaluate functional limitation because of visual impairment using both observed and self-reported performance on daily activities. METHODS: Performance on 27 daily activities was evaluated for 155 visually impaired subjects. Subjects also provided ratings of task difficulty. RESULTS: Correlations between observed performance and visual acuity, contrast sensitivity, and visual field loss severity were moderate, r = -0.60 to r = 0.34. Correlations between self-reported task performance difficulty and measures of visual clinical state were weaker, r = -0.44 to r = 0.21. CONCLUSIONS: The LVFSE shows promise as a sensitive measure of low vision-related functional status but more work is needed to refine the measure.

Activities of Daily Living↗
PubMed1995

Printed cards for measuring low-vision reading speed.

There is a growing consensus that clinical evaluation of the real-world consequences of eye disease requires new performance-based tests. This is because Snellen acuity and other common clinical tests are often poor predictors of everyday function. Ahn and Legge [(1995) Vision Research, 35, 1931-1938] validated a computerized test of reading speed by showing that it provides an accurate prediction of low-vision reading performance with magnifiers. Here, we describe development of a printed-card version of the test suitable for clinical use. This printed-card test retains key design features of the validated computerized test, including the same set of sentences and display format. Data from 23 low-vision subjects showed that a very simple testing procedure using printed cards and a stop watch could be used effectively to estimate reading speed. Reading speed based on a single card was quite accurate (SD equal to about 18% of the mean) and showed no practice effects from one card to the next. Reading speeds obtained with printed cards correlated highly (r = 0.887) with those from computerized testing. We conclude that a simple test, using printed cards, can be used to obtain useful estimates of low-vision reading speed.

Adult↗
PubMedDate not supplied

Loneliness in low-vision older women.

The purpose of this analysis was to identify predictors of loneliness in women 75 years of age and older with low vision. The sample of 56 women was derived from a larger study of low-vision adults. Women's loneliness, optimism, social support, living arrangement, vision, and perceived health were examined using the revised University of California, Los Angeles, Loneliness Scale, the Life Orientation Test, the Social Support Questionnaire, and a demographic questionnaire. Data were analyzed using descriptive statistics, Pearson correlations, multiple regressions, and t-tests. Optimism and social support satisfaction were found to predict degree of loneliness in the sample. Women who were less optimistic and less satisfied with their social support system experienced higher levels of loneliness. Duration of visual impairment was associated with duration of loneliness. The findings provide nurses with information for identifying low-vision older women who are at risk for loneliness.

Aged↗
PubMed1991

Preliminary examination of the reliability and relation to clinical state of a measure of low vision patient functional status.

An evaluation of the reliability and relation to clinical state of a measure of low vision patient functional status was conducted. The measure included discrete tasks aggregated into three different areas: identifying objects, reading, and daily/leisure activities. Data were obtained retrospectively from case records of 247 low vision patients and 144 complete cases were used for statistical analyses. Evidence of reliability was found with coefficient alpha scores for the three areas ranging from 0.90 to 0.96. Significant relations between functional status and clinical states (acuity, contrast sensitivity, and visual field) were found with R2 values ranging from 0.39 to 0.58, p less than 0.001.

Activities of Daily Living↗
PubMed1999

Elicited sequential presentation for low vision reading.

This paper reports on a variant of the rapid serial visual presentation (RSVP) technique for low vision reading called elicited sequential presentation (ESP). In both techniques, words are presented sequentially at a constant screen location, but with ESP, the reader elicits presentation of each new word by means of a button press, rather than (as with RSVP) being presented with it automatically at fixed intervals. An experiment comparing reading speeds using, ESP, RSVP and a conventional closed-circuit television (CCTV) reading aid showed that for 15 slow readers who were customary CCTV users with low vision, ESP is superior to RSVP and yields reading speeds averaging 47% faster than RSVP--about the same as CCTV reading speed. The log of the ratio of ESP to RSVP reading speeds was significantly negatively correlated with the log of RSVP reading speed, showing that slower readers benefit more than faster readers; regression predicted no benefit for readers who read with RSVP at 133 wpm or greater. Finally, word length and word presentation duration chosen by subjects reading with ESP were significantly correlated, suggesting that part of the benefit of ESP is due to reader's ability to allocate time based on word length and difficulty.

Audiovisual Aids↗
PubMed1985

Treatment of low vision in fundus flavimaculatus.

Twenty-eight patients with fundus flavimaculatus were evaluated retrospectively after they had undergone examination for and treatment of low vision. Despite poor distance acuity, 27 (96%) of the patients could read 1M (20/50 reduced Snellen) or smaller print with a spectacle lens, and all patients could read standard-sized print (1M text) with some optical aid. Because such uniform improvement is uncommon among patients with low vision, we recommend examination for and trial of low-vision aids for those patients with this disorder who are having visual difficulties.

Adolescent↗
PubMed1987

Assessment of the Catford drum in visual acuity testing and its use as a measurement of visual performance in low-vision patients.

Objective measurements of visual acuity were determined with the Catford drum in 82 eyes of patients in our Low-Vision Clinic who typically suffered from visual loss due to macular disease. The results were compared with subjective measurements of visual acuity by the Snellen chart. The findings indicated a significant overestimation of Snellen visual acuities by the Catford drum in 90.2% of eyes tested by a factor of 1.05 to 20.0, average 4.73. The correlation coefficient for the study was +0.40. This differs from the original results of Catford and Oliver in 1971. In addition, the Catford drum was used on follow-up visits in the same patients to assess 'visual performance'. The initial results showed an improvement in visual acuities when the Catford drum was used in 12 of 15 patients, while the Snellen acuities remained stable when retested after one month of basic instruction and use of standard low-vision aids. This improvement in 'Catford' acuity was by a factor of 0.3 to 10.0, average 4.08. This is thought to represent the patient's ability to learn the use of eccentric viewing or parafoveal retinal areas for vision. It confirms previous intuitive findings and helps to explain why low-vision patients seem to function at a higher level than expected from their Snellen visual acuities.

Follow-Up Studies↗
PubMed1991

Visual rehabilitation in low vision patients with age-related macular degeneration.

Using optical visual aids, visual rehabilitation was performed in 14 low vision patients (25 eyes) with age-related macular degeneration. With distance aids, visual acuity improvement appeared in 24 eyes (95%) out of the 25 eyes. Twelve eyes (48%) obtained a visual acuity equal to or better than 0.4. With near visual aids, near acuity of all eyes (100%) was improved. Thirteen eyes (52%) got the near vision equal to or better than 0.5. Ten patients could read No. 5 Chinese Reading Card. The reading success rate was 71.4%. The results suggest that application of visual aids is an effective method to improve the distant and near visual acuity of low vision patients with AMD.

Aged↗
PubMed2005

Visual disability variables. I: the importance and difficulty of activity goals for a sample of low-vision patients.

OBJECTIVE: To test the validity and reliability of latent trait measures estimated from ratings by low-vision patients of the importance and difficulty of selected activity goals. DESIGN: Validation of a telephone-administered functional assessment instrument using Rasch analysis of self-assessment ratings. SETTING: Telephone interviews of respondents in their homes. Participants Consecutive series of 600 outpatients with low vision. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Ratings of the importance and difficulty of achieving 41 activity goals. Person and item traits were measured with the Andrich rating scale model. Measurement validity and reliability were tested statistically by comparing response patterns and distributions with measurement model expectations. RESULTS: Patients could distinguish only 3 categories of importance and 4 categories of difficulty. The distributions of person and item measure fit statistics were consistent with 2 unidimensional constructs: value of independence estimated from importance ratings and visual ability estimated from difficulty ratings. However, 8 of 41 activity goals were poor estimators of value of independence and 7 of 41 activity goals were poor estimators of visual ability. Person measure distributions could be divided into 3 statistically distinct strata for estimates from both importance ratings and difficulty ratings. Item measure distributions could be divided into 21 strata for estimates from importance ratings and 7 strata for estimates from difficulty ratings. CONCLUSIONS: The 2 variables that define visual disability-value of independence and visual ability-are valid constructs that can be estimated accurately and reliably from patient ratings of the importance and difficulty of activity goals.

Activities of Daily Living↗