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At least 1,243 records · Page 69Linked to original sources
PubMed2004

Serious ophthalmic pathology compromising vision in HCV/HIV co-infected patients treated with peginterferon alpha-2b and ribavirin.

OBJECTIVE: To characterize the ocular changes associated with peginterferon alpha 2b (peg-IFN alpha-2b) and ribavirin therapy for chronic hepatitis C infection in HIV co-infected individuals. METHODS: A prospective, open-label trial treating HIV/hepatitis C (HCV) co-infected individuals with peg-IFN alpha-2b and ribavirin at the Warren Grant Magnusson Clinical Center, National Institutes of Health, Bethesda, Maryland, USA. Twenty-three patients with a high mean CD4+ T-cell count were treated with peg-IFN alpha-2b and ribavirin and followed for 40 to 88 weeks. Ophthalmologic evaluations including visual acuity, visual field testing, color vision examination and indirect ophthalmoscopy were performed at baseline and every 3 months. RESULTS: Eight of the 23 patients (35%) developed ophthalmologic pathology, including cotton wool spots, cataracts, and two patients developed decreased color vision. These two patients regained their color vision, one after cessation of anti-HCV therapy. CONCLUSIONS: Although retinal pathologies have been reported in patients treated with interferon-alpha, they have not been reported during peg-IFN alpha-2b therapy nor in HIV/HCV co-infected patients. The incidence of serious ocular pathology associated with anti-HCV therapy may be very high and is probably associated with peg-IFN alpha-2b. Increased monitoring of patients treated with peg-IFN alpha-2b for retinal and visual changes is warranted.

Adult↗
PubMed1992

Vision defects in albinism.

We have examined the possible presence of color vision anomalies in 9 individuals (17 eyes, 1 blind) with fundus findings suggesting ocular albinism using the Ishihara plates, the 28-hue Roth test, and the Davico anomaloscope. Results indicate that four of these individuals show no sign of the anomalies expected in an albino in either of the two eyes. Of the remaining cases, two are simple deuteranomals in both eyes, according to Pickford's classification criteria. The rest have protanomaly; however, in these the deviation toward red appears in both eyes in only one subject, whereas in the other two subjects it appears in only one eye, their binocular color vision being basically normal. Our study shows that a large proportion of these albinos have photophobia, pendular nystagmus, strabismus, noticeable refractive errors (astigmatism and high myopia), and poor visual acuity [usually less than 6/30 (20/100) with correction]. The measurement of contrast sensitivity function (CSF) indicates that the frequency of 12 cpd cannot be perceived, even in binocular vision.

Adolescent↗
PubMed1993

New procedures for evaluating vision functions of special populations.

Research over the last few decades has demonstrated the rapid development of vision function that occurs in infancy with near-adult levels reached before the age of 1 year. This period of rapid development coincides with the period of maximum sensitivity to insult. These facts emphasize the importance of effective screening techniques for visual disorders. Off-axis photorefraction is described as a new and effective screening technique for detection of refractive errors, media opacities, and strabismus. Separate from screening, a significant need exists for optometric vision evaluations in special populations. Normal infants, developmentally delayed or multi-handicapped children and adults, and cognitively impaired adults are examples of special populations who are difficult to examine with standard optometric techniques. New procedures for measuring visual acuity, contrast sensitivity, color vision, and stereopsis using behavioral or electrophysiological measures are described. Advantages and disadvantages of the different techniques are discussed.

Color Perception↗
PubMed1994

Comparison of functional mobility performance with clinical vision measures in simulated retinitis pigmentosa.

Simulations of retinitis pigmentosa (RP) under various conditions of retinal illuminance were designed and investigated in order that they might be used in the mobility training of clients with early RP. Goggles incorporating a 2.5 neutral density (ND) filter with a 0.5-mm diameter pinhole were found to be a potentially useful simulation device for this purpose. This investigation also compared mobility performance with clinical vision measures under photopic, mesopic, and scotopic conditions of retinal illuminance. Although none of the clinical vision measures we used was entirely predictive of mobility performance, some measures were better predictors than others. For a severe constriction of the visual field and decreasing retinal illuminance, both edge contrast sensitivity and visual acuity, measured outdoors, accounted for a greater proportion of the variance in mobility performance than did low contrast visual acuity measured under the same circumstances. The same clinical vision measures, taken indoors, were of no value in predicting outdoor mobility performance.

Adult↗
PubMed1995

Evaluation of vision services delivered by a mobile eye clinic in Costa Rica.

A number of private voluntary organizations provide mobile eye services to underserved populations in the developing world. This paper seeks to determine what segment of the population makes use of mobile vision clinics and whether the clinics are identifying significant eye conditions previously undetected by local eye care providers. The population studied were those attending the 1989 vision screening project conducted in rural Costa Rica by members of Volunteer Optometric Services to Humanity (VOSH). Sources of data include patient records of clinic attendees (N = 1530), patient interviews, and Costa Rican census data. Most of the clinic attendees were female (56.9%), over 35 years of age, and literate (71.1%). The three most commonly stated occupation categories were (1) housewife; (2) agriculture, forestry, or fishery worker; and (3) student. Over one-half reported having had a previous eye examination. Presbyopia and low hyperopia were the predominant refractive conditions encountered. Over one-third of patients presented with visual acuities 6/15 (20/50) or worse, and one-third of this group had never had an eye examination. Three-quarters of the patients required prescription lenses and over 20% had cataract. The dispensing of presbyopic corrections to first time patients is clearly the most valuable service provided by the clinics. Teaming up with mobile cataract camps may improve the access to surgical care for patients with cataract. It is important that mobile vision projects target future efforts toward those likely to be missed by conventional screenings.

Adolescent↗
PubMed1996

Vision defects in patients with peri-chiasmal lesions.

BACKGROUND: Patients with chiasmal lesions frequently suffer loss of vision, but some may be visually asymptomatic and have little, if any, visual field loss. This study addressed two questions about the nature of such loss: (1) which tests are best able to detect visual loss and (2) what is the relation between the size of a lesion and the degree and type of visual loss. METHODS: Visual acuity (VA), Goldmann perimetry, pattern evoked potentials, contrast sensitivity (CS), and color vision (CV) were assessed, in addition to a full ophthalmologic examination. Thirty-five patients were recruited from neurology, endocrinology, and ophthalmology departments; 31 had pituitary tumors and 4 had tumors of other origin (1 secondary) close to the chiasm. For analysis, patients were classified (1) according to whether they had visual symptoms on presentation and (2) according to lesion size. RESULTS: Seventeen patients had visual symptoms; all had visual field defects and all but one had two or more additional abnormal test results. Of the 18 visually asymptomatic patients, 12 had visual field defects and 14 had at least 2 abnormal test results; 7 had tumors with less than 5 mm of suprasellar extension, of whom 5 had field loss or at least 2 abnormal test results. CS was abnormal most often (85% of patients), followed by Goldmann perimetry (80%), visual evoked potentials (VEPs) (57%), CV (49%), and VA (26%). CONCLUSION: Our results support previous reports that asymptomatic patients and those with intrasellar tumors or only small amounts of suprasellar extension may have demonstrable visual dysfunction. Perimetry did not appear to be significantly worse than other more recently developed tests, which have often been regarded as being more sensitive, for detecting vision loss. However, VA and clinical observation of pupil reactions had poor sensitivity.

Adolescent↗
PubMed1997

An assessment of the efficacy of sports vision training programs.

BACKGROUND: The claim that sports vision training programs can enhance visual skills and the level of sporting performance was investigated. METHODS: Thirty young subjects were assigned equally to visual training, reading (placebo), and control groups. Visual and motor tests were administered before and after 4 weeks of training or control activity to determine whether any improvements in performance had occurred. RESULTS: Significant improvements on some aspects of vision were apparent for the visual training group, but their improvements in both vision and motor performance were no greater than for either of the other groups. DISCUSSION: There was no evidence for visual training improving either visual or motor performance beyond levels due simply to test familiarity. The benefits of the visual training exercises commonly used by optometrists to enhance sports performance are therefore open to question.

Accommodation, Ocular↗
PubMed1999

What is low vision? A re-evaluation of definitions.

PURPOSE: To re-evaluate definitions of low vision, visual impairment, and disability. METHODS: We review current definitions of legal blindness and low vision and how these definitions are variably based on disability or impairment. We argue for a definite distinction being made between criteria for visual impairment and visual disability, low vision being defined as the presence of a visual impairment that results in a disability. Visual impairment is defined according to population norms and a statistical cut-off is used. Visual disability is defined by consideration of the level of visual measures which result in measurable or reportable disability. We consider the evidence that contrast sensitivity should be a criterion for visual disability in addition to visual acuity and visual field. CONCLUSIONS: According to the current information, we define visual impairment as best monocular or binocular visual acuity <(worse than) 6/7.5, total horizontal visual field <146 degrees (Goldmann III-4e) or <109 degrees (III-3e), and contrast sensitivity <1.5 (PelliRobson); we define visual disability as best monocular or binocular visual acuity <6/12 or contrast sensitivity <1.05.

Blindness↗
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↗
PubMed2002

Vision and mobility performance of subjects with age-related macular degeneration.

PURPOSE: To investigate the effects of age-related macular degeneration (ARMD) on mobility performance and to identify the vision determinants of mobility in subjects with ARMD. METHODS: Walking speed and the number of obstacle contacts made on a 79-m indoor mobility course were measured in 21 subjects with ARMD and 11 age-matched subjects with normal vision. The mobility measures were transformed to percentage preferred walking speed and contacts score. The vision functions assessed included binocular visual acuity, contrast sensitivity, and visual field. RESULTS: In this study, subjects with ARMD did not walk significantly slower or make significantly more obstacle contacts on the mobility course than the normally sighted subjects of similar age. Between 29% and 35% of the variance in the ARMD mobility performance was accounted for by visual field and contrast sensitivity measures. The most significant predictor of mobility performance scored as percentage preferred walking speed was the size of a binocular central scotoma. CONCLUSION: As the size of a binocular central scotoma increases, mobility performance decreases.

Aged↗
PubMed2004

Reading speed benefits from increased vertical word spacing in normal peripheral vision.

PURPOSE: Crowding, the adverse spatial interaction due to proximity of adjacent targets, has been suggested as an explanation for slow reading in peripheral vision. The purposes of this study were to (1) demonstrate that crowding exists at the word level and (2) examine whether or not reading speed in central and peripheral vision can be enhanced with increased vertical word spacing. METHODS: Five normal observers read aloud sequences of six unrelated four-letter words presented on a computer monitor, one word at a time, using rapid serial visual presentation (RSVP). Reading speeds were calculated based on the RSVP exposure durations yielding 80% correct. Testing was conducted at the fovea and at 5 degrees and 10 degrees in the inferior visual field. Critical print size (CPS) for each observer and at each eccentricity was first determined by measuring reading speeds for four print sizes using unflanked words. We then presented words at 0.8x or 1.4x CPS, with each target word flanked by two other words, one above and one below the target word. Reading speeds were determined for vertical word spacings (baseline-to-baseline separation between two vertically separated words) ranging from 0.8x to 2x the standard single-spacing, as well as the unflanked condition. RESULTS: At the fovea, reading speed increased with vertical word spacing up to about 1.2x to 1.5x the standard spacing and remained constant and similar to the unflanked reading speed at larger vertical word spacings. In the periphery, reading speed also increased with vertical word spacing, but it remained below the unflanked reading speed for all spacings tested. At 2x the standard spacing, peripheral reading speed was still about 25% lower than the unflanked reading speed for both eccentricities and print sizes. Results from a control experiment showed that the greater reliance of peripheral reading speed on vertical word spacing was also found in the right visual field. CONCLUSIONS: Increased vertical word spacing, which presumably decreases the adverse effect of crowding between adjacent lines of text, benefits reading speed. This benefit is greater in peripheral than central vision.

Adolescent↗
PubMed1991

Visual prostheses and visual rehabilitation in low vision research, assessment, and management.

This review is a highly selective and personal viewpoint regarding the past year's publications in low vision clinical practice and clinical research. This article reviews and provides references on selected aspects of low vision technology, reading, pediatric considerations, visual assessment for the multiply handicapped, and the psychosocial aspects of low vision and rehabilitation. We are impressed that the wealth of current publications underscores that this is an important, productive, and growing area of research and clinical activity.

Aged↗
PubMed2004

Vision in athletes with intellectual disabilities: the need for improved eyecare.

BACKGROUND: Special Olympics provides sporting opportunities for people with intellectual disabilities (ID), and Lions Clubs International Opening Eyes GB offers vision screening for athletes at Special Olympics Games. METHODS: Opening Eyes GB screened the vision of 505 UK athletes at its inaugural event in 2001. The results were analysed and are presented here. RESULTS: Results showed that athletes do not differ from other people with ID in being at high risk of ocular and visual defects and many are not accessing eyecare. 15% reported never having an optometric eye examination, and yet 19% of these athletes had a significant refractive error, 32% had ocular anomalies and 6% were visually impaired. Overall, findings confirmed the high prevalence of refractive errors and strabismus amongst people with ID. 40% of athletes had ocular abnormalities, including 15.6% with blepharitis, a readily treatable condition that causes discomfort. 9% had lens opacities, of which half were probably impairing sight. An important finding was that many athletes have reduced vision and 14% could be classified as visually impaired (WHO definition) even when refractive errors were fully corrected. CONCLUSIONS: Special Olympics athletes should be encouraged to have regular eye examinations (as indeed, should all people with ID), and educators, carers and coaches need appropriate information about the visual status of their charges.

Adolescent↗
PubMed1996

Vision testing in atrophic macular degeneration.

PURPOSE: To determine the correlation between a group of vision tests in atrophic macular degeneration (AMD) in an office setting. METHODS: Patients with documented vision loss from atrophic macular degeneration in one eye were invited to attend an eye clinic every three months for a series of six vision tests for their good eye followed by fundus photography. Modified contrast sensitivity, blue/yellow anomaloscopy, flicker fusion frequency, Amsler grid, and photostress recovery time were correlated with Snellen acuity using the Pearson correlation coefficient. The regression of the Snellen acuity on sex, age and the presence of disciform macular degeneration in the other eye was obtained using a general linear model. RESULTS: The correlation with Snellen acuity result was low for all tests. It was highest for Amsler grid abnormality (r = -0.33345) and blue/yellow anomaloscopy matching range (r = -0.20742), where r denotes the correlation coefficient. Patient age was strongly correlated with Snellen results (P = 0.0001), but it was not significantly related to sex (P = 0.1187) or the presence of disciform macular degeneration in the other eye (P = 0.9989). The photostress recovery time showed enormous inter-visit variations and poor correlation with Snellen acuity (P = 0.0526). CONCLUSIONS: The course of AMD is routinely assessed by Snellen acuity and any of several additional tests. When employing a test battery in an office setting, a clinician needs to know the relative utility and correlation between the tests at his disposal. Of the tests used in this study, the Amsler grid was the most useful addition to the Snellen acuity at all stages of atrophic macular degeneration, and blue/yellow anomaloscopy was useful only in mild macular degeneration where Snellen acuity was 6/12 or better.

Aged↗
PubMed1993

Reading performance with low vision aids: relationship with contrast sensitivity.

Reading performance and contrast sensitivity were measured in 30 subjects with low vision due to a variety of pathologies. The Pepper test was used to quantify reading rate and accuracy with the subject's own prescribed optical reading low vision aid. It was found that both reading rate and accuracy were repeatable measures. Reading rates were found to be correlated with contrast sensitivity at 0.5 c/deg (r = 0.62). Multiple regression analysis also showed that the best predictor of reading rate was contrast sensitivity at 0.5 c/deg and that no other components of the contrast sensitivity function helped to explain more of the variance. This indicates that primarily low spatial frequencies are necessary for reading with optical low vision aids, as has been found previously for reading with a close circuit TV system.

Adult↗
PubMed2000

Binocular vision in older people with adventitious visual impairment: sometimes one eye is better than two.

PURPOSE: To determine the effect of adventitious visual impairment (low vision) on monocular and binocular spatial contrast sensitivity of older people. DESIGN: A between-within repeated measures design. PARTICIPANTS: Fifty-nine older adults between the ages of 50 and 96; 49 of the observers had age-related macular degeneration (AMD). MEASURES: Visual acuity screening and spatial contrast sensitivity. RESULTS: In almost half of the population with AMD, the sensitivity to spatial information, as measured by spatial contrast sensitivity, is worse when both eyes are used than when the stimuli are viewed with only one eye. This "binocular inhibition" is not related to the contrast sensitivity of the better eye or to acuities. Furthermore, this inhibition process is reflected primarily in images with medium to low spatial frequency components (medium to large size bars). CONCLUSIONS: These results have important implications for understanding the functional impact of low vision in older people. They suggest that almost one-half of older people with AMD view the world best using only one of their eyes, whereas for the other half, there is an advantage to using binocular vision for certain visual tasks.

Aged↗
PubMed1978

Visual disorders in 7-year-old children with and without previous vision screening.

An analysis of visual defects among 310 children referred from a vision screening of 2 178 7-year-old children revealed a 50% frequency of significant eye defects among the referrals (7% of screened children). Of the screened children, one group (1 530 children) had previous visual screening three years earlier. The other group (648 children) had no previous vision screening until the age of seven. A comparison between the two groups showed that the risk of finding a new significant eye disorder in a school entrant was more than 6 times greater for a child who was not examined in his preschool years, and the risk of finding an amblyopic child was more than 10 times greater. The results do indicate the need for continuation of the present vision screening program of pre-school children.

Astigmatism↗
PubMed1991

Primary success with low vision aids in age-related macular degeneration.

The benefit obtained from various low vision aids (LVAs) was studied in 65 consecutive patients with atrophic (70.3%) or disciform (29.7%) age-related macular degeneration (ARMD). 13.8% were able to read newsprint with age-related reading correction under proper lighting conditions. The primary success achieved with LVAs was good, 91.4% of patients being able to read newsprint. In most cases a simple magnifier (52.3%), high-powered reading glasses (10.8%) or Fonda's glasses (12.8%) were sufficient. The magnification preferred was 5x or less in 25.6% and greater than 5x to 9x in 48.8%. Patients with disciform degeneration required higher magnification than those with atrophic degeneration. It is concluded that most patients with ARMD found low vision aids useful for reading purposes and that a simple optical device was sufficient to achieve reading vision.

Age Factors↗