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PubMed2003

Blindness and vision impairment in a rural south Indian population: the Aravind Comprehensive Eye Survey.

OBJECTIVE: To determine the prevalence of blindness and vision impairment in a rural population of southern India. DESIGN: A population-based cross-sectional study. PARTICIPANTS: A total of 17200 subjects aged 6 years or older, including 5150 subjects aged 40 years or older from 50 clusters representative of three southern districts of Tamil Nadu in southern India. METHODS: All participants had preliminary screenings consisting of vision using a LogMAR illiterate E chart and anterior segment hand light examinations at the village level. Subjects aged 40 years or older were offered comprehensive eye examinations at the base hospital, including visual acuity using LogMAR illiterate E charts and refraction, slit-lamp biomicroscopy, gonioscopy, applanation tonometry, dilated fundus examinations, and automated Humphrey central 24-2 full threshold perimetry; subjects younger than 40 years of age who had any signs or symptoms of ocular disease were also offered comparable examinations at the base hospital. MAIN OUTCOME MEASURES: Visual impairment was defined as best-corrected visual acuity <6/18, and blindness was defined using both Indian (<6/60) and World Health Organization (<3/60) definitions. RESULTS: Comprehensive examinations at the base hospital were performed on 5150 (96.5%) of 5337 persons 40 years of age or older. Among those 40 years of age and older, presenting visual acuity at the <3/60 level was present in 4.3% (95% confidence interval [CI]: 3.8, 4.9) and 11.4% (95% CI: 10.6, 12.3) at the <6/60 level. After best correction, the corresponding figures were 1.0% (95% CI: 0.79, 1.2) and 2.1% (95% CI: 1.7, 2.5). Over 70% of subjects improved their vision by at least one line, and nearly a third by three lines after refraction. Age-related cataract was the most common potentially reversible blinding disorder (72.0%) among eyes presenting with blindness. CONCLUSIONS: Blindness and vision impairment remain major public health problems in India that need to be addressed. Cataracts and refractive errors remain the major reversible causes for the burden of vision impairment in this rural population.

Adolescent↗
PubMed1994

The relation of socioeconomic factors to the incidence of proliferative diabetic retinopathy and loss of vision.

PURPOSE: To investigate the relations between socioeconomic factors and the incidence of proliferative retinopathy and loss of vision. METHODS: A population-based sample of younger-onset persons with diabetes 25 years of age or older (n = 334) and older-onset persons with diabetes (n = 906) was followed over a 4-year period. Education, occupational status, employment status, and marital status were measured at baseline and follow-up. Main outcome measures were incidence of proliferative retinopathy and loss of vision measured using standard protocols. RESULTS: Proliferative retinopathy was more likely to develop in younger-onset women with less education than in those with more education; no relation was found in the older-onset group. Education was associated inversely with incidence of loss of vision in younger-onset women and older-onset men. CONCLUSION: These data suggest that education is associated with the development of loss of vision, independent of other risk factors. The associations vary between men and women and between younger-onset and older-onset people with diabetes. Further understanding of these relationships may lead to interventions to prevent loss of vision in people with diabetes.

Adult↗
PubMed2001

Patient outcomes of refractive surgery. The refractive status and vision profile.

PURPOSE: To evaluate the performance of a questionnaire, the Refractive Status and Vision Profile (RSVP), in the assessment of patient outcomes following refractive surgery. SETTING: Patients recruited from 5 refractive surgery practices. METHODS: The RSVP was self-administered by patients before and 2 to 6 months after bilateral refractive surgery. Information on uncorrected visual acuity (UCVA), refractive error, and self-reported satisfaction with vision was also collected. Changes in total RSVP scores and in the scores of RSVP subscales (concern, functioning, driving, symptoms, optical problems, glare, and trouble with corrective lenses) were assessed. The relationship between change in the RSVP and subscale scores was assessed in relation to change in traditional clinical measures. The responsiveness of the RSVP to clinically meaningful changes in patients' vision was measured by calculating its effect size. RESULTS: One hundred seventy-six patients completed baseline and postoperative RSVPs and had bilateral refractive surgery. Postoperatively, 92.0% of patients had a UCVA of 20/40 or better in at least 1 eye. Fifteen percent had some worsening in the total RSVP score, and there was substantial variation in the proportion of patients who had worsening in particular subscale scores, ranging from 7.0% who reported worsening in trouble with corrective lenses to 41.5% who reported worsening in driving. Change in satisfaction with vision following surgery was correlated with change in the overall RSVP and subscale scores but not with change in refractive error. A significant worsening in 3 or more RSVP subscales was independently associated with an almost 6-fold (odds ratio 5.84, 95% confidence interval: 1.88,18.13) likelihood of patient report of dissatisfaction with vision, after adjusting for age, sex, preoperative refractive error, and postoperative UCVA. Low scores (ie, minimal dysfunction) on 2 of the RSVP subscales (physical functioning and optical problems) at baseline were predictive of poor postoperative patient outcomes. The RSVP was very sensitive to the intervention of refractive surgery (effect size of 1.2 to 1.4). CONCLUSIONS: The RSVP was able to detect clinically relevant changes in functional status and quality of life after refractive surgery. Change in the RSVP score was correlated with change in patient report of satisfaction and was predictive of postoperative patient satisfaction. The RSVP provides a valuable new metric to assess outcomes of refractive surgery.

Activities of Daily Living↗
PubMed1997

Mesopic vision in myopia corrected by photorefractive keratectomy, soft contact lenses, and spectacles.

PURPOSE: To evaluate contrast vision and glare sensitivity under mesopic conditions in eyes having uncomplicated excimer laser photorefractive keratectomy (PRK) for myopia and in eyes corrected by disposable soft contact lenses, soft contact lenses, and spectacles. SETTING: Division of Experimental Ophthalmic Surgery, University of Tübingen, Germany. METHODS: The Mesoptometer II test was used to evaluate mesopic vision (glare sensitivity and contrast vision) in 28 eyes of 14 patients wearing disposable soft contact lenses, 20 eyes of 10 patients wearing soft contact lenses, 39 eyes of 20 patients wearing spectacles, 30 eyes of 15 emmetropic patients, and 33 eyes of 22 patients after PRK with 5.0 mm optical zone. Follow-up was between 15 and 60 months after PRK (mean 34.5 months). RESULTS: The guidelines of the German Ophthalmologic Society state that patients must recognize Mesoptometer II contrast levels of 1:5 or better with and without glare to meet the minimum legal night-driving standards for private cars. All eyes with disposable soft contact lenses and soft contact lenses, all emmetropic eyes, and 38 eyes corrected by spectacles recognized contrast levels of 1:5 or better without glare. In contrast, 18 eyes in the PRK group were unable to recognize contrast level 1:5 without glare. With glare, 1 eye in the disposable soft contact lens group, 1 in the soft contact lens group, and 7 with spectacles were unable to recognize the 1:5 contrast level. All emmetropic eyes recognized contrast levels of 1:5 or better; 22 PRK eyes were unable to recognize contrast level 1:5 with glare. CONCLUSION: Myopic PRK may lead to long-term impairment of mesopic vision, while soft contact lens use does not seem to markedly influence mesopic vision in eyes with low to moderate myopia.

Adolescent↗
PubMed1998

The ophthalmic registered nurse's responsibility to the adult patient with low vision.

A key goal in the care of adult patients with low vision is to help them focus on their visual abilities rather than their disabilities. This article presents information that every ophthalmic nurse can use to teach patients with low vision some practical ways to change their personal environment to enhance visibility and safety. There are also some myths and misunderstandings about low vision that the nurse can dispel. Before referring patients to low-vision specialty clinics or organizations, every ophthalmic nurse can begin the visual rehabilitation for patients with low vision.

Activities of Daily Living↗
PubMed1997

Improving stoma management in the low-vision patient.

Teaching the low-vision patient with an ostomy to manage a stoma independently provides a significant challenge for the WOC nurse. Although guide strips, lighted mirrors, and other handheld devices are available to patients with impaired eyesight, these products, when used alone, may be inadequate for the patient with an ostomy. In addition, there is a paucity of literature available to the WOC nurse describing specific interventions for the low-vision patient with an ostomy. Common visual problems encountered when managing people with an ostomy are reviewed. Specific interventions are discussed, including products designed to assist the low-vision patient with an ostomy with stoma care. A case study is provided that underscores the importance of consulting a low-vision specialist in the care of the patient with a new ostomy who has low vision as a result of albinism.

Adult↗
PubMedDate not supplied

A novel mutation in the short-wavelength-sensitive cone pigment gene associated with a tritan color vision defect.

Inherited tritan color vision deficiency is caused by defects in the function of the short-wavelength-sensitive (S) cones. This heterozygous group of disorders has an autosomal dominant pattern of inheritance. Amino acid variations of the S cone opsin are rare and all that have been identified thus far are associated with inherited tritan color vision defects. Here we report the identification of a 30-year-old male who made errors on standard color vision tests consistent with the presence of a mild tritan color vision deficiency. We tested the hypothesis that his color vision impairment was due to a mutation in the S cone photopigment gene. He was found to be heterozygous for a mutation that caused the amino acid proline to be substituted in place of a highly conserved leucine at amino acid position 56 in the S cone opsin. This mutation was absent in 564 S cone photopigment genes from 282 subjects who did not make tritan errors. Thus, we conclude that this mutation disrupts the normal function of S cones.

Adult↗
PubMed2002

Retinol-binding protein-deficient mice: biochemical basis for impaired vision.

We reported previously that mice lacking plasma retinol-binding protein (RBP) are phenotypically normal except that they display impaired vision at the time of weaning. This visual defect is associated with greatly diminished eyecup levels of retinaldehyde and is reversible if the mutants are maintained for several months on a vitamin A-sufficient diet. Here we provide a biochemical basis for the visual phenotype of RBP-deficient mice. This phenotype does not result from inadequate milk total retinol levels since these are not different for RBP-deficient and wild-type mice. The eye, unlike all other tissues that have been examined, takes up dietary retinol very poorly. Moreover, compared to other tissues, the eye displays a strong preference for retinol uptake when retinol is delivered bound to RBP. The poor uptake of dietary retinol by the eye coupled with its marked ability to take up retinol from RBP, we propose, provides a basis for the impaired vision observed in weanling RBP-deficient mice. Further study of the mutants suggests that the impaired vision is reversible because the eyes of mutant mice slowly acquire sufficient retinol from the low levels of retinol present in their circulation either bound to albumin or present in lipoprotein fractions. Thus, the eye is unlike other tissues in the body in that it shows a very marked preference for acquiring retinol needed to support vision from the retinol-RBP complex and is unable to meet adequately its retinol need through uptake of recently absorbed dietary retinol. This provides an explanation for the impaired vision phenotype of RBP-deficient mice.

Administration, Oral↗
PubMed2001

A utility analysis correlation with visual acuity: methodologies and vision in the better and poorer eyes.

OBJECTIVE: To ascertain the correlation between visual acuity levels and ophthalmic utility values obtained using time tradeoff and standard gamble utility analysis methodologies. METHODS: Three hundred twenty-five consecutive patients with visual loss to 20/40 or less in at least one eye with predominantly vitreoretinal pathology were evaluated in a cross-sectional fashion using a standardized testing methodology to obtain ophthalmic time tradeoff and standard gamble utility values. Spearman correlation coefficients were employed to correlate the utility values with visual acuity in better seeing and poorer seeing eyes. RESULTS: The Spearman correlation coefficient for time tradeoff utility values and vision in the better seeing eye was 0.455 (p < 0.001), while that for time tradeoff utility values and visual acuity in the poorer seeing eye was 0.268 (p < 0.001). The coefficient for standard gamble utility values and the better seeing eye was 0.371 (p < 0.001), while that for standard gamble utility values and vision in the poorer seeing eye was 0.250 (p < 0.001). CONCLUSIONS: There is a greater correlation between ophthalmic utility values and vision in the better seeing eye, as versus vision in the poorer seeing eye. Time tradeoff ophthalmic utility values demonstrate a greater correlation with vision in the better seeing eye than do standard gamble utility values.

Aged↗
PubMed1998

Need for vision rehabilitation in India. Survey of a private eye hospital.

PURPOSE: To determine the visual success outcomes following treatment in an urban private eye hospital in India. METHODS: A retrospective survey was done of 4122 consecutive files of fee-paying patients admitted to a private eye hospital in Hyderabad during a 3-month period in 1996. Data obtained a minimum of 4 months after completion of treatment included age, sex, diagnosis and distance visual acuity in the best eye. RESULTS: After completion of treatment 86.5% of patients had normal vision, 10.9% had low vision and 2.5% were blind. Of the people with low vision or blindness after treatment, 81.7% had a best corrected visual acuity of between 6/18 and 6/60. The 4 most common causes of low vision after treatment were unoperated cataract (20.4%), glaucoma (13.3%), diabetic retinopathy (12.4%) and retinitis pigmentosa (10.2%). CONCLUSION: The visual success rates in an urban Indian private eye hospital appear high with nearly 90% of patients achieving normal vision after the completion of treatment.

Adolescent↗
PubMed1998

Childhood blindness and low vision in Uganda.

PURPOSE: To examine the causes and outcome of subnormal vision starting in childhood in Uganda, to aid in planning for its avoidance and for rehabilitation. METHODS: All those seen having subnormal vision with onset from birth to 15 years (total 1135) (schools 1983-97; community 1988-97) were included in the study. Clinical examination was performed and a World Health Organisation (WHO) form completed, with analysis by its computer program. Main outcome measures were visual acuity, signs of eye pathology, outcome of treatment and refraction and low vision assessment. RESULTS: By WHO category 14.8% had visual impairment, 6.5% severe visual impairment, 63.2% were blind and 15.2% were too young to test. The acuities and causes were similar in school and community groups, excepting cortical visual impairment and multiple impairment, which are much commoner in the community. Cataract was the largest cause of visual impairment (30.7%) and surgical outcome was unsatisfactory. Visual loss following corneal ulceration was the second commonest cause of subnormal vision (22.0%). CONCLUSIONS: Cataract and corneal damage cause half of all subnormal vision, which is avoidable for both. Cataract surgery needs to be upgraded. To prevent corneal visual loss, primary health care should continue to be expanded, especially measles immunisation and nutrition care; rubella immunisation should be added. Special education needs to be greatly expanded. Public perceptions need changing if results are to be improved and help offered to more than the present minority.

Adolescent↗
PubMed2002

A new method of biofeedback in the management of low vision.

Twenty-eight patients with low vision were enrolled into the study. A preliminary study was carried out on 18 eyes of 13 patients with low vision who underwent visual rehabilitation with a new instrument for biofeedback (BF) applied to vision; improved biofeedback integrated system (Ibis). Successively, eight patients (16 eyes) with bilateral low vision were subjected to biofeedback in one eye. The experimental and control eye were evaluated separately. Then a placebo training was developed on seven patients (12 eyes). Visual acuity, colour vision, automated perimetry, contrast sensitivity and flash VEP were evaluated. A brief review of the literature and the possible mechanisms behind the results are discussed.

Adult↗
PubMed2004

Specifying colours for colour vision testing using computer graphics.

AIMS: This paper describes a novel test of colour vision using a standard personal computer, which is simple and reliable to perform. METHODS: Twenty healthy individuals with normal colour vision and 10 healthy individuals with a red/green colour defect were tested binocularly at 13 selected points in the CIE (Commission International d'Eclairage, 1931) chromaticity triangle, representing the gamut of a computer monitor, where the x, y coordinates of the primary colour phosphors were known. RESULTS: The mean results from individuals with normal colour vision were compared to those with defective colour vision. Of the 13 points tested, five demonstrated consistently high sensitivity in detecting colour defects. CONCLUSION: The test may provide a convenient method for classifying colour vision abnormalities.

Adolescent↗
PubMed2005

Prevalence of blindness and low vision in an Italian population: a comparison with other European studies.

AIM: The scientific literature contains recent data on the prevalence of blindness and low vision for a few European countries, but most of these studies have been focused exclusively on the elderly sector of the populations. The purpose of the present study was to provide age-specific estimates of the prevalence and causes of visual loss in an Italian population aged 40 years and over. METHODS: In total, 847 of the 1,200 citizens >40 years of age (70.6%) in the island community of Ponza underwent complete standardized ophthalmological examinations. Visual acuity (VA) was measured using a standard logarithmic chart. World health organization (WHO) definitions of blindness and low vision were adopted (respectively, VA>1.3 logMAR or a visual field <10 degrees around central fixation, and VA >0.5 to 1.3 logMAR or a visual field <20 degrees around central fixation). Prevalence rates based on presenting VAs were also calculated. RESULTS: The overall best-corrected prevalence rates were 0.6% (presenting, 0.8%) for better eye blindness, 2.1% (presenting, 6.7%) for better eye low vision, 1.8% (presenting, 2.6%) for monocular blindness, 5.0% (presenting, 11.2%) for monocular low vision. Cataract, glaucoma, degenerative myopia, and AMD were the main causes of better eye visual loss. CONCLUSION: Age-specific prevalence rates in Ponza are fairly consistent with those for other European countries with similar socio-economic conditions and public healthcare systems. A substantial percentage of visual losses remains uncorrected despite the availability of potentially curative therapy. Greater emphasis needs to be placed on educating the public regarding the importance of good vision.

Adult↗
PubMed2002

Low vision rehabilitation in patients with age-related macular degeneration at a tertiary eye care centre in southern India.

PURPOSE: To evaluate the specific needs and types of low vision devices (LVDs) in patients with age-related macular degeneration (AMD) so as to use the residual vision effectively. METHODS: One hundred consecutive patients with diagnosis of AMD were evaluated to ascertain the degree of visual disability. Different LVDs were used to suit the specific needs of individual patients. The distribution of LVDs for distance and near and other rehabilitation measures were stratified for vision >or=6/18 and <6/18. Statistical analysis was performed using chi2 test/Fisher's exact test and paired t-test. RESULTS: The percentage of patients with visual acuity <6/18 reduced from 72.2% (26/36) to 47.2% (17/36) with the use of standard spectacles (P = 0.03). Similarly, the percentage of patients with visual acuity <6/18 reduced from 85.7% (6/7) to 14.3% (1/7) with the use of a telescope (P = 0.029). The optical devices for near tasks included spectacle magnifiers (n = 59), stand magnifiers (n = 19), and hand magnifiers (n = 18). With these LVDs, the near vision improved from 0.13 (decimal notations) to 0.39 (P < 0.001). Eighty-six patients were given at least one of the LVDs and 20% were prescribed more than one near device (bifocals, spectacle magnifiers, hand magnifiers, stand magnifiers). Additionally, patients also needed counselling (n = 89) and training on eccentric viewing (n = 39), coin identification (n = 45), and independent mobility (n = 41). CONCLUSION: The overall management of a patient with AMD must include counselling, prescription of appropriate LVDs and training to utilize the residual vision to its fullest advantage. This is expected to improve the patient's quality of life.

Aged↗
PubMed2002

Do tinted lenses or filters improve visual performance in low vision? A review of the literature.

This is a review of studies that have investigated the proposed rehabilitative benefit of tinted lenses and filters for people with low vision. Currently, eye care practitioners have to rely on marketing literature and anecdotal reports from users when making recommendations for tinted lens or filter use in low vision. Our main aim was to locate a prescribing protocol that was scientifically based and could assist low vision specialists with tinted lens prescribing decisions. We also wanted to determine if previous work had found any tinted lens/task or tinted lens/ocular condition relationships, i.e. were certain tints or filters of use for specific tasks or for specific eye conditions. Another aim was to provide a review of previous research in order to stimulate new work using modern experimental designs. Past studies of tinted lenses and low vision have assessed effects on visual acuity (VA), grating acuity, contrast sensitivity (CS), visual field, adaptation time, glare, photophobia and TV viewing. Objective and subjective outcome measures have been used. However, very little objective evidence has been provided to support anecdotal reports of improvements in visual performance. Many studies are flawed in that they lack controls for investigator bias, and placebo, learning and fatigue effects. Therefore, the use of tinted lenses in low vision remains controversial and eye care practitioners will have to continue to rely on anecdotal evidence to assist them in their prescribing decisions. Suggestions for future research, avoiding some of these experimental shortcomings, are made.

Adaptation, Physiological↗
PubMed1988

[The effect of posterior chamber lenses or YAG laser capsulotomy on sensitivity to glare and twilight vision in comparison to phakic control groups (corrected)].

Patients who had undergone extracapsular cataract extraction with implantation of a posterior chamber intraocular lens, and normal subjects of corresponding age and vision were examined with the mesoptometer and nyktometer to compare their twilight vision and glare sensitivity. All the results were poorer in patients with intraocular lenses. Statistically, some of the differences in the results of examinations performed in the two groups were highly significant. As the controls were strictly matched in age and visual acuity, these results confirm other studies with similar objectives. Additionally, some patients with posterior chamber lenses were examined who had also undergone YAG laser capsulotomy for secondary cataract. Although the number of cases was too small for statistical evaluation, it appeared that in this group twilight vision and glare sensitivity could not be improved in the same way as daylight visual acuity by means of this treatment. These findings indicate that since intraocular lenses are increasingly being implanted in younger patients, special attention should also be paid to scotopic vision and glare sensitivity during examinations for drivers' licenses, particularly in cases of good daylight vision. Special examinations, e.g., with the mesoptometer or nyktometer, should be carried out in all such cases. Increased glare sensitivity in eyes with lens implants should also be taken into consideration with regard to the increasing importance of computer and TV screens.

Adaptation, Ocular↗
PubMed1986

Analog "neuronal" networks in early vision.

Many problems in early vision can be formulated in terms of minimizing a cost function. Examples are shape from shading, edge detection, motion analysis, structure from motion, and surface interpolation. As shown by Poggio and Koch [Poggio, T. & Koch, C. (1985) Proc. R. Soc. London, Ser. B 226, 303-323], quadratic variational problems, an important subset of early vision tasks, can be "solved" by linear, analog electrical, or chemical networks. However, in the presence of discontinuities, the cost function is nonquadratic, raising the question of designing efficient algorithms for computing the optimal solution. Recently, Hopfield and Tank [Hopfield, J. J. & Tank, D. W. (1985) Biol. Cybern. 52, 141-152] have shown that networks of nonlinear analog "neurons" can be effective in computing the solution of optimization problems. We show how these networks can be generalized to solve the nonconvex energy functionals of early vision. We illustrate this approach by implementing a specific analog network, solving the problem of reconstructing a smooth surface from sparse data while preserving its discontinuities. These results suggest a novel computational strategy for solving early vision problems in both biological and real-time artificial vision systems.

Humans↗