Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Vision, Low”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources
PubMed2005

An evaluation of the Mars Letter Contrast Sensitivity Test.

PURPOSE: The Mars Letter Contrast Sensitivity Test (initially known as the Lighthouse Letter Contrast Sensitivity Test) is similar in design to the Pelli-Robson Test but may offer several advantages. This study evaluates the repeatability of the Mars test and its agreement with the Pelli-Robson test in normal and low-vision subjects. METHODS: Fifty-four subjects were tested (age 22-86 years), including 20 normally sighted young adults, 17 normally sighted older adults, and 17 adults with low vision (20/16 to 20/250). Subjects were tested with both contrast sensitivity tests and with the ETDRS visual acuity chart. After a short break, subjects were retested with an alternate form of each contrast sensitivity test. The chart forms used (two Pelli-Robson and three Mars) and the order of testing were varied systematically. Testing was monocular with habitual correction and, for subjects over 40 years of age, included appropriate near add. Letter-by-letter scoring was used for both tests. Repeatability and agreement were assessed by determining the 95% limits of agreement (LoA): +/- 1.96 standard deviations of the differences between administrations or tests. RESULTS: The Mars test showed excellent agreement with the Pelli-Robson test, with 95% LoA of +/- 0.21 log units for all subjects. The Mars test was similarly repeatable (95% LoA = +/-0.20 log units) to the Pelli-Robson test (95% LoA = +/-0.20 log units) among all subjects. CONCLUSION: The new Mars Letter Contrast Sensitivity Test shows excellent agreement with the Pelli-Robson test and has similar repeatability. There are subtle differences in the actual contrast levels on different forms of the Mars test, and adjusting for these differences leads to superior repeatability of the Mars test. Thus, the Mars test may be a useful alternative to the Pelli-Robson test offering several advantages, including smaller size, improved durability, and ease of use.

Adult↗
PubMed2001

Vision of low astigmats through thick and thin lathe-cut soft contact lenses.

Distance and near visual acuity of 13 low astigmats were determined in a double-masked experiment through thick and thin (centre thickness 0.12 mm and 0.06 mm, respectively) spherical lathe-cut soft lenses. For each lens type, distance and near LogMAR VA and over-refraction were assessed with different logMAR VA charts. For 70% of the subjects, the residual astigmatism was significantly lower than the refractive astigmatism with thicker lenses. No statistically significant differences in the distance and near logMAR VA was found between the two lens types using any of the charts used, though, in general, logMAR VA obtained through the thicker lens was better than logMAR VA through the thinner lens. The variabilities in distance and near logMAR VA between the two lens types increased with decreased contrast. The variabilities in distance logMAR VA were greater with Chinese charts than with English charts, and LogMAR VA with Chinese charts were significantly worse for both lens types. Based on the results of this study, we concluded that thicker spherical lathe-cut soft lenses provide better vision in low astigmats. The Snellen acuity test is inadequate for vision assessment of soft contact lens wearers. When a patient wearing thin soft contact lenses complains of poor vision in spite of 6/6 or 6/5 Snellen acuity, changing to thicker lenses may be considered.

Journal Article↗
PubMed2001

Illumination and reading performance in age-related macular degeneration.

BACKGROUND: Previous studies have compared low vision reading performance at optimal task illuminance and consulting room illuminance (500 to 600 lux). However, it is uncertain the extent to which low vision reading performance can be improved when task illumination is increased from levels more representative of those found in the typical living room (50 lux) to levels likely to maximise performance. METHODS: Reading performance of 20 subjects with age-related macular degeneration (AMD) was assessed for a range of print sizes using sentence reading charts at six levels of task illuminance (50 to 5,000 lux). Subjects read without low vision devices. RESULTS: Sentence reading acuity and critical print size improved by a factor of two over the 50 to 5,000 lux range, while maximum reading rate improved by a factor of 1.4. For the majority of subjects (70 per cent), the optimal task illuminance (determined objectively) was higher (median 3,500 lux) than the subjectively preferred task illuminance (median 2,450 lux). Reading performance was significantly better at the optimal illuminance than at illuminances equivalent to those found in the domestic environment (50 lux) or consulting room (600 lux). CONCLUSIONS: The majority of AMD patients will require task illumination of at least 2,000 lux to maximise reading performance. Optimal illumination should be determined individually for each patient using both objective measures of performance, such as reading acuity, and subjective assessments of visual comfort.

Journal Article↗
PubMed2004

Use of Rasch person-item map in exploratory data analysis: a clinical perspective.

The National Institutes of Health (NIH) includes visual impairment in the 10 most prevalent causes of disability in America. As rehabilitation programs have the potential to restore independence and improve the quality of life for affected persons, NIH research priorities include evaluating their effectiveness. This paper demonstrates a clinical perspective on the use of the Rasch person-item map to evaluate the range and precision of a new vision function questionnaire in early analysis (prior to full sample). A self-report questionnaire was developed to measure the difficulty that persons with different levels of vision loss have performing daily activities. This 48-item Veterans Affairs Low-Vision Visual Functioning Questionnaire (VA LV VFQ-48) was administered to 117 low-vision patients. Preliminary analysis indicates that the questionnaire items are applicable to persons of differing abilities. The Rasch person-item map demonstrates that the field-test version of the VA LV VFQ-48 has good range and is well centered with respect to the person measure distribution. Construct validity and reliability are also demonstrated.

Adult↗
PubMed1994

Prevalence and causes of blindness and visual impairment in Mongolia: a survey of populations aged 40 years and older.

The survey was conducted in 3 out of the 18 administrative regions (aimaks); 4345 people aged > or = 40 years were examined, which represented 95.7% of the proposed sample. The prevalences of blindness and low vision in the sample were 1.5% (95% CI, 0.8-2.3%) and 8.1% (95% CI, 5.5-10.7%), respectively, from which the prevalences of blindness and low vision in the Mongolian population aged 40 years and older were estimated to be 1.4% and 7.7%, respectively. The prevalence of climatic droplet keratopathy was high (ranging from 15% to 50%) in this population, which included a large number of semi-nomadic cattle breeders, and was responsible for 7.2% of the blindness and 19.3% of the low vision. Cataract and glaucoma were the commonest blinding disorders, each accounting for around 35% of the blindness. Trauma accounts for a high proportion of those monocularly blind. Trachoma and xerophthalmia were not found.

Adult↗
PubMed1995

The Charles Bonnet syndrome: a large prospective study in The Netherlands. A study of the prevalence of the Charles Bonnet syndrome and associated factors in 500 patients attending the University Department of Ophthalmology at Nijmegen.

BACKGROUND: The aims were to determine the prevalence of the Charles Bonnet syndrome (CBS) in low-vision patients and analyse possible associated ophthalmic and sociodemographic factors. METHOD: A semi-structured interview on visual hallucinations was given to 300 adult low-vision patients and 200 elderly general ophthalmic patients. Positive cases were examined with the Geriatric Mental State Schedule and the Mini Mental State Examination. Diagnostic criteria were as follows: complex, persistent, or repetitive visual hallucinations; full or partial retention of insight; no hallucinations in other modalities; and no delusions. Ophthalmic and sociodemographic data were gathered for all patients. RESULTS: The prevalence of CBS in low-vision patients was 11%. CBS was significantly associated with an age over 64 years and a visual acuity in the best eye of 0.3 or less. No significant associations with ophthalmic diagnoses, patient sex, marital status, or social circumstances were found. CONCLUSION: Our findings support association of CBS with sensory deprivation and advanced age.

Age Factors↗
PubMed2001

The development of the Ocutech VES-autofocus telescope and a future binocular version.

Conventional optical low-vision devices are hampered by the physical constraints of magnification-shallow depth of field and narrow field of view, and for telescopes, the need to change focus for different distances. These characteristics make low-vision telescopic aids difficult to use, especially at important midrange distances. The Ocutech VES Autofocus bioptic telescope (VES-AF) funded with National Institutes of Health-Small Business Innovation Research and Ontario (Canada) Ministry of Health grants, eliminates the need to manipulate the device to maintain focus. Clinical experience with the VES-AF has shown that autofocus (AF) enhances the acceptance and utilization of telescopic devices. Difficulty ignoring the fellow eye while sighting through the device has been a complaint of users that has undermined device acceptance. Although occlusion is an option to alleviate the diplopia experienced, the development of a binocular version may further enhance the acceptance, adaptation to, and utilization of telescopic devices and may offer wider fields of view as well.

Adult↗
PubMed1993

A driving program for the visually impaired.

This driving program for the visually impaired individual was devised in 1986, as a specific adjunct to the pre-existing training program, designed for the cognitive and physically impaired patients. Two important purposes of the program are: 1) To give the low vision practitioner and staff the capability to be able to recommend a specific training program for telescopic and visually impaired drivers. 2) To try to ensure that every visually impaired telescopic driver (prescribed with a telescopic system by the low vision center) would not only meet legal visual acuity and visual field requirements for the State of Michigan, but would also improve the competency of using their telescopic system for driving.

Automobile Driver Examination↗
PubMed1995

Scrolled and rapid serial visual presentation texts are read at similar rates by the visually impaired.

Visually impaired observers read dynamically displayed text faster than text displayed in a normal page view. The goal of this study was to compare reading rates from two dynamic-presentation methods that have been proposed to facilitate reading from computer-based displays. Prior research has shown that both normally sighted and low-vision observers read text displayed to the same location, one word at a time [known as rapid serial visual presentation (RSVP)], faster than a page of text. A similar comparison with text scrolled continuously across the screen also shows faster reading for low-vision patients, but the relative change from a standard page view is substantially less (15% faster for the scroll display versus 80% faster for RSVP). In this study we directly compared these techniques. For those with normal vision, reading from the RSVP display was 1.3 times faster than reading from the scroll display [t(9) = 3.32, P = 0.009]. Although the difference in reading rates for the visually impaired group did not reach statistical significance, as a group they read 13% slower from the RSVP than from the scroll display.

Adult↗
PubMed1995

Prevalence and visual consequences of macular changes in a population aged 70 years and older.

In a population based study on 500 persons aged 70 years and older, photographic and/or ophthalmoscopic evaluation of the macula at least in one eye was possible for 478 persons (96%). No macular pathology in either eye was observed in 46%, signs of age-related maculopathy in one eye or both eyes occurred in 41% and other pathology in 16%. Early age-related maculopathy was diagnosed in 32%, geographic atrophy in 4.4% and disciform degeneration in 3.8%. Geographic atrophy was most common in persons aged 90 years and older (36%), and the highest prevalence of disciform degeneration was found in the age group of 85-89 years (17%). Of the 155 eyes with low vision or blindness and visible fundus, early age-related maculopathy was found in 35%, geographic atrophy occurred in 14% and disciform degeneration in 14%. Age-related maculopathy was considered the main cause for low vision and blindness in 4.7% of the 468 persons in whom visual acuity and information on fundus could be obtained, and in 3.6% it was one of the causes, usually together with cataract. The other macular disorders caused 1.5% of low vision and blindness.

Aged↗
PubMed2004

Cogan syndrome in children: early diagnosis and treatment is critical to prognosis.

PURPOSE: To present two cases of pediatric Cogan Syndrome and to highlight the differences between the adult and pediatric forms of the disease, as well as the importance of early diagnosis and treatment. DESIGN: Interventional case report. METHODS: Institutional setting. RESULTS: Corneal lesions were much more diffuse than those observed in adult Cogan syndrome. Immunosuppressive drug combination therapy successfully resolved systemic and ocular inflammation, but the involvement of the pupillary area caused permanent low vision in one case and amblyopia in the other. CONCLUSION: When chronic ocular inflammation is observed in association with sensory neural hearing loss and any systemic signs of autoimmune inflammation, a diagnosis of Cogan syndrome should be suspected. If immunosuppressive treatment is not initiated as soon as possible, permanent low vision and deafness can result.

Amblyopia↗
PubMed2004

Identification of fixation location with retinal photography in macular degeneration.

BACKGROUND: Identification of fixation location is an integral part of low vision assessment and subsequent rehabilitation. We performed a study to determine whether retinal photography is able to identify fixation location in eyes with age-related macular degeneration (AMD). METHODS: In a prospective, observational case series, consecutive patients with AMD attending a low-vision clinic underwent monocular fixation attempts at a fixation target of a standard ophthalmic fundus camera. Inclusion criteria included AMD with documented macular disease, low vision in both eyes and best-corrected visual acuity of 20/50 to 20/200 in the tested eye. Retinal photography was used to document retinal location of attempted fixation. Macular perimetry was used to confirm acceptable fixation maintenance behaviour. Outcome measures included acceptable fixation maintenance during retinal photography and retinal location of fixation pattern. RESULTS: Twenty-one patients (14 women and 7 men with an average age of 78 [range 53 to 86] years) met the inclusion criteria. In nine cases both eyes met the study criteria, for a total of 30 eyes. Of the 30 eyes, 24 (80%) had acceptable fixation maintenance with retinal photography (p = 0.939). In 17 (71%) of the 24 eyes the retinal fixation location was superior to the macular scar. INTERPRETATION: The results suggest that retinal photography may provide a reliable method to identify retinal location of fixation in eyes with AMD.

Aged↗
PubMed1996

The necessary field of view to read with an optimal stand magnifier.

BACKGROUND: For most people with low vision, some form of magnification is necessary to read. Using a magnifier reduces the number of letters that can be seen simultaneously (field of view), which has been shown to decrease reading rates. This study sought to determine how many letters are necessary to attain maximal reading rates with a stand magnifier. METHODS: Younger and older normally-sighted and visually-impaired observers read short passages using a fiber optic stand magnifier (taper). The optical properties of this magnifier allowed the field of view to be precisely varied. Each subject read using at least four field sizes (3, 5, 9 and 13 characters visible) while reading speed was measured. RESULTS: Reading rates continued to increase with as many as 13 characters visible, regardless of age or vision status. In addition, reading with the taper was slower for all subject groups than reading without the magnifier. CONCLUSIONS: This study confirms reports that reading rates increase as the field of view increases when reading from a page of text. The need for this large field of view relative to other low vision reading aids (i.e., computer-generated scroll displays) is likely the result of the readers' need to actively navigate across the page of text.

Adolescent↗
PubMed2005

[Infantile cataract: the importance of early treatment and diagnosis].

PURPOSE: To establish the frequency of infantile cataract in the Low Vision Service of São Geraldo Hospital (HSG-HCUFMG) and to analyze basis of history, ophthalmologic examination and optical prescription in these patients. METHODS: Retrospective study of infantile cataract recorded in the Low Vision Service from January/1992 to December/2002. Age, sex, race, age at the first evidence of leukocoria and who noticed it, ages at diagnosis and phacectomy, family history of cataract, intraocular lens implantation, visual acuity (VA) and optic prescription were evaluated. RESULTS: There were 44 patients. The age ranged from 0-15 years: 19 (43.0%) 0-3, 14 (32.0%) 4-10 and 11 (25.0%) from 11-15 years. Twenty-eight (63.6%) were female and 19 (43.2%) leukodermic. The first evidence of leukocoria was observed by the mother in 17 patients (38.6%). Leukocoria was observed in the first 2 months of life in 45.5% of the patients; phacectomy was performed in 43.2% of the patients with more than 1 year of age. Optic prescription was performed in 61.4% of the cases with 9.1% of the patients below 1 year of age. Intraocular lens was implanted in 13.6% and 4 patients (9.1%) had a family history of congenital cataract. In 20.4% VA was lower than 20/400 and secondary glaucoma was observed in 18.2% of the cases. Low vision aids included two glasses and one telescope. CONCLUSION: More information about congenital cataract should be provided for families and pediatricians, and early surgical treatment, optic correction and treatment of amblyopia should be performed promptly.

Adolescent↗
PubMed2004

2002 global update of available data on visual impairment: a compilation of population-based prevalence studies.

PURPOSE: For the past 25 years, the WHO Programme for the Prevention of Blindness and Deafness has maintained a Global Data Bank on visual impairment with the purpose of storing the available epidemiological data on blindness and low vision. The Data Bank has now been updated to include studies conducted since the last update in 1994. METHODS: An extensive literature search was conducted in international and national scientific and medical journals to identify epidemiological studies that fulfilled basic criteria for inclusion in the Data Bank, namely a clearly stated definition of blindness and low vision, and prevalence rates derived from population-based surveys. Sources such as National Prevention of Blindness Programmes, academic institutions or WHO country or regional reports were also investigated. RESULTS: Two-hundred-and-eight population-based studies on visual impairment for 68 countries are reported in detail, providing an up-to-date, comprehensive compilation of the available information on visual impairment and its causes globally.

Adolescent↗
PubMed2001

Development of the 25-item National Eye Institute Visual Function Questionnaire.

OBJECTIVE: To develop and test the psychometric properties of a 25-item version of the National Eye Institute Visual Function Questionnaire (NEI VFQ-25). DESIGN: Prospective observational cohort study of persons with 1 of 5 chronic eye diseases or low vision who were scheduled for nonurgent visits in ophthalmology practices and a reference sample of persons without eye disease. SETTING: Eleven university-based ophthalmology practices and the NEI Clinical Center. PATIENTS: Eligible participants had to have 1 of the following eye conditions: age-related cataracts, age-related macular degeneration, diabetic retinopathy, primary open-angle glaucoma, cytomegalovirus retinitis, or low vision from any cause. Seven of the 12 sites also enrolled persons in a reference sample. Reference sample participants had no evidence of underlying eye disease but were scheduled for either screening eye examinations or correction of refractive error. All eligible persons had to be 21 years or older, English speaking, and cognitively able to give informed consent and participate in a health status interview. MEASUREMENTS AND MAIN RESULTS: To provide the data needed to create the NEI VFQ-25, all subjects completed an interview that included the 51-item NEI VFQ. Estimates of internal consistency indicate that the subscales of the NEI VFQ-25 are reliable. The validity of the NEI VFQ-25 is supported by high correlations between the short- and long-form versions of the measure, observed between-group differences in scores for persons with different eye diseases of varying severity, and the moderate-to-high correlations between the NEI VFQ-25 subscales that have the most to do with central vision and measured visual acuity. CONCLUSIONS: The reliability and validity of the NEI VFQ-25 are comparable to those of the 51-item NEI VFQ field test version of the survey. This shorter version will be more feasible in settings such as clinical trials where interview length is a critical consideration. In addition, preliminary analyses indicate that the psychometric properties of the NEI VFQ-25 are robust for the eye conditions studied; this suggests that the measure will provide reproducible and valid data when used across multiple conditions of varying severity.

Chronic Disease↗
PubMed2001

Determinants of locomotor disability in people aged 55 years and over: the Rotterdam Study.

Locomotor disability, as defined by difficulties in activities of daily living related to lower limb function, can be the consequence of diseases and impairments of the cardiovascular, pulmonary, nervous, sensory and musculoskeletal system. We estimated the associations between specific diseases and impairments and locomotor disability, and the proportion of disability attributable to each condition, controlling for age and comorbidity. The Rotterdam Study is a prospective follow-up study among people aged 55 years and over in the general population. Locomotor disability in 1219 men and 1856 women was assessed with the Stanford Health Assessment Questionnaire. Diseases and impairments were radiological osteoarthritis, pain of the hips and knees, morning stiffness, fractures, hypertension, vascular disease, ischemic heart disease, stroke, heart failure, chronic obstructive pulmonary disease (COPD), depression, Parkinson's disease, osteoporosis, diabetes mellitus, overweight, and low vision. Adjusted odds ratios, etiologic and attributable fractions were calculated for locomotor disability. The occurrence of locomotor disability can partly be ascribed to joint pain, COPD, morning stiffness, diabetes and heart failure in both men and women. In addition in women osteoarthritis, osteoporosis, low vision, fractures, stroke and Parkinson's disease are significant etiologic fractions. In men with morning stiffness, joint pain, heart failure, diabetes mellitus, and COPD a significant proportion of their disability is attributable to this impairment. In women this was the case for Parkinson's disease, morning stiffness, low vision, heart failure, joint pain, diabetes, radiological osteoarthritis, stroke, COPD, osteoporosis, and fractures of the lower limbs, in that order. We conclude that locomotor complaints, heart failure, COPD and diabetes mellitus contribute considerably to locomotor disability in non-institutionalized elderly people.

Activities of Daily Living↗
PubMed1997

Blindness in glaucoma patients.

In order to determine the risk for bilateral blindness from glaucoma and to which extent other diseases are responsible for the disability, the registers of low vision clinics were surveyed. All registered patients still alive in 1991 with the diagnosis of glaucoma were included. Eighteen hundred and ninety-five patients fulfilled these criteria. Blindness was defined as bilateral visual acuity < or = 0.1. The majority of the patients (68%) had a visual acuity better than 0.1. The remaining 590 patients had a visual acuity < or = 0.1. In this latter group glaucoma was the reason for the low visual acuity in 20%, glaucoma in combination with other eye diseases in 35% and other eye diseases in 44%. Macular degeneration and cataracts were the main causes of the low vision in the latter group. The prevalence of glaucoma blindness in the Stockholm region was found to be 0.007% for glaucoma and 0.020% for glaucoma in combination with other eye diseases.

Aged↗