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At least 271 records · Page 15Linked to original sources
PubMed1998

[Low Vision Enhancement System (LVES). Initial clinical experiences with a new kind of optoelectronic rehabilitation system].

BACKGROUND: The Low-Vision-Enhancement-System (LVES) is the first binocular optoelectronic rehabilitation device with variable focus distance. METHOD: LVES was attempted on 25 patients who were not adequately treatable with classic rehabilitation devices. Using the new device, short-distance vision as well as the ability to read and write were tested. RESULTS: In six patients, a significant improvement was achieved using LVES. In these patients, short-distance vision as measured by LVES varied from 0.63 to 1.0. All succeeded in reading fluently, and five patients, in writing. Of these patients, five suffered from large central scotomas due to macular disease, and one female patient, from post-traumatic optic nerve atrophy. In 10 patients, near-sighted vision could be improved although the ability to read and write could not be restored, while nine patients did not show any benefit. In the latter group, were four patients with retinopathia pigmentosa, who complained of the further reduction in visual field due to the system. CONCLUSION: LVES is an additional device for the rehabilitation of low-vision patients which is especially useful in cases of macular diseases.

Adult↗
PubMed1994

Low vision reading with sequential word presentation.

Individuals with scotomas in the center of their visual fields usually read much more slowly than visually impaired individuals without central scotomas. This study determines the extent to which inefficient eye movements could account for this difference. Using a technique described previously [Rubin and Turano (1992) Vision Research, 32, 895-902] text was presented sequentially, one word at a time at the same location in the visual field. Reading performance for rapid serial visual presentation (RSVP) was compared to conventional text presentation (PAGE) in 14 subjects with dense central scotomas (central field loss, CFL) and 9 without central scotomas (noCFL). Reading rates were faster with RSVP compared to PAGE, but CFL subjects improved less (by a factor of 1.5 +/- 0.41) than noCFL subjects (by a factor of 2.1 +/- 0.38). When reading rate (words/min) was converted to average word duration (msec/word) the reduction in word duration for RSVP compared to PAGE text averaged 150 msec for normal subjects, 171 msec for noCFL subjects, and 250 msec for CFL subjects. We hypothesized that the reduction in word duration was attributable to a reduced number of saccades/word. We confirmed this hypothesis by measuring the number of saccades during RSVP and PAGE reading using a scanning laser ophthalmoscope in four subjects with CFL. All of the subjects made fewer saccades during RSVP than PAGE reading (average reduction = 1.3 +/- 0.5 saccades/word). But even with the reduced number of saccades, CFL subjects required longer word durations than noCFL subjects. These results indicate that inefficient eye movements account for only part of the reduction in reading speed caused by CFL. An additional and potentially more important factor is the limited rate at which peripheral retina can perform the pattern decoding tasks required for reading.

Aged↗
PubMed2004

Prevalence of refractive error in Bangladeshi adults: results of the National Blindness and Low Vision Survey of Bangladesh.

PURPOSE: To determine the prevalence of refractive errors and to investigate factors associated with refractive error in adults 30 years of age and older in Bangladesh. DESIGN: Cross-sectional study. PARTICIPANTS: A nationally representative sample of 12 782 adults 30 years of age and older. METHODS: The sample of subjects was selected based on multistage, cluster random sampling with probability-proportional-to-size procedures. The examination protocol consisted of an interview that included measures of literacy, education, occupation, and refractive correction. Visual acuity testing (logarithm of the minimum angle of resolution [logMAR]), automated refraction, and optic disc examination were performed for all subjects. Subjects with <6/12 (0.3 logMAR) acuity in either eye were graded additionally for cataract and underwent a dilated fundal examination. Subjects for whom no refractive error was recorded (312 subjects; 2.7%) or who had undergone cataract surgery (123 subjects; 1.1%) were excluded from the analysis. MAIN OUTCOME MEASURES: Refractive error and socioeconomic variables (literacy, education, occupation). RESULTS: Eleven thousand six hundred twenty-four subjects were examined (90.9% response rate; mean age+/-standard deviation, 44+/-12.6 years). Five thousand four hundred eighty-nine subjects (49.1%) were men and 5700 subjects (50.9%) were women. Mean spherical equivalent was -0.19 diopters (D; +/-1.50 D). Six thousand four hundred twelve subjects (57.3%) were emmetropic, 2469 (22.1%) were myopic (<-0.5 D), and 2308 (20.6%) were hypermetropic (>+0.5 D). Two hundred six subjects (1.8%) were highly myopic (<-5 D). Myopia was more common in men (26.3%) than in women (21.0%), whereas hyperopia was more common in women (27.4%) than in men (15.8%). Overall, myopia increased with age (17.5% of those aged 30-39 years were myopic, compared with 65.5% of those age 70 years and older). A subanalysis of subjects without cataract showed increasing hyperopia with age and an association between myopia and higher education. Myopia was more common among the employed than in unemployed subjects. Astigmatism (>0.5 D), present in 3625 subjects (32.4%), was more common among women, illiterate subjects, and unschooled subjects. Against-the-rule astigmatism was more common (58.7%) than oblique astigmatism (29.3%), which was more common than with-the-rule (WTR) astigmatism (12.1%). Against-the-rule astigmatism and oblique astigmatism increased with age, unlike WTR astigmatism. Of 830 (7.5%) subjects, women were more commonly anisometropic (>1.0 D). Anisometropia increased with age. CONCLUSIONS: Refractive error data are described for a country and region that previously have lacked population-based data. Prevalence and factors associated with refractive error are presented, with a detailed comparison with other population-based surveys regionally and internationally.

Adult↗
PubMed2006

The prevalence of low vision and blindness in a Canadian inner city.

PURPOSE: To ascertain the prevalence and primary causes of visual impairment in a sample of patients from Vancouver's downtown eastside (VDES). MATERIALS AND METHODS: A total of 200 patients seeking nonophthalmic medical care at the Vancouver Native Health Society (VNHS) clinic in Vancouver's inner city (downtown eastside) participated in this observational case-series study. For each participant, we obtained demographic information, a medical and ocular history, and performed a complete eye exam. The prevalence of visual disability using standard North American criteria was reported. Causes of visual loss were also reported based on Canadian National Institute for the Blind (CNIB) guidelines. RESULTS: A total of 200 patients participated in our study. The median age of our sample was 46 years, 69% were male. There were very high rates of comorbid medical conditions including HIV, Hepatitis B/C, IV drug use, and diabetes. The raw prevalence of visual disability based on best-corrected visual acuity (BCVA) was 500 per 10,000; this was over nine times greater than in the general Canadian population. The raw prevalence rate of 'presenting visual disability' based on presenting visual acuity (PVA) was 2400 per 10,000. Major causes of visual disability were cataract and retinal disease. Although age-related macular degeneration and diabetic retinopathy represent major causes of vision loss in North America, no cases were noted in our sample. CONCLUSION: The overall prevalence of visual disability was alarmingly high in this disadvantaged community. These results identify both ophthalmic disease and access to refraction and prescription spectacles as a significant health concern among people living in the VDES.

Adolescent↗
PubMed1997

[The low vision cyclist: handicapped orientation and assessment with the nystagmogram].

BACKGROUND: Visually impaired individuals who are unable to obtain a driving licence may use a bicycle and feel fit for traffic as part of this "bio-physical model". MATERIALS AND METHODS: Five nystagmic amblyopes who claimed to ride a bicycle were tested in respect to visual acuity, peripheral vision and oculomotor functions. In three of these cases visual acuity amounted to 0.3, in one to 0.6, in another one only to 1/35. Eye movements were recorded by electro-oculography. The following qualities of gaze were determined: Fixation-saccadic eye movements-pursuit eye movements-behaviour in light and dark-vestibulo-optokinetic movements-eye positioning in resting states and influence of mood. RESULTS: In four of the cases oculomotor regularities were found. These were explained to the patients. One of the cases was affected with a form of chaotic nystagmus. CONCLUSION: Bicycling demands on both the vestibular and the visual system. Deficiencies relevant to behaviour in traffic and the possibilities to compensate for these may be estimated based on a oculographic evaluation. This should therefore be used to advise bicyclists with a visual impairment.

Adolescent↗