PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Visual Acuity”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 883 records · Page 49Linked to original sources
PubMedDate not supplied

Assessing responses of the macula in patients with macular holes using a new system measuring localized visual acuity and the mfERG.

PURPOSE: To evaluate acuity and multifocal electroretinogram (mfERG) responses from the macula in affected and unaffected fellow eyes of patients with macular holes. METHODS: We tested 10 eyes with macular hole and 10 fellow eyes from 11 patients. We measured local visual acuity thresholds at 27 discrete locations within 21 degrees diameter using the Functional Fundus Imaging System (FFIS), a psychophysical system that measures visual acuity as a function of visual field location, and local ERG responses within 45 degrees diameter using the mfERG. RESULTS: In the affected eyes, the mean FFIS visual acuity thresholds were significantly elevated within the central 21 degrees diameter area, compared to a group of control eyes. No significant differences were found between the acuities of the fellow eyes compared to those of the control group. The amplitudes of the first positive peak of the mfERG were reduced in the central 7.8 degrees in affected eyes. In the central 2 degrees , 4 out of 10 affected eyes showed non-measurable ERG signals. The remaining six eyes showed significantly reduced mean amplitudes, but not delayed implicit times, when compared to the control group. For the fellow eyes, the mean amplitudes of the mfERG and implicit times did not differ from the means of the control eyes. CONCLUSIONS: Both local psychophysical and electrophysiological testing demonstrated retinal dysfunction extending beyond the site of the macular holes in some patients (three of the patients had central mfERG amplitudes falling within the normal range).

Aged↗
PubMed1989

[Assessment of visual acuity in simulation and aggravation].

Following a review of various tricks and techniques described in the literature for measuring the visual acuity of less cooperative patients, three new methods are presented. The first is based on the so-called "preferential-looking" method, which has been in use for several years to determine the visual acuity of infants and small children. The second method uses polarizing filters to separate the beam paths of the two eyes and a flashlamp to project the test symbols, to prevent the patient from finding out by blinking which eye is being tested. In the third method the stimuli are presented on a computer monitor; the beam paths of the two eyes are separated by special spectacles which can briefly cover either eye while a test symbol is being shown. The results so far are encouraging.

Humans↗
PubMed2004

[Reduction of astigmatism after perforating keratoplasty by adjustment of single running sutures and its influence on visual acuity].

The authors assess the outcomes of postkeratoplasty single running suture adjustment in 14 eyes (16 adjustments) of 14 patients (4 women, 10 men). The average age of patients was 39.68 year (ranging from 19 to 70 years). The suture adjustment was done in time span 2 to 39 weeks following after perforating keratoplasty (PKP), average 7.5 weeks. Follow up time was from 1 to 12 months, average 10.8 months. The value of keratometric and topographic astigmatism before suture adjustment were compared to the value of keratometric and topographic astigmatism 1, 6 and 12 months after suture adjustment. The changes of corneal refractive power and changes of uncorrected and best-corrected visual acuity were noticed as well. The mean value of keratometric astigmatism 7.47 +/- 2.69 D and mean topographic astigmatism 7.75 +/- 3.25 D before suture adjustment was decreased to 4.92 +/- 2.41 D and 4.83 +/- 1.46 D respectively one month after suture adjustment. These reductions of keratometric and topographic astigmatism (2.55 D and 2.92 D respectively) were statistically significant (p = 0.0416, and p = 0.0211 respectively). The mean keratometric astigmatism was still significantly lower (p < 0.05) after 6 and 12 months after suture adjustment in comparison to status before suture adjustment. In assessment of topographic changes we noticed small continuous increasing of astigmatism (1.27 D after 6 months and 0.2 D after 12 months after suture adjustment). These changes of topographic astigmatism were not statistically significant. The changes of mean corneal refractive power were not statistically significant as well. The mean uncorrected visual acuity increased significantly (from 0.13 to 0.34, p < 0.05) 1 month after suture adjustment. This improvement of uncorrected visual acuity was not significant after 6 and 12 months after suture adjustment. The best-corrected visual acuity improved from 0.37 to 0.61 after one month after suture adjustment but was not statistically significant and stayed still at the same level with minimal changes during follow up time.

Adult↗
PubMedDate not supplied

Measuring visual acuity--mesopic or photopic conditions, and high or low contrast letters?

PURPOSE: To develop single-valued wavefront aberration metrics that correlate strongly with visual performance. The purpose of this study is to explore whether photopic high contrast visual acuity (VA) is an appropriate visual performance reference and whether mesopic and/or low contrast testing provides any advantage. METHODS: Subjects from the Texas Investigation of Cataract Optics study (N = 148) ranged in age from 21.6 to 83.8 years and from clear lens to dense nuclear cataract. Visual acuity was measured under four conditions: photopic high (VA(PHC)) and low (VA(PLC)) contrast, mesopic high (VA(MHC)) and low (VA(MLC)) contrast (photopic = 280 cd/m(2), mesopic = 0.75 cd/m(2)). Variables were tested for compliance with normality (-2.00 < skew and kurtosis < 2.00) and transformed if required. Linear regression and Bland-Altman 95% limits of agreement (+/-1.96 SD) were used to examine relationships between VA variables and between VA and wavefront aberration metrics. RESULTS: The two photopic measures VA(PHC) (skew = 2.57, kurtosis = 12.2) and VA(PLC) (1.67, 5.41) were poorly distributed, but the two mesopic measures VA(MHC) (0.88, 1.67) and VA(MLC) (0.29, -0.18) were normally distributed. Strong correlations existed between the (transformed) VA variables (R: 0.53 to 0.84). However, limits of agreement ranged over 0.30 to 0.42 logMAR, whereas retest data suggested a range of 0.15. All four were offered in stepwise multiple linear regression for 30 wavefront metrics: 20 included VA(MLC) alone, two included VA(PLC), two included VA(MHC) and six included both VA(MLC) and VA(MHC); R(2) averaged 25%. CONCLUSION: Although strongly correlated, low contrast and/or mesopic VA testing provides different information. Wave aberration metrics correlates better with VA(MLC) making this the visual performance test of choice.

Adult↗
PubMed2003

[Loss of visual acuity due to choroidal ischemia in Fabry's disease].

We report a case of a 21-year-old man with Fabry's disease who presented with a sudden decrease in visual acuity to 20/200 in the left eye. Pale areas with a lobular choroidal distribution were seen on fundus examination. No retinal vascular causes were found on further evaluation. With anticoagulation treatment, the patient's subsequent course was good, with visual recovery to 20/25 and normalization of the funduscopic appearance. Recovery of both visual acuity and the pale, lobular areas suggested a choroidal etiology, probably ischemic because of the sudden onset. Choroidian ischemia is therefore a cause of visual acuity loss in Fabry's disease, so far not described in the literature.

Adult↗
PubMed1991

Measurement of visual acuity with logarithmic charts: comparison between methods of threshold estimation.

The variability of the repetition of visual acuity measurements with a log MAR acuity chart with five optotypes in each row of acuity was studied in four groups of subjects. In three groups the threshold was calculated by probability of seeing curves, but the optotypes were read in different orders. For the fourth group the acuity was taken as the smallest row discriminated. Estimating the threshold by a probability of seeing curve did not improve the threshold's stability. Poorer acuity was detected when the optotypes were read vertically. It is suggested that clinical visual acuity charts are not suitable tools for generating data points to be fitted by probability of seeing curves.

Adolescent↗
PubMed2005

[Visual acuity after surgical management of ciliary body melanoma].

The aim was to evaluate the visual acuity after transcleral resection of ciliary body melanoma. 42 patients were treated by trans-scleral resection of melanoma between January 1995 and June 2001. Additional rutenium brachytherapy was performed in 29 cases. Cataract surgery and intraocular lens implantation was necessary in 7 cases. Postoperative filtration bleb appeared in 6 eyes. The evaluation of functional results has shown no impairment of visual acuity in 56% of cases and did not change during follow up. These observations show that functional results after trans-scleral resection with additional brachytherapy are satisfactory and stable during follow-up.

Adult↗
PubMed2003

How sensitive to clinical change are ETDRS logMAR visual acuity measurements?

PURPOSE: To determine the sensitivity to change and specificity achieved when published test-retest variability (TRV) data are used to determine whether measured changes in ETDRS logarithm of the minimum angle of resolution (logMAR) visual acuity reflect true clinical change or are attributable to measurement error alone. METHODS: Various degrees of change in visual acuity were simulated in a group of normal subjects by adjusting test difficulty through manipulation of viewing distance. Sensitivity to simulated change and specificity were determined with change criteria derived from published Bland-Altman 95% ranges for TRV. RESULTS: The relationship between viewing distance and measured acuity was as predicted theoretically. Simulated acuity change of 0.2 logMAR (two lines of letters) or greater can be reliably distinguished from no change (both sensitivity and specificity >95%) with the ETDRS chart, but a change of 0.1 logMAR or less cannot. CONCLUSIONS: The use of 95% ranges for TRV to establish the smallest measured visual acuity change that can be reliably detected ensures a high specificity but does not take account of sensitivity. Use of change criteria derived from published 95% ranges results in a sensitivity of approximately 50% (assuming identical levels of TRV). Sensitivity may be improved by using a change criterion that is smaller than the minimum change sought, providing the change criterion is still at least as large as the 95% range for TRV, so that specificity is maintained. Reducing TRV allows smaller changes in acuity to be reliably detected.

Humans↗
PubMed2005

Comparison of mean macular thickness using optical coherence tomography and visual acuity in diabetic retinopathy.

BACKGROUND: The purpose of the present study was to quantitatively assess the mean macular thickness in diabetic patients using optical coherence tomography and its correlation with visual acuity. METHODS: A prospective case series study was undertaken of consecutive diabetic patients referred to a tertiary eye care centre for an eye check up from January 2003 to June 2003. One hundred and five eyes from 55 patients with varying degree of diabetes underwent optical coherence tomography examination. The study patients were divided into four groups: group I, non-proliferative diabetic retinopathy (NPDR); group II, NPDR with clinically significant macular oedema (CSME); group III, proliferative diabetic retinopathy (PDR); and group IV, PDR with CSME. RESULTS: The mean macular thickness of the entire group was 256.0 +/- 129.7 microm. A positive correlation (r = 0.424, P < 0.0001) was evident between mean macular thickness and visual acuity. CONCLUSION: Optical coherence tomography is a useful tool for objectively monitoring macular thickness in patients with diabetic retinopathy. Mean macular thickness correlates with visual acuity.

Adult↗
PubMed2002

Changes in visual acuity from 4 to 12 years of age in children operated for bilateral congenital cataracts.

AIMS: To investigate the long term effects of age at surgery on the development of visual acuity (VA) by measuring VA from preschool age to puberty. Furthermore, to report the VA levels at 12 years of age in a geographically based cohort of operated congenital bilateral cataracts. METHODS: All children born in four western counties of Sweden between January 1980 and December 1993 who were diagnosed with congenital cataracts were included in a longitudinal prospective study. The monocular VA of the better eye in 38 subjects was analysed at 4, 7, 10, and 12 years of age, with 20 total and 18 partial cataracts. The mean follow up time was 9.3 years after surgery. RESULTS: The final value of VA was 0.4 or above for approximately 50% of the subjects at 12 years of age. Visual acuity improved to a considerable extent after school age, especially in children who underwent surgery between the ages of 7 weeks and 1 year. Results for partial cataracts were favourable compared to those for total cataracts, reaching a mean of approximately 0.5 at age 12. The mean VA in the group of total congenital cataracts operated on before 7 weeks of age achieved higher values of VA at 4 years of age compared to children with total cataracts operated on between 7 weeks and 1 year of age. However, no statistically significant difference in VA results among these groups could be proved. CONCLUSION: Visual acuity improves to a considerable extent after school age in children with delayed visual development caused by congenital cataracts. Surgery within 7 weeks results in a more rapid development of VA, initially.

Age Factors↗
PubMed2000

Prevalence of usual-corrected distance visual acuity impairment in Hispanic and non-Hispanic children and adolescents.

Data from the Hispanic Health and Nutrition Examination Survey and the National Health and Nutrition Examination Survey I were analysed to determine the prevalence of visual acuity impairment among US Hispanics and non-Hispanics aged 6-19 years. The prevalence of 20/30 or worse distance visual acuity with usual or habitual correction ranged from 10.8% in non-Hispanic whites to 19.1% in Puerto Ricans. Puerto Rican boys aged 13-19 years had significantly greater rates of moderate or greater impairment (20/70 or worse) than 6-12-year-old Puerto Rican boys (5.7% vs. 0.7%). The prevalence of visual impairment was generally greater in girls than in boys. Assessment and comparison of refractive error and eye disease prevalence rates are necessary in future studies to determine factors influencing prevalence of visual acuity impairment in children.

Adolescent↗
PubMed1986

Instruments for predicting visual acuity. A clinical comparison.

A series of 54 eyes in 50 patients had preoperative predictions of postoperative visual acuity, using both a white-light interferometer (Lotmar Visometer) and a Snellen chart projector (Guyton-Minkowski Potential Acuity Meter). The predicted vision by each instrument was compared with the actual postoperative vision. Forty eyes in 36 of these patients, 25 with concurrent eye disease, had cataract extraction with intraocular lens implantation. Fifteen eyes in 15 patients, 11 with concurrent eye disease, had neodymium-YAG laser posterior capsulotomy. The Visometer gave more accurate predictions than the Potential Acuity Meter in cataract patients with open angle glaucoma, even with glaucomatous visual field loss, and in patients with a visual acuity of less than 20/400 due to advanced cataract formation.

Adult↗
PubMed1994

Visual acuity after radiation for orbital rhabdomyosarcoma.

PURPOSE/METHODS: We reviewed follow-up data on 32 patients with orbital rhabdomyosarcoma, who were treated with external beam radiation with and without adjunctive chemotherapy between 1960 and 1992. RESULTS/CONCLUSIONS: Patients were followed up from five to eight years. Of the 32 patients, six (19%) had best-corrected visual acuity of 20/70 or better; five patients (15%) had best-corrected visual acuity of light perception to 20/300; 21 patients (66%) had no light perception. The reported long-term visual acuities should be factored in the equation for selecting treatment for patients with orbital rhabdomyosarcoma.

Combined Modality Therapy↗
PubMed2000

Improvement of visual acuity over time in patients with bilateral geographic atrophy from age-related macular degeneration.

PURPOSE: To study the improvement in visual acuity over time in patients with central scotomas. METHODS: In a prospective natural history study of geographic atrophy (GA) from age-related macular degeneration (ARMD) with annual follow-up, 36 patients with bilateral GA completed 3 years of follow-up. Protocol visual acuity (VA) measurements were performed. Scanning laser ophthalmoscopy (SLO) was performed, and the areas of GA were measured from fundus photographs. RESULTS: Six eyes of six patients with VA ranging from 20/80 to 20/500 had a VA improvement of two or more lines (mean, 3.2 lines). This was found only in the worse-seeing eyes of the patients and was contemporaneous with the deterioration in VA of the better-seeing eyes. Four of six eyes that improved in acuity had an improvement in the ability to find and hold the fixation target in an area of seeing retina, as assessed by SLO at follow-up, and a fifth eye changed from one fixation site that had little functional retina to another site. CONCLUSIONS: Spontaneous improvement in VA in eyes with bilateral GA and central scotomas may occur. It appears to be related to deterioration in VA of the better-seeing fellow eye and is associated with improvement of fixation in the worse-seeing eye. The worse-seeing eye of a patient with bilateral ARMD may have the potential for better vision than measured VA indicates. This finding may have implications for the choice of patients in treatment trials, for interpretation of long-term results, and for planning and assessment of low vision intervention.

Aged↗
PubMed1999

Behavioural visual acuity of wild type and bcl2 transgenic mouse.

Since the advent of gene manipulating techniques, it has become increasingly important to study the neural functional properties of the mouse. The bcl2 gene has a powerful inhibitory action on naturally occurring cell death. As a consequence the brain of bcl2 overexpressing mouse is 1.5 times bigger than the brain of a wild type animal and the retina has more than twice the ganglion cells than normal (Martinou, Dubois-Dauphin, Staple, Rodriguez, Frankowski, Missotten, Albertini, Talabot, Catsicas, Pietra, & Huarte (1994). Neuron, 13: 1017-1030). Since in most mammals the upper limit of behavioural visual acuity is imposed by ganglion cells density, the visual acuity should be higher in bcl2 mice than in wild type mice. We measured behavioural visual acuity in wild type and transgenic mice and, contrary to the expectation, we found it to be of the same order (0.5-0.6 c/deg) in the two groups of animals, indicating that an increase in ganglion cells density is not effective in improving visual resolution.

Animals↗
PubMedDate not supplied

P.C. Sen Memorial best paper award on rural health practice: A study on visual acuity and vitamin A deficiency among primary school students in Naxalbari Village, Darjeeling district of West Bengal.

331 primary school students studying from Nursery classes to Class IV in 2 randomly selected schools in Naxalbari Village in Darjeeling district of West Bengal were tested for visual acuity (VA), Vitamin A deficiency (VAD) and Bitot's spot. 329 students could be tested for visual acuity whereas all 331 students were tested for VAD and Bitot's spot. The prevalence of abnormal Visual Acuity (VA) (VA < 6/9 in any eye) in this study group was 3.65% and it was highest in 7-8 years age group in both the sexes contributing to 75% of the total students having abnormal VA. All these children fell within 50th percentile of weight and height for their respective age and sex. Hindu & ST children accounted for 91.67% & 50% abnormal VA respectively; however, when presence of abnormal VA was compared with its absence between 2 sexes, Hindu and Muslim students and in different castes, no statistically significant differences were found (p > .05). Students of Class-I and Class-II contributed 25% and 50% respectively and together accounted for 75% of abnormal VA. Prevalence of VAD was 8.16%. Among sufferers of VAD Hindus (81.48%) and ST (51.85%) were the main contributors; the differences between presence and absence of VAD in 2 sexes, among 3 religious groups were not statistically significant (p > .05); however, differences among ST and NonSCST groups, and again SC, ST and Non-SCST groups were statistically significant (p < .05). Prevalence of Bitot's spot was 3.63%. Among the students having Bitot's spot, females (58.33%) outnumber the males (41.67%); but the difference between presence and absence of Bitot's spot in 2 sexes was not statistically significant (p > .05). 83.33% each of Hindus and STs had Bitot's spot. No SC and no Muslim student had this spot; the differences between presence and absence of Bitot's spot between Hindu and Christian students were statistically significant (p < .01); similarly when the findings were considered between ST and NonSCST students the difference was found to be statistically highly significant (p < .001).

Child↗
PubMed1987

Visual acuity loss in rhesus monkey infants fed a taurine-free human infant formula.

This study examined the effects of dietary taurine deprivation on visual development in rhesus monkeys. From birth to 3 months of age, rhesus monkeys were fed a taurine-free, soy protein-based infant formula, or the same formula supplemented with taurine. The early postnatal development of visual function was assessed with behavioral measurements of visual acuity. Plasma taurine levels in the taurine-deprived group fell to 35-50% of control values, as in human infants fed similar formulas. The visual acuity of the taurine-deprived infants was significantly impaired: acuity thresholds differed from control values by nearly a factor of 2 at 4, 8, and 12 weeks of age. The loss of acuity is associated with morphological changes in photoreceptors, particularly cones in the foveal region. These results provide direct evidence that taurine is essential for normal visual development in primates, and they support the nutritional importance of taurine for human infants.

Age Factors↗