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Results for “Visual Acuity”

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PubMedDate not supplied

Visual acuities after levodopa administration in amblyopia.

PURPOSE: To investigate the effect of the augmentation of levodopa with part-time and full-time occlusion on visual acuity and to determine its late results in amblyopia. METHODS: Seventy-two patients with amblyopia were prospectively studied and randomly distributed into groups A, B, and C consisting of 24 patients each. Group A patients received levodopa alone, group B received levodopa and part-time (3 hours/day) occlusion, and group C received levodopa and full-time (during all waking hours) occlusion of the dominant eye. Levodopa 0.50 mg/kg body weight, with a 25% fixed dose combination of carbidopa, was administered orally three times a day for 7 weeks. Snellen visual acuity and its logMAR equivalent were recorded before treatment, at weeks 1, 3, 5, and 7 after starting treatment, and every 6 weeks for 1 year after the completion of treatment. RESULTS: Fifty-three (74%) of the 72 patients had an improvement in visual acuity after treatment. Forty-four of the 53 patients with improved visual acuities completed 1-year post-treatment follow-up. Twenty-three (52%) of the 44 patients had a regression in visual acuity. CONCLUSION: The augmentation of levodopa with part-time or full-time occlusion does not enhance the recovery of vision in amblyopia. Improved visual acuity after levodopa administration persists at least 1 year in almost half of patients after cessation of treatment. Addition of full-time occlusion to levodopa helps maintain improved visual acuity for a longer duration compared to levodopa alone or combined with part-time occlusion.

Administration, Oral↗

PubMed2004

See clearly: suggestion, hypnosis, attention, and visual acuity.

Some reports claim that positive suggestion (e.g., using hypnosis) can significantly improve visual acuity (e.g., in myopes). Based on behavioral, neurocognitive, and ophthalmological findings, the authors provide a critical account to review and challenge some of these data. While acknowledging the relative merits of hypnosis for investigating visual phenomena, an array of arguments converges to propose caveats to the apparent influence suggestion can exert on visual acuity. The authors argue that neither suggestion nor hypnotic phenomena are likely to significantly improve myopic vision and contend that a responsible scientific attitude should carefully outline what hypnosis and suggestion cannot do in addition to what they can. It seems likely that the small apparent influence of suggestion on visual acuity is mediated by changes in attention. The authors outline how attention can affect visual acuity.

Attention↗

PubMed1978

Visual acuity in hard and soft contact lens wearers: a comparison.

Visual acuity measurements with spectacles, with hard contact lenses and with hard contact lenses plus overrefraction were made on 75 eyes. Similar data was taken on 75 eyes wearing soft contact lenses. In each case, some eyes showed a decrease in visual acuity with contact lenses but the soft lenses wearers showed a greater percentage of eyes with visual acuity decrease.

Contact Lenses↗

PubMed2004

A new source of variance in visual acuity.

In an ocularly healthy population, decimal visual acuities range from 1 to 3. We wondered how this spread can be understood. Using a maximum likelihood adaptive procedure, "visual acuity" was measured in a healthy population with four stimulus sets: unblurred Landolt Cs and Cs blurred with a Gaussian of width sigma = 2.12', 4.24' and 8.48'. A simple model based on scale invariance of the visual system was applied. This model was tested by predicting the outcomes of the 2.12' measurements based on the other measurements. The minimum angle of resolution (MAR) values found are closely proportional to "equivalent blur" of the stimulus defined as the convolution of a value for intrinsic blur of the eye and added blur. The proportionality factor is different between individuals and is an important source for the spread in acuities found in a healthy population. The differences between the proportionality factors are interpreted as differences in the (neuronal) judgment capability between individuals. The total standard deviation of log(MAR) found in our study was 0.11. This value can be subdivided in 0.06 for the (neuronal) judgment capability, 0.08 for the intrinsic retinal blur and a measurement accuracy of 0.04.

Adolescent↗

PubMed1999

Functional complaints, visual acuity, spatial contrast sensitivity, and glare disability in preoperative and postoperative cataract patients.

PURPOSE: To quantify cataract patients' functional visual complaints and correlate them with their objective glare disability and spatial contrast sensitivity (SCS) scores. SETTING: Sir Mortimer B. Davis Jewish General Hospital. Montreal, Quebec, Canada. METHODS: Thirty patients scheduled for cataract surgery with a visual acuity of 20/70 or better at the time of patient selection and no other ocular pathology were evaluated objectively and subjectively for visual function preoperatively and within 3 months postoperatively. Objective measures of SCS and visual acuity in the presence and absence of glare were obtained with the Optec 3000 vision tester. Subjective visual function was evaluated with the Activities of Daily Vision Scale (ADVS), a questionnaire that evaluates patients' visual function by assessing the degree of difficulty they experience in performing tasks involving distance vision, near vision, and glare conditions. RESULTS: Preoperatively, patients had decreased visual acuity and SCS in the presence of glare. The ADVS scores were correlated with visual performance. Postoperatively, there was a statistically significant improvement in all dependent measures (i.e., visual acuity and SCS in the presence of glare) as well as in the subjective report of visual performance assessed by the ADVS. CONCLUSION: Spatial contrast sensitivity, glare disability, and the ADVS questionnaire should be considered as adjuncts to visual acuity testing in evaluating certain cataract patients.

Adult↗

PubMed1998

Prevalence of uncorrected binocular distance visual acuity in Hispanic and non-Hispanic adults. Results from the HHANES and the NHANES I.

OBJECTIVE: This study aimed to provide a comparative analysis of American population-based prevalence of uncorrected binocular distance visual acuity in Hispanics and non-Hispanics. DESIGN: The study design was a population-based survey. PARTICIPANTS: Data from the Hispanic Health and Nutrition Examination Survey between 1982 and 1984 and the National Health and Nutrition Examination Survey I from 1974 through 1975 were analyzed to investigate the epidemiology of uncorrected binocular distance visual acuity in adults 25 to 74 years of age in Cuban Americans (N = 391), Mexican Americans (N = 1350), Puerto Ricans (N = 504), African Americans (N = 245), and non-Hispanic white Americans (N = 2571). MAIN OUTCOME MEASURE: Uncorrected binocular distance visual acuity in both eyes was assessed using Sloan letters or Landolt rings. RESULTS: Prevalence rates of 20/50 or worse uncorrected binocular distance visual acuity were 22%, 24%, 19%, 18%, and 32% for African Americans, Cuban Americans, Mexican Americans, Puerto Ricans, and non-Hispanic whites, respectively. After adjustment for gender and age, the rates were significantly higher (P < 0.05) for non-Hispanic whites compared to each of the other ethnic groups. Significant increases in the prevalence of 20/50 or worse distance visual acuity were observed for increasing age groups (25-39, 40-59, and 60-74 years) within each gender-ethnic subgroup. Analysis of differences in prevalence by gender (controlling for age) indicated a slightly higher prevalence of 20/50 or worse distance visual acuity in women than in men (range of odds ratios, 1.1-2.1). Based on 1993 census population estimates in the United States, more than 42 million adults 25 to 74 years of age have an uncorrected binocular distance visual acuity of 20/50 or worse. Approximately 1.7 million of these adults are of Hispanic origin. CONCLUSION: The prevalence of impaired uncorrected binocular distance visual acuity generally is lower in Hispanics than in non-Hispanic whites.

Adult↗

PubMed1981

How good is normal visual acuity?. A study of letter acuity thresholds as a function of age.

Visual acuity levels were studied in 100 normal subjects of different ages, using a finely graduated letter chart under carefully optimized test conditions. Each line on the chart contained 10 letters of similar difficulty, arranged in random order. A statistical analysis of different response criteria showed a clear superiority of fractional criteria (e.g. 50% correct responses) over the traditional 100% correct requirement. The average difference between right and left eyes was 0.04 +/- 0.15 (decimal notation). Regression analysis of the dependence of visual acuity on age showed a monotonic rise towards the age of 25 years, and a gradual decline thereafter. The most marked decline occurred after the age of 60. Age-dependent confidence intervals were tabulated. The results indicate that minor modifications of the conventional test procedure can enhance the diagnostic potential considerably.

Adolescent↗

PubMed1985

An automated visual acuity testing computer program using the Apple II system.

We developed an automated visual acuity testing program that uses an E optotype with surrounding confusion bars. The computer software program runs on Apple II equipment and a black-and-white monitor with a five-inch screen. The program is available in response box and joystick versions. The test is suitable for children older than 31/2 to 4 years of age and for adults. A t-test on the same floppy disk as the visual acuity programs is used to test the probability that the differences in test results are greater than chance. Visual acuities of 20 normal subjects were reduced by means of plus lenses. Test-retest acuity correlation coefficients were similar for letter charts and computer-generated E optotypes, suggesting approximately equal reliability under the test conditions employed. Visual acuities of 12 amblyopic eyes were obtained by a Ferris-type letter chart and computer-generated E optotypes. The correlation coefficient was +0.93, suggesting similar test results by these two methods.

Adult↗

PubMed1987

Effect of age on visual acuity after cataract extraction.

The best Snellen visual acuity in the three months after cataract extraction was found to decline with the age of the patient. The relationship was identical in 111 patients who had extracapsular extraction and a Pearce tripod posterior chamber intraocular lens and in 50 patients who had intracapsular extraction with spectacle correction. Vision after operation varied from a mean value of 6/5 at 50 years to 6/12 at 90 years, a decline of 1 line per 13.4 years. In the intracapsular group, over a mean follow-up period of 14 years, the rate of fall in acuity with increasing age after operation was found to be statistically similar to that of the early postoperative acuity plotted against age for both types of operation. This suggests that the rate of decline with age is unchanged after a prolonged period of aphakia with presumed increased exposure to ultraviolet and blue light. The data were found to be similar to the decline in the neurosensory elements of vision with age measured experimentally in 20 phakic subjects by laser interferometry. This method of assessment of contrast sensitivity threshold effectively bypasses changes in the optical media. The findings indicate that the previously recognised drop in visual acuity with age is not related to changes in the aging crystalline lens and support the view that there is a decline in the neurosensory elements of vision. It is important to recognise this deterioration so that results of surgery or other treatment are adjusted to allow for the age of the patients.

Adult↗

PubMed2006

Late-stage diffuse unilateral subacute neuroretinitis: photocoagulation of the worm does not improve the visual acuity of affected patients.

BACKGROUND AND OBJECTIVE: To evaluate the visual outcome following direct laser photocoagulation of the worm in patients with late-stage diffuse unilateral subacute neuroretinitis (DUSN). PATIENTS AND METHODS: The study reports on 22 DUSN patients diagnosed in its late stage, in whom the worm was identified and subsequently destroyed by laser photocoagulation. Information gathered included initial and final visual acuities and length of follow-up. Statistical analysis was performed with the Paired Student's t-Test. A p value of less than 0.05 was considered significant. RESULTS: After a mean follow-up of 13.1 months, visual acuity improved in 2 patients, remained unchanged in 19 patients and decreased in one patient. Comparison of the visual outcome before and after laser treatment was not statistically significant (p = 0.302). CONCLUSION: Destruction of the worm by laser photocoagulation in eyes with late-stage DUSN does not improve the visual acuity of affected patients.

Acute Disease↗

PubMed1983

Laser interferometric prediction of postoperative visual acuity in patients with cataracts.

I used the laser interferometer to test 137 eyes to determine whether preoperative interference visual acuity tests could accurately predict postoperative Snellen visual acuities. In 60 patients with immature cataracts and normal maculas the postoperative Snellen visual acuity was predictable within one line in 53 patients and within two lines in seven others. In 29 other patients with cataracts and senile macular scars or macular degeneration without subretinal fluid postoperative Snellen visual acuity was predictable within one line in 26 patients and within two lines in two others. Several easily recognizable clinical conditions make the interferometer test unreliable. Those that produce false-positive responses are serous detachment of the sensory epithelium of the macula, cystoid macular edema, visual fields cut through fixation, amblyopia, macular holes or cysts, geographic atrophy of the pigment epithelium of the macula, and early postoperative retinal detachment. Those that produce false-negative responses are mature cataracts and testing without pupillary dilatation.

Cataract↗

PubMedDate not supplied

Laser in situ keratomileusis improves visual acuity in some adult eyes with amblyopia.

PURPOSE: To report the results of laser in situ keratomileusis (LASIK) in a series of adult patients with amblyopia. METHODS: A retrospective noncomparative review was performed on patients with amblyopia who underwent LASIK for correction of ametropia, using the Summit Krumeich Barraquer microkeratome and the Nidek EC-5000 excimer laser. Data were collected on uncorrected visual acuity, best spectacle-corrected visual acuity, manifest refraction, anterior segment evaluation, intraocular pressure, corneal topography, and dilated fundus examination (preoperative and postoperatively on day 1, months 2 and 6). RESULTS: Eight eyes of seven patients were included, with a mean patient age of 30 +/- 10 years (range 21 to 49 yr). Mean preoperative spherical equivalent refraction was -4.70 D (range -12.62 to +4.71 D) and the best spectacle-corrected visual acuity varied from 20/32 to 20/80. At 2 months after LASIK, mean spherical equivalent refraction was -0.37 +/- 0.60 D (range -1.37 to + 0.60 D), uncorrected visual acuity ranged between 20/20 to 20/30, and a mean gain of 3 Snellen lines (range 2 to 4 lines) was observed. All patients reported significant subjective improvement in their perception of vision. The visual acuity and subjective improvement were maintained throughout 6 months postoperatively. CONCLUSIONS: LASIK with the Nidek EC-5000 laser for correction of ametropia in adult amblyopic eyes provided encouraging results for visual acuity improvement beyond correction of the refractive error.

Adult↗

PubMedDate not supplied

Does encouragement boost visual acuity testing results?

AIM: To investigate the hypothesis: 'Patients who receive encouragement during visual acuity testing achieve better scores than patients who receive no encouragement'. METHOD: Fifty patients were randomly selected from general eye clinics with five exclusions. A quasi-experimental, non-equivalent comparison before/after design was used to consider the way patients' vision is tested using the Snellen visual acuity chart in the eye department at Kettering General Hospital. RESULTS: The results were significant (t = 5.78 df=49 p < 0.001) and supported the initial hypothesis that 'patients who receive encouragement during visual acuity testing achieve better scores than patients who receive no encouragement'. CONCLUSION: The results of the study suggest that the subjects did get better visual acuity scores when encouragement was used and recommendations were made to change the clinic protocol.

Adult↗

PubMed2001

Change of visual acuity and related factors in idiopathic optic neuritis.

PURPOSE: To study the change of visual acuity and related factors in idiopathic optic neuritis. METHODS: Retrospectively studying 136 cases (210 eyes) of idiopathic optic neuritis hospitalized in our department during last 5 years. The data was analyzed with the methods of multivariate stepwise regression analysis by SPSS statistic package. RESULTS: The final visual acuity was very strongly related positively to the initial visual acuity at the time point of starting treatment and negatively to the time span beginning the treatment to the time showing improvement, age of patient and the duration from onset of the disorder to the time point of treatment beginning. CONCLUSIONS: Promptly right treatment can significantly change the natural course and the final vision of optic neuritis. Severe visual loss, old age, longer time without right therapy and slow improvement after the treatment may indicate an unfavorable final visual recovery. The different dosages of steroid applied in this study was not significant in view of the final visual acuity.

Adolescent↗

PubMed1995

Visual acuities and scotomas after 3 weeks' levodopa administration in adult amblyopia.

BACKGROUND: Previous studies have shown that both a single dose of levodopa and a 1-week administration of levodopa improve visual functions in adult amblyopic patients. In the present study, we investigated the effect of increased dosage and duration of levodopa on amblyopes' visual functions. METHODS: Visual acuity and visual fields were examined before and after 3 weeks of daily administration of levodopa/carbidopa as well as 1 month and 2 months after completion of drug therapy in a double masked-design. RESULTS: A significant increase in visual acuities and a decrease in fixation point scotomas were found. Changes were of comparable dimension to those found after 1 week of levodopa administration. Improvement of visual functions persisted 2 months after the levodopa/carbidopa administration was completed. CONCLUSION: The present study confirms previous findings of improvement in visual function in amblyopia after levodopa/carbidopa administration. However, increasing the dosage and the duration of levodopa did not enhance the effect in adults.

Administration, Oral↗

PubMed1993

Long-term follow-up study of 268 diabetic patients undergoing haemodialysis, with special attention to visual acuity and heterogeneity.

We studied the long-term outcome of 268 patients suffering from diabetic end-stage renal disease (DM-ESRD) treated with long-term haemodialysis between 1978 and 1991, with special emphasis on visual acuity as well as the heterogeneity of DM-ESRD. The 50% patient survival on haemodialysis was 60 months. Visual disturbances were found in 73.1% (392/536) of eyes at the start of haemodialysis. Chronological assessment of visual acuity demonstrated the stabilization of visual acuity and 87.1% (364/418) of eyes were stable, 4.8% (20/418) were improved, and 8.1% (34/418) were aggravated in the long term respectively. The change of visual acuity was frequently seen in the short term, and rapid shifts of body fluid to correct overhydration induced abrupt changes of glycaemic control as well as retraction of macular oedema. Hence it might be one of the factors affecting rapid change of visual acuity in the short term. Meanwhile, long-term deterioration of visual acuity resulted from either hypertension unresponsive to medical treatment or poor glycaemic control. Some DM-ESRD patients had only background retinopathy at the start of haemodialysis and these were likely to have the nephrosclerotic glomerular lesion. They were old, not nephrotic and had a mild degree of diabetes during the predialysis stage. Thus, DM-ESRD patients seem to have some heterogeneity in their clinical characteristics, and old DM-ESRD patients with only background retinopathy have the appearance of diabetic macroangiopathy rather than microangiopathy.

Adult↗

PubMed1999

Creation and testing of a practical visual function assessment for use in Africa: correlation with visual acuity, contrast sensitivity, and near vision in Malawian adults.

AIM: To develop and test a practical visual function assessment for use in developing countries. METHODS: Using focus group discussions and interviews with eyecare workers and low vision specialists in Malawi, 13 questions related to visual characteristics of activities of daily living were designed. Patients presenting to an eye clinic were recruited and interviewed. Visual acuity, near vision, and contrast sensitivity were measured. Analysis sought to determine the degree of correlation between the vision indices and visual function. RESULTS: The visual function questionnaire was easy to administer. Visual function correlated with visual acuity, contrast sensitivity, near vision, and patient reported visual problem. People with a higher frequency of "not applicable" responses had lower visual function scores. Multivariate modelling revealed that visual acuity and number of questions felt to be applicable were independently associated with visual function. Reducing the questionnaire to nine questions did not affect the degree of correlation with any of the visual indices. CONCLUSION: The authors' visual function assessment correlates well with different measures of visual acuity. People with reduced vision for a prolonged period may no longer consider doing certain tasks and the number of questions considered appropriate by an individual may be an additional measure of visual function. Assessment of visual function by health workers may be a valuable tool in improving surgical uptake by encouraging both health personnel and patients to recognise that they have difficulties undertaking activities of daily living as well as a measure of monitoring and evaluating cataract outcomes.

Contrast Sensitivity↗

PubMed1976

Subjective and objective visual acuity testing techniques.

The Catford apparatus for determining the objective visual acuity was elevated with 20 normal (20 eyes) and 40 abnormal (75 diseased eyes) patients. The vision of the normal individuals was fogged with neutral-density filters and convex lenses. Eyes with normal or near normal vision showed good correlation between optokinetic response and visual acuity, but no correlation was observed in eyes with poor vision. These findings, which vary from those of Catford, indicate that objective methods of visual acuity testing using a nystagmoid response do not appear useful for general clinical purposes.

Evaluation Studies as Topic↗