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PubMed2004

Recovery of contour integration in relation to LogMAR visual acuity during treatment of amblyopia in children.

PURPOSE: In several studies, researchers have found that integration of orientation information along contours defined by Gabor patches is abnormal in patients with strabismus and in untreated patients with anisometropic amblyopia. In this study, the rate and degree of recovery of contour-integration deficits were compared with the recovery of logMAR (logarithm of the minimum angle of resolution) visual acuity deficits in patients newly diagnosed with amblyopia secondary to anisometropia, strabismus, or both. METHOD: Contour-detection thresholds and optotype acuity were measured in 17 newly diagnosed anisometropic amblyopes, in 6 patients with strabismic amblyopia, and in 4 patients with combined anisometropic and strabismic amblyopia. Contour-detection thresholds were measured with a card-based procedure. Treatment comprised full refractive correction and full-time total occlusion therapy, when necessary. Visual function was measured at monthly visits during the course of treatment, with an average follow-up period of 16 weeks (12-24 weeks) for the entire group. Complete data were obtained from 23 patients through 8 weeks of follow-up. RESULTS: Significant interocular differences in contour-detection thresholds were present in 16 of the 27 patients at the first visit after initial refractive correction. Interocular differences in contour-detection thresholds declined to normal levels in most of the patients within 8 weeks of the initiation of treatment. Interocular acuity differences remained significant in many of the patients (19/23) at 8 weeks of follow-up and continued to decline, but did not fully normalize, over the remainder of the follow-up period. CONCLUSIONS: Refractive correction alone or in combination with occlusion therapy produces a normalization of contour-integration thresholds in amblyopia that is more rapid and complete than that achieved for visual acuity.

Adolescent↗
PubMed1993

Psychophysical visual function, retinopathy, and glycemic control in insulin-dependent diabetics with normal visual acuity.

We studied relations between psychophysical visual function and grade of retinopathy, glycemic control and clinical background data in 51 insulin-dependent diabetic patients, aged 17-47 years. Three separate qualities of visual function were examined, macular recovery time (nyctometry; 2 min adaptation), contrast sensitivity (Vistech 6000 chart; between 1.5 and 18 cycles per degree (cpd)) and colour vision (Fletcher DS8; protan/deutan and tritan). Only contrast sensitivity of 6 cpd was associated with the grade of retinopathy; reduced function was found in patients with retinopathy compared to those without. No correlations between macular recovery, contrast sensitivity and colour vision were found. None of the visual functions was significantly related to glycemic control, age, duration of diabetes, blood pressure, intraocular pressure, or urinary albumin excretion. Our data suggests that the neurosensory function of contrast sensitivity correlates more sensitively to the grade of diabetic retinopathy than macular recovery and colour vision. Cross-sectional assessments of different psychophysical visual functions seem to be of restricted clinical value as indicators of preceding glycemic control in diabetic patients with no or mild nonproliferative retinopathy.

Adolescent↗
PubMed1995

Visual acuity after scleral buckling surgery.

We reviewed 745 cases of retinal detachment which had been successfully treated by scleral buckling and had presented without preoperative ocular problems precluding visual recovery. Final visual acuity (VA) was 0.5 or better in 517 cases (69.4%). The main causes of final VA below 0.5 were photoreceptor dysfunction, macular pucker, cystoid macular edema, and intraoperative retrofoveal hemorrhage. Stepwise logistic regression analysis revealed that five variables predicted visual failure: patient's age of 71 years or more; preoperative VA reduced either to light perception counting fingers or to 0.1-0.4; low or high macular detachment for more than 7 days; grade B preoperative proliferative vitreoretinopathy, and intraoperative hemorrhage.

Adolescent↗
PubMed1992

Role of visual acuity, stereoacuity, and ocular dominance in monovision patient success.

Monovision (MV) contact lens correction of presbyopia induces substantial reductions in stereoacuity and small reductions in binocular visual acuity (VA). This study examined those effects in a group of successful and a group of unsuccessful MV patients. Compared to performance with a full binocular correction, the unsuccessful group demonstrated significant losses in both functions. These reductions were smaller in the successful group and of marginal statistical significance only for stereoacuity. Laterality of sighting dominance and laterality of distance/near correction had minimal effect on the results.

Adult↗
PubMed1980

Visual acuities of monocular IOL and non-IOL aphakic children.

The vision of 341 monocular aphakic children was corrected with contact lens, intraocular lens, or spectacles and the visual results of each series were compared. The acquired and infantile contact lens and IOL cataract patients achieved similar levels of aphakic visual acuities. Seventy percent of the IOL and 64% of the contact lens-acquired cataract patients achieved 20/20 to 20/40, while 22% of the IOL and 16% of the contact lens infantile cataract patients also reached this level. Twenty patients wore monocular spectacles and none achieved adequate levels of visual rehabilitation. Forty-six patients were unable to wear or did not receive aphakic correction because of patient or parental refusal or ocular pathologic contraindications.

Aphakia, Postcataract↗
PubMed1986

Visual acuity screening of infants and young children with the acuity card procedure.

A new acuity test for infants and young children between 1 and 36 months of age is described. The test was used to evaluate the acuities of 66 infants and young children during a one-day vision screening. At least one estimate of visual acuity was obtained from 63 of the 66 children. Fifty-two of the children completed two monocular acuity tests (or two monocular tests plus a binocular test). The average total test time for these 52 children was less than 15 minutes. Results indicate that the acuity card procedure can be used as a complement to standard optometric tests for large-scale screening of infants and young children.

Child, Preschool↗
PubMed1980

Apparatus for the measurement of retinal visual acuity by moiré fringes.

Moiré fringes generated by two equal gratings in contact, looked at in Maxwellian view, are well suited for the assessment of retinal visual acuity. High-contrast fringes practically free from spatial harmonics (higher Fourier components) are obtained if, instead of the zero diffraction order, one first-order diffraction spectrum from each of the gratings is isolated by a stop. Thus a pair of coherent light sources is produced, the distance of which can be varied by relative rotation of the gratings. The resulting fringe pattern of variable pitch is characterized by achromatic intensity minima seen against a background of variable color depending on the direction of viewing. These colors can, however, be compensated for by an additional dispersing element near the gratings, e.g., a spectral prism. The device then is an achromatic interferometer, enabling the use of white light. Results do not systematically deviate from those obtained with a monochromatic interferometer using a laser. If desired, fringe contrast can be measurably varied by superimposition of a white light beam, with the intensities of both fields being controlled by polarizers.

Humans↗
PubMed2005

The effect of overnight contact lens corneal reshaping on higher-order aberrations and best-corrected visual acuity.

PURPOSE: The purpose of this study is to determine the effect of higher-order aberrations after Corneal Refractive Therapy (CRT) on best-corrected visual acuity (BCVA) and the impact of pupil size on BCVA. METHODS: High-contrast (HC) and low-contrast (LC) Bailey-Lovie BCVA was measured in the morning before and after pupil dilation on 20 myopes (mean spherical equivalent -3.11 D +/- 0.96 D) under age 40. BCVA was measured again in the afternoon after dilation. Dilated am and pm aberrations were measured using the Complete Ophthalmic Analysis System (WaveFront Sciences). Patients were fit with CRT lenses in each eye. One month after finalizing the lens fit, BCVA and aberration testing were repeated. Average higher-order RMS error (third to sixth order), spherical aberration, third-, fourth-, fifth-, and sixth-order RMS error were calculated at each visit for a 3-mm and 5-mm pupil. BCVA and aberration data were analyzed using a repeated measures analysis of variance. Linear regression was used to describe the relationship between aberrations and BCVA reductions after CRT. RESULTS: Mean refractive error changed by +3.33 D +/- 0.96 D. No clinically significant changes were found in HC BCVA post-CRT, whereas LC BCVA reductions of 0.07 logarithm of the minimum angle of resolution (logMAR) (nondilated, p = 0.002) and 0.12 logMAR (dilated, p < 0.001) were found. No additional decrease in HC BCVA was found after pupil dilation, whereas a mean additional decrease of 0.08 logMAR in LC BCVA was found with dilation post-CRT (p = 0.013). Higher-order RMS error increased for both 3-mm and 5-mm pupils (p < 0.0001) and remained stable between measurements. Spherical aberration increased for 5-mm pupils after CRT (p < 0.0001). For a 5-mm pupil, a 0.1-mum increase in spherical aberration was associated with an additional decrease in LC BCVA after pupil dilation post-CRT of 0.056 logMAR (R = 0.382, p = 0.004). CONCLUSIONS: CRT results in reduced low-contrast BCVA as a result of increased higher-order aberrations. Higher-order aberrations appear to be relatively stable after CRT. Spherical aberration appears to drive additional low-contrast BCVA losses as pupil size increases.

Adult↗
PubMed1995

[Idiopathic juxtafoveolar telangiectasis. Long-term follow-up of visual acuity].

The beneficial effect of laser therapy on idiopathic juxtafoveolar telangiectasis is questionable. We therefore studied retrospectively the spontaneous course of the disease and tried to show a correlation between the initial angiographic findings and visual outcome. In addition, the results after laser therapy were compared with untreated patients. Thirteen patients (24 eyes) with idiopathic juxtafoveolar telangiectasis diagnosed by fluorescein angiography were reexamined after a mean time interval of 38 months. Argon laser coagulation had been performed in 6 patients. The initial extension of fluorescein leakage was divided angiographically into three different stages. The existence of secondary macular changes and peripheral involvement was noted. The mean visual acuity decreased from 0.71 to 0.62 over the follow-up period. No correlation could be found between the final visual outcome and initial extension of telangiectasis or existence of secondary changes. After laser coagulation the patients did not show a better visual outcome. Due to the relatively benign spontaneous course of idiopathic juxtafoveolar telangiectasis laser coagulation cannot be recommended in general. Only in exceptional cases (e.g., development of subretinal neovascularization) can laser coagulation be of benefit.

Aged↗
PubMed1993

[Correlation of the grade of nuclear and cortical cataract, visual acuity, and contrast sensitivity].

A correlative investigation of 125 eyes with senile cataractous lenses was conducted to determine the relationships between cortical (CC) and nuclear cataracts (NC), corrected visual acuity (VA), and contrast sensitivity (CS). The CS for the spatial frequency of 1.5 cycles/degree (c/d) and 12.0 c/d was analyzed in particular detail. The results were as follows: (1) CC and CS for both 1.5 and 12.0 c/d showed statistically significant negative correlations with a coefficient (CE) of -0.250 and -0.288 respectively. No correlation was found between CC and VA. (2) NC and VA showed a significant negative correlation with CE of -2.29. No correlation was found between NC and CS for at 1.5 and 12.0 c/d. (3) VA and CS showed a significant positive correlation with a CE of +0.436 at 1.5 c/d and +0.270 at 12.0 c/d. The CS at 1.5 and the CS at 12.0 c/d also showed a significant negative correlation with a CE of +0.477. (4) NC and CC showed a significantly negative correlation (r = -0.224, p < 0.01), suggesting that scattered light from the nucleus may be interfered with by cortical opacities during slitlamp examinations. (5) In 29 cases of no cortical opacity, nuclear opacity showed significant negative correlation with VA (r = 0.556 p < 0.01) but no significant correlation with CS of both 1.5 and 12 c/d. (6) In 30 cases with less than 0.085 of nuclear opacity, cortical opacity showed significant negative correlation with CS at 12.0 c/d (r = 0.364 p < 0.01) but showed no significant correlation with VA and CS at 1.5 c/d.

Aged↗
PubMed1998

The relation between visual acuity and the size of fixational eye movements in patients with diabetic and non-diabetic macular disease.

PURPOSE: To study fixational eye movements as a function of visual acuity (VA) in patients with diabetic maculopathy and in patients with non-diabetic macular disease. MATERIAL: Two groups of patients each with VA ranging between 0.05-0.77 were studied, i.e. 24 patients with diabetic maculopathy and 23 patients with non-diabetic macular lesions. Fixational eye movements were quantified from video recordings of the ocular fundus obtained with the Rodenstock scanning laser ophthalmoscope. RESULTS: Within both groups of patients we found a similar significantly negative relation between the amplitude of fast saccadic eye movements and the VA. Patients with VA > 0.20 showed a normal directional pattern with larger amplitudes of the fast saccadic movements in the horizontal than in the vertical plane, whereas for patients with VA < or = 0.20 the amplitudes of the saccadic movements in the vertical plane had enlarged to equal the saccadic amplitude in the horizontal plane. Four patients with VA < or = 0.10 had the fixation centre located more than three degrees (approximately 500 microns at the retinal plane) from the centre of the foveal avascular zone, whereas the fixation centre of the remaining 43 patients was within one degree of the centre of this zone. CONCLUSION: Patients with VA < or = 0.20 may have retinal areas of fixation located more than 500 microns from the fovea. This fact should be taken into account when planning retinal photocoagulation in macular disease.

Adolescent↗
PubMed1986

Visual acuity in Danish school children.

The medical records of 8769 school children attending the 2nd-5th grades in the Municipality of Odense have been scrutinized with regard to visual acuity. 1216 children were subject to examination, of these 1034 were found to have reduced vision due to anomalies of refraction other causes. Bilateral reduction in vision of less than or equal to 6/18 was observed in 8 children corresponding to 0.09%. Unilateral reduction in sight of less than or equal to 6/12 (employed here as the definition of amblyopia) was seen in 1.07% of the children. This applied to 1.39% of the boys and 0.73% of the girls; the difference is statistically significant. The lower frequency of amblyopia as compared to earlier investigations is probably a consequence of better vision screening during preschool age.

Adolescent↗
PubMed1981

Simulating decreased visual acuity with a contact lens system.

We use a soft contact lens with a central depression into which a hard contact lens can be fitted to simulate conditions that cause decreased visual acuity. This "piggy-back" system can simulate central scotoma, various peripheral field defects, and opacities of the media.

Contact Lenses↗
PubMed1984

Influence of dark-rearing on the ontogenetic development of Sarotherodon mossambicus (Cichlidae, Teleostei): I. Effects on body weight, body growth pattern, swimming activity and visual acuity.

The ontogenesis of the cichlid fish, Sarotherodon mossambicus was investigated under normal- and dark-rearing conditions from hatching to 100 days. Light deprivation did not change normal increase in body weight. The increase in body length was slightly retarded in dark-reared animals (DR), whereas the increase in body height was more pronounced as compared to normal-reared animals (NR). DR failed to swim up after resorption of the yolk sack. Visual acuity was severely impaired. The first deficits in visual discrimination were observed after 20-30 days in the dark. After 50 days DR failed to show any optokinetic nystagmus.

Animals↗
PubMed2001

Retrospective longitudinal study of visual acuity change in patients with retinitis pigmentosa.

PURPOSE: To determine the extent that clinically evident macular lesions in patients with retinitis pigmentosa (RP) help to establish their prognosis for visual acuity (VA) retention. METHODS: The records of 182 patients with RP were reviewed. The macular lesion status at the initial examination was determined to be no lesion, a bull's-eye atrophic lesion, or a geographic atrophic lesion. Multiple linear regression analysis was used to evaluate the relationship of initial VA, macular lesion type, and RP genetic subtype to predict the VA change per 5-year period. RESULTS: The regression effect of lesion type on the VA change was statistically significant (P < 0.0001). Patients with no macular lesion had a predicted 5-year change of less than 1 line, whereas those with either a bull's-eye or geographic atrophic lesion had a predicted 5-year change of three to four lines. The 5-year changes were not related to a patient's age or level of VA at initial presentation, when controlling for type of macular lesion. CONCLUSION: By examining longitudinal data, the authors found that the presence or absence of a macular lesion at the patient's initial visit was an important determinant of VA loss in this cohort of patients with RP. These findings are of value when counseling patients with RP regarding their prognosis for preservation of VA.

Adolescent↗
PubMed2005

The Bristol cataract listing survey: profile of listed patients with visual acuity 6/12 or better.

INTRODUCTION: The aim of this study was to assess the vision-related quality of life (VR-QOL) in patients with good distance Snellen visual acuity (VA) who are listed for cataract surgery. METHODS: An observational cross-sectional prospective study of patients listed for cataract surgery. VA and VR-QOL data using the VCMI questionnaire were collected on patients attending preoperative assessment during June 2002. RESULTS: A total of 397 cataract patients were listed during this month. Following exclusions there were 378 eligible individuals, 210 (56%) of whom had a VA of 6/12 or better in the eye scheduled for surgery. Of these, 40% patients had only mild VR-QOL impairment. More than half of the patients with good VA (6/12 or better) in the surgery eye and mild VR-QOL impairment described their vision as poor in this eye. However, most of these patients were not dissatisfied with their overall level of vision. CONCLUSION: A significant number of patients listed for cataract surgery with VA of 6/12 or better had only mild VR-QOL impairment and were not dissatisfied with their overall level of vision. The decision to list a patient for surgery may have been based on the patient's perception of monocular vision rather than their quality of life.

Aged↗
PubMed2006

Sensitivity and specificity of a visual acuity screening protocol performed with the Lea Symbols 15-line folding distance chart in preschool children.

PURPOSE: The aim of this study was to assess the feasibility of a visual acuity (VA) test using the Lea Symbols 15-line folding distance chart and its diagnostic validity in detecting VA deficiency in preschool children. METHODS: A group of 149 children aged 38-54 months underwent VA examination performed with the Lea 15-line folding optotype at a distance of 3 metres, according to a test protocol described in the Methods section. After the VA test, a complete ophthalmological examination, including cycloplegic retinoscopy, a cover test and examination of the anterior and posterior segments, was performed on each child in order to detect any VA-threatening ocular abnormality. The Lea Symbols test's sensitivity, specificity, positive and negative likelihood ratios (LR +, LR -) and the receiver operating characteristic (ROC) curve were calculated by means of standard procedures using each VA level of the chart from 0.1 to 1 (1-0 logMAR) as a cut-off point. RESULTS: The Lea Symbols test could be successfully used in 95.9% of the population. The most useful cut-off points for screening preschool children were found to be 0.8 (LR + 5.73, LR - 0.05) or 0.63 (LR + 11.7, LR - 0.23). CONCLUSION: The Lea Symbols test proved to be clinically useful in detecting VA deficiency in preschool children. The choice between the two best performing cut-off levels should be made according to the expected cost-effectiveness of the screening programme.

Child, Preschool↗