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PubMed1983

Use of various measures of visual acuity and contrast sensitivity in the evaluation of monocular occlusion and active vision training of three adult amblyopes.

Three adult amblyopic patients who underwent vision training involving monocular occlusion of the nonamblyopic eye and stimulation of the amblyopic eye using simple fixation exercises and a spinning grating procedure were evaluated using five different types of acuity testing and two methods of contrast sensitivity. It was found that contrast sensitivity and isolated Landolt C acuity improved sooner and to a greater extent than the more complex visual acuity tasks. One patient who improved only on the simpler tasks complained that the enhanced contrast due to training made vision in that eye less acceptable because it was more confusing. The results show that multiple measures of visual acuity and contrast sensitivity are necessary to adequately monitor the effects of occlusion therapy.

Adult↗
PubMed1998

Computerized dynamic visual acuity test in the assessment of vestibular deficits.

OBJECTIVE: The study was designed to measure dynamic visual acuity (DVA) during head movement as an assessment of the functional impact of vestibular deficits. STUDY DESIGN: The study design was a prospective, clinical study. SETTING: The study was performed in a tertiary, ambulatory referral center. PATIENTS: Forty-two normal subjects, 29 patients with unilateral vestibular loss, and 26 patients with bilateral vestibular hypofunction who were 19-87 years of age were examined. INTERVENTION: Diagnostic intervention was performed. MAIN OUTCOME MEASURE: Main outcome measures included the reliability, sensitivity, and specificity of a computerized test that measures visual acuity during head movement in normal subjects and in patients with vestibular deficits. RESULTS: The computerized DVA test was reliable in both normal subjects (intraclass correlation coefficient [ICC] r=0.87) and in patients with vestibular deficits (ICC r=0.83). The sensitivity of the DVA test was 94.5% and the specificity was 95.2%. The positive predictive value (individuals who test positive on the DVA test who will have a vestibular deficit) was 96.3%. The negative predictive value (individuals who test negative on the DVA test who will not have a vestibular deficit) was 93%. CONCLUSIONS: The computerized DVA test is reliable and is able to distinguish among normal subjects and patients with vestibular deficits.

Adult↗
PubMed2001

ETDRS-fast: implementing psychophysical adaptive methods to standardized visual acuity measurement with ETDRS charts.

PURPOSE: To measure visual acuity (VA) on Early Treatment Diabetic Retinopathy Study (ETDRS) charts with a modified faster procedure (ETDRS-Fast), based on adaptive psychophysics methods and to assess the method's validity and reproducibility. METHODS: Whereas the standard method for measuring VA with the ETDRS charts requires that the subject read all the letters beginning with the top row, in the ETDRS-Fast procedure, the subject is asked to read only one letter per row until a mistake is made. Then, following simple rules, the examiner finds a row from which the subject can begin reading all the letters downward, thus making the method identical with the standard method near threshold. VA determination was performed twice with both methods in 57 subjects in two separate sessions to assess validity and reproducibility. RESULTS: In both sessions the correlation between the two procedures was high (intraclass correlation coefficient 0.95), confirming the validity of the ETDRS-Fast procedure. Reproducibility was good for both procedures, with intraclass correlation coefficients of 0.94 for the standard and 0.96 for the ETDRS-Fast method. The ETDRS-Fast procedure allowed a significantly shorter test duration (-30%; P < 0.0001). CONCLUSIONS: Adaptive procedures allow accurate and fast determination of psychophysical thresholds by reducing the number of stimulus presentations when the subject is far from threshold. In the ETDRS-Fast method a few simple rules applied to optotype chart reading allow adaptation to each patient's level of VA. The ETDRS-Fast procedure significantly reduces test time and still yields results that are as accurate as those obtained with the standard method.

Adult↗
PubMed2000

Correlation of visual acuity and ocular pigmentation with the 16-bp duplication in the HPS-1 gene of Hermansky-Pudlak syndrome, a form of albinism.

OBJECTIVE: Patients with the Hermansky-Pudlak syndrome (HPS), a form of albinism, were studied. The first purpose of this investigation was to determine if visual acuity was related to the presence or absence of the 16-bp duplication in the HPS-1 gene. The second was to study the correlation between the degree of ocular pigmentation and visual acuity within the two genetic groups described above. DESIGN: Cross-sectional study of a series of consecutive patients. PARTICIPANTS: Forty-nine patients with HPS with or without the 16-bp duplication in HPS-1. METHODS: Best corrected visual acuity (VA) using Early Treatment Diabetic Retinopathy Study (ETDRS) charts, photographic gradings of iris transillumination and of visibility of choroidal vessels in the macula (macular transparency). MAIN OUTCOME MEASURES: Association between VA and the presence or absence of the 16-bp duplication in HPS-1 and correlation between VA and the degree of iris transillumination (iris score) and macular transparency (fundus score), as determined by masked reading of photographs, with respect to the presence or absence of the 16-bp duplication in HPS-1 were the main outcome measures. RESULTS: The VA of the better eye did not differ between the two genetic groups (P = 0.322, two-sided t test). Spearman's rank correlation between VA and iris scores in 39 eyes of 20 patients with the duplication was not statistically significant (P = 0.698) but was statistically significant in 36 eyes of 19 patients without the duplication (P < 0.001). Among all patients, the correlation was statistically significant (r = -0.36 in RE and r = -0.51 in LE). Spearman's rank correlation between VA and fundus scores in 36 eyes of 19 patients with and 34 eyes in 18 patients with and without the duplication was statistically significant (P = 0.035 and P = 0.008, respectively). Among all patients, it was also statistically significant (r = -0.39 in RE and r = -0.45 in LE). CONCLUSIONS: The mean VA of the better eye did not differ in patients with the 16-bp duplication compared with those without the duplication. There were statistically significant associations between VA and the iris score and the fundus score except for the VA and iris scores in patients with the 16-bp duplication. However, because of the variability of VA, these associations were not large enough for useful prediction of VA based on the degree of ocular pigmentation.

Adolescent↗
PubMed2004

[Stability of postoperative visual acuity after rt-PA -SF6-treatment of submacular hemorrhage in age-related macular degeneration].

PURPOSE: Treatment of submacular hemorrhage with recombinant tissue plasminogen activator(rt-PA) and SF6 induces blood displacement out of the fovea by maintaining prone positioning. The underlying disease, e.g. the choroidal neovascularisation remains untreated. Nevertheless, it has been noted that the visual results of this method are more favorable than those expected in the natural course. Contributing long-term results the present study intends to give more information concerning this phenomenon. METHOD: A total of 45 consecutive eyes were treated using a standardized procedure (duration of hemorrhage < or =1 week, area of hemorrhage 1-10 disc areas, 50 gammag rt-PA, 0.5 ml SF6 24 h later, prone positioning for 3 days). Those with a follow-up of > or =6 months were included in the study. RESULTS: From 25 patients a total of 25 eyes fulfilled the criteria. Postoperative visual acuity(3-7 days) was improved or unchanged in 19 eyes and worse in 6 eyes. Comparison of postoperative visual acuity after follow-up of an average of 14.2 months (range 6-28 months) revealed an improvement in 10 eyes, no change in 7 eyes and a deterioration in 8 eyes. A second treatment was performed in 2 eyes and photocoagulation in 1 eye. CONCLUSION: After more than 1 year the postoperative visual acuity was stable or even better in about two-thirds of the eyes therefore treatment with rt-PA and SF6 may also influence the choroidal neovascularisation.

Aged↗
PubMed1978

[The random dot test as a screening method for the visual acuity in children (author's transl)].

The Random Dot Test was used for a screening of the visual acuity of children of 6 to 10 years of age. The testing time is reduced by 50% as compared with the examination by means of illiterate E images on cardboard charts. Children with refractive errors of up to 3 delta but normal visual acuity after correction are not detected at the examination distance of 1.30 m used in this study. None out of 672 children with severe eye diseases gave false negative results with the Random Dot Test. Disturbances of the binocular vision could also be detected with the Random Dot Test.

Child↗
PubMed2003

Recovery of dynamic visual acuity in unilateral vestibular hypofunction.

OBJECTIVE: To determine the effect of vestibular exercises on the recovery of visual acuity during head movement in patients with unilateral vestibular hypofunction. STUDY DESIGN: Prospective, randomized, double-blind study. SETTING: Ambulatory referral center. PATIENTS: Twenty-one patients with unilateral vestibular hypofunction, aged 20 to 86 years. INTERVENTION: One group (13 patients) performed vestibular exercises designed to enhance the vestibulo-ocular reflex, and the other group (8 patients) performed placebo exercises. The placebo group was switched to vestibular exercises after 4 weeks. OUTCOME MEASURES: Measurements of dynamic visual acuity (DVA) during predictable (DVA-predictable) and unpredictable (DVA-unpredictable) head movements by means of a computerized test and measurement of intensity of oscillopsia by means of a visual analog scale. RESULTS: As a group, patients who performed vestibular exercises showed a significant improvement in DVA-predictable (P<.001) and DVA-unpredictable (P<.001), while those performing placebo exercises did not (P =.07). On the basis of stepwise regression analysis, the leading factor contributing to improvement was vestibular exercises. This reached significance for DVA-predictable (P =.009) but not DVA-unpredictable (P =.11). Other factors examined included age, time from onset, initial DVA, oscillopsia, and duration of treatment. Changes in oscillopsia did not correlate with DVA-predictable or DVA-unpredictable. CONCLUSIONS: Use of vestibular exercises is the main factor involved in recovery of DVA-predictable and DVA-unpredictable in patients with unilateral vestibular hypofunction. Exercises may foster the use of centrally programmed eye movements that could substitute for the vestibulo-ocular reflex. The DVA-predictable would benefit more from this than would DVA-unpredictable.

Adult↗
PubMed1983

Light intensity and visual acuity following cataract surgery.

The authors analyzed 310 cataract operations that were randomly distributed between two operating rooms, each containing a microscope with different light intensities. The light intensity of one microscope was almost threefold greater than the other. One hundred seventy-seven patients were excluded from this study because of medical or ocular problems that might affect visual acuity. The remaining 133 patients are the subjects of this paper. Seventy-one were operated upon under high intensity light, and 62 were subjected to lower illumination in the operating room. Visual acuity after operation was correlated with type of microscope, age, sex, method of cataract extraction, and use of intraocular lenses. Reduced visual acuity (20/40 or worse) was consistently more common with high intensity light and with increasing age. Further investigation is recommended to establish the cause of this reduced acuity.

Age Factors↗
PubMed2005

Effect of myopia on visual acuity measured with laser interference fringes.

The aim was to determine how visual acuity is affected by myopia when optical factors of the eye are controlled. Grating acuity was measured with interference fringes to avoid the effects of aberrations, and ocular biometry was used to compensate for differences in retinal image size among subjects. Distance spectacle refractions ranged from +2.25 to -14.75 D. The retinal magnification factor (RMF) in mm/deg was computed for each eye from the distance refraction, central corneal power and ultrasound biometry. A forced-choice orientation discrimination method was used to measure acuity for high-contrast 543 nm laser interference fringes in three retinal locations: the fovea, and at 4 deg and 10 deg eccentricity in the temporal retina. Acuity, expressed in c/deg and adjusted for spectacle magnification, was not significantly correlated with refraction at any of the three retinal locations. When acuity was converted to retinal spatial frequency units (c/mm) via the RMF, acuity decreased with increasing myopia at all three retinal locations (significantly at the fovea and at 10 deg eccentricity). Retinal acuity values in highly myopic subjects (>6 D) are consistent with retinal sampling distances that are larger than published values of human cone or ganglion cell spacing. The results imply that a highly myopic eye has retinal neurons that are more widely spaced than normal, but the increased axial length enlarges the retinal image enough to compensate for the retinal stretching. The data are consistent with a retinal stretching model that primarily affects the posterior pole.

Adult↗
PubMed1995

Contrast sensitivity evaluation in eyes predisposed to age-related macular degeneration and presenting normal visual acuity.

In order to test the validity of contrast sensitivity (CS) measurements in the early detection of visual impairment in age-related macular degeneration (AMD), we have evaluated the findings of CS in patients with drusen and normal visual acuity (17 eyes), as well as in the contralateral 'healthy' eye of patients with AMD (14 eyes). We also tried to estimate the validity of CS measurements in the prognosis of neovascular macular degeneration. The CS findings were evaluated in comparison to the findings of CS measurements in age-matched controls (32 eyes). CS loss is a constant finding in eyes with drusen and normal visual acuity. CS loss is more important at the middle range and high spatial frequencies. CS loss and degree of CS loss are not prognostic indicators of neovascular macular degeneration.

Adult↗
PubMed2003

Changes in visual acuity associated with shunt failure.

OBJECT: The object of this article was to report on a retrospective analysis of the clinical findings in a series of patients with changes in visual acuity associated with shunt failure. METHODS AND RESULTS: Over a 10-year period, 350 patients underwent revisions for shunt failure. The clinical course of patients who demonstrated changes in visual acuity (VA) before or during hospitalization were reviewed; follow-up was achieved using outpatient records and telephone calls with physicians, family, or caregivers. Six patients (4 male) ranging in age from 2.5 years to 40 years demonstrated changes in vision associated with shunt failure. The youngest patient lapsed into coma before transfer and showed bilateral occipital lobe infarctions on the CT scan. Three patients had no complaints referable to the visual system prior to revision. Two patients with symptoms lasting more than 21 days showed unequivocal signs of increased intracranial pressure. Serial CT scans remained unchanged in 2 patients. A 3rd patient showed questionable progression in ventricular volume, while another patient's ventricles dilated after a period of 48-72 h. Four patients demonstrated a pattern of aqueductal stenosis, long-term shunting without revision, small ventricles, and poor outpatient follow-up. Four patients showed partial or complete recovery following revision. CONCLUSIONS: Changes in vision are uncommon and can be an isolated finding associated with shunt failure. Patients with aqueductal stenosis, long-term shunting without revision, and small, potentially non-compliant ventricles may be at risk of this complication. Misdiagnosis or inadequate follow-up places these patients at additional risk, but rapid revision can result in partial or complete recovery.

Adolescent↗
PubMed1997

Improvements in visual acuity following limbal lensectomy for subluxated lenses in children.

BACKGROUND AND OBJECTIVE: To report the surgical results of limbal lensectomy using an automated vitrectomy instrument for the treatment of subluxated lenses in children. PATIENTS AND METHODS: The authors reviewed the charts of children who underwent surgery for subluxated lenses. Limbal lensectomies with an "in the bag" technique were performed on 18 eyes of 10 patients. The indications for surgery were a best-corrected visual acuity of less than 20/60, bisection of pupil by the lens, or both. RESULTS: Best-corrected visual acuity improved in all 18 eyes (paired t test, P < .01). In 1 eye, transient anterior chamber hyphema occurred during the early postoperative period. No other significant complications were found during an average follow-up of 19.6 months. CONCLUSION: Limbal lensectomy for subluxated lenses in children improved visual acuity without severe complications.

Adolescent↗
PubMed2003

The association between myopic shift and visual acuity outcome in pediatric aphakia.

PURPOSE: The advent of intraocular lens implantation after pediatric cataract surgery necessitates an increased understanding of refractive development. The significant variation in rate and amount of refractive change among eyes, both aphakic and pseudophakic, is well recognized, although the causes of such variation remain unclear. The purpose of this study was to determine if a correlation exists between the rate of refractive growth (RRG) and visual acuity outcome in pediatric aphakia. METHODS: Multicenter, retrospective observational case series. One hundred and twenty-five eyes of 85 patients with cataract surgery before 1 year of age and a minimum of 3 years of follow-up were analyzed. RRG was calculated for each eye using the logarithmic model of ocular growth and compared with final logMAR acuity using linear regression. RESULTS: The correlation of RRG with final logMAR acuity was statistically significant (r(2) = 0.10; P <.01), ie, 10% of variance in RRG is related to acuity outcome. The correlation was higher in unilaterally aphakic patients (n = 44; r(2) = 0.19; P <.01) than in bilaterally aphakic patients (n = 81; r(2) = 0.08; P <.01). Eyes with visual acuity of 20/60 or better had a significantly lower RRG than those with poorer acuity (4.1 v 5.4 diopters (D); P <.01). CONCLUSIONS: RRG in aphakia is correlated with visual acuity outcome. Eyes with poorer acuity have a greater RRG.

Aphakia, Postcataract↗
PubMed2003

Visual acuity with reversed-contrast charts: I. Theoretical and psychophysical investigations.

When the contrast polarity of a visual acuity chart is reversed by using bright letters on a dark background instead of dark on light, the shape and height of the resolution feature in the retinal image is identical but inverted compared with the normal situation. However, the contrast is different in the two cases because the background light level, which is a dividing factor when contrast is calculated, is much less when only the letters are bright. To the extent that contrast is a limiting factor in visual acuity, reversed-contrast acuity would be expected to be better, and proportionally more so in eyes where light scatter and aberrations widen and flatten the point-spread function. In a careful psychophysical study of Landolt C resolution, the minimum angle of resolution was found to be significantly smaller for white letters on a dark background than for the traditional dark on bright situation.

Contrast Sensitivity↗