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At least 19 recordsLinked to original sources
PubMed1988

[Behavior of visual acuity, visual fields and contrast sensitivity in simulated cataract].

Visual acuity, contrast sensitivity, and visual fields were examined with and without occluders both in a group of healthy subjects and in a group of patients with field defects (mostly caused by glaucoma). The various results were compared with one another as well as with the results obtained from a group of cataract patients examined before and after surgery. The results confirm clinical experience: visual acuity enables some conclusions to be drawn on the degree and progression of opacity of a lens. The changes in contrast sensitivity and in the visual field, however, represent rather the quality of the visual degradation. Contrast sensitivity and diffuse alterations in the visual field have similar progression patterns. The alterations in contrast sensitivity are more pronounced at higher frequency levels. The contrast sensitivity test can be recommended as a simple and complementary functional test, particularly on cataract patients with severe complaints and relatively good visual acuity. The results of occlusive experiments afford some practical conclusions which enhance knowledge and differentiation of visual field changes induced by cataract and glaucoma. These conclusions can provide a basis for further and more detailed investigations.

Adult↗
PubMed1994

The effect of panretinal laser photocoagulation on visual acuity, visual fields and on subjective visual impairment in preproliferative and early proliferative diabetic retinopathy.

The effect of panretinal laser scatter treatment on visual fields, visual acuity and subjective complaints was assessed in 11 patients with severe nonproliferative or early proliferative diabetic retinopathy. Patients were prospectively examined before and after panretinal treatment using automated static threshold perimetry with program 30-2 on the Humphrey perimeter, and they were interviewed. Visual field sensitivity was often depressed even before treatment with mean MD -4.3 (-1, -11.6) dB, but was significantly lower (p < 0.01, ANOVA) 2 weeks after treatment with mean MD -8.6 dB. Visual fields remained stable 4 months later. Treatment increased the number of eyes with visual fields as defined by abnormal MD values at the p < 0.05 level from 8 to 16 among the 17 treated. In spite of considerable impairment of visual fields after treatment, subjective problems were small and the visual field impairment seemed to have little influence on everyday life.

Adult↗
PubMed1979

An analysis of visual acuity, visual fields, and disk cupping in childhood glaucoma.

We analyzed the long-term functional results in 102 eyes of 59 patients with childhood glaucoma with specific reference to the pattern of optic nerve damage. Optic disk photography and quantitative perimetry were used to judge the degree of damage that had been sustained. There was a predilection for initial visual field damage in the arcuate area, followed by further arcuate and nasal field loss, similar to the pattern of visual field loss seen in adult glaucoma. In children, as in adults, neural tissue appeared to be lost preferentially at the vertical disk poles. The selective pattern of glaucomatous optic nerve damage seemed not to depend upon the age of the optic nerve structures. In contrast to adult eyes, the scleral canal in children apparently enlarges with high IOP. Thus, disk cup size increase in children could occur from neural tissue loss, from scleral canal enlargement, or from a combination of the two processes.

Adolescent↗
PubMedDate not supplied

Comparison of subjective visual acuity with visual acuity predicted from C-scan topography.

PURPOSE: To compare the capability of objective measures of visual acuity (potential visual acuity from C-scan) to predict subjective visual acuity (best spectacle-corrected visual acuity [BSCVA]). METHODS: Patients with BSCVA > or = 20/20 were enrolled in four groups (Group 1: normal [33 eyes]; Group 2: < -7.00 D myopia [43 eyes]; Group 3: > or = -7.00 D myopia [28 eyes]; Group 4: At least 1 month after LASIK [93 eyes]). Videokeratography was performed with the ray tracing Technomed C-scan. The potential visual acuity from C-scan was obtained with pupils undilated and intact precorneal tear films. All visual acuity was recorded in logMAR, and the significance of differences between acuities was assessed with a one-way ANOVA test. RESULTS: The potential visual acuity from C-scan ray tracing of normal and myopic eyes in response to both photopic and mesopic stimuli did not differ. In a given eye, the potential visual acuity from C-scan ray tracing was better than BSCVA, and the difference was statistically significant. Although the potential visual acuity from C-scan of postoperative LASIK eyes in response to photopic stimuli was the same, it decreased under mesopic conditions. CONCLUSIONS: Potential visual acuity from C-scan overestimates subjective visual acuity due to the inadequate assumptions in ray tracing or individual retinal resolution ability. In addition, the potential visual acuity from C-scan ray tracing varies with pupil diameter in different illumination.

Adolescent↗
PubMed1995

[Relationship between kinetic visual acuity and visual acuity with limited exposure].

Using a kinetic vision tester which we developed, kinetic visual acuity (KVA) at target velocity of 0-100 km/h was measured at background luminance of 0.1-200 cd/m2 in 19 eyes of 10 normal volunteers ranging in age from 20 to 31 years. The decrease in KVA was slow at a target velocity of 30 km/h or more as reported before. KVA was best at background luminance of 100 cd/m2. In 3 eyes of 2 normal subjects, 3 eyes of 2 patients with tonic accommodation and 1 eye of 1 patient with central serous chorioretinopathy, visual acuity at limited exposure times was also measured. In patients with tonic accommodation, visual acuity at limited exposure times was good, but KVA was poor as compared to normal eyes. In the eyes of patients with central serous chorioretinopathy, results were poor for both. The quantity of light required to obtain the same visual acuity was similar for both normal eyes and eyes with central serous chorioretinopathy in terms of both KVA and visual acuity at limited exposure times. In eyes with tonic accommodation, difference was seen in the required quantity of light. We conclude that functions of accommodation are involved in kinetic vision and that higher visual functions are required than those for visual acuity at limited exposure times.

Adult↗
PubMed1998

Visual acuity and visual field impairment in Usher syndrome.

OBJECTIVE: To determine the extent of visual acuity and visual field impairment in patients with types 1 and 2 Usher syndrome. METHODS: The records of 53 patients with type 1 and 120 patients with type 2 Usher syndrome were reviewed for visual acuity and visual field area at their most recent visit. Visual field areas were determined by planimetry of the II4e and V4e isopters obtained with a Goldmann perimeter. Both ordinary and logistic regression models were used to evaluate differences in visual acuity and visual field impairment between patients with type 1 and type 2 Usher syndrome. RESULTS: The difference in visual acuity of the better eye between patients with type 1 and type 2 varied by patient age (P=.01, based on a multiple regression model). The maximum difference in visual acuity between the 2 groups occurred during the third and fourth decades of life (with the type 1 patients being more impaired), while more similar acuities were seen in both younger and older patients. Fifty-one percent (n=27) of the type 1 patients had a visual acuity of 20/40 or better in at least 1 eye compared with 72% (n=87) of the type 2 patients (age-adjusted odds ratio, 3.9). Visual field area to both the II4e (P=.001) and V4e (P<.001) targets was more impaired in the better eye of type 1 patients than type 2 patients. A concentric central visual field greater than 20 degrees in at least 1 eye was present in 20 (59%) of the available 34 visual fields of type 1 patients compared with 70 (67%) of the available 104 visual fields of type 2 patients (age-adjusted odds ratio, 2.9) with the V4e target and in 6 (21%) of the available 29 visual fields of type 1 patients compared with 36 (38%) of the available 94 visual fields of type 2 patients (age-adjusted odds ratio, 4.9) with the II4e target. The fraction of patients who had a visual acuity of 20/40 or better and a concentric central visual field greater than 20 degrees to the II4e target in at least 1 eye was 17% (n=5) in the type 1 patients and 35% (n=33) in the type 2 patients (age-adjusted odds ratio, 3.9). CONCLUSIONS: Visual acuity and visual field area were more impaired in patients with type 1 than type 2 Usher syndrome. Of note, 27 of 53 type 1 (51%) and 87 of 120 type 2 (72%) patients had a visual acuity of 20/40 or better in at least 1 eye. These data are useful for overall counseling of patients with Usher syndrome.

Adult↗
PubMed1983

[Age and photopic and mesopic visual acuity].

Visual acuity at high luminance (100 cdm2) and at low luminance (0.8 cdm2) was measured in normal subjects aged between 20 and 50 years. A decrease of visual acuity at Low luminance was noted with increasing age whereas high luminance acuity remained unchanged (20/20). At thirty years of age, low luminance visual acuity was an average of 20/30 decreasing at 40 years to 20/40. Results were confirmed by statistical analysis. A short study with interference fringes, formed by a coherent light (neon-helium laser) produced directly on the retina and thus by-passing optical effects on the eye, suggested that the retina-brain system was responsible for decreased mesopic visual acuity, night myopia or right presbyopia not playing any part in this decrease as suggested by some authors. Consequences of these findings, concerning particularly workers at low luminance such as pilots or drivers, are discussed.

Adult↗
PubMed1976

Behavioral correlates of 'tectal compression' in goldfish. II. Visual acuity.

Visual acuity was measured in three normal goldfish and two goldfish in which the caudal optic tectum had been ablated bilaterally. Compression of the retinotectal map was assumed to have occurred in the two operated fish, which were tested more than 200 days after surgery. The results indicated that the visual acuity of the normal fish ranged from 0.94 to 0.95 degrees of visual angle. The visual acuity of the fish with presumed compression of their retinotectal maps ranged from 1.91 to 2.07 degrees. The results suggest that compression of the retinotectal map occurs at the expense of the spatial-resolution ability of the visual system.

Animals↗
PubMed1994

The change of visual acuity and visual field by diminished illumination in eyes with multifocal intraocular lens.

To investigate the effect of illumination on visual acuity and visual field in eyes with multifocal intraocular lens (IOL), the near and far visual acuity of the eyes with multifocal implants were compared to those of the eyes with monofocal implants in the diminished illumination, and the visual fields of two groups were also compared by the different target size and intensity. The near and far visual acuity of the eyes with multifocal implants were significantly decreased as compared to those of the eyes with monofocal implants under diminished illumination, and the visual field of the multifocal implanted eyes also significantly decreased as compared to that of the monofocal implanted eyes by the reduction of spot size and intensity. From the above results, it is assumed that the bifocal separation of incident light to two simultaneous focal points in the multifocal implants causes more decreased visual acuity and narrower visual field in the diminished illumination as compared to that of the eyes with monofocal implants.

Adult↗
PubMed1999

Losses of hemifield contrast sensitivity in patients with pituitary adenoma and normal visual acuity and visual field.

OBJECTIVE: To detect early losses of contrast sensitivity (CS) in patients with pituitary adenomas, before the occurrence of visual acuity and visual field defects. METHODS: CS has been evaluated in both hemifields of 28 patients with different kinds of pituitary adenoma (mainly intrasellar) and normal visual acuity and visual field, as well as in 15 age-matched controls. Two different stimuli were used: a coarse (0.3 c/deg) dynamic (10 Hz) grating and a finer (2 c/deg) static grating. RESULTS: On average, CS and/or hemifield asymmetry were reduced in patients, whereas perimetric sensitivity was normal. CS losses were more frequent for 2 c/deg static-, as compared with 0.3 c/deg, 10 Hz stimuli. However selective losses for either stimuli were also found. CS losses did not correlate with anatomical measurements (size, chiasm involvement) of tumors as established by MRI scans. CONCLUSIONS: CS evaluation may provide a simple and effective tool for early detection and monitoring of visual dysfunction in patients with pituitary adenoma. The lack of correlation between CS losses and chiasm involvement suggests causes different from chiasmal compression for visual dysfunction.

Adenoma↗
PubMed1997

[Objective assessment of visual acuity with visual evoked potential].

PURPOSE: To study the technique for objectively assessment of visual acuity with Pattern Visual Evoked Potential (PVEP) and Discrete Fourier Transform (DFT). METHOD: Thirty-three normal eyes were tested in this study. Reversal square-wave gratings of eight different sizes (30, 20, 18, 12, 10, 6, 4, 2 min. of arc) were used as stimuli. The reversal rate of the stimuli was 10 times/sec. The harmonic amplitudes of VEP at 10 Hz were calculated with Discrete Fourier Transform. A relation curve between the harmonic amplitude and the size of grating was plotted from the data of each tested eye. Regression line was fitted to the data points in the approximately linear section of the curve which is near the threshold of zero amplitude. The threshold of the grating size was obtained by extrapolating of the regression line to zero amplitude, and the visual acuity was assessed with the threshold. RESULT: In seventy percent of tested eyes, the visual acuities assessed with VEPs were consistent with those measured with the International Standard Test Chart. CONCLUSION: The VEP technique for visual acuity assessment is reliable.

Adolescent↗
PubMed2006

Effect of static visual acuity on dynamic visual acuity: a pilot study.

The aim of this pilot study was to evaluate whether dynamic visual acuity changes with or without refractive correction. 42 healthy enrolled subjects with normal vision were divided into two age-matched groups. In Group A, dynamic visual acuity was measured first with the refractive error fully corrected and then without. In Group B, dynamic visual acuity measurements were taken in the reverse order of that performed by Group A. The measurements were binocularly performed five times using free-head viewing after dynamic visual acuity values were stable. Significant changes in dynamic visual acuity (static visual acuity 20/20 vs 12/20) were observed in both Group A (171.6 +/- 36.0 deg./sec. vs 151.8 +/- 39.6 deg./sec., Wilcoxon test, p < .001) and Group B (169.8 +/- 30.0 deg./sec. vs 151.2 +/- 36.0 deg./sec., Wilcoxon test, p < .001). The interaction was significant (F1.20 = 8.12, p = .009). These results indicated that refractive correction affected dynamic visual acuity.

Adult↗
PubMed1989

Effects of visual acuity and visual motor speed and dexterity on cognitive test performance.

This study examined the hypothesis that near visual acuity and visual motor speed and dexterity contribute significantly to performance on cognitive tests that place a premium on these functions. Near visual acuity for both eyes, Finger Tapping Test - average taps with dominant hand, and Grooved Pegboard Test - dominant hand time, served as the independent variables. The dependent variables were Trail Making Test-Part B and the Performance subtests of the Wechsler Adult Intelligence Scale. Results indicated that while visual acuity was significantly correlated with all six test variables, it did not contribute to the regression model as well as Pegboard time or Tapping speed. Pegboard time and Tapping speed contributed to the regression model, but in different ways depending upon which test was examined.

Journal Article↗
PubMed1989

Binocular depth perception, visual acuity and visual fields in cats following neonatal section of the optic chiasm.

We studied the role of the transcallosal pathway in stereopsis by measuring binocular and monocular depth perception in two cats that had undergone section of the optic chiasm at the age of 21 d. To ensure that the surgery did not impair vision to the extent that depth perception could not be evaluated, visual acuity and visual fields were also measured. In both of the chiasm-sectioned animals the visual fields were reduced and the visual acuity was substantially lower than in normal cats, with a maximum of about 2 cyc deg-1. Binocular depth thresholds of the chiasm-sectioned cats were worse than those of the normal cat but were better than their own monocular thresholds. These results suggest that the chiasm-sectioned animals were still able to use binocular cues to judge depth and indicate that the indirect pathway through the corpus callosum is sufficient to mediate binocular depth perception.

Depth Perception↗
PubMed2006

Objective measurement of human visual acuity by visual evoked potentials.

Electrophysiological studies were performed to measure the threshold (upper end of range) spatial frequency using visual evoked potentials and comparison with visual acuity neuron 26 healthy subjects. The aim of the present work was to create a method for objective measurement of visual acuity. This was addressed by initial measurements using a universally accepted method of visual stimulation and processing of electroencephalograms, which allows errors due to individual differences in visual system function to be minimized. These experiments yielded a strong correlation between the threshold spatial frequency of the test grid yielding an evoked potential on presentation and visual acuity, in degrees, expressed as the resolving ability of the visual system for this optotype. A logarithmic relationship was found between these values and an equation allowing automated calculation of visual acuity (resolving ability) from electrophysiological data was derived. The results were independent of the subject's responses and therefore provides a maximally objective assessment of visual acuity.

Adolescent↗
PubMed1992

Visual acuity and visual field development after cryocoagulation in infants with retinopathy of prematurity.

Visual development was studied in 10 very-low-birth-weight infants (less than 1500 g) with retinopathy of prematurity (ROP) stage 3+ who had been treated with cryocoagulation in both eyes. Binocular visual acuity (acuity cards method) and binocular visual fields (kinetic perimetry) were assessed repeatedly in the first year of life. At 12 months corrected age, visual acuity was normal in seven and impaired in three infants, who appeared to be severely myopic. Normal visual fields were found in eight infants at this age. The results indicate that cryotherapy in cases of ROP stage 3+ does not interfere with visual acuity development. The effect on visual field development needs further investigation.

Cryosurgery↗