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PubMed1982

The pigeon's distant visual acuity as a function of viewing angle.

Distant visual acuity was determined for several viewing angles in two restrained White Carneaux pigeons. The behavioral technique was a classical conditioning procedure that paired presentation of sinusoidal gratings with shock. A conditioned heart rate acceleration during the grating presentation indicated resolution of the grating. The bird's acuity was fairly uniform across a large range of their lateral visual field; performance decreased slightly for posterior stimulus placement and sharply for frontal placements. The data suggest that foveal viewing is relatively less advantageous for acuity in pigeons than in humans. The data are also consistent with the current view that pigeons are myopic in frontal vision.

Animals↗

PubMed1995

Causes of decreased visual acuity after cataract extraction.

We analyzed a consecutive series of cataract extractions to determine the causes of unsuccessful results. Our criterion was a decrease in visual acuity from the preoperative measurement. Fourteen of 1237 eyes met this criterion. In three of the 14, visual acuity was decreased by more than two Snellen lines. Vitreous loss occurred in seven of the eyes. In six of these, cystoid macular edema developed. The reasons for reduced visual acuity were cystoid macular edema (eight eyes), an aggravation of age-related maculopathy (three eyes), and vitreous hemorrhage and herpetic keratitis (one eye each). A branch vein occlusion caused macular edema and vitreous hemorrhage in one eye. From this data, we recognize the importance of avoiding vitreous loss. If it does occur, we recommend that meticulous anterior vitrectomy be performed, with as little manipulation as possible.

Aged↗

PubMed1984

Decrease of visual acuity in patients with clear media and normal fundi. Objective screening methods for differentiation and documentation.

For differentiation of unilateral reduction of visual acuity in patients with clear media and normal fundi, the Swinging Flashlight Test was used. Optic neuropathies as a rule give pathological results. On the other hand refraction scotomas, functional amblyopias and malingering produce a normal outcome of this test in general. For documentation of afferent pupillary defects a photographic method is described. Electronystagmography is advocated as a method for detection of malingerers and neurotics among patients complaining of acute uni- or bilateral visual acuity reduction. Optokinetic nystagmus is recorded using Bangerter's filters in front of the patient's eye. This method allows a certain estimation of the visual acuity.

Electronystagmography↗

PubMed1975

Variation of visual acuity with soft contact lenses: a function of luminance.

The relationship between visual acuity and luminance with soft contact lenses, compared with the same one obtained with glasses or the naked eye, shows that acuity decreases at the same rate as luminance is reduced. This result differs from what had previously been found in comparing acuity with hard contact lenses and glasses. In the present case, soft lenses conform to the aspherical curvature of the cornea, and therefore the eye wearing soft contact lenses is not affected by spherical aberration, as in the case of hard contact lenses. At the outset, soft lenses produce a somewhat lower visual acuity but with adaptation, acuity improves and becomes equal or better, as evinced by measurements made after three months of wear.

Adult↗

PubMed2006

Visual acuity, contrast sensitivity, reading speed, and wavefront analysis: pseudophakic eye with multifocal IOL (ReSTOR) versus fellow phakic eye in non-presbyopic patients.

PURPOSE: To compare the visual performance in the pseudophakic eye and the phakic eye in four patients who underwent unilateral intraocular lens (IOL) implantation. METHODS: Four patients presenting with unilateral cataract underwent ReSTOR (Alcon Laboratories, Ft Worth, Tex) IOL implantation in their nondominant eye, targeting emmetropia. RESULTS: Uncorrected near visual acuity was >20/32 in all operated eyes and best spectacle-corrected distance visual acuity was 20/16 for two eyes, 20/25 for one eye, and 20/32 for one eye. Reading speed was similar between the eyes, but not for critical print size. Contrast sensitivity was lower in the pseudophakic eyes. Wavefront analysis showed no considerable difference in total high order aberrations, coma, and spherical aberration between eyes for all patients. CONCLUSIONS: In young patients with unilateral cataract surgery, unilateral multifocal IOL implantation provides satisfactory visual acuity and may be considered an alternative treatment option in this patient population.

Adult↗

PubMed2001

A comparison of grating visual acuity, strabismus, and reoperation outcomes among children with aphakia and pseudophakia after unilateral cataract surgery during the first six months of life.

PURPOSE: The method of correcting aphakia after unilateral cataract extraction during infancy is controversial. Some authorities advocate correction with an intraocular lens (IOL) whereas others advocate correction with a contact lens (CL). We compared grating visual acuity, alignment, and reoperative outcomes in age-matched children treated with these 2 modalities at 5 clinical centers. METHODS: Twenty-five infants born in 1997 or 1998 with a dense unilateral congenital cataract who had cataract surgery coupled with (IOL group, n = 12) or without (CL group, n = 13) primary IOL implantation were enrolled in this study. All patients were prescribed half-time occlusion therapy. In July 1999, their grating visual acuities, ocular alignments, and reoperation rates were assessed. RESULTS: The mean grating visual acuity (LogMAR) for the affected eye was 0.70 +/- 0.32 for the IOL group and 0.87 +/- 0.31 for the CL group (P =.19). The mean interocular difference in grating visual acuity was 0.26 +/- 0.30 for the IOL group and 0.50 +/- 0.28 for the CL group (P =.048). The incidence of strabismus (>10 PD) was 75% in the IOL group compared with 92% in the CL group (P =.24). The incidence of reoperations was 83% in the IOL group compared with 23% in the CL group (P =.003). CONCLUSIONS: Our preliminary data suggest that correcting aphakia after unilateral congenital cataract surgery with primary IOL implantation results in an improved visual outcome but a higher rate of complications requiring reoperation. A randomized clinical trial, the Infant Aphakia Treatment Study, is planned to further study the optimal treatment for aphakia following unilateral cataract extraction during infancy.

Aphakia, Postcataract↗

PubMed1985

Autosomal dominantly inherited retinitis pigmentosa. Visual acuity loss by subtype.

Sixty-eight patients with autosomal dominant retinitis pigmentosa were divided into two distinct subtypes and studied for visual function using a life-table analysis. Type 1 patients (n = 23) had diffuse pigmentation, concentric visual field loss, and no recordable electroretinogram. Type 2 patients (n = 45) as a group had regionalized pigmentation, sectorial field loss, and some recordable electroretinogram. The cumulative probability of maintaining a visual acuity of 6/12 (20/40) or better over each decade of life decreased rapidly in eyes of type 1 patients; for type 2 eyes, this probability remained above 90% through the fifth decade of life. The presence of an atrophic-appearing foveal lesion was associated with a reduction in visual acuity to 6/15 (20/50) or worse in a majority of patients. Data from this study indicate that investigators should look for subtypes within the major genetic groupings of retinitis pigmentosa for more accurate assessment of a patient's potential for maintaining good central visual acuity.

Adolescent↗

PubMedDate not supplied

Visual acuity and color vision deficiency in amblyopia.

PURPOSE: To investigate color vision and its relation with the type of amblyopia and visual acuity of amblyopic eyes. METHODS: In this prospective study, 67 amblyopic eyes of 64 patients, aged from 4 to 13 years (mean 6.8 +/- 2.1) and 26 eyes of 13 control subjects aged from 5 to 13 years (mean 7.3 +/- 1.6) were examined with the Farnsworth-Munsell 100 Hue Test (FM-100). Amblyopic eyes were grouped as strabismic (21 eyes) and anisometropic (46 eyes). Each group was subdivided according to their visual acuity, as less than 5/10 and 6/10 or better. The total errors, blue-yellow (B-Y) and red-green (R-G) partial error scores were obtained for each group. One-way ANOVA was used to assess differences between groups. RESULTS: The error scores of all axes were lower in the control group than the amblyopic groups (p<0.001), but the differences within amblyopic groups were not significant (p>0.05). CONCLUSIONS: Deficient color vision in the amblyopic eyes was not related to the visual acuity and type of amblyopia.

Adolescent↗

PubMed1983

Comparative studies of color fields, visual acuity fields, and movement perception limits among varsity athletes and non-varsity groups.

This paper examined effects of sports practice on patterns of color fields, limits of peripheral movement perception, and visual acuity field by comparing varsity ball players and non-varsity control groups. The first study measured extent of color fields and limits of horizontal and vertical meridians for peripheral movement perception of 139 college students. The second study tested visual acuity fields of female and male basketball players and female and male controls. The first study indicated that athletes had wider limits for horizontal movement perception, while the non-athletes had better vertical movement perception limits. Basketball players demonstrated color fields and limits for peripheral movement perception superior to those of soccer players. In the second study, athletes did not have any wider visual acuity fields than non-athletes, but their movement-perception limits were significantly wider than those of non-athletes.

Color Perception↗

PubMed1979

Visual acuity following retinal detachment surgery.

A poor visual acuity following an anatomical cure of a retinal detachment was in this series always associated with a change in macular morphology, the commonest maculopathy being the appearance of a cellophanemembrane. Factors influencing the visual prognosis are duration and extent of the detachment, involvement of the macula, the age of the patient and the presence of pre-operative periretinal membrane formation. The type of buckling procedure is not related to the visual outcome and while the conversion of the procedure into an intra-ocular operation, either by way of drainage of subretinal fluid or by intra-vitreal injection, can cause serious complications we suggest that uncomplicated drainage of subretinal fluid has not been a cause of macular pucker in this series but that this conditions is related to the indication for drainage, namely a varying degree of rigidity of the retina due to periretinal membrane formation.

Age Factors↗

PubMed2001

Depression, visual acuity, comorbidity, and disability associated with age-related macular degeneration.

OBJECTIVE: To examine (1) the prevalence of depressive disorders in community-dwelling adults with advanced age-related macular degeneration (AMD) and (2) the relationship in this population between depression, visual acuity, the number of comorbid medical conditions, disability caused by vision loss as measured by the National Eye Institute-Vision Function Questionnaire (NEI-VFQ) and the vision-specific Sickness Impact Profile (SIPV), and disability caused by overall health status as measured by the Sickness Impact Profile-68 (SIP). DESIGN: Analysis of cross-sectional baseline data from a randomized clinical trial. PARTICIPANTS: Participants were 151 adults aged 60 and older (mean age, 80 years) with advanced macular degeneration whose vision was 20/60 or worse in their better eye. METHODS: Subjects were interviewed using measures of depression, disability, and chronic medical conditions. Visual acuity was obtained. Nonparametric correlation analyses and linear regression analyses were performed. MAIN OUTCOME MEASURES: Structured Clinical Interview for DSM-IV (SCID-IV), Geriatric Depression Scale (GDS), NEI-VFQ, SIPV, and SIP. RESULTS: Of the participants, 32.5% (n = 49) met SCID-IV criteria for depressive disorder, twice the rate observed in previous studies of community-dwelling elderly. Over and above depression (GDS), visual acuity aided in prediction of the level of vision-specific disability (NEI-VFQ and SIPV). CONCLUSIONS: Depressive disorder is a significant problem for the elderly afflicted with advanced macular degeneration. Further research on psychopharmacologic and psychotherapeutic interventions for depressed AMD patients is warranted to improve depression and enhance functioning. Over and above depression, visual acuity aided in predicting vision-specific disability. Treatment strategies that teach patients to cope with vision loss should be developed and evaluated.

Aged↗

PubMed2004

Photorefractive keratectomy for pediatric anisometropia: safety and impact on refractive error, visual acuity, and stereopsis.

PURPOSE: To establish the safety and possible efficacy of excimer laser photorefractive keratectomy (PRK) for treatment of pediatric anisometropia. DESIGN: Interventional case series METHODS: This is a prospective, noncomparative interventional case series at an individual university practice of photorefractive keratectomy in 11 children aged 2 and 11 years with anisometropic amblyopia who were unable or unwilling to use contact lens, glasses, and occlusion therapy to treat the amblyopia. The eye with the higher refractive error was treated with PRK using a standard adult nomogram. The refractive treatment goal was to decrease the anisometropia to 3 diopters or less. Main outcome measures were cycloplegic refraction, refractive correction, degree of corneal haze, uncorrected and best spectacle-corrected visual acuity, and stereopsis over 12 months. RESULTS: All patients tolerated the procedure well. The mean refractive target reduction was -10.10 +/- 1.39 diopters for myopia and +4.75 +/- 0.50 diopters for hyperopia. The mean achieved refractive error reduction at 12 months for myopia was -10.56 +/- 3.00 diopters and for hyperopia was +4.08 +/- 0.8 diopters. Corneal haze at 12 months was minimal. Uncorrected visual acuity improved by 2 or more lines in 6 (75%) of the eight children able to perform psychophysical acuity tests. Best spectacle-corrected visual acuity improved by 2 lines in 3 (38%) of patients. Stereopsis improved in 3 (33%) of nine patients. CONCLUSIONS: Pediatric PRK can be safely performed for anisometropia. The refractive error response in children appears to be similar to that of adults with comparable refractive errors. Visual acuity and stereopsis improved despite several children being outside the standard age of visual plasticity. Photorefractive keratectomy may play a role in the management of anisometropia in selected pediatric patients.

Amblyopia↗

PubMed2003

The relationship between stereopsis and visual acuity after occlusion therapy for amblyopia.

PURPOSE: To investigate the relationship between visual acuity (VA) and stereoacuity after occlusion therapy in patients with various types of amblyopia. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Sixty-one children with amblyopia caused by anisometropia with no strabismus (26 children), small angle (</=8 prism diopters) or intermittent strabismus (20), or both (15). METHODS: All were treated with occlusion therapy. Visual acuity and near stereopsis using the Titmus test (Stereo Optical Inc., Chicago, IL) were measured at each clinic visit. MAIN OUTCOME MEASURE: The change in near stereopsis relative to distance VA after occlusion therapy. RESULTS: Mean age at initiation of therapy was 5.1 years (range = 3.5-8) and mean follow-up 52.3 weeks (range = 13-192). Mean duration of occlusion was 36 weeks (range = 12-102). After occlusion treatment, mean VA of all children improved from 0.43 to 0.78 (P<0.0001), whereas mean stereoacuity improved from 1167.4 seconds of arc to 101 (P<0.0001). By the last visit, 85.2% (52 of 61) of patients demonstrated at least 2 lines of improvement in VA. There was a significant linear relationship between VA and stereoacuity (P<0.001). The 26 anisometropic patients without strabismus enjoyed improvement in VA and stereopsis (P<0.0001) similar to that of the 35 with small-angle or intermittent strabismus (P<0.0001). CONCLUSIONS: When employing occlusion therapy for amblyopia (due to anisometropia, small-angle or intermittent strabismus, or a combination), as VA improves, stereopsis generally also improves.

Amblyopia↗

PubMed1997

[The impact of long-term isolation on visual acuity].

During the experiment with 90- and 7-day isolation and confinement tests were applied to evaluate, along with static, expositional and dynamic (DVA) visual acuity using automated system VZGLIAD (Gaze). Test distance was 1 meter. To assess DVA, the subjects were requested to make oscillatory movements with the head in the horizontal plane with a metronome frequency at 1 Hz. An upward trend in static visual acuity was interpreted as a result of myopization engendered by exposure to confinement and video display. A significant loss in expositional (and dynamic) visual acuity was stated in the main (p > 0.01) and visiting (p > 0.1) crews. These shifts could be associated with the dominance of inhibitory processes in the visual cortex due to monotony of the visual environment and insufficient oculomotor and accommodative activities.

Humans↗

PubMed2006

Late changes in refraction, pachymetry, visual acuity, and corneal topography after penetrating keratoplasty.

PURPOSE: To analyze the late changes in refraction, corneal topography, and pachymetry after penetrating keratoplasty. METHODS: We have retrospectively analyzed data of 64 eyes of 56 patients with a clear corneal graft and no other ocular diseases. The eyes were examined soon and several years after all sutures were removed, at 19.5 +/- 3.1 months and 76.8 +/- 25.2 months, respectively, after keratoplasty. All eyes were examined using the EyeSys 2000 videokeratograph and the Tomey SP2000 ultrasonic pachymeter. Corneal surface regularity was studied using the indices provided by the Holladay Diagnostic Summary (ie, asphericity coefficient Q; corneal uniformity index CU; predicted corneal acuity PCA). Irregular astigmatism was quantified using semimeridian data from videokeratographs (refractive power symmetry index). RESULTS: Visual acuity increased by an average of 0.35 +/- 0.93 lines (P = 0.002) between the 2 examinations, whereas no significant changes in refraction and videokeratoscopy (ie, power, indices, and irregular astigmatism) were observed (P > or = 0.08). Central corneal thickness significantly increased from 542 +/- 31 microm to 572 +/- 38 microm (P < 0.001). Change in BSCVA did not significantly correlate with the change in refraction, in topographic indices, or in irregular astigmatism (rs < or = 0.13; P > or = 0.16). CONCLUSION: Late after penetrating keratoplasty, best corrected visual acuity shows a small but statistically significant improvement, whereas refraction and corneal surface regularity are stable. This late improvement in visual acuity is not explained by current techniques.

Adolescent↗

PubMed2001

Subnormal visual acuity syndromes (SVAS): albinism in Swedish 12-13-year-old children.

BACKGROUND: The vision of 12-13-year-olds in Sweden was examined in a field study. The study was designed as being a part of a large European-Latin American study, the DESAMI project. The objective was to evaluate the prevalence of residual amblyopia and ocular disorders, atiologies of subnormal vision and some normal visual parameters in this group of children. The children had to be born in Sweden in 1985 in order to have the opportunity to be included in the voluntary screening visual examinations. The full results of the study will be presented elsewhere. This paper presents clinical and VEP data of those children who had visual acuity of 0.8 or below in one or both eyes which could not be increased with glasses, or other visual/eye disturbances not explained as common amblyopia, i.e., subnormal visual acuity or pathological visual states of unknown cause, SVAS (subnormal visual acuity syndromes). SUBJECTS AND METHODS: In all, 1046 children were examined: 76 had visual disturbances of such severity that they were referred to a paediatric ophthalmologist (AS). Eighteen children could not be pathologically classified, and they were referred to another ophthalmological examination and VEP (visual evoked potential) recordings. VEP reveals an asymmetric response after monocular stimulation in albinism. RESULTS: Twelve children turned up for a second examination and VEP was recorded from 10 children. Nine children showed iris translucency. Seven children showed an asymmetric VEP and were classified as albinos. The albinoic VEPs could be subdivided into two types, (1) including all parts of the response and (2) partly excluding the P1/P100 potential complex. The VEP response was normal, showing symmetry and no other abnormality, in three of the children. CONCLUSIONS: The results indicate that albinism is common in Sweden. A prevalence value of approximately 1% is about 100 times higher than previous figures. This high prevalence may indicate another form of heredity, with genetical contribution to albinism from a varying number of albino genes and varying expression in the phenotypes, in the Scandinavian population. It is emphasised that in investigations of children with SVAS, electrophysiological examinations are important, not only to reveal albinism but also to exclude or verify neurometabolic conditions, for example.

Adolescent↗

PubMed2001

Subnormal visual acuity syndromes (SVAS): albinism in Swedish 12-13-year-old children.

BACKGROUND: The vision of 12-13-year-olds in Sweden was examined in a field study. The study was designed as being a part of a large European-Latin American study, the DESAMI project. The objective was to evaluate the prevalence of residual amblyopia and ocular disorders, aetiologies of subnormal vision and some normal visual parameters in this group of children. The children had to be born in Sweden in 1985 in order to have the opportunity to be included in the voluntary screening visual examinations. The full results of the study will be presented elsewhere. This paper presents clinical and VEP data of those children who had visual acuity of 0.8 or below in one or both eyes which could not be increased with glasses, or other visual/eye disturbances not explained as common amblyopia, i.e., subnormal visual acuity or pathological visual states of unknown cause, SVAS (subnormal visual acuity syndromes). SUBJECTS AND METHODS: In all, 1046 children were examined: 76 had visual disturbances of such severity that they were referred to a paediatric ophthalmologist (AS). Eighteen children could not be pathologically classified, and they were referred to another ophthalmological examination and VEP (visual evoked potential) recordings. VEP reveals an asymmetric response after monocular stimulation in albinism. RESULTS: Twelve children turned up for a second examination and VEP was recorded from 10 children. Nine children showed iris translucency. Seven children showed an asymmetric VEP and were classified as albinos. The albinoic VEPs could be subdivided into two types, (1) including all parts of the response and (2) partly excluding the P1/P100 potential complex. The VEP response was normal, showing symmetry and no other abnormality, in three of the children. CONCLUSIONS: The results indicate that albinism is common in Sweden. A prevalence value of approximately 1% is about 100 times higher than previous figures. This high prevalence may indicate another form of heredity, with genetical contribution to albinism from a varying number of albino genes and varying expression in the phenotypes, in the Scandinavian population. It is emphasised that in investigations of children with SVAS, electrophysiological examinations are important, not only to reveal albinism but also to exclude or verify neurometabolic conditions, for example.

Adolescent↗

PubMed2003

Visual acuity assessment: a comparison of two tests for measuring children's vision.

PURPOSE: To compare the Kay Picture Test and the logMAR Crowded Test. METHODS: Monocular visual acuity measurement was attempted on 103 paediatric subjects (aged between 2.5 and 16 years) attending eye clinics, using each of the visual acuity tests. RESULTS: The results obtained with the two tests were found to be comparable as confirmed with the Intra-class Correlation Coefficient, which revealed good agreement between the two tests. There was significant correlation between the visual acuity results measured and high conformity in the results from the weaker eye. There was a statistical difference in acuity scores between the tests; the Kay Picture Test gave a lower logMAR score with a mean difference of 0.08 logMAR. This 0.08 difference represents an actual difference of less than one line of acuity measure which can be considered to be clinically insignificant. There was a significant difference in the ability to perform each of the tests under binocular conditions, with more of the 50 children, aged 5 and under, able to perform the Kay Picture Test than the logMAR Crowded Test. CONCLUSIONS: The results obtained with the two tests are comparable. Both tests can be considered to be appropriate for amblyopia detection and the use of picture-based logMAR tests should be considered for younger children.

Adolescent↗