SEARCH · PubMed Health

Results for “Visual Acuity”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources

PubMed1999

Visual acuity screening versus noncycloplegic autorefraction screening for astigmatism in Native American preschool children.

INTRODUCTION: Visual acuity screening (VAS) is less reliable in preschoolers than in school-aged children as a means of detecting significant refractive error. We wished to compare the effectiveness of VAS with the effectiveness of an objective method, noncycloplegic autorefraction screening (NCARS), in detecting the presence of significant astigmatism warranting spectacle correction. METHODS: We examined 245 Native American Head Start registrants aged 3 to 5 years. We attempted to obtain uncorrected visual acuity using Lea Symbols logMAR Chart (Precision Vision Inc, Villa Park, Ill), noncycloplegic autorefraction using the Nikon Retinomax K-plus (Nikon Corp, Melville, NY), and cycloplegic refraction (CR) on each eye. The VAS failure criterion was either a 2-line acuity difference between eyes or acuity worse than 20/40 in either eye. The NCARS and CR failure criterion was the spectacle correction threshold exceeding the 50th percentile on the basis of a survey of AAPOS members. RESULTS: We completed VAS in 96% of children and NCARS and CR in 100% of children. There was high prevalence (31%) of significant astigmatic refractive error in this sample. Ten subjects who did not permit bilateral visual acuity measurements were scored as having a positive test result. The sensitivity and specificity of VAS were 90% and 44%, respectively. NCARS had sensitivity and specificity of 91% and 86%, respectively. NCARS becomes cost-effective after 1044 children are screened, assuming that the cost of the autorefractor is 300 times the cost of the referral examination. CONCLUSION: VAS offers high sensitivity but suffers from poor specificity. NCARS greatly reduces the number of unnecessary referrals. In this population, NCARS becomes cost-effective after approximately 1000 children are screened.

Arizona↗

PubMed1983

The dot visual acuity test--a new acuity test for children.

A new visual acuity test is described for children between the ages of 2 and 4 years who are unable to respond to the tumble E games. For children old enough to respond to both tests, the visual threshold are the same. Fifty percent of the children who could not respond to the tumble E game will be able to be tested with this new method. The new is rapid, inexpensive, and cannot be memorized, thereby allowing the test to be given at frequent intervals.

Child↗

PubMed2002

[Characteristics of visual acuity and contrast sensitivity in students of different ages].

To investigate the peculiarities of the visual acuity and contrastive sensitivity 60 healthy pupils (120 eyes) of different ages (7-16) were examined with a help of the computer diagnostic program "Oculus-W" V95. The increase in both the visual acuity and the contrastive sensitivity with age have been shown, as well as the parametres of their normal levels for different ages have been determined. It makes estimating the functional state of the visual analyzer more exact. The processes of making the visual acuity and the contrast sensitivity in the schoolchildren have been proved to interdependent.

Adolescent↗

PubMed1999

[Determining visual acuity with LH symbols and Landolt rings].

PURPOSE: Lea (LH) symbols seem to be favourable for visual acuity assessment in childhood. The symbols of the LH test are well standardized and applicable to preschool children. We compared the visual acuity determined by LH single symbols (LH) and the acuity measured with the Landolt-C (LC). PATIENTS AND METHODS: 138 cooperative subjects aged 7 to 91 years were examined. Their visual acuity was either normal or reduced due to various etiologies. Their refractive error was corrected. The monocular LH and LC were determined by a 3/4 criterion (study 1). In 19 healthy subjects aged 21 to 58 years, acuity was reduced stepwise by 5 different calibrated occlusives (study 2). A Lighthouse single symbol book (LH symbols) was used at a distance of 3 m. LC was determined at a distance of 5 m. The luminance of the test field was 180-200 cd/m2. The right eye of each patient and the amblyopic eye of the squinting patients was taken for statistical evaluation. The strabismic patients' interocular differences of LC and LH were compared. RESULTS: Within study 1, LC ranged from 0.02 to 2.0 and LH from 0.03 to 2.5. LH overestimated LC by 1.4 lines on an average (t-test p < 0.0001). The regression equation lgLH = 0.95 lgLC + 0.11 describes a high correlation (r = 0.95) between LH and LC. The relations between LH and LC of 43 strabismic amblyopic patients and the remaining subjects did not significantly differ. Due to the criterion of an interocular LH-difference > 1 line, 85.7% resp. 90% of the strabismic amblyopic patients with an interocular LC difference > 1 resp > 2 lines were detected. In study 2, LC ranged from 0.1 to 1.6, LH from 0.12 to 2.0. The mean difference LH-LC was 1.3 lines. The regression equation was lgLH = 0.91 lgLC + 0.08 (r = 0.95). CONCLUSION: LH symbols allow a reliable measurement of recognition acuity. Due to the design of the symbols, they are excellently suitable for application to preschool children. Age related normal values should be established. The systematic difference between the LC acuity and the LH acuity measured with the Lighthouse LH single symbol book by 1.4 lines has to be considered.

Adolescent↗

PubMed1988

Visual acuities and dark-adapted thresholds of children with Bardet-Biedl syndrome.

We studied the visual acuities and dark-adapted sensitivities of 12 children with Bardet-Biedl syndrome. All except one child, who was seen only once, were tested serially. In the first decade of life, all visual acuities were within 2 octaves of normal. All but two final visual acuities obtained from patients in their second and third decades were more than 2 octaves poorer than normal. Dark-adapted sensitivities of all patients were, or became, significantly less than normal even in those patients whose period of follow-up was limited to the first decade of life. Of the 11 patients measured serially, seven showed decreases in dark-adapted sensitivities of at least 0.5 log unit during the follow-up period, and the last measured sensitivities of all patients were at least 2 log units less than the normal mean.

Child, Preschool↗

PubMed1996

Visual acuity and erythrocyte docosahexaenoic acid status in breast-fed and formula-fed term infants during the first four months of life.

It has been recognized that preterm infants have a more rapid development of visual acuity if fed human milk or a formula enriched with the long-chain polyunsaturated fatty acid (LCPUFA) docosahexaenoic acid (DHA) compared to a standard formula devoid of LCPUFA. Few studies have addressed whether the same is also true in term infants. The aim of the present study was to follow visual acuity and fatty acid composition in red blood cells (RBC) for the first 4 mon of life in 17 breast-fed and 16 formula-fed term infants. The formula used did not contain LCPUFA, but contained 1.7 wt% alpha-linolenic acid, and the linoleic/alpha-linolenic acid ratio was 8.5. The increase in visual acuity measured by Teller acuity cards developed more rapidly in breast-fed infants compared to formula-fed infants (P < 0.001). This was parallelled by a decrease in DHA of RBC in formula-fed infants, and with a significantly lower level at two and four months as compared to breast-fed infants. The content of DHA in milk from the breast-feeding mothers was high compared to other Western countries. The difference in visual acuity between the two feeding groups could be due to differences in DHA status as reflected by the RBC levels, but other explanations are possible. Intervention studies are required to verify if development of visual acuity in term formula-fed infants is dependent on the DHA level of formula.

Breast Feeding↗

PubMed1987

Macular thickening and visual acuity. Measurement in patients with cystoid macular edema.

Cystoid macular edema (CME) is commonly associated with many ocular conditions. The presence of CME on fluorescein angiographic examination need not, however, preclude good visual acuity. The hypothesis that the degree of macular thickening is associated with visual acuity was tested. Ten consecutive stereoscopic fluorescein angiograms were graded by 13 ophthalmologists using a set of four standards. Linear regression showed a significant relationship between mean macular thickening and the visual acuity recorded at the time of angiography. However, no significant relationship could be made between the estimation of visual acuity and the amount of fluorescein staining measured in the posterior pole. Although the observation of fluorescein leakage is indispensable for documenting a breakdown in the blood-retinal barrier, the observation of retinal thickening is important for identifying the sites of edema accumulation, and may be the useful parameter to follow when trying to assess improvement or worsening of retinal edema and in cases of uveitis when the cause of poor vision may be multifactorial.

Adult↗

PubMed2007

The Freiburg Visual Acuity Test-variability unchanged by post-hoc re-analysis.

BACKGROUND: The Freiburg Visual Acuity and Contrast Test (FrACT) has been further developed; it is now available for Macintosh and Windows free of charge at http://www.michaelbach.de/fract.html . The present study sought to reduce the test-retest variability of visual acuity on short runs (18 trials) by post-hoc re-analysis. METHODS: The FrACT employs advanced computer graphics to present Landolt Cs over the full range of visual acuity. The sequence of optotypes presented follows an adaptive staircase procedure, the Best-PEST algorithm. The Best-PEST threshold obtained after 18 trials was compared to the result of a post-hoc re-analysis of the acquired data, where both threshold and slope of the psychometric function were estimated via a maximum-likelihood fit. RESULTS: Testing time was 1.7 min per run on average. Test-retest reproducibility was +/-2 lines (or +/-0.2 logMAR) for a 95% confidence band (using 18 optotype presentations per test run). Post-hoc psychometric fitting reproduced the Best-PEST result within 1%, although the individual slopes varied widely; test-retest reproducibility was not improved. CONCLUSIONS: The FrACT offers advantages over traditional chart testing with respect to objectivity and reliability. The similarity between the results of the Best-PEST vs. post-hoc analysis, fitting both slope and threshold, suggest that there is no disadvantage to the constant slope assumed by Best PEST. Furthermore, since variability was not reduced by post-hoc analysis, for high reliability more trials should be employed than the 18 trials per run used here.

Adult↗

PubMed2005

The effect of bilateral horizontal rectus recession on visual acuity, ocular deviation or head posture in patients with nystagmus.

PURPOSE: This work was undertaken to evaluate the effect of bilateral horizontal rectus recession on visual acuity, ocular deviation and head posture in patients with nystagmus. METHODS: Twenty patients underwent recession of 4 horizontal rectus muscles to dampen the nystagmus. At least 2 muscles were recessed posterior to the equator. RESULTS: Monocular and binocular visual acuity improved from 1 to 3 Snellen lines after the procedure in 13 patients (76.5%). Visual changes in log MAR notations were statistically significant with Wilcoxon analysis in each and both eyes. Preoperative binocular visual acuity was 0.73 +/- 0.26 log MAR that reached to 0.62 +/- 0.32 log MAR after surgery (P = 0.02). The greatest improvement was observed in patients with congenital motor nystagmus. Ten patients had horizontal strabismus in addition to nystagmus before the surgery. One-millimeter additional recession of both medial rectus muscles caused an average reduction of 6 PD in esotropia. Corresponding figures for similar additional recessions of the lateral rectus muscles was 11 PD for correction of exotropia. Abnormal head posture decreased in all the cases and improved completely in most of them. CONCLUSIONS: Large horizontal rectus recession can improve visual acuity and decrease nystagmus in sensory and motor types. By revision in surgical planning, strabismus and abnormal head posture can also be corrected.

Adolescent↗

PubMed2005

Correlation of retinal sensitivity measured with fundus-related microperimetry to visual acuity and retinal thickness in eyes with diabetic macular edema.

AIM: To determine whether significant correlations exist between retinal sensitivity measured by fundus-related microperimetry and the visual acuity and the foveal thickness measured by optical coherence tomography (OCT) in eyes with diabetic macular edema (DME). METHODS: A retrospective chart review of 32 eyes with DME and 17 normal healthy eyes that had undergone fundus-related microperimetry and OCT. The macular sensitivity was measured using the recently introduced fundus-related microperimeter, Micro Perimeter 1. The mean retinal sensitivities within the central 2 degrees and 10 degrees were correlated with the best-corrected visual acuity and OCT-measured foveal retinal thickness. RESULTS: The mean sensitivities in the central 2 degrees and 10 degrees were significantly lower in patients with DME than in normal subjects (P<0.0001). The mean retinal sensitivities in the central 2 degrees and 10 degrees were inversely correlated with visual acuity (r(2)=0.623, P<0.0001; r(2)=0.581, P<0.0001) and foveal thickness (r(2)=0.581, P<0.0001; r(2)=0.551, P<0.0001). CONCLUSIONS: The mean retinal sensitivities measured with fundus-related microperimetry were significantly lower in eyes with DME than in normal eyes. Because a significant correlation of the microperimeter-determined retinal sensitivity to visual acuity and foveal thickness was observed, the retinal sensitivities obtained by fundus-related microperimetry may be another measure that can be used to assess the effects of DME.

Adult↗

PubMed1987

An evaluation of visual acuity with the Corning CPF 527 lens.

The effect of visual acuity on the Corning 527 photochromatic lens was studied for a group of 50 normal patients and 53 low vision patients. Visual acuity was measured at 10 feet using three Lighthouse Low Vision Distance Acuity Charts, whose letters were randomly arranged. Acuity measurements were performed under three conditions: through a plano lens, a Corning 527 lens and an equivalent neutral density filter, each placed over the best corrective lenses. No statistically significant difference in acuity measurements were found between these three conditions.

Absorption↗

PubMed2002

Recovery of the visual acuity in a family with Reis-Bückler dystrophy.

BACKGROUND: The hereditary Reis-Bückler dystrophy is one of the anterior localised corneal dystrophies with superficial reticulated opacities, sometimes in combination with recurrent attacks of corneal erosion. Phototherapeutic keratectomy (PTK) is now the first method to consider for managing this disease when intervention is required. METHODS: We treated six eyes of four related patients with Reis-Bückler dystrophy, who had a demonstrable reduction in visual acuity due to corneal opacities within their virgin corneas (three eyes), penetrating (one eye) or lamellar (two eyes) grafts. We present the results of change in visual acuity and best corrected spherical spectacle and contact lens refraction at 1 year following surgery. In one case, we had to fit a rigid contact lens to correct the hyperopic shift which caused anisometropia. RESULTS: The mean spherical refractive change 1 year after PTK surgery was 0.33+/-S.D., 1.8D. A hyperopic shift was observed in four eyes. Visual acuity remained stable in all patients 1 year after surgery. The central corneal area remained clear, and mean best spectacle corrected visual acuity improved from +0.8 logMAR before PTK to +0.15 logMAR after 1 year. There was no significant change (P>0.8) between the mean 1 year best spectacle corrected visual acuity (+0.125 log MAR +/- S.D. 0.15) and the best contact lens corrected visual acuity (+0.108 log MAR +/- S.D. 0.16). After fitting a contact lens in one patient to correct anisometropia, the hyperopic shift did not change significantly during 12 months of follow-up. It was not necessary to adjust the lens parameters. One patient required cataract surgery. CONCLUSION: PTK corneal surgery is the treatment of first choice when intervention is required in patients with Reis-Bückler dystrophy because it is safe and much less invasive than lamellar or penetrating keratoplasty. Contact lens fitting following PTK has not changed corneal shape.

Journal Article↗

PubMed1998

Correlation of varicella-zoster virus copies and final visual acuities of acute retinal necrosis syndrome.

BACKGROUND: Herpes viruses may play an important role in acute retinal necrosis (ARN) syndrome, and raised antibody titer or virus genome have been detected in intraocular fluids of patients with ARN. In spite of aggressive anti-viral therapy, the clinical courses and final visual acuities among these patients have varied. Our purpose was to estimate the amount of virus and compare it to final visual acuity in patients with ARN. METHODS: The number of varicella-zoster virus copies in aqueous and vitreous before and after administration of anti-viral therapy were estimated by polymerase chain reaction (PCR) and by semi-nested PCR in 12 eyes of 11 patients with ARN and were compared with clinical characteristics. RESULTS: Viral genome DNA was amplified in ocular fluids diluted between 10(-3) and 10(-6) in patients whose final visual acuities were 0.3 or less. Conversely, the dilution required was between 10(-1) to 10(-3) in the patients whose final visual acuities were 0.4 or better. The difference was statistically significant. Further, patients in the latter group reacted to the anti-viral drug acyclovir more promptly than did the former patients. CONCLUSION: Our results showed that final visual acuity may partly depend on the number of virus copies in ocular fluids. The number of virus copies tended to be higher in elderly or immunocompromised patients than in others, and the treatment was less efficacious in these patients.

Acyclovir↗

PubMed1983

Visual acuity and cone spatial density in retinitis pigmentosa.

Cone increment thresholds were measured psychophysically in 42 patients (ages 10 to 59) with retinitis pigmentosa and visual acuities of 20/20 to 20/70. A 6-min arc diameter stimulus was flashed to the foveola at a background retinal illuminance for which Weber's law was in effect; under these test conditions, cone increment thresholds depended on the number of remaining functioning cones (cone spatial density) but not on their outer segment length (cone optical density). Log threshold and log visual acuity were correlated inversely (P less than 0.001). The slope of the regression line relating these two measures was compatible with the idea that reduced cone spatial density is a major determinant of reduced visual acuity in retinitis pigmentosa. In a subset of these patients with visual acuities of 20/25 or better, results of cone increment threshold testing suggested that cone spatial density was reduced significantly less in the foveola than in the parafovea.

Adolescent↗

PubMed2001

Effects of early postfiltration ocular hypotony on visual acuity, long-term intraocular pressure control, and posterior segment morphology.

PURPOSE: To determine whether hypotony after filtration surgery has any influence on visual acuity and intraocular pressure (IOP) lowering. PATIENTS AND METHODS: We prospectively investigated 43 eyes of 43 patients undergoing trabeculectomy without the use of antimetabolites for 12 months. RESULTS: The lowest postoperative IOP valued 4.9 +/- 3.6 mm Hg (range, 0-14 mm Hg). It correlated statistically significant with the IOP 6 weeks (P = 0.016), 6 months (P = 0.009), and 1 year after surgery (P = 0.027). Eyes with a deterioration of visual acuity 6 weeks after surgery had undergone a stronger postoperative hypotony (correlation with lowest postoperative IOP, P = 0.035). The mean period with an IOP less than 5 mm Hg was 3.5 +/- 8.0 days, and the mean period with an IOP less than 10 mm Hg lasted 45.4 +/- 68.8 days (range, 0-276 days). A hypotony score based on IOP and duration of hypotony was introduced. A correlation was detected between morphologic signs of hypotony, such as tiny retinal folds, at the 6-month follow-up and the duration of hypotony (P = 0.029) and hypotony score (P = 0.001). CONCLUSIONS: Hypotony after filtration surgery may decrease visual acuity in the early postoperative period. Conversely, early postoperative hypotony correlated with better long term IOP control. There was no deleterious effect on visual acuity after 6 months.

Adult↗

PubMed2001

Visual acuity, residual amblyopia and ocular pathology in a screened population of 12-13-year-old children in Sweden.

PURPOSE: To establish the distribution of visual acuity and the prevalence of residual amblyopia and other ocular disorders in a vision-screened population group of 12-13-year-old children. METHODS: In total 1046 children were examined in a field study in Sweden. The examination included visual acuity, stereopsis, cover testing, red reflex, refractive retinoscopy and examination of the posterior pole. In selected cases VEP was also performed. RESULTS: Visual acuity > or =1.0 in at least one eye was present in 98% of cases. Residual amblyopia (< or =0.5) was found in 1.1% of the population. Manifest strabismus was found in 2.7%. There were only a small number of ocular opacities and posterior pole abnormalities. Ocular albinism was found in 7 cases. In 15 children the cause of subnormal VA was unexplained. CONCLUSION: Results for visual acuity, residual amblyopia and other ocular disorders are very similar to previous Nordic, vision-screened populations.

Adolescent↗

PubMed1994

Pattern reversal visual evoked response and Snellen visual acuity.

Because the pattern-reversal visual evoked response (PVER) reflects the central retinal function, PVER results generally agree with those of psychophysical tests. The visual acuities (VAs) calculated from PVER recordings and Snellen acuity (SA) measurements were compared in 500 eyes (261 patients; ages 8 to 88 years; mean, 44.5 years). The best-corrected VA was measured using the ETDRS chart, and the PVER acuity was determined by the smallest check size that produced a definite PVER (critical check size). In 288 eyes with a critical check size of 10 min of arc, the SAs ranged from 20/15 to 20/800 (mean 20/38). In 68 eyes with a critical check size of 20 min, the SAs ranged from 20/15 to 20/800 (mean 20/97). In 70 eyes with a critical check size of 40 min, the SAs ranged from 20/20 to 20/1600 (mean 20/156). In 29 eyes with a critical check size of 80 min and 14 eyes with a critical check size of 160 min, the SAs ranged from 20/50 to 20/1600 (mean 20/312 and 20/398, respectively). In 31 eyes in which the PVER was non-recordable, the SAs ranged from 20/70 to 20/3200 (mean 20/1177). The PVER acuity using the smallest check size seemed to agree with the SA, but large deviations were observed in certain subjects.

Adolescent↗

PubMed2001

Visual discrimination learning in the water maze: a novel test for visual acuity.

Learning about space, the environment and specific objects comprising three-dimensional arrangements requires processing of visual information. As learning and memory experiments in mammals rely heavily on normal processing of visual cues, drug-induced disruption of acquisition learning or memory formation necessitates the important control for visual acuity. A popular task used frequently for rats is the Morris water maze. However, previously used visual tasks in the water maze only control for gross visual disturbances. Here we describe a new training procedure enabling visual acuity to be tested in the water maze. Animals were trained to discriminate between two cue cards containing a pattern of vertical black and white stripes. Cards were presented in two adjacent quadrants separated by a barrier with the escape platform located in front of the smaller stripes (1 cm wide). Once 80% correct responses were attained, the wider cue card (normally 5 cm wide stripes) was randomly changed to gratings of 1,2,3,4,5, and 10 cm width. Animals learned the discrimination with acuity of 1.5 c/deg. A detailed analysis of the swim patterns further suggests that, independent of the grating used, animals make a choice immediately after release and swim along the walls towards the cue. In a further acuity test taken a few weeks later when animals were given saline infusions, performance was better than in the first test suggesting an effect of learning. This novel test may prove useful in determining subtle drug-induced deficits in visual acuity that may contribute to disruption of spatial performance in the water maze.

Animals↗