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At least 91 records · Page 5Linked to original sources
PubMed2003

Evaluating the visual experience: visual acuity and the visual analogue scale.

PURPOSE: To attempt a comparison of the visual experience [assessed using a visual analogue scale (VAS)] with visual acuity in a group of normally-sighted adult optometric patients. METHODS: A single-item 100 mm paper VAS was administered to a sequence of 142 normally-sighted pre-presbyopic patients. Each individual was invited to indicate their recent subjective distance visual experience between the extremes of 'dreadful' (0 mm) and 'perfect' (100 mm). Each patient's binocular visual acuity was then determined at 6 m using a high-contrast logMAR chart under usual consulting room conditions. RESULTS: A weak association was revealed between the subjective indication of recent visual experience and the actual level of binocular acuity recorded in this normally-sighted group of subjects. On the basis of group responses a statistically significant discontinuity in the scores recorded with the VAS was demonstrated between patients who attained a clinical acuity better or worse than 0.10 logMAR units (6/7.5). Patient gender, age, and whether spectacles were habitually worn for distance viewing, were each revealed to be not statistically significant features. CONCLUSIONS: For normally-sighted optometric patients the subjective criterion of visual satisfaction would appear to be only loosely associated with the contemporaneous record of clinical acuity.

Adult↗
PubMed1985

Effectiveness of a pinhole method for visual acuity screening.

Visual acuity screening was performed in the home in an adult population, using a standardized, retroilluminated chart. A pinhole disk was utilized to retest those subjects who initially failed the screening. All subjects failing the screening with the pinholes, and an equal number of age-matched subjects passing the screening (controls), were asked to have a complete ophthalmologic examination, including a protocol refraction in an eye clinic (clinic examination). Without use of the pinhole disk, 14.4% of subjects failed to read a 20/40 line. Use of the pinholes reduced the failure rate to 6.9%. Fifty-seven percent of those failing and 55% of controls had the clinic examination. Determination of best-corrected visual acuity after protocol refraction in the clinic indicated that the false-positive rate (the percentage of subjects who failed the screening but had visual acuity of 20/40 or better on the clinic examination) for the screening was 26%, and the false-negative rate (the percentage of subjects who passed the screening but had visual acuity of worse than 20/40 on the clinic examination) was 1.5%. Use of a pinhole disk is highly effective for visual acuity screening, reducing the false-positive rate by more than half.

Adult↗
PubMed2003

Visual acuity testing in diabetic subjects: the decimal progression chart versus the Freiburg visual acuity test.

PURPOSE: To study reproducibility and biological variation of visual acuity in diabetic maculopathy, using two different visual acuity tests, the decimal progression chart and the Freiburg visual acuity test. METHODS: Twenty-two eyes in 11 diabetic subjects were examined several times within a 12-month period using both visual acuity tests. The most commonly used visual acuity test in Denmark (the decimal progression chart) was compared to the Freiburg visual acuity test (automated testing) in a paired study. RESULTS: Correlation analysis revealed agreement between the two methods (r(2)=0.79; slope=0.82; y-axis intercept=0.01). The mean visual acuity was found to be 15% higher (P<0.0001) with the decimal progression chart than with the Freiburg visual acuity test. The reproducibility was the same in both tests (coefficient of variation: 12% for each test); however, the variation within the 12-month examination period differed significantly. The coefficient of variation was 17% using the decimal progression chart, 35% with the Freiburg visual acuity test. CONCLUSION: The reproducibility of the two visual acuity tests is comparable under optimal testing conditions in diabetic subjects with macular oedema. However, it appears that the Freiburg visual acuity test is significantly better for detection of biological variation.

Adult↗
PubMed1996

Spatial frequency sweep pattern reversal VER acuity vs Snellen visual acuity: effect of optical defocus.

The effect of artificially induced image defocusing on visual acuities (VAs) measured by spatial frequency sweep pattern reversal visual evoked response (SPVER) and Snellen measurement was studied in six normal subjects. The steady-state SPVER was recorded using vertical gratings of 10 different spatial frequencies ranging from 0.52 to 30.36 c/deg. The SPVER acuity was compared with Snellen acuity (SA) measured under the same conditions of optical defocus. With moderate defocusing [< + 1.0 diopter (D), VA > 20/40], the SPVER acuities were equal to or poorer than the SAs. With more defocus (> + 1.5 D, VA < 20/70), the SPVER acuities became better than the SAs. The discrepancies between the SA and SPVER acuities may be the result of the influence of the parafoveal area on the SPVER at lower visual acuity levels.

Adult↗
PubMed1977

Visual acuity and behavior of monocularly deprived monkeys after retinal lesions.

One eyelid of each of three Macaca nemestrina monkeys was sutured shut at 3 weeks of age. One animal had the central 10 degrees of the open eye retina lesioned at 3 weeks of age (EL1), a second at 9 months of age (LL1), and the third had no lesion (MD1). After a reverse suture at 9 months of age, the deprived eye was tested for grating acuity, visual behavior, and visual field. EL1 tested positively on all behavioral tasks by 1 month and showed good visual ability to negotiate a playroom but never performed better than 20/1,250 on grating acuity. MD1 showed little visual behavior in the playroom but tested at 20/400 acuity. LL1 rapidly recovered all aspects of visual behavior and tested at 20/80 visual acuity. Perimetry shows that LL1 and EL1 respond mainly in the central portion of the deprived eye visual field but not to the periphery or the monocular segment. We conclude that removal of the open eye retina after the critical period allows much visual recovery by the deprived eye but that removal of the open eye retina within the critical period does not prevent many of the effects of monocular deprivation.

Animals↗
PubMed2004

[Strategies of visual acuity assessment].

Visual acuity can be assessed by different strategies. The constant-stimulus-, the stair-case-, the Best-PEST-strategies, and the EN ISO 8596 are discussed. In cases of presumed psychogenic visual impairment and malingering it can be useful to modify these strategies striving for a determination of the (minimum) visual acuity based on statistical analysis rather than "clinical experience". The EN ISO 8596 defines visual acuity by a 60 % criterion, thus implying guesswork, if recognition of the optotypes is uncertain. Therefore, the forced-choice-procedure is mandatory. Objective psychophysical (preferential looking, induction or suppression of rhythmic eye movements) and electrophysiological methods (VEP) of visual acuity assessment can be useful in infants, in the mentally handicapped, and in patients with presumed psychogenical influence or malingering.

Data Interpretation, Statistical↗
PubMed1998

Armaignac's 1906 paper on the recording of visual acuity and the progression of letter sizes on visual acuity charts.

BACKGROUND: Henry Armaignac, a French ophthalmologist in the early twentieth century, criticized the Monoyer optometric scale, which was used to measure visual acuity. METHODS: This article discusses the "optometric scale" for visual acuity letter sizes proposed by Armaignac in a 1906 publication. CONCLUSION: Armaignac pointed out the flaws of the Monoyer visual acuity chart commonly used in France at the time and suggested an improvement in the progression of letter sizes on the chart.

Equipment Design↗
PubMed1986

Age related changes in visual acuity.

Longitudinal visual acuity assessments of men, and cross-sectional assessments of men and women in the Baltimore Longitudinal Study of Aging are presented. The longitudinal data relate presenting far, uncorrected far, presenting near and uncorrected near visual acuities to age. The cross-sectional data relate presenting far acuity to age. The prevalence of cataract, glaucoma and retinal pathologies are reported for the longitudinal sample at the time of their last vision test. The effect of visual pathologies in general, and cataract in particular, upon presenting far visual acuity was examined. The longitudinal data are consistent with cross-sectional data from previously published reports. Older persons who were free from specific visual pathologies exhibited an age-related decline in presenting far acuity as did those with documented visual pathologies. Despite the demonstrated loss in acuity with age, the majority of persons maintain at least fair acuity (20/40 or better) into their 80's.

Adult↗
PubMed2006

Visual acuities "hand motion" and "counting fingers" can be quantified with the freiburg visual acuity test.

PURPOSE: The visual acuity (VA) of patients with very low vision is classified using the semiquantitative scale "counting fingers" (CF), "hand motion" (HM), "light perception" (LP), and "no light perception." More quantitative measures would be desirable, especially for clinical studies. The results of clinical VA measurements, Early Treatment Diabetic Retinopathy Study (ETDRS) charts, and the Freiburg Visual Acuity Test (FrACT) were compared. The FrACT is a computerized visual acuity test that can present very large Landolt C optotypes when necessary. METHODS: Examined were 100 eyes of 100 patients with various eye diseases (e.g., diabetic retinopathy, ARMD), covering a range of VAs from LP to decimal 0.32. The FrACT optotypes were presented on a 17-inch LCD monitor with random orientation. After extensive training, two ETDRS and FrACT measurements were obtained. The testing distance was 50 or 100 cm. RESULTS: ETDRS and FrACT coincided closely for VA > or = 0.02 (n = 80). ETDRS measures were successfully obtainable down to CF (at 30 cm; test-retest averaged over all patients, coefficient of variation [CV](ETDRS) = 9% +/- 8%), and FrACT provided reproducible measurements down to HM (test-retest CV(FrACT) =12% +/- 11%). For CF (n = 6), both ETDRS and FrACT resulted in a mean VA of 0.014 +/- 0.003 (range, 0.01-0.02). The VA results of FrACT for HM (n = 12) were 0.005 +/- 0.002 (range, 0.003-0.009); the individual values were highly reproducible. No results were obtainable for LP (n = 2). CONCLUSIONS: The three acuity procedures concur above a VA of 0.02. The results suggest that the category CF at 30 cm can be replaced by 0.014, using ETDRS or FrACT. Using FrACT, one can even reproducibly quantify VA in the HM-range, yielding a mean VA of 0.005.

Adult↗
PubMed1997

[Visual acuity measured by pattern visual evoked potential].

We investigated the appropriateness of a method for the assessment of visual acuity using pattern visual evoked potentials (PVEP) in which retinal X-ganglion cells are predominantly stimulated. Eighteen normal eyes (average 22.2 years old) with normal acuity of 1.0 were examined. The stimulus consisted of white and black checkerboards (39', 26', 15' and 9') with a visual angle of eight degrees and a contrast level of 15%. The pattern reversal frequency was 0.7 Hz. This resulted in 100 averaged PVEP per session. We judged visual acuity from responses of the P100 component. Visual acuity was judged to be 0.1, so that there was response to the 39' checkerboard stimulus pattern, but not to the 26' pattern. Consequently, the accuracy for visual acuity was 76.9% for 0.1, 71.4% for 0.2, 70.0% for 0.5 and 58.3% for 1.0. This method, which uses a stimulus pattern with a small visual angle, low contrast, and low pattern reversal frequency, is useful for subjective measurement of the visual acuity of infants or handicapped children whom it is difficult to measure by the conventional objective method of measuring visual acuity with Landolt's rings.

Adult↗
PubMed1983

Psychophysical assessment of visual acuity in infants with visual disorders.

The measurement of visual acuity is an essential part of the eye examination of adults, but is rarely attempted in infants being examined for presumed or known eye disease. We have used a preferential looking technique to test visual acuity of infants attending a hospital eye clinic. Serial measurements of acuity of infants attending a hospital eye clinic. Serial measurements of acuity in infants with certain eye diseases can provide examples of the effects of visual deprivation on the developing human visual system. Amongst 14 cases of monocular visual form deprivation in early life, there were 9 infants who had monocular occlusion as therapy for esotropia; 3 infants who had unilateral opacities of the ocular media; and 2 infants who had unilateral eyelid closure from infection or burns. Despite differences in exact mode of deprivation, the effects on visual acuity were similar. There was a reduction of visual acuity in the deprived eye and a simultaneous increase in acuity of the non-deprived eye. These effects of monocular deprivation were not permanent. Recovery occurred with reverse deprivation or by simple cessation of the deprivation. Of 10 children with binocular visual form deprivation, there were 5 who had bilateral congenital cataracts and 5 who had bilateral uncorrected high refractive errors. Infants with cataract surgery before 2 months of age showed normal early development of visual acuity. A 4-6 month delay before treatment resulted in reduced acuity, but recovery subsequently occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1988

Stability of visual acuity in amblyopic patients after visual maturity.

One hundred thirty patients with strabismic amblyopia who underwent full-time occlusion therapy (FTO) and were followed through to at least 9 years of age were evaluated to determine the stability of visual acuity after visual maturity (after 9 years of age). Of these 130 patients, 89 are included in this review. At the conclusion of the FTO therapy, 92% (82/89) had attained a visual acuity of 20/40 or better, 6% (5/89) had attained 20/50-20/100, and 2% (2/89) remained at 20/200 or less. Of the nine patients in this series in whom patching was initiated between the ages of 6 and 9 years of age, a good visual result was seen in 89% (8/9), with 63% (5/8) of those attaining 20/20 vision. The final visual acuity in this group of patients was taken at an average patient age of 15.9 years. In 75% of the patients (67/89) there was no change in visual acuity over time, while 17% (15/89) showed a one- or two-line decrease, and in 8% (7/89) vision dropped more than two lines. Of those patients who had greater than or equal to 20/40, 88% (56/64) who had a posttreatment visual acuity of 20/20 showed no change at the final evaluation, but only 50% (9/18) of those whose posttreatment vision was between 20/25 and 20/40 were stable. In those patients who needed part-time occlusion (PTO) to maintain equal visual acuity, their stability appeared to be the same as the vision of those whose vision was maintained without PTO.

Adolescent↗
PubMed1988

Prediction of post cataract extraction visual acuity: 10 Hz visually evoked potentials.

Cataract patients suspected of having disease that might interfere with good postoperative visual function were evaluated by eliciting monocular steady-state luminance visual evoked potentials (VEPs) with closed eyes at a stimulus rate of 10 flashes/sec. VEPs were rated as either normal or abnormal. Patients with normal VEPs were predicted to have visual acuity of 6/15 (20/50) or better. Patients with abnormal VEPs were predicted to have acuities of 6/18 (20/60) or worse. Postoperative acuities were determined for all patients who underwent surgery and who had no intraoperative or early postoperative complications. The predicted and observed postoperative acuities were quantitatively compared for the 59 patients who met these criteria, using a 2 X 2 contingency table. The chi-square was significant (p less than .001). The overall accuracy of prediction was 80%. Accuracy of the predictions for patients with preoperative acuities of 6/60 (20/200) or better was compared with the accuracy of the predictions for those with preoperative acuities of 60/120 (20/400) or worse. There was no significant difference (p greater than 0.10).

Cataract Extraction↗