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PubMed2006

[Optical coherence tomographic findings of the retinal pigment epithelium tear in macular area preserving good visual acuity].

PURPOSE: It has been reported that the visual outcome of retinal pigment epithelial tear (RPE tear) in the fovea is worse than that of RPE tear sparing the fovea. We report optical coherence tomography (OCT) findings of 3 cases with RPE tear in the fovea who preserved good visual acuity. PATIENTS: All patients had serous retinal pigment epithelial detachment involving the macula. The RPE was torn and rolled RPE was observed in the fovea. In OCT findings, a fovea was observed on the RPE flap, and visual acuity was preserved after RPE tear repair. CONCLUSION: We considered that preservation of good visual acuity was due to the presence of a fovea on the RPE flap. We could precisely analyze the location of the fovea and RPE tear using OCT.

Aged↗
PubMed1995

The relationship of macular microcirculation to visual acuity in diabetic patients.

OBJECTIVE: To assess the perifoveal microcirculation in diabetic maculopathy without clinically significant macular edema and its relationship to visual acuity. DESIGN: Prospective analysis. SETTING: A teaching hospital. PATIENTS: Fifteen patients with impaired visual acuity of 20/50 or worse, a diabetic control population with unaffected visual acuity (matched age, gender, retinopathy stage), and 52 healthy controls were enrolled. INTERVENTIONS: Study consisted of video-fluorescein angiography with image analyses and hemoglobin A1c measurements. MAIN OUTCOME MEASURES: Macular capillary blood velocity, capillary density (perifoveal intercapillary area), and foveal avascular zone. RESULTS: The capillary blood velocity was significantly reduced in both diabetic groups (P < .001) when compared with healthy controls, but did not differ significantly among the two diabetic groups. The perifoveal intercapillary area and foveal avascular zone were significantly enlarged in both diabetic groups compared with healthy controls (P < .001). The foveal avascular zone (P < .01) and perifoveal intercapillary area (P = .01) were further enlarged in the diabetics with reduced visual acuity. The visual acuity correlated significantly with foveal avascular zone (R2 = .51) and perifoveal intercapillary area (R2 = .24), indicating an association between enlargement and declined visual acuity. CONCLUSIONS: Capillary blood velocity remained unchanged regardless of presence of visual impairment, whereas foveal avascular zone and perifoveal intercapillary area indicated ischemia. This may help in defining a critical hypoxic threshold for visual loss and identifying the presence of an ischemic diabetic maculopathy.

Adult↗
PubMed1986

Lessons from the Visual Acuity Impairment Survey pilot study.

The Visual Acuity Impairment Survey (VAIS) pilot study was carried out in three large metropolitan areas of the United States to determine whether it would be feasible to conduct a large two-stage survey of the prevalence of visual acuity impairment and its causes. The study was conducted in conjunction with the Health Interview Survey (HIS), performed by the National Center for Health Statistics and the Census Bureau. In the first stage, a simple vision screening test was administered to 1,868 adults in their homes by specially trained Census Bureau interviewers. All those who failed the test, and a sample of those who passed it, were invited to a local clinic for a check on the accuracy of the screen and a detailed eye examination to establish the cause of the impairment. About 89 per cent of the HIS interviewees took the vision screening test in the home and agreed to have the results released, making it possible for the clinic to invite them for an examination. The principal obstacle to the success of the feasibility study was a low rate (less than 50 per cent) of participation in the clinic examination by the target population. Such low participation would leave the survey open to a serious question about its representativeness. The methods and findings of the pilot study are presented because the lessons may be of value to those attempting similar studies in the future. Suggestions are made for methodological modifications that may enhance the chances for success.

Adult↗
PubMed2006

Visual acuity in simple myopic astigmatism: influence of cylinder axis.

PURPOSE: The relationship between astigmatic refractive errors and their associated visual acuity has been studied in recent years in the context of refractive power space. The influence of the axis of astigmatism remains a matter of controversy. Our goal in this study is to provide additional experimental evidence to clarify this subject. The influence of the simulated axis orientation was compared with other factors that affect visual acuity such as the particular design of the test and the differences between eyes. METHODS: Simple myopic astigmatism from 0 to -3.00 D, in steps of -0.25 D, and with five different axes between 0 degrees and 90 degrees , were simulated on four healthy eyes of young observers. In each case, visual acuity was recorded for three different tests. Refractions were expressed in the form of vectors and visual acuity was represented as a function of strength. RESULTS: No significant differences in visual acuity were found for astigmatism of the same power but different axes. In fact, our results show these differences are even less important than those recorded for the same astigmatism induced in different eyes. The highest discrepancies in visual acuity were found when different charts were used to test the same astigmatic error. CONCLUSIONS: The strength of the vector representing the astigmatic refractive state describes very accurately the performance of visual acuity across simple myopic astigmatic errors. In these cases, visual acuity can be associated with a single refractive parameter. This fact could be useful, especially in statistical studies involving visual performance.

Adult↗
PubMed1986

Visual acuity results following treatment of persistent hyperplastic primary vitreous.

The visual acuity outcome of patients with persistent hyperplastic primary vitreous (PHPV) was reviewed. A total of 48 patients with the diagnosis of PHPV were seen at the University of Iowa, Iowa City, from 1971 through 1984. Twenty-five patients were managed nonsurgically, of which 23 had a poor visual acuity outcome (less than or equal to 5/200). Two with mild cases had visual acuities of 20/100 and 20/30. Twenty-three patients were treated surgically. Five of these had no further postoperative rehabilitation. Eighteen patients underwent surgery and aggressive optical and occlusion therapy. Eight of these 18 patients (44%) had postoperative visual acuities of 20/200 or better. These eight patients represent 17% of the study population. Therefore, lensectomy-membranectomy procedures for the purpose of effecting visual development are reasonable therapeutic options in patients with PHPV in whom the findings are primarily anterior in nature, surgery is performed at an early age, and aggressive amblyopia therapy is instituted.

Amblyopia↗
PubMed1999

Visual acuity and quality of life in patients with cataract in Doumen County, China.

PURPOSE: To evaluate the effectiveness of cataract surgery in achieving sight restoration and vision-related quality-of-life (QOL) in patients from rural southern China. DESIGN: Population-based, cross-sectional study. PARTICIPANTS: A total of 109 cataract operated persons (152 eyes) and 654 unoperated persons. METHODS: Cluster sampling was used in identifying a random sample of 5342 persons 50 years of age and older for visual acuity and eye examinations. Visual functioning (VF) and QOL questionnaires were administered to aphakic and pseudophakic individuals, unoperated persons with presenting visual acuity less than 0.10 in either eye, and a sample of those with normal vision. MAIN OUTCOME MEASURES: Distance visual acuity, VF, and QOL questionnaire scores. RESULTS: Among the cataract operated participants, 43 (39.4%) were bilaterally operated on, 32.1% had presenting visual acuity less than 0.10 in both eyes with 8.3% greater than or equal to 0.32 in both eyes. Of operated eyes, 52.6% presented with visual acuity less than 0.10, 23.7% greater than or equal to 0.32; with best correction, the corresponding percentages were 21.1% and 42.1%. Uncorrectable aphakia due to surgical complications was common. In a multivariate regression model, better visual acuity outcomes were associated with higher level surgeon practice settings and recent surgery. On a 0 to 100 scale, mean VF and QOL scores for the cataract operated population were 41.6 and 54.5, respectively. Mean scores ranged from 84.4 and 93.4, respectively, for the unoperated persons with normal vision, to 14.6 and 31.2, respectively, for those with visual acuity less than 0.05 in both eyes. The VF and QOL scores were closely correlated with presenting visual acuity in both cataract operated and unoperated populations (r = 0.49-0.64). Scores among the cataract operated population were not influenced by age, gender, or education level. Among the unoperated population, lack of education was associated with lower VF and QOL scores (P = 0.017 and P = 0.005, respectively), and older age was associated with lower QOL scores (P < 0.001). CONCLUSION: Patients in rural southern China are not realizing the full sight-restoring potential of modern-day cataract surgery. Remedial efforts are needed to improve the performance of local eye surgeons.

Aged↗
PubMed1995

The relationship between visual acuity and functioning and well-being among diabetics.

Given the enormous recent interest in functional capabilities related to vision, the goal of this study was to examine the relationship of standard clinical measures of vision (e.g. Snellen acuity) to functioning and well-being. The association between Snellen visual acuity, Amsler grid distortion and presence of diabetic retinopathy with self-reported functioning and well-being (SF-36) were examined in a sample of 327 diabetics from the Medical Outcomes Study (MOS). There was little or no correlation between Snellen visual acuity, Amsler grid distortion or diabetic retinopathy and functioning and well-being (i.e. SF-36 scales). Maximum product-moment correlation was 0.15 with worst eye visual acuity, 0.13 with best eye visual acuity, 0.08 with presence of retinopathy, and 0.10 with Amsler grid distortion. Analysis of variance revealed that visual acuity (both best and worst eye) was statistically related only to the physical function scale; no other exam measure was related to any other SF-36 scale score. Snellen visual acuity, Amsler distortion and diabetic retinopathy correlate weakly with patient self-reported functioning and well-being. Thus, the information provided by functioning and well-being measures is complementary to that of standard clinical measures of visual ability.

Activities of Daily Living↗
PubMed2005

Predictive factors for visual acuity after intravitreal triamcinolone treatment for diabetic macular edema.

OBJECTIVE: To evaluate which factors influence maximum gain in best-corrected visual acuity after intravitreal injection of triamcinolone acetonide as treatment for diffuse diabetic macular edema. METHODS: This prospective clinical interventional study included 53 eyes with diffuse diabetic macular edema receiving an intravitreal injection of about 20 mg of triamcinolone. The mean +/- SD follow-up was 10.2 +/- 7.6 months. RESULTS: In a multiple linear regression analysis, maximum gain in best-corrected visual acuity after the intravitreal injection of triamcinolone was significantly (P < .001) and negatively correlated with an increased degree of macular ischemia and a higher preoperative visual acuity. Improvement in best-corrected visual acuity was significantly and positively correlated with increased degree of macular edema (P = .001). Change in best-corrected visual acuity after the intravitreal triamcinolone injection was statistically independent (P > .15) of age, sex, pseudophakia, and macula grid laser treatment before inclusion into the study. The results were comparable for gain in visual acuity at 6 months after the injection. CONCLUSION: Pronounced macular edema may have a positive impact, and marked macular ischemia and a high preoperative best-corrected visual acuity may have a negative impact, on an increase in best-corrected visual acuity after intravitreal triamcinolone injection in patients with diabetic macular edema.

Adult↗
PubMed1986

Visual acuity and stereopsis between the ages of 5 and 10 years. A cross-sectional study.

The development of visual acuity and stereopsis was studied in 321 boys and 340 girls aged between 5 and 10 years. Visual acuity was assessed by the E test and a modified version of the STYCAR test, stereo acuity by the Lang-Stereo test [17]. Both vision tests showed an increase in the median visual acuity between the ages of 5 and 10 years. The E test indicated an increase from 1.2 between 5 and 6 years to 1.5-1.7 between 7 and 10 years. The values obtained with the STYCAR test were 0.6-1.3 higher, depending on the test rating used. Visual acuity norms between 5 and 10 years are presented as empirical centile curves. No significant differences were observed in visual acuity between the left and right eyes, nor between the sexes. The right eye was found to be the leading eye in 54.8% of the boys and 54.5% of the girls (P less than 0.001). The Lang-Stereo test was passed by 87.9%-94.3% of all children, and there were no significant differences with respect to age and sex. Children who failed the test had a significantly lower visual acuity than those who passed it. In the former group a significant interocular difference in visual acuity was present (P less than 0.01).

Age Factors↗
PubMed1996

Factors associated with visual acuity loss after noncontact transscleral Nd:YAG cyclophotocoagulation.

PURPOSE: To determine the factors associated with visual acuity loss following transscleral Nd:YAG cyclophotocoagulation (TYC). METHODS: The authors retrospectively studied 479 patients followed for a mean of 22 months after the initial TYC in one eye and analyzed the data with univariate and multivariate analysis for the factors associated with visual acuity loss. Data analyzed included age, race, sex, preoperative intraocular pressure (IOP) and visual acuity, type of glaucoma, total energy per treatment, number of retreatments, final IOP, and duration of follow-up. RESULTS: The preoperative factors associated with visual acuity loss after TYC as determined by both univariate and multivariate analysis were neovascular glaucoma (p = 0.001, odds ratio = 2.80) and black race (p = 0.044, odds ratio = 1.67). Postoperative hypotony and follow-up of > 6 months were also associated with visual acuity loss (p < 0.001, odds ratio = 6.68 and p = 0.046, odds ratio = 2.61, respectively). CONCLUSIONS: Transscleral Nd:YAG cyclophotocoagulation is associated with a greater risk of visual acuity loss in patients with neovascular glaucoma and in the black population. Postoperative hypotony is associated with a poor visual outcome, whereas the association with longer follow-up duration suggests that other factors, related to the patient's underlying disease, are also significant factors.

Adolescent↗
PubMed1994

Compared optical performances of multifocal and monofocal intraocular lenses (contrast sensitivity and dynamic visual acuity)

The functional results (contrast sensitivity and dynamic visual acuity) of 19 multifocal (3M design) and 14 all polymethylmethacrylate biconvex monofocal intraocular lenses (IOLs), 6 mm in optical diameter were compared. Best corrected visual acuity was > or = 8/10 (Monoyer chart) Parinaud 2 in all cases. Major differences of functional performance in favour of monofocal IOLs were found outside standard conditions of vision (low contrast and illumination levels). A significant difference in contrast sensitivity was found for each spatial frequency in favour of multifocal IOLs (0.0016 < p < 0.05). Mesopic vision was statistically higher in the monofocal IOL group (p = 0.0015). Moreover, dynamic visual acuity allowed accurate evaluation of the difference in performance between these two models of implant. In view of these results multifocal IOLs should be reserved for patients with normal psychosensitive adaptation; an ocular pathology that could alter contrast sensitivity or mesopic vision is a contraindication for multifocal IOLs.

Aged↗
PubMed1999

[Fluctuations in uncorrected visual acuity after refractive surgery using intra-stromal corneal rings].

PURPOSE: Refractive surgery is meant to provide early stable and good uncorrected visual acuity. Our main concern in this study was to take special interest in fluctuation in uncorrected acuity within the first three months after implantation of Schanzlin intracorneal ring segments (ICRS) produced by Keravision. PATIENTS AND METHODS: Ten eyes in 6 patients underwent implantation of 2 intrastromal corneal segments for myopias ranging from -1.00 to -3.50 Dipoters. Visual acuity was measured with cytoplegy on day one, on day 8, two weeks, 1 month, and 2 months after surgery. The fluctuations of visual acuity were noted between observations. RESULTS: Uncorrected visual acuity varied up to 4 lines without an obvious pattern of progression over time. Fifty percent of the eyes had a variation of 2 lines. The best spectacle corrected visual acuity was preserved in all patients. DISCUSSION: Corneal topography with measurement of keratometry, intraocular pressure, and examination of the anterior chamber must be studied to identify the parameter that could condition these fluctuations of visual acuity. No parameter was found to predict these variations that may result from individual corneal healing factors peculiar to each patient. The fluctuations of uncorrected visual acuity were relatively important during the 3 first postoperative months. In all patients, final uncorrected visual acuity was always at least 10/10.

Adult↗
PubMed1998

[Determining visual acuity using European normal values: scientific principles and possibilities for automatic measurement].

PSYCHOMETRIC FUNCTION: According to the European standard EN ISO 8596 the Landolt-C in 8 different orientations has to be used to measure visual acuity. With decreasing size of the Landolt-C the hit rate declines from 100% to the chance level of 12.5%. This gradual transition is described by the "psychometric function". The steepest point of the psychometric function is in the middle between 100 and 12.5, i.e., at 56.25%. This point of the psychometric function (approximated by 5 of 8 Landolt-Cs) has been selected as the threshold for visual acuity, because it is there that the visual acuity is influenced least by (incidental) fluctuations. The subject has to answer by forced choice; a response like "I cannot detect anything" is not acceptable. "NORMAL" VISUAL ACUITY: Cannot be assigned to a certain value, like 1.0 or 6/6. With the standard test procedure, visually healthy, young subjects achieve a visual acuity of about 2.0 or 12/6, while in senior subjects 0.5 (3/6) may be "normal". AVERAGING VISUAL ACUITY: Logarithmic, not arithmetic, scaling of visual acuity approximates the perceptual metric. Consequently, visual acuity values may not be averaged arithmetically. Instead, three steps are required: all values have to be converted to logarithms, then averaged, and finally the average can be reconverted. Geometric averaging is equivalent. "MINIMUM ANGLE OF RESOLUTION" NOT NECESSARY: MAR is the reciprocal of visual acuity. In many studies, clinical outcome has been assessed using log(MAR). Though statistically correct, this term is unnecessary, as log(acuity) has identical statistical properties. Furthermore, log(MAR) is contra-intuitive as its value becomes smaller when vision improves. COMPUTER-ASSISTED INSTRUMENTATION: Facilitates complying with the EN ISO 8596. For instance, the Freiburg Visual Acuity Test relieves the examiner from observing whether 5 responses have been correct, and that not more than 8 tests are given per level.

Europe↗
PubMed2001

Closed surfaces of constant visual acuity in symmetric dioptric power space.

This paper demonstrates a multivariate approach to understanding the complicated relations of visual acuity to refractive state or ametropia. Other approaches, as previously used, included graphical representations of lines or profiles of iso-oxyopia (Peters, 1961). But one limitation of Peters' method is that cylinder axis was ignored. However, here the relationship between visual acuity and refractive power will be represented by estimated closed surfaces of constant visual acuity in symmetric dioptric power space. At or near the common center (of several closed surfaces, for example) is the refractive compensation. Coming outwards from such a center, the visual acuity drops in all directions in the space. The primary purpose of this paper was to present estimated closed surfaces of constant visual acuity for several eyes. Various procedures were performed on several subjects including measurement of iris aperture diameter, subjective refraction, and autorefraction. Thereafter, an automated phoropter and either Jackson cross-cylinders or spheres were used to influence dioptric blur or defocus in the subjects. The visual stimulus was a computer-generated nondirectional or meridionally independent letter O. Ovoidal surfaces fit the measurements obtained (with Jackson cross-cylinders and spheres) better than ellipsoidal surfaces. The cross-section, in symmetric dioptric power space, at powers with the same nearest equivalent sphere as the refractive compensation is elliptical in many cases and reflects a dependence of visual acuity on cylinder axis. The surfaces differ when powers are changed so that one is moving away from (decompensation surfaces) or toward (accompensation surfaces) the refractive compensation. The multivariate and graphical methods used in this paper probably have implications for the direction of future research in a number of areas involving measures of vision function such as autorefraction, retinoscopy, subjective refraction, and visual acuity.

Accommodation, Ocular↗
PubMed1977

Visual acuity and contrast sensitivity in multiple sclerosis--hidden visual loss: an auxiliary diagnostic test.

In 48 patients with multiple sclerosis sine-wave gratings were used to test visual sensitivity for coarse, medium, and fine detail rather than measuring visual acuity for fine detail only, as in conventional clinical tests. In 20/48 patients the test revealed a visual defect of neural origin, qualitatively different from that caused by refractive error. In 11 of these 20 patients, visual sensitivity to detail of medium coarseness was markedly degraded, even though sensitivity to both coarse and fine detail was unimpaired. In 3 of these 20 patients visual sensitivity to coarse detail was selectively degraded. These visual defects could not be detected by the Snellen test, yet the patient might experience visual problems in everyday life and also experience distorted visual perception. Possible neural bases for these visual impairments are discussed. Since 8 of the 14 patients with selective loss showed no clinical evidence of visual involvement, the test can aid the earlier diagnosis of multiple sclerosis.

Adolescent↗
PubMed1986

Diurnal change in refraction, corneal curvature, visual acuity, and intraocular pressure after radial keratotomy in the PERK Study.

Selected patients who complained of fluctuating visual acuity in the Prospective Evaluation of Radial Keratotomy (PERK) Study were examined before 8:00 a.m. and after 7:00 p.m. on the same day to determine diurnal change in uncorrected visual acuity, best corrected visual acuity, manifest refractive error, average central keratometric power, and intraocular pressure. Sixty-three operated eyes were examined at three months, while 46 operated and 40 unoperated contralateral eyes were examined at one year after radial keratotomy. One year after surgery, 42% of the operated eyes had an increase in minus power of the manifest refraction of 0.50 to 1.25 diopters, 26% of the eyes changed their uncorrected visual acuity by 2 to 4 Snellen lines, and 35% of the operated eyes showed central steepening of the cornea by 0.50 to 1.25 diopters. These changes in the operated eyes at one year were similar to the changes at three months. Minimal diurnal changes occurred in the unoperated eyes at one year. Only 11% of the unoperated eyes changed their manifest refraction by 0.50 to 1.00 diopters, none changed their uncorrected visual acuity by 2 to 4 Snellen lines, and only one of the unoperated eyes changed its central keratometric power by 0.50 diopters. This study documents that many patients who experience diurnal fluctuation of vision have steepening of the cornea and an increase in the minus power of their refraction during the day.

Biomechanical Phenomena↗
PubMed1985

The Parsons visual acuity test for screening children 18 to 48 months old.

The Parsons visual acuity test (PVAT) uses modified Allen test targets for visual acuity assessment in young children and persons who are difficult to test. Using this method, we were able to obtain a visual acuity threshold in 44% of 18- to 24-month-old children and in 90% of children aged 25 to 36 months. At all ages tested, the mode for visual acuity was 20/30; however, the percentage of those with 20/20 increased with age. The decision whether to refer was correctly made by means of the PVAT criterion 83% of the time.

Child, Preschool↗