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PubMedDate not supplied

Predicting visual acuity in early onset nystagmus.

In preverbal children, it is difficult to assess visual acuity accurately. If nystagmus waveforms can be used to predict visual acuity in these young patients, then they would be a useful additional clinical tool. Existing acuity predictors were assessed in 10 adults with idiopathic early onset nystagmus. The most reliable predictor in this group of patients was mean velocity of the waveform. The mean velocity of the waveform may be used in preverbal children to give an estimate of best potential visual acuity in adulthood, and estimated best potential visual acuity at the current age.

Adolescent↗

PubMed2006

Distance and near visual acuity in infantile nystagmus.

PURPOSE: Infantile nystagmus (IN) has been reported to decrease with convergence. However, previous studies reported equivocal results regarding a corresponding improvement in acuity with near viewing. The aim of this study was to determine whether visual acuity improves with near viewing in patients with IN. METHODS: In the first experiment, visual acuities were measured using clinical test charts at standard test distances of 3 or 6 m and 40 cm and using S Charts at 3.75 m and 40 cm. In the second experiment, visual acuities were measured using a Bailey-Lovie chart at distance and a Lighthouse modified ETDRS near card held by each subject at his or her preferred working distance. S-chart acuities were obtained again at 3.75 m and 40 cm for comparison. Horizontal eye movements were recorded using infrared limbal reflection for 20 of the 34 subjects in the first experiment and for all 20 subjects in the second experiment. RESULTS: The S-chart acuities measured at distance and near were almost all within 0.1 logMAR (logarithm of the minimum angle of resolution) in experiments 1 and 2. Clinically measured acuity averaged nearly one line better at 40 cm than at distance in experiment 1, but the mean difference between near acuity using the ETDRS card and distance acuity using the Bailey-Lovie chart was less than one letter in experiment 2. No consistent relationship existed between the changes in visual acuity with viewing distance and the subject's eye movements. CONCLUSION: Despite a reduction of nystagmus at near distances in many patients with IN, the visual acuity at near does not improve significantly. These results imply that visual acuity in patients with IN is determined primarily by sensory limitations rather than by the moment-by-moment characteristics of these patients' eye movements.

Adolescent↗

PubMed2000

Visual acuity outcomes with and without surgery in patients with persistent fetal vasculature.

PURPOSE: To investigate visual acuity outcomes in patients with persistent fetal vasculature (PFV) left untreated or treated with vitreoretinal surgical techniques and to investigate clinical features associated with prognosis. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: All patients with PFV examined at the Bascom Palmer Eye Institute from January 1, 1983 through December 31, 1998. INTERVENTION: All patients in the study had unilateral PFV. Of 42 PFV patients identified, 30 patients underwent vitreoretinal surgery. Indications for surgery included media opacity (e.g., cataract), vitreoretinal traction, and retinal detachment. MAIN OUTCOME MEASURES: Final best postoperative visual acuity, prognostic ocular clinical features, and surgical complications. RESULTS: In the surgical group of patients, median age at diagnosis was 8 weeks, and median length of follow-up was 32 months, with all patients having at least 1 year of follow-up. Two patients had clinical and echographic findings consistent with anterior PFV, 2 patients had strictly posterior PFV, and the remaining 26 patients had components of both anterior and posterior PFV. Fourteen eyes (47%) achieved a final visual acuity of 20/400 or better at last follow-up. Risk factors for a poor visual acuity outcome (<20/400) included microphthalmia (28% of patients with microphthalmia versus 67% of patients with normal axial length achieved a final vision of 20/400 or better; P = 0.061) and preoperative retinal detachment or retinal or optic nerve abnormalities, or both, such as hypoplasia, folds, or indistinct macula with hypopigmentation (25% of patients with any of these anomalies versus 61 % of patients without these findings achieved a final vision of 20/400 or better; P = 0.072). After surgery, retinal detachment developed in three eyes, chronic hypotony in two other eyes, and neovascular glaucoma in one eye. In the nonsurgical group there were 6 male and 6 female patients. Two patients with posterior PFV had minimal disease and were not considered surgical candidates, whereas 10 patients with combined anterior and posterior PFV had advanced pathologic features, and it was believed that surgery would not offer significant visual improvement; median age at diagnosis was 9.5 months, and median length of follow-up was 36 months, with all patients having at least 1 year of follow-up. At last follow-up, 3 eyes (25%) had a final visual acuity of 20/400 or better. During follow-up, retinal detachment developed in 2 eyes and chronic hypotony in an additional 2 eyes. CONCLUSIONS: The current study indicates that approximately 50% of patients undergoing surgery for PFV will achieve useful vision. Visual acuity outcomes in patients with PFV are correlated with the nature and extent of ocular risk factors. Some patients may not be candidates for surgery because of either minimal changes or advanced disease that limit the potential of visual improvement.

Cataract Extraction↗

PubMed1995

The relationship of age-related maculopathy, cataract, and glaucoma to visual acuity.

PURPOSE: To investigate the relationship of age-related maculopathy, cataract, and glaucoma to visual acuity in the population-based Beaver Dam Eye Study. METHODS: A cross-sectional, population-based study was performed in people 43 through 86 years of age residing in Beaver Dam, Wisconsin, who were identified between 1987 and 1988 and examined (n = 4926) between 1988 and 1990. Of those who participated, 99.4% were white. Visual acuity was measured (n = 4886) using a modification of the Early Treatment Diabetic Retinopathy Study protocol. Stereoscopic color fundus photographs and slit lamp and retroillumination photographs of the lens were graded in a masked fashion using standardized protocols to determine the presence of age-related maculopathy and central cataract. RESULTS: Fifty-seven percent of those who were legally blind had late age-related maculopathy in both eyes. The frequency of visual acuity of 20/200 or worse was not significantly different in eyes with exudative macular degeneration (48%) than in eyes with pure geographic atrophy (42%). While controlling for other factors (age, central cataract, and glaucoma) in participants with both gradable age-related maculopathy and visual acuity measurable in at least one eye (n = 4716), investigators found that each of the early age-related maculopathy lesions was associated with a decrease in visual acuity of approximately two letters or fewer when compared to eyes without these lesions. Late age-related maculopathy was associated with a decrease of approximately seven lines of letters read correctly. CONCLUSION: These data demonstrate that exudative macular degeneration and pure geographic atrophy are the most important causes of legal blindness in this population and that early age-related maculopathy, central cataract, and glaucoma had a small effect on visual acuity.

Adult↗

PubMed1985

Nursing home glaucoma and visual acuity screening results in western Oklahoma.

Six hundred and four patients from 19 nursing homes in rural western Oklahoma underwent visual acuity and glaucoma screening. Thirty-seven percent (221/604) had corrected near visual acuity less than or equal to 20/200 in one or both eyes. Fourty-nine percent (298/604) had best distance visual acuity less than or equal to 20/200 in one or both eyes. Improvement of distance visual acuity of two or more lines of vision by the use of pinhole viewing (indicating a possible need for glasses lens change) was helpful in only 12% (36/298) of patients with distance visual acuity less than or equal to 20/200. Fifteen percent (50/316) had intraocular pressure (Schiotz tonometry) greater than or equal to 24 mm hg. The incidence of significant visual acuity impairments and borderline-elevated glaucoma testing in the nursing home population is significantly higher than for a comparable general community vision and glaucoma screening of a more mobile and youthful population (Table 7). Eleven percent (66/604) were determined to have had an eye examination (ophthalmological or optometric) within the previous two years. Because potentially severe visual loss caused by cataracts, glaucoma, some forms of macular degeneration, and diabetic retinopathy may be reduced by timely medical or surgical eye treatment, the study suggests that many nursing home patients who might benefit from ophthalmologic care are currently not receiving it. Consideration, therefore, should be given for similar future screenings at other nursing home populations.

Adolescent↗

PubMed2006

Ultrahigh-resolution optical coherence tomography in patients with decreased visual acuity after retinal detachment repair.

OBJECTIVE: To assess microstructural changes in the retina that may explain incomplete visual recovery after anatomically successful repair of rhegmatogenous retinal detachments (RD) using ultrahigh-resolution optical coherence tomography (UHR OCT). DESIGN: Retrospective observational case series. PARTICIPANTS: Seventeen patients with decreased visual acuity after RD repair. Twelve patients had macula-involving and 5 had macula-sparing RDs. METHODS: The UHR OCT prototype capable of approximately 3 mum axial resolution was developed for clinical use. The UHR OCT images through the center of the fovea in 17 patients with visual complaints after RD surgery were obtained. Patients were either postoperative patients from the New England Eye Center or tertiary referrals. Baseline visual acuity, preoperative lens status, location of retinal detachment, macular involvement, and postoperative visual acuity were recorded. MAIN OUTCOME MEASURES: The UHR OCT images after RD repair. RESULTS: The UHR OCT images were obtained 1 to 84 months (median, 5 months) postoperatively. The mean preoperative logarithm of the minimum angle of resolution (logMAR) visual acuity was 1.37 (Snellen equivalent, 20/390). The mean postoperative logMAR visual acuity was 0.48 (Snellen equivalent, 20/60). Anatomical abnormalities that were detected included distortion of the photoreceptor inner/outer segments (IS/OS) junction in 14 of 17 patients (82%), epiretinal membranes in 10 of 17 patients (59%), residual subretinal fluid in 3 of 17 patients (18%), and cystoid macular edema in 2 of 17 patients (12%). Of the 5 patients with preoperative macula-on detachments, 4 had distortion of the outer retina after RD repair. CONCLUSIONS: The higher resolution of UHR OCT facilitates imaging of the IS/OS junction. Therefore, UHR OCT is able to confirm prior histopathologic findings that damage to photoreceptor outer segments may occur as a consequence of retinal detachment. This may explain poor postoperative visual acuity in eyes with anatomically successful repair.

Adult↗

PubMed1998

[Visual acuity outcome and recurrence in large or huge pituitary adenomas operated with transcranial approach: comparison between frontotemporal and interhemispheric approaches].

Pituitary macroadenomas which required transcranial removal were reviewed concerning visual acuity outcome as well as recurrence. We encountered 173 pituitary adenomas of which 27 (15.6%) were removed transcranially during the past 13 years. Eight cases were excluded due to inadequate information and improper utilization. Thus, a total of nineteen cases were reviewed in which the frontotemporal (FT) approach was utilized for seven cases and the interhemispheric (IH) approach for 12 cases. The mean size and volume of the tumors in the FT group were 3.0 x 3.7 x 3.1 cm and 18.2 cm3. The main reason for utilizing this approach was the fact that the tumors extended laterally involving the unilateral cavernous sinus or that unilateral preoperative visual acuity was obstructed. The visual acuity outcome was as follows: In six cases showing useful visual acuity on both sides before surgery, no apparent aggravation on either side was found in four cases, while in two cases there was complete obstruction on the operative side. The remaining case showed aggravation on both sides, though the approach side was decided upon because of the obstructed vision on that side. The mean size and volume of the tumors in the IH group were 4.6 x 4.8 x 4.9 cm and 71.1 cm3. This approach was used due to the extreme suprasellar extension because of the large size of the tumors. Although the tumors were relatively large and the visual acuity was assessed as fair prior to surgery, visual acuity showed no significant deterioration after the operation and was found to be satisfactory in 11 out of 12 cases. The complications in the FT group were oculomotor palsy in 3 cases, hemorrhage in one case, and frontal infarction in one case. On the other hand, three cases suffered hemorrhage in the tumor cavity of the IH group, though none needed surgical evacuation. Most of the cases in the IH group showed pituitary hypofunction following the surgical removal of the tumors as compared to the cases in the FT group. Recurrence had occurred, in some cases, several years after the operation. Furthermore, some of the tumors are still growing larger following only partial or subtotal removal. The prime aim of the treatment for huge pituitary adenomas which require the transcranial removal is to retain as much visual acuity as possible. In conclusion, the IH approach has been shown to be preferable in this situation. The FT approach was found to be more dangerous in terms of visual outcome than had been expected, even if the tumors were not particularly large.

Adenoma↗

PubMed2005

Visual acuity in northern China in an urban and rural population: the Beijing Eye Study.

AIM: To evaluate prevalence and demographic associations of visual impairment in an urban and rural population in northern China. METHODS: In the Beijing Eye Study, a population based cohort study in northern China, visual acuity was assessed for 8876 eyes (4438 subjects) according to a response rate of 83.4%. The study was divided into a rural part (1972 subjects) and an urban part (n=2466). Mean age was 56.20 (SD 10.59) years (median 56 years; range 40-101 years). RESULTS: Mean uncorrected visual acuity measured 0.72 (0.32) (median, 0.80), and mean best corrected visual acuity measured 0.91 (0.21) (median, 1.0). In a multiple regression analysis, best corrected visual acuity was significantly correlated with age (p<0.001), degree of nuclear cataract (p<0.001), amount of cortical cataract (p=0.014), amount of subcapsular cataract (p<0.001), educational background (p<0.001), and refractive error (p<0.001). Rural region versus urban region (p=0.34) and sex (p=0.053) were not statistically significantly associated with best corrected visual acuity. CONCLUSIONS: In northern China, determinants of a low degree of best corrected visual acuity are age, cataract, low educational background, and myopia. Despite marked differences in educational background and family income, sex, and rural area versus urban area are not markedly associated with best corrected visual acuity.

Adult↗

PubMed1987

Tobias Mayer--experiments on visual acuity (1755).

The pioneering experimental work of Tobias Mayer (1723-1762) on visual acuity, published in 1755 in Latin, is presented in English translation. Mayer distinguished between two kinds of visual acuity, the one (30 arc sec) for single objects seen against a uniform background, the other (1 arc min) for more complex objects such as gratings, grids, or checkerboards. Strong illumination did not improve visual acuity. For targets seen in the light of a candle, the visual angle needed for resolution was inversely proportional to the cube root of the distance of the candle and therefore to the sixth root of 'brightness'. The historical significance of Mayer's work on visual acuity is briefly outlined.

Germany↗

PubMed1988

Recovery of visual acuity following the repair of pseudophakic retinal detachment.

Postoperative visual acuities were evaluated in a series of 100 pseudophakic eyes in which rhegmatogenous retinal detachments involved the macula and in which reattachment surgery was successful. Preoperative visual acuity and duration of macular detachment were directly and indirectly related to visual outcome, respectively. Eyes in which extracapsular surgery had been followed by posterior chamber lens implantation had significantly better postoperative visual acuities than cases in which older iris-fixation IOLs were placed following intracapsular procedures.

Adult↗

PubMed2000

The relation between visual acuity and other spatial vision measures.

PURPOSE: To examine to what extent measurement of standard visual acuity allows prediction of other spatial vision measures on an individual basis when high correlations exist between visual acuity and the other measures. METHODS: A series of spatial vision functions were measured in a sample of 900 community-dwelling older observers. Regression analysis was performed, and correlation coefficients were calculated between standard high-contrast visual acuity and other spatial vision measures including contrast sensitivity, low-contrast acuity, low-contrast low-luminance acuity (SKILL card), and disability glare acuity. RESULTS: All measures were highly and significantly correlated with standard visual acuity (r = 0.68 to 0.91). Despite the high correlations, many predictions of the other spatial vision measures from the correlation with standard acuity fell considerably outside of acceptable ranges determined by repeatability. The influence of the range of values in correlations is emphasized. CONCLUSIONS: Other spatial vision measures cannot be predicted on an individual basis from visual acuity despite high and significant correlations between the measures.

Aged↗

PubMed1992

Visual acuity and stereoacuity among mentally retarded children.

To evaluate the reliability and the validity of Landolt Rings and of the Frisby Test as measures of visual acuity and stereoacuity, respectively, the visual acuity of 30 mentally retarded children was measured with Landolt Rings shown as games, the Sjögren Test, the Dot Visual Acuity Test and stereoacuity with the Frisby Test. Subjects were tested 3 times over a period of 3 weeks to measure the reliability of the tests. No significant difference was observed among these tests. The validity of the Landolt Rings was measured by a correlation of .55 for the highest logMAR values of the Sjögren Test with the highest logMAR values of the Landolt Rings. Visual acuity was systematically lower on the Dot Visual Acuity Test. The Frisby Test was not reliable among a group of 16 normal children who improved systematically over 3 weeks.

Adolescent↗

PubMed2006

Single spot PDT in patients with circumscribed choroidal haemangioma and near normal visual acuity.

BACKGROUND: In circumscribed choroidal hemangiomas (CCH) a long observation period and decreased visual acuity before treatment are risk factors for poor visual outcome. Therefore, we studied the use of limited, single spot photodynamic therapy (PDT) with Visudyne for the timely treatment of CCH. METHODS: Six consecutive patients with CCH, and metamorphopsia but (near) normal visual acuity were treated with PDT, using a single spot covering only the most prominent part of the tumour, and a radiance exposure of 50 J/cm(2). Start of treatment was 6 min following a 1-min infusion with Visudyne (6 mg/m(2) BSA), using a diode laser (692 nm). RESULTS: In all patients, the metamorphopsia disappeared, the OCT images returned to a normal foveal contour, and visual acuity remained 20/20 or improved to 20/20. In five patients, the tumour became ultrasonographically undetectable; in three after one PDT session, in one patient after two and in another patient after three PDT sessions. The last patient had a residual tumour height of 1.2 mm, but no metamorphopsia, a normal foveal contour on OCT, and fluorescein angiography showed no residual leakage. CONCLUSION: The present series demonstrates that single spot PDT might be an effective treatment for CCH with a visual acuity > or =20/30, without serious side-effects during a follow-up of at least 18 months.

Adult↗

PubMed2004

Liquid crystal display microperimetry in eyes with reduced visual acuity from macular pathology.

PURPOSE: To correlate fixation stability and retinal sensitivity measured by liquid crystal display (LCD) microperimetry to visual acuity in eyes with macular pathology. DESIGN: Retrospective chart review METHODS: The cohort included 26 eyes of 26 patients, divided into two groups according to visual acuity (Group 1 eyes 6/15 - 6/48, Group 2: < or = 6/60). Macular sensitivity and fixation stability were measured using the LCD microperimeter. Mean retinal sensitivity (at central 12 degrees) and fixation stability (at 2 degrees and 4 degrees) were correlated with best-corrected visual acuity. RESULTS: Mean retinal sensitivity correlated with the visual acuity in both groups [Group 1 eyes: 28 point central 12 degrees (9.0 dB); Group 2: central 12 degrees (4.183 dB)] (P < 0.05). The fixation stability correlated similarly with the visual acuity for the groups [Group 1 eyes: 2 degrees (81.2%) and 4 degrees (94.6%); Group 2 eyes: 2 degrees (44.1%) and 4 degrees (80.7%] (P < 0.05). CONCLUSION: In the present study, the mean retinal sensitivity and fixation stability measured with LCD microperimeter correlated with visual acuity. LCD microperimetry reliably measures fixation stability and retinal sensitivity in eyes with various macular pathologies.

Adult↗

PubMed2004

The electronic visual acuity tester: testability in preschool children.

PURPOSE: To evaluate the ability of preschool children to have their threshold visual acuity assessed using a standardized, computer-based letter test. METHODS: Participants were 1195 3.5- to 5-year-old children enrolled in the Vision in Preschoolers Study. Monocular visual acuity was assessed by licensed eye care professionals (optometrists and pediatric ophthalmologists experimented in the examination of children), using the Electronic Visual Acuity tester, which uses the letters H, O, T, and V with a crowded surround. RESULTS: Overall, 99.1% of children passed the training that consisted of identifying the letters H, O, T, and V by naming or matching the letters at 60 cm. Among those who passed the training, 99.6% completed the binocular pretest at 3 m, and 97.6% of those passing the training and the pretest completed monocular threshold visual acuity testing of each eye with the Electronic Visual Acuity tester. Testability increased with age for training (p = 0.03), pretesting (p = 0.04), and acuity testing (p = 0.07). Overall, 93.3% of 3.5-year-olds, 96.7% of 4-year-olds, and 98.8% of 5-year-olds completed training, pretesting, and monocular threshold acuity testing of each eye using standard letter optotypes. CONCLUSION: Using the computer-based Electronic Visual Acuity system, nearly all 3.5- to 5-year-old children can complete monocular acuity testing of each eye.

Child, Preschool↗

PubMed2006

Correlations between optical coherence tomography measurement of macular thickness and visual acuity after cataract extraction.

PURPOSE: To investigate correlations between optical coherence tomography macular thickness measurements and visual acuity after cataract surgery. METHODS: Sixty-two patients underwent routine cataract surgery as part of a randomized clinical trial of oral Cox-2 inhibitor prophylaxis of cystoid macular oedema. Optical coherence tomography was used to quantify several parameters of macular thickness. Optical coherence tomography measurements were obtained before surgery, day one, week two and week six after surgery. These measurements were then correlated with logMAR best-corrected visual acuity. RESULTS: Optical coherence tomography macular thickness parameters increased after surgery by up to 20%. A significant correlation was identified between foveal minimum macular thickness and best-corrected visual acuity at day one and week six after surgery. Other macular parameters failed to show any significant correlation. At day one and week six, the 10 patients with greatest macular thickness had significantly lower visual acuity than the other patients. CONCLUSION: In this study routine cataract surgery caused an increase in macular thickness. Some significant positive correlations between macular thickness and best-corrected visual acuity were found, although not for all parameters or time points. There may be a threshold relationship between degree of foveal anatomic change and significant loss of visual acuity.

Aged↗

PubMed1988

Visual acuity changes with age: some new perspectives.

Snellen chart visual acuity is thought to change very little up to age 60 years. However, any changes in contrast in the retinal and/or neural image with age may only be detected in low contrast and low luminance testing conditions. Only under these conditions does contrast significantly influence visual acuity measurements. In this pilot experiment we show that low contrast visual acuity is considerably worse (two lines of Snellen acuity) for an older group (N = 8, mean age 57) than for a younger group (N = 9, mean age 24.6) in spite of the fact that each subject was referred to the study with 6/6 (20/20) or better acuity. At conventional contrast and luminance levels there is no significant difference between the two groups. The results also suggest that a simple measurement of contrast sensitivity for a small spot of light may allow a contrast correction factor to account for both age and luminance level differences in the contrast vs. acuity function.

Adult↗

PubMed1990

Expanding the limits of the Teller Visual Acuity Cards.

A nomogram is presented that permits quick determination of Snellen visual acuity values for the Teller Visual Acuity Cards at distances up to 10 feet. With this nomogram, it is now possible to determine visual acuity in nonverbal populations, other than infants, while taking into account the effect of refractive error, especially myopia. The formula for constructing the nomogram is also included as generated by the Lotus 1-2-3 spreadsheet.

Humans↗