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PubMed1993

Correlating visual acuity and electrooculogram recordings in Best's disease.

The visual function in 54 eyes of 27 patients with Best's disease was analyzed by retrospectively examining the Snellen visual acuities and the electrooculogram (EOG). Visual acuities, generally well maintained in most patients, were 20/40 (0.5) or better in 41 of 54 (75.9%) eyes, and showed no correlation with age. Those in the cicatricial stage had worse visual acuities than those in the previtelliform stage. The EOG was abnormal in 47 eyes (87.0%) with a subnormal light peak/dark trough (Lp/Dt) ratio less than 1.85. Seven eyes (13.0%) with an Lp/Dt ratio 1.85 or higher had significantly smaller Dt values compared with those with a low Lp/Dt ratio. The Lp/Dt ratio did not correlate with patient age or disease stage. No correlation existed between visual acuities and Lp/Dt ratios. The Lp/Dt ratio did not reflect the severity of the macular lesions. The results indicate that not only a low Lp/Dt ratio but also a low dark trough value in cases with a normal Lp/Dt ratio are helpful in diagnosing Best's disease.

Adolescent↗

PubMedDate not supplied

Carcinoma of pancreas presenting as a decrease in visual acuity.

Recent unilateral decrease in visual acuity of a 72-year-old woman was the background of a comprehensive medical investigation that led to the definitive diagnosis of metastatic pancreatic carcinoma. Visual improvement was achieved after ocular irradiation but the patient died two months later because of bilateral pneumonia and sepsis. Ocular metastasis from advanced carcinoma of various organs is well known and usually is an indicative sign of poor prognosis. Ocular metastases from pancreatic carcinoma are extremely rare, and to the best of our knowledge, it has not been reported previously in English. It should be emphasized that unilateral decrease in visual acuity must be thoroughly investigated.

Adenocarcinoma↗

PubMed1993

Repeated visual acuity measurement: establishing the patient's own criterion for change.

We measured visual acuity in 10 young subjects, 10 times each over a period of approximately 3 weeks, using Bailey-Lovie charts. We used a consistent end-point criterion and scored each letter read on the chart. We derived the mean and standard deviation of visual acuity measures for each subject, and for the group. The standard deviation for the group was about 3 times that of the individuals in the group. We calculated the criterion for reduction of visual acuity for the group, as group mean plus 1.96 group standard deviations; use of this criterion would consistently fail to detect patients with clinically significant reductions in visual acuity. We recommend that visual acuity be measured to threshold for every patient. Measuring visual acuity between three and five times provides an estimate of the patient's variability and allows a criterion for reduction of visual acuity to be established for the individual patient. Use of this criterion will enhance the sensitivity of visual acuity measurement as a diagnostic tool.

Adolescent↗

PubMed1989

Validation of a self-report inventory for the measurement of visual acuity.

Previous attempts to assess visual acuity via self-report survey items have shown low sensitivity. This may be due to use of dichotomous response formats, too few items, and reliance upon face valid, rather than laboratory-validated items. On the basis of a preliminary sample of 164 individuals, we developed a self-report inventory, suitable for group testing or survey administration. The inventory was then validated against laboratory measures of acuity in a separate sample of 570 subjects. The resulting, brief, ten-item scale was shown to be a reliable and valid predictor of visual acuity. Conversion tables were developed which allow scale totals to be used to predict Snellen acuity. For 91% of the sample, the inventory predicts objectively measured acuity within plus or minus one Snellen line. A copy of the inventory and scoring procedure is appended to this report.

Humans↗

PubMed1987

Evaluation of the Parsons Visual Acuity Test in screening exceptional children.

The Parsons Visual Acuity Test (PVAT) is a non-verbal picture based visual acuity test designed for the difficult-to-test preschool child, school age child and adult with handicapping conditions. It is designed primarily for vision screening of the exceptional child and adult with special needs. Since visual acuity measures are quite important in these populations, a comparative study between the PVAT and standard Snellen acuity were designed and completed. There was no significant difference in acuity measures at near, however, the validity of the distance PVAT visual acuity measure was not supported in this study. Implications of the findings and cautions for the use of this test in screening and clinical situations for exceptional children and adults are discussed.

Adolescent↗

PubMed2000

Factors influencing the visual acuity of primary school pupils.

To investigate the factors influencing the visual acuity of primary school pupils, an epidemiological study of 480 pupils in the 6th grade (11-12 years of age) was conducted in 8 primary schools in Sapporo City, Japan. Questionnaires were used to inquire into their current and past visual acuity and related factors. Dividing the subjects into those whose visual acuity of both eyes was 0.7 or more and those whose visual acuity of at least one eye was less than 0.7, odds ratios of various factors were calculated. Lifestyle and dietary factors showed no significant odds ratios. Parental myopia and age of parents at the birth of subjects showed significant odds ratios. Visual acuity of the pupils whose parents were myopic or older than 30 years when they were born tended to have worse visual acuity as they got older. Till the ages 11 or 12, hereditary factors seem much more contributory to visual acuity than environmental ones.

Chi-Square Distribution↗

PubMed1996

Illuminated near card assessment of potential visual acuity.

PURPOSE: To determine the accuracy of predicting potential visual acuity in patients having neodymium:YAG (Nd:YAG) laser capsulotomy using a new device, the illuminated near card (INC). SETTING: Private practice, New York, New York. METHODS: Thirty-eight consecutive patients having Nd:YAG laser capsulotomy were studied prospectively by comparing the postoperative distance Snellen acuity to the visual acuity obtained preoperatively using (1) a near reading card, (2) the INC, and (3) the INC viewed through a pinhole. RESULTS: Patients reported that the INC was easy to use; none with a visual acuity better than 20/200 had difficulty finding the illuminated letters through the pinhole. In eyes with a precapsulotomy distance acuity of better than 20/200, the correlation between precapsulotomy and postcapsulotomy acuities was statistically significant (P < .001) for the INC viewed through the pinhole. A significant correlation between precapsulotomy and postoperative acuities was not found for the INC viewed alone or for the near card (P > .05). In patients with a precapsulotomy distance acuity of 20/200 or worse, the INC with pinhole, the INC, or the near card did not predict postoperative acuity (P > .05). CONCLUSION: In eyes with a precapsulotomy distance acuity better than 20/200, the INC with pinhole predicted postoperative distance acuity within one Snellen line in 97% of eyes (29/30), which is comparable to reports using other potential acuity testers. The INC viewed through a pinhole improves image resolution by the stenopaic hole without the low light intensity of the reduced aperture.

Aged↗

PubMed1997

Visual acuity outcomes among patients with appositional suprachoroidal hemorrhage.

OBJECTIVE: The purpose of the study is to investigate visual acuity outcomes among patients with appositional suprachoroidal hemorrhage and to identify clinical features associated with visual prognosis. DESIGN: The study design was a retrospective chart review. PARTICIPANTS: All patients whose ocular echographic examination results showed appositional suprachoroidal hemorrhage at the Bascom Palmer Eye Institute between January 1, 1987, and December 31, 1996 were included. Fifty-one patients were identified. INTERVENTION: Demographic and clinical data were abstracted from patients' medical records. MAIN OUTCOME MEASURES: Visual acuity at 3, 6, and 12 months posthemorrhage and clinical features associated with visual prognosis were defined. RESULTS: At final follow-up fifteen (29.4%) patients achieved either their prehemorrhage visual acuity (n = 7) or a visual acuity of 20/200 or better (n = 8), but 14 (27.5%) patients had no light perception. Predictors of a poor visual outcome include vitreous incarceration in the wound/bleb (P = 0.014), concurrent or delayed retinal detachment (P = 0.003), and afferent pupillary defect on presentation (P = 0.002). Poorer visual acuity on presentation (r = 0.37, P = 0.008) and longer duration of central retinal apposition (r = 0.51, P < 0.001) also were significantly associated with poor final visual acuity. Patients in whom the suprachoroidal hemorrhage maintained an appositional configuration for more than 14 days were more likely to have worse final visual acuities than were patients with appositional choroidals for fewer than 14 days (P = 0.006). The association between duration of apposition and final visual acuity was significant, both among patients whose suprachoroidal hemorrhages were observed (n = 26, r = 0.60, P = 0.001) and among patients who underwent secondary surgical intervention (n = 23, r = 0.66, P = 0.001). Patients with postoperative suprachoroidal hemorrhages achieved better final visual acuities than did patients in whom suprachoroidal hemorrhages developed intraoperatively or after trauma (P = 0.038). CONCLUSIONS: Appositional suprachoroidal hemorrhage is a serious ocular complication with a guarded visual prognosis. A variety of clinical features, including vitreous incarceration in the wound/bleb, concurrent or delayed retinal detachment, afferent pupillary defect, presenting visual acuity, and duration of central retinal apposition, may help predict visual outcome.

Adult↗

PubMed2004

Parent-administered visual acuity testing: is it reliable and can it improve office efficiency?

PURPOSE: To evaluate the accuracy of a parent-administered visual acuity test, using the electronic visual acuity tester (EVA) (JAEB Center, Tampa, FL) and evaluate its use as a means to improve efficiency of office acuity testing. METHODS: This was a prospective experimental study. Part I: Sixty-four children had their visual acuity determined using the EVA, first by their parents and then by an ophthalmic technician. Acuity scores were compared. Part II: Forty-four other children were randomly assigned to one of 2 groups. Group A (parent-prescreen) children had their visual acuity determined first by the parents using the EVA. The visual acuity result in that child was then rechecked by the technician using the Reinforcement Phase and Phase 2 of the Amblyopia Treatment Study (ATS) visual acuity testing protocol. Group B (full ATS protocol) children had their acuity determined by the technician using the full ATS protocol. The number of optotypes presented by the technician in order to determine the acuity in each group was compared. RESULTS: Part I: Reliability of parent-determined visual acuity scores was high (r = 0.91 and 0.81 for right eyes (OD) and left eyes (OS), respectively), with 93% of right eye parent scores and 85% of left eye parent scores within 0.11 logarithm of minimal angle of resolution (logMAR) units (ie, within one line of vision) of the technician score. Part II: The parent prescreen group (Group A) required presentation of 66% fewer optotypes to the OD and 68% fewer optotypes to the OS than the full ATS protocol group (Group B) (OD: P = 5.4 x 10(-18); OS: P = 6.5 x 10(-18)). CONCLUSIONS: Visual acuity testing results by parents using the EVA are reliable. Electronic visual acuity prescreening by parents reduces the number of optotype presentations required to be shown by the technician to accurately determine acuity. Use of a parent-assisted screening system in the waiting room may translate to increased office efficiency.

Caregivers↗

PubMed1995

Effects of luminance, contrast, and blur on visual acuity.

Although previous investigations have reported that changes in background luminance, stimulus contrast, and dioptric blur can each affect visual acuity independently, it has not been shown how these three variables interact to influence visual acuity. This is a particularly important issue if one is interested in predicting how individuals with different refractive characteristics will be able to perform acuity-based tasks in degraded visual environments with low background lighting and contrast levels. To investigate these relations, we conducted a series of experiments in which measurements of visual acuity were obtained for four subjects using Landolt C targets of varying contrast at several background luminances for levels of blur between 0 and 8 diopters (D). Our results show that visual acuity is significantly affected by all three factors, and that their effects are essentially additive. At all luminance and contrast levels, the reduction in visual acuity is greatest for dioptric blur up to 2.0 D, with a more gradual reduction in visual acuity for dioptric blur of greater than 2.0 D. At all blur and luminance levels, visual acuity decreases gradually for contrast levels down to 20%, and decreases sharply for lower contrast levels. Over the range of background luminances we tested (75.0 to 0.075 cd/m2), visual acuity decreases linearly with reductions in luminance. The additive effects of dioptric blur, contrast, and luminance provide a basis for predicting visual acuity-related task performance for individuals in different visual environments. For example, an individual with 6/6 (20/20) visual acuity under high luminance-high contrast conditions will fall to 6/18 (20/60) acuity for low luminance conditions and 6/30 (20/100) for low luminance-low contrast conditions. Similarly, an individual with an uncorrected visual acuity of 6/30 (20/100) under optimal conditions will fall to approximately 6/120 (20/400) under low luminance conditions and 6/240 (20/800) under low luminance-low contrast conditions.

Adult↗

PubMed1991

[Visual acuity and refraction in pseudophakia].

Visual acuity with correction was checked in 86 persons with anterior and posterior chamber lenses in various postoperative periods. In the majority of examines of both groups in the late postoperative period the visual acuity was correct. The results obtained in both groups of patients were compared. The causes of astigmatism detected in some cases were considered.

Adult↗

PubMed1993

Loss of visual acuity after trabeculectomy.

BACKGROUND: Glaucoma filtration surgery can result in loss of visual acuity by a variety of mechanisms. The existence of "wipe-out" (loss of the central visual field in the absence of other explanation) as a cause of postoperative loss of visual acuity has been debated. This study defines the incidence and etiology of visual acuity loss within 3 months of trabeculectomy. METHODS: The authors reviewed 508 eyes of 440 patients who underwent trabeculectomy to find cases of postoperative visual acuity loss (2 or more Snellen lines or a category change) and randomly selected a control group of 85 eyes to analyze the risk factors for each cause of visual acuity loss. RESULTS: Forty-two eyes (8.3%) showed loss of visual acuity after 3 months, caused mainly by lens opacification (n = 16), hypotony maculopathy (n = 6), and "wipe-out" (n = 4). Older patients (P = 0.0108), those in whom the visual field preoperatively showed macular splitting (P = 0.0084) and those who had severe hypotony (intraocular pressure [IOP] < or = 2 mmHg) on the first postoperative day (P = 0.0246) were more likely to experience "wipe-out." Older age (P = 0.0495) and shallow anterior chamber (P = 0.0003) were correlated to the development of lens opacification. Hypotony maculopathy was associated with coronary artery disease (P = 0.0397) and systemic hypertension (P = 0.0118). CONCLUSIONS: Lens opacification was the main cause of early visual acuity loss after trabeculectomy, followed by hypotony maculopathy. "Wipe-out," although rare, does exist, and older patients with advanced visual field defects are at increased risk.

Age Factors↗

PubMedDate not supplied

Video-endoscope versus endoscope for paranasal sinus surgery: influence on visual acuity and color discrimination.

Endoscopic and video-endoscopic visual acuity and color discrimination were investigated using a standard disk for testing visual acuity and a color discrimination test. A 1-chip-CCD-Camera (CCC) or 3-chip-CCD-Camera plus digital image processing (digivideo) on the endoscope and a 15 inch high resolution video monitor were used. Color discrimination was investigated by comparing the ability to sort colored disks of low chromatic saturation (desaturated Panel D-15 Test), ranging from yellow to red, under direct vision or via monitor using the same 1-CCC- and 3-CCC-system. Visual acuity deteriorated by 1.58 +/- 0.16 steps (+/- SEM) for the 1-CCC and 1.21 +/- 0.16 steps for the 3-CCC plus digivideo compared to vision through the endoscope (p < 0.001 and p < 0.001). Visual acuity was significantly better for the 3-CCC-video-endoscope compared to the 1-CCC-video-endoscope (p = 0.0045). The difference in color discrimination between the naked eye and the 1-CCC-monitor system was not significant. More mistakes were made with the 3-CCC-monitor system. The impairment of image quality with the video endoscope, which is experienced by many surgeons, is reflected in a marked loss of visual acuity in our experiments. Sharpness and contrast of the video-image are significantly enhanced by the 3-CCC plus digital image processing, compared to the 1-CCC. Color discrimination, however, was not impaired by the 1-CCC, indicating that color perception with the video-endoscope can be very good and may not contribute significantly to the loss of image quality.

Color Perception↗

PubMed1989

Peripheral visual acuity and age.

We measured the peripheral visual acuity of a group of eleven older subjects (mean age 54.2 years) and a group of seventeen young subjects (mean age 22.1 years). Peripheral visual acuity was measured using Konig bars with critical detail subtending 2.4 and 4.8 minutes of arc. The older group showed a substantial reduction of peripheral visual acuity.

Adult↗

PubMed1995

Binocular interactions and visual acuity loss in esotropic cats.

Visual acuity was measured behaviorally in various groups of cats by using a two-choice discrimination procedure. Cats in group 1 were rendered strabismic soon after birth by sectioning the tendon of the lateral rectus muscle (unilateral esotropia); at adulthood, their visual acuity (VA) was evaluated, after which the optic chiasm was sectioned and VA reassessed. Cats in group 2 were not only tenotomized but also chiasmatomized neonatally, while cats in group 3 underwent a neonatal section of the optic chiasm only. VA was measured at adulthood in the two latter groups. Group 4 consisted of adult cats whose VA was evaluated before and after an optic chiasm section. Stimuli consisted of square-wave gratings of various spatial frequencies. Results showed that in normal cats, the average threshold values under monocular viewing were identical for each eye (4.76 cycles/degree); however, following optic chiasm section, monocular VA was reduced to 1.23 cycles/degree. VA in early optic chiasm section cats was lower than that of the normal cats but higher than that of late-lesioned animals (2.33 cycles/degree). In strabismic cats, mean VA was 1.25 cycles/degree for the deviated eye and 2.8 cycles/degree for the normal eye. Following the optic chiasm section at adulthood, VA was lower not only for the deviated eye (< 0.17 cycles/degree) but also for the normal eye (1.14 cycles/degree). Similar results were found when both the deviation and chiasmatomy were performed neonatally. The elimination of interocular interactions through chiasm transection failed to improve VA in the strabismic eye.

Animals↗

PubMed1980

Stimulus and communication demands of visual acuity tests.

Comparative evaluations of visual acuity tests designed for young children have been difficult because tests vary both by stimulus target and by response methods required to communicate what is seen. To determine the independent effect of stimulus targets and response methods, four methods of response were systematically varied across four types of visual acuity tests and given to 59 preschool and early primary school children at three distances. An analysis of variance revealed that tests in which the stimulus target included a directional component were more difficult than those which did not, and that verbal report was the easiest method of answering; pointing to a picture on a key card which matched a target stimulus was the most difficult. Results are discussed in terms of developmental theory.

Child↗

PubMed1995

Studies on development of visual acuity in infants measured by the Teller Acuity Cards.

In order to confirm the reproducibility of visual acuity measurements in infants and to elucidate the cause of the plateau and decrease in the developmental curve between the ages of 9 and 15 months, we have retrospectively studied visual acuity measured by the Teller Acuity Cards (TAC) in infants aged 2 to 28 months. The visual acuity measured by TAC was higher than that obtained by the conventional preferential looking (PL) method in infants until the age of 14 months. No statistically significant difference was observed between the first eye and the second (fellow) eye measurements. Although monocular visual acuity decreased in infants aged from 9 to 12 months, binocular visual acuity showed an increase in the same age group. The first binocular measurement was better than the last binocular measurement on the same day. Although the first binocular measurement showed an increase in infants aged from 9 to 15 months, the second binocular measurement decreased in the same age group. Our results suggest that all these phenomena mentioned above are likely to be due to the psychological or behavioral rejection to the examinations.

Child Development↗

PubMed1999

Association among visual hallucinations, visual acuity, and specific eye pathologies in Alzheimer's disease: treatment implications.

OBJECTIVE: Studies suggest a link between visual acuity and visual hallucinations in dementia, but links with specific eye pathologies have not been evaluated. METHOD: Fifty patients (20 with visual hallucinations, 30 without) with probable Alzheimer's disease had an evaluation of psychotic symptoms. Visual acuity was measured before and after refractions, and ophthalmological examinations included standardized assessments for cataracts and macular degeneration. RESULTS: Impaired visual acuity and the severity of cognitive impairments were significantly associated with visual hallucinations. No patients with normal acuity (6/5 or 6/6 on the Snellen chart) experienced these symptoms. Impaired acuity improved with refraction in 60% (N = 12) of the patients with visual hallucinations. Of specific eye pathologies, only cataracts were significantly associated with visual hallucinations. Descriptive follow-up information suggests that an optician's assessment for glasses improves outcome. CONCLUSIONS: Glasses and cataract surgery need evaluation as prophylactic or adjunctive treatments for visual hallucinations in patients with probable Alzheimer's disease.

Aged↗