Dataset Information

Grating acuity and contrast tests for clinical trials of severe vision loss.

ABSTRACT: To evaluate the reliability and validity of grating visual acuity (VA) and contrast sensitivity (CS) tests, which could be useful outcome measures to assess changes in severely reduced vision.The Grating Acuity Test (GAT) and Grating Contrast Sensitivity (GCS) tests, which involve the detection of grating orientation in a four-Alternative Forced Choice paradigm on a liquid crystal display screen, were compared with the well-validated Early Treatment of Diabetic Retinopathy Study (ETDRS) and Pelli-Robson (PR) charts. Grating tests were repeated two or three times within-visit, across three or four sessions, in 20 legally blind subjects: 8 with retinitis pigmentosa (RP) (16 eyes) and 12 with other retinal diseases (OR) (16 eyes).VA determined by ETDRS and GAT was in good agreement and scaled very similarly, as shown by regression of the within-session difference between the two measures against their mean [RP group: slope (m) = 0.11; 95% confidence interval [CI]: -0.06, 0.29; p = 0.21; OR group: m = -0.07; 95% CI: 0.33, 0.20; p = 0.62]. On average, higher logCS levels were obtained using the GCS than the PR in both groups. The two CS measures scaled similarly in the RP group (m = 0.07; 95% CI: -0.09, 0.22; p = 0.39) but not in the OR group (m = 0.41; 95% CI: 0.12, 0.70; p = 0.005). The within- and between-visit 95% coefficient of repeatability (CR.95) were 0.11 to 0.17 log units for the ETDRS charts and GAT in both groups and 0.14 to 0.15 log units for the PR and GCS in the RP group, whereas the OR group demonstrated more variability in CS. Between-visit CR.95 did not significantly change with mean VA or CS for the ETDRS, PR, or GCS tests, but RP patients' CR.95 on the GAT increased significantly with decreasing VA. Floor effects occurred for some RP eyes with ETDRS and PR charts but not with the GAT and GCS.Computer-driven grating tests appear to be reliable, capable of evaluating vision that may fall outside of the range of standard clinical tests and may be useful during clinical trials for advanced eye disease.

SUBMITTER: Bittner AK

PROVIDER: S-EPMC3183246 | biostudies-other | 2011 Oct

REPOSITORIES: biostudies-other

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Grating acuity and contrast tests for clinical trials of severe vision loss.

Bittner Ava K AK Jeter Pamela P Dagnelie Gislin G

Optometry and vision science : official publication of the American Academy of Optometry 20111001 10

<h4>Purpose</h4>To evaluate the reliability and validity of grating visual acuity (VA) and contrast sensitivity (CS) tests, which could be useful outcome measures to assess changes in severely reduced vision.<h4>Methods</h4>The Grating Acuity Test (GAT) and Grating Contrast Sensitivity (GCS) tests, which involve the detection of grating orientation in a four-Alternative Forced Choice paradigm on a liquid crystal display screen, were compared with the well-validated Early Treatment of Diabetic Re ...[more]

PMID: 21747309

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Project description:BackgroundExisting patient-reported outcome (PRO) measures may not be relevant to the full range of functional and vision-related quality of life (VR-QOL) concerns of individuals with vision impairment due to severe peripheral field loss (PFL). Measurement of VR-QOL in severe PFL is important in order to determine the effectiveness of vision rehabilitation interventions for this population. The purpose of this study was to characterize the impact of severe PFL due to retinitis pigmentosa (RP) and glaucoma on VR-QOL as the initial phase in the development of a novel PRO measure.MethodsIndividuals with severe PFL due to RP or glaucoma were recruited from the Kellogg Eye Center and the Association for the Blind and Visually Impaired. Participants completed semi-structured qualitative interviews, the Impact of Vision Impairment (IVI) questionnaire and the RAND 36-Item Health Survey. Interviews were analyzed by two coders using thematic analysis. A matrix analysis was conducted to compare VR-QOL by cause of severe PFL. Sample size was determined by thematic saturation.ResultsThe study included 37 participants (19 RP, 18 glaucoma). Median best-corrected visual acuity for those with RP and glaucoma was 20/40 and 20/27.5, while Pelli-Robson contrast sensitivity was 1.2 log contrast sensitivity (logCS) and 1.1 logCS, respectively. Median domain scores on the IVI (reading, mobility, well-being) ranged from a low of - 0.2 to a high of 0.7 logits in those with RP and from 0.5 to 1.2 logits in those with glaucoma. Qualitative interviews identified six VR-QOL themes relevant across participants with both RP and glaucoma, including activity limitations, driving, emotional well-being, reading, mobility, and social function. VR-QOL concerns were largely consistent among those with severe PFL due to RP and glaucoma. These overarching themes contained content relevant to specific challenges related to severe PFL.ConclusionsThere are commonly occurring VR-QOL concerns among individuals with severe PFL due to RP and glaucoma. The outlined themes will serve as the basis for development of the Low Vision Severely Constricted Peripheral Eyesight (LV-SCOPE) Questionnaire.

Project description:ImportanceAlthough anti-vascular endothelial growth factor treatment of neovascular age-related macular degeneration (AMD) results in improved vision overall, loss of substantial vision can occur. Understanding the processes that lead to loss of vision may lead to preventive strategies.ObjectiveTo determine the incidence, characteristics, causes, and baseline predictors of sustained visual acuity loss after 2 years of treatment with ranibizumab or bevacizumab for neovascular AMD.Design, setting, and participantsA cohort study within a randomized clinical trial of participants in the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT).InterventionsParticipants were randomly assigned to treatment with ranibizumab or bevacizumab and to 2 years of monthly or as needed injections or monthly injections for 1 year and as needed injections the following year.Main outcomes and measuresSustained visual acuity loss, defined as loss of 15 or more letters from baseline at weeks 88 and 104.ResultsAmong 1030 participants, 61 eyes (5.9%) developed sustained visual acuity loss in 2 years. Within this group, visual acuity decreased gradually over time, with a mean decrease of 2, 19, and 33 letters from baseline at 4 weeks, 1 year, and 2 years, respectively. At 2 years, eyes with sustained visual acuity loss had more scarring (60.0% vs 41.4%, P = .007), more geographic atrophy (GA) (31.6% vs 20.7%, P = .004), larger lesions (16 vs 8 mm2, P < .001), and higher proportions of intraretinal fluid (82.5% vs 51.0%, P < .001), subretinal hyperreflective material (84.5% vs 44.2%, P < .001), retinal thinning (43.3% vs 23.0%, P < .001), and thickening (20.0% vs 12.1%, P < .001). Likely causes of sustained visual acuity loss included foveal scarring (44.3%), pigmentary abnormalities (27.9%), and foveal GA (11.5%). Baseline factors independently associated with a higher incidence of sustained visual acuity loss were the presence of nonfoveal GA (odds ratio [OR], 2.86; 95% CI, 1.35-6.08; P = .006), larger area of choroidal neovascularization (OR for a >4-disc area vs ≤1-disc area, 3.91; 95% CI, 1.70-9.03; P = .007), and bevacizumab treatment (OR, 1.83; 95% CI, 1.07-3.14; P = .03).Conclusions and relevanceSustained visual acuity loss was relatively rare in CATT. The development of foveal scar, pigmentary abnormalities, or GA contributed to most of the sustained visual acuity loss. Risk was 3% higher among eyes treated with bevacizumab. Treatment that targeted the prevention of scarring or GA may improve vision outcomes.Trial registrationclinicaltrials.gov Identifier: NCT00593450.

Project description:BackgroundSelf-reported questions on blindness and vision problems are collected in many national surveys. Recently released surveillance estimates on the prevalence of vision loss used self-reported data to predict variation in the prevalence of objectively measured acuity loss among population groups for whom examination data are not available. However, the validity of self-reported measures to predict prevalence and disparities in visual acuity has not been established.ObjectiveThis study aimed to estimate the diagnostic accuracy of self-reported vision loss measures compared to best-corrected visual acuity (BCVA), inform the design and selection of questions for future data collection, and identify the concordance between self-reported vision and measured acuity at the population level to support ongoing surveillance efforts.MethodsWe calculated accuracy and correlation between self-reported visual function versus BCVA at the individual and population level among patients from the University of Washington ophthalmology or optometry clinics with a prior eye examination, randomly oversampled for visual acuity loss or diagnosed eye diseases. Self-reported visual function was collected via telephone survey. BCVA was determined based on retrospective chart review. Diagnostic accuracy of questions at the person level was measured based on the area under the receiver operator curve (AUC), whereas population-level accuracy was determined based on correlation.ResultsThe survey question, "Are you blind or do you have serious difficulty seeing, even when wearing glasses?" had the highest accuracy for identifying patients with blindness (BCVA ≤20/200; AUC=0.797). The highest accuracy for detecting any vision loss (BCVA <20/40) was achieved by responses of "fair," "poor," or "very poor" to the question, "At the present time, would you say your eyesight, with glasses or contact lenses if you wear them, is excellent, good, fair, poor, or very poor" (AUC=0.716). At the population level, the relative relationship between prevalence based on survey questions and BCVA remained stable for most demographic groups, with the only exceptions being groups with small sample sizes, and these differences were generally not significant.ConclusionsAlthough survey questions are not considered to be sufficiently accurate to be used as a diagnostic test at the individual level, we did find relatively high levels of accuracy for some questions. At the population level, we found that the relative prevalence of the 2 most accurate survey questions were highly correlated with the prevalence of measured visual acuity loss among nearly all demographic groups. The results of this study suggest that self-reported vision questions fielded in national surveys are likely to yield an accurate and stable signal of vision loss across different population groups, although the actual measure of prevalence from these questions is not directly analogous to that of BCVA.

Dataset Information

Grating acuity and contrast tests for clinical trials of severe vision loss.

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Grating acuity and contrast tests for clinical trials of severe vision loss.

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