Binocular Measures of Visual Acuity and Visual Field versus Binocular Approximations

Abstract

Purpose: To assess the relationship of binocular visual function tests with binocular approximations using data from the Collaborative Initial Glaucoma Treatment Study (CIGTS).

Design: Case series based on existing data from a clinical trial.

Participants: Six hundred seven patients with newly diagnosed open-angle glaucoma from the CIGTS.

Methods: Monocular visual field (VF) and visual acuity (VA) tests were performed at baseline and every 6 months thereafter. Binocular tests of visual function (Esterman VF score, binocular VA) were added to the CIGTS protocol 3 years into the study. The binocular approximations of binocular visual function were better or worse eye, average eye, better or worse location, and binocular summation or pointwise binocular summation. Associations between binocular tests and binocular approximations to represent binocular visual function were assessed with Pearson's correlations (r), as was the relationship between vision-related quality of life (VR QOL; Visual Activities Questionnaire [VAQ] and the 25-item National Eye Institute Visual Function Questionnaire [NEI VFQ-25]) and binocular tests or binocular approximations of visual function.

Main outcome measures: Binocular visual function (VF and VA) and VR QOL.

Results: Five hundred seventy-five patients underwent at least 1 binocular visual function test. The Esterman score was correlated significantly with all binocular approximations of VF, with r values ranging from 0.31 (worse-eye mean deviation [MD]) to 0.42 (better-eye MD; P < 0.0001 for all). Binocular VA showed stronger correlations with binocular approximations, with r values ranging from 0.65 (worse-eye VA) to 0.80 (binocular summation; P < 0.0001 for all). Correlations between the VAQ and Esterman score were stronger in 7 of 9 subscales (r = -0.14 to -0.25; P < 0.05 for all) than correlations with all 7 binocular approximations. In contrast, correlations between the VAQ and binocular VA (r = -0.07 to -0.21) were weaker in all subscales than those with better-eye, average-eye, and binocular summation of VA (r = -0.12 to -0.25), but not different from worse-eye values. These trends also were found in relevant subscales of the NEI VFQ-25.

Conclusions: We found limited benefit in binocular testing of VA in the clinical setting as a means of approximating a patient's reported visual functioning. In contrast, we found some benefit in performing binocular VF testing, because the results correlated more closely with reported functioning than binocular approximations.

Trial registration: ClinicalTrials.gov NCT00000149.

Figure 1

Correlations between measures at consecutive visits over time for binocular tests and binocular approximations of (a) visual field and (b) visual acuity

Figure 2

Correlations between binocular tests of visual function and corresponding binocular approximations, all measured at a 5-year cross-section

Figure 3

Scatterplot of (a) Esterman binocular visual field versus average eye mean deviation and (b) binocular visual acuity versus average eye visual acuity, all measured at a 5-year cross-section

Figure 4

Correlations of quality of life measures with binocular tests and binocular approximations of visual function measures, all obtained at a 5.5-year cross-section of follow-up (to maximize sample size). Correlations include total and subscale scores of the (a) VAQ with visual field, (b) NEI-VFQ with visual field, (c) VAQ with visual acuity, and (d) NEI-VFQ with visual acuity. VAQ = Visual Activities Questionnaire; NEI-VFQ = National Eye Institute Visual Function Questionnaire; VF = Visual Field; VA = Visual Acuity