Interactive Thresholding of Central Acuity under Contrast and Luminance Conditions Mimicking Real World Environments: 1. Evaluation against LogMAR Charts

Walter Gutstein ,Peter Presti ,Rachel Valerie North ,Stephen Sinclair

doi:10.4172/jcsb.1000193

Walter Gutstein , Peter Presti + Show 2 more

Open Access

https://doi.org/10.4172/jcsb.1000193

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Abstract

Purpose: The Central Vision Analyzer (CVA) is an interactive, automated computer device that rapidly thresholds central acuity under conditions mimicking customary photopic and mesopic activities. In sequence, the CVA may test up to 6 environments, and in this series was used to test 3 mesopic environments (98% and 50% MC against 1.6 cd/m2 background, 25% MC against 5 cd/m2), then 3 glare environments (98%, 10% and 8% MC, against 200 cd/m2 background). This report compares the CVA thresholded acuity with that measured utilizing standard letter acuity charts. Methods: In 481 normal eyes acuity was measured with best spectacle and contact lens refraction using both CVA and 0.1 logMAR ETDRS charts presenting similar contrast and luminance. In addition for 162 emmetropic, eyes, acuity was tested with a 15% MC chart placed outdoors with sun overhead and with sun at 15° off-axis and compared with the CVA thresholded acuity at 10% and 8% MC presented in a darkened room. Results: All CVA modules demonstrated high Pearson correlation coefficients (r=0.51 to r=0.94, p<0.01), Bland and Altman statistical similarity with the acuity measured from similar contrast charts as well as between the acuity measured with a 15% MC letter chart with the sun overhead and CVA 10% glare module and between acuity with a 15% MC chart viewed with the sun 15° off-axis and that with CVA 8% glare module presented in the darkened room. Conclusions: The CVA demonstrates the ability to accurately threshold the acuity of normal eyes compared with chart acuity under conditions of contrast, luminance and fixation times simulating normal photopic and mesopic activities and appears to provide the clinician rapidly with a better understanding of visual function under a variety of day and evening tasks.

Highlights

The measurement of vision utilizing charts in the clinic is most often done with one chart using one or a minimal set of contrasts of black letters or gratings that are presented against a white background of one luminance and in a single, moderate photopic environment represented by the examination lane
The 1 to 4 second fixations that are usually allowed for chart testing do not mimic fixations that are typically required for daily activities
The mean age and range of all of the 3 refractive groups was similar as assessed by a one-way analysis of variance (ANOVA)

Summary

Introduction

The measurement of vision utilizing charts in the clinic is most often done with one chart using one or a minimal set of contrasts of black letters or gratings that are presented against a white background of one luminance and in a single, moderate photopic environment represented by the examination lane. The 1 to 4 second fixations that are usually allowed for chart testing do not mimic fixations that are typically required for daily activities In order to understand the vision problems in eyes with pathology, a vision test that mimics real world visual task requirements is desperately needed [17,18,19,20,21]

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