Mesopic visual acuity is less crowded

Mesopic visual acuity is less crowded Purpose The decrease in visual acuity under low luminance conditions is well known. Recent laboratory evidence showed that crowding under low luminance (mesopic) light levels is less robust than under photopic conditions. The present study examines whether such differences in crowding influence clinical measurements of mesopic visual acuity, including test-retest repeatability. Methods Twenty adult subjects with normal or corrected to normal visual acuity were recruited for the study. Monocular visual 2 2 acuity was measured under photopic (228 cd/m ) and mesopic (0.164 cd/m ) luminance conditions using a letter chart, similar in principle to the ETDRS logMAR chart, presented on a computer monitor. Three rows of five letters, each row differing in size by 0.05 logMAR from largest to smallest were displayed at the center of the monitor. The level of crowding was varied by varying the separation between horizontally adjacent letters from 100% optotype size to 50, 20, and 10% optotype size. Inter-row spacing was proportional to optotype size. Observers read the letters on the middle row only. Measurements continued by reducing the size of the letters, until three or more errors on the middle row were made. Each correctly identified letter contributed 0.01 to the recorded http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Graefe's Archive for Clinical and Experimental Ophthalmology Springer Journals
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Publisher
Springer Berlin Heidelberg
Copyright
Copyright © 2018 by Springer-Verlag GmbH Germany, part of Springer Nature
Subject
Medicine & Public Health; Ophthalmology
ISSN
0721-832X
eISSN
1435-702X
D.O.I.
10.1007/s00417-018-4017-6
Publisher site
See Article on Publisher Site

Abstract

Purpose The decrease in visual acuity under low luminance conditions is well known. Recent laboratory evidence showed that crowding under low luminance (mesopic) light levels is less robust than under photopic conditions. The present study examines whether such differences in crowding influence clinical measurements of mesopic visual acuity, including test-retest repeatability. Methods Twenty adult subjects with normal or corrected to normal visual acuity were recruited for the study. Monocular visual 2 2 acuity was measured under photopic (228 cd/m ) and mesopic (0.164 cd/m ) luminance conditions using a letter chart, similar in principle to the ETDRS logMAR chart, presented on a computer monitor. Three rows of five letters, each row differing in size by 0.05 logMAR from largest to smallest were displayed at the center of the monitor. The level of crowding was varied by varying the separation between horizontally adjacent letters from 100% optotype size to 50, 20, and 10% optotype size. Inter-row spacing was proportional to optotype size. Observers read the letters on the middle row only. Measurements continued by reducing the size of the letters, until three or more errors on the middle row were made. Each correctly identified letter contributed 0.01 to the recorded

Journal

Graefe's Archive for Clinical and Experimental OphthalmologySpringer Journals

Published: May 28, 2018

References

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