Analysis of Variation in Viewing Distance among Low Vision Individuals under Chinese Free-Viewing Condition

Abstract

Previous studies report that sighted people adjust their viewing distance from one reading material or print size to another under the free-viewing condition. Is this tendency true for individuals with low vision? The study uses a reading material with traditional Chinese characters to investigate changes in the viewing distance of people with low vision under the free-viewing condition. What then is the difference between theoretical and observed values? The study recruited 60 participants with low vision and randomly used 17 reading charts with print sizes ranging from 0.3 to 1.3 logMAR. The average of change for all character sizes is 2.56±1.43 cm. From the smallest to the largest character sizes, the difference between the two values then becomes larger. Finally, 99.33% of the data is classified under the same cluster. Thus, viewing distance fluctuates over time, and the result of optimal character size in traditional Chinese needs to be adjusted during assessment. Nearly all results demonstrate that viewing distance decreases with the increase in reading time.