STUDY OF OCULOMOTER PARAMETERS IN YOUNG MYOPES

Title STUDY OF OCULOMOTER PARAMETERS IN YOUNG MYOPES
Author, Co-Author Ling Zheng, Jia-Xin Yu, Chun-yan Yao, Kenneth Ciuffreda, Ying Han
Topic
Year
2002
Day
Friday
Program Number
Room
Room 1 SP
Affiliation
Abstract PURPOSE: To explore the oculomotor mechanisms of early-onset myopia by analysis of accommodative components at near: accommodative lag, phoria, and the stimulus AC/A ratio.

METHODS: Subjects consisted of 186 Chinese myopes aged 10-16 years (M 90 and F 96) with corrected visual acuity of 20/20 or better. The refractive correction ranged from -0.75 - 5.0 D. Subjects were divided into groups by refractive correction in 1D bins, with equal numbers in each bin. Refractive error was determined by objective autorefractor and subjective refraction. Accommodative lag was measured open-loop using a DOG target and dynamic retinoscopy. Phoria was determined by the von Graefe technique. AC/A ratio was measured with minus lenses.

RESULTS: There was no statistically significant difference in accommodative lag between groups (p>0.05), although a trend for a progressively increased lag with greater myopia was evident. However, there was a statistically significant difference between groups with respect to phoria (p<0.05) and AC/A ratio (p<0.01); the higher the myopia, the larger the exophoria, and the greater the AC/A ratio.

CONCLUSIONS: We speculate that the higher AC/A ratio may represent an adaptive phenomenon in the early years prior to refractive correction to maintain fusion at near in the presence of reduced accommodative drive, as well as a compensatory mechanism for the larger exophoria at near. These adaptations may be exacerbated by prolonged nearwork and the imbalance between accommodative and vergence drives.
Affiliation of Co-Authors Eye Hospital, First Clinical Medical Institution, Harbin Medical University, Eye Hospital, First Clinical Medical Institution, Harbin Medical University, State University of New York, College of Optometry, State University of New York, College of Optometry
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