The characteristics of near prism induced fixation disparity curve in Hong Kong Chinese.
The characteristics of prism induced fixation disparity curve at near were studied in 56 asymptomatic young adult Hong Kong Chinese (average age 21 years). The percentage distribution of types of fixation disparity curves was found to be similar to some previous studies, with a higher prevalence of Type I curve (64.3%), followed by Type II (28.6%) and Type III (7.1%) curves. No Type IV curve was revealed from the sample. Two modified measurement approaches were applied to study the effect of measurement techniques on the parameters of fixation disparity curve obtained. A thorough description of the techniques was given. Although a significant difference in the x- and y-intercepts was obtained between different methods, the curve type and slope were not affected. The average y-intercepts (fixation disparity) were 2.72 min of arc and 3.54 min of arc from two methods respectively. Forty-one subjects had x-intercept (associated phoria) found from the curve. The average values were 2.42 delta base-out and 3.54 delta base-out from two methods respectively.
Kwan
L K
LK
Department of Optometry and Radiography, Hong Kong Polytechnic University, Kowloon, Hong Kong.
Lam
A K
AK
Kwan
C K
CK
Yeung
P H
PH
D000328:Adult; D002681:China / Q000208:ethnology; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D006723:Hong Kong; D006801:Humans; D008297:Male; D008432:Mathematical Computing; D055095:Optics and Photonics; D012107:Research Design; D015357:Vision Disparity / Q000502:physiology*