The characteristics of near prism induced fixation disparity curve in Hong Kong Chinese

Lawrence K.H. Kwan, Kwok Cheung Andrew Lam, Calvin K.F. Kwan, Pauline H.N. Yeung

Research output: Journal article publicationJournal articleAcademic researchpeer-review


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 2.42Δ base-out and 3.54Δ base-out from two methods respectively.
Original languageEnglish
Pages (from-to)393-400
Number of pages8
JournalOphthalmic and Physiological Optics
Issue number5
Publication statusPublished - 1 Jan 1999

ASJC Scopus subject areas

  • Ophthalmology
  • Optometry
  • Sensory Systems


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