Purchase this article with an account.
V Lakshminarayanan, V Rajaram, S Joseph, JA Beatty; Empirical Longitudinal Horopter With Induced Optical Displacment . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4715.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose:This study compares methods used to calculate R0and H values for the longitudinal horopter. Using a glass plate to induce a lateral image displacement in one eye, the ability of the equation R= R0+H tan alpha2 (Ogle’s original formula) to predict R0 and H values was compared with that of the equation R= R0+H tan(alpha2-alpha1) (new formula; ARVO 2001 submitted). Methods:Subjects were asked to align test rods in an Apparent Frontoparallel Plane (AFPP) horopter device. Subjects performed two baseline trials followed by two sets of trials, one with a 1.8mm glass plate and another with a 15mm glass plate placed before the right eye. Results:R0 and H values were calculated as described by Ogle (J.O.S.A. Vol 22, 1932, 538-631). Paired-sample, T-tests (two-tailed) were performed to compare values between the baseline and each glass plate and the plates with each other. Significance was found between the baseline and 15mm glass plate (p<.001). Analytical plots as described by Ogle were performed for the baseline, 1.8mm plate and 15mm plate data. R2 values were calculated for each regression line with a baseline R2=.752, 1.8mm plate R2=.698, and 15mm plate R2=.705. Analytical plots of R against tan(alpha2-alpha1) were performed. Here a plot was constructed for negative alpha2 and again for positive alpha2 values. For the baseline R2=.938 and .861, 1.8mm plate R2=.879 and .945, and the 15mm plate R2=.982 and .952 values were obtained. The analysis was also performed using geometrical optics methods giving similar results. Conclusion:This study shows the inadequacy of Ogle’s formulation for the horizontal longitudinal horopter and points out the need for a fuller analytic description for horopter data.
This PDF is available to Subscribers Only