Objective To investigate the distribution of the preferred retinal locus (PRL) of eccentric fixation in eyes with high myopia.Methods A total of 40 highly myopic patients (54 eyes ) with eccentric fixation were examined by MP1 microperimeter to identify the PRL. The position of PRL relative to the fovea was estimated using the 90% confidence ellipse of normal adult foveal fixation. The differences of visual acuity between ldquo;desirablerdquo; and ldquo;undesirablerdquo; PRL were tested by analysis of variance.Results In 54 eyes with high myopia, 24 eyes (44.44%) had PRL of eccentric fixation below the scotoma after loss of central vision; 19 eyes ( 35.19% ) had a leftfield PRL; 6 eyes ( 11.11% ) had an upperfield PRL; and 5 eyes ( 9.26% ) had rightfield PRL. In 14 patients who had binocular eccentric fixation, 13 had the same fixation pattern in both eyes, including lowerfield PRL in 7 （50.00%）, leftfield PRL in 5 （35.71%）, and upperfield PRL in 1 patient （7.14%）. The difference of visual acuity between lower and leftfield PRL group and right and upperfield undesirable PRL group was not statistically significant（F=0.144, Pgt;0.05）. Conclusions The eccentric fixation in eyes with high myopia is usually situated as near as possible to the fovea. The optimal PRL is inferior visual field.
Objective To observe the relationship between position of normal central fixation and the position of the optic disc, and to find out the features of stability of fixation. Methods The position of central fixation of 120 eyes of 60 healthy adults was determined by MP-1 microperimeter. The position of central fixation relative to the position of the optic disk was measured. The relationship between the central fixation and the age or refraction was analyzed statistically. The difference between the right and left eye in each individual was analyzed with t test. Results The central fixation located at the retina with the horizontal distance of 14.48deg;plusmn;1.85deg; and vertical distance of －2.14deg;plusmn;1.26deg; from the temporal edge of the optic disk. In the 120 eyes, 90% of the central fixation located in a bivariate normal ellipse. The normal eyes usually kept in a slightly moving condition when a normal person fixing on a subject. The median of horizontal and vertical deviation was 0.4deg; and 0.3deg; respectively. Conclusion The distribution of central fixation in healthy adults is a bivariate normal ellipse. When fixing on a subject, the moving extent of the eyes in the horizontal direction is larger than that in the vertical direction.