Preferred retinal locus of eccentric fixation in eyes with high myopia

Abstract

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 MP-1 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 desirable and 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 left-field PRL; 6 eyes (11.11%) had an upper-field PRL; and 5 eyes (9.26%) had right-field PRL. In 14 patients who had binocular eccentric fixation, 13 had the same fixation pattern in both eyes, including lower-field PRL in 7 (50.00 %), left-field PRL in 5 (35.71 %), and upper-field PRL in 1 patient (7.14%). The difference of visual acuity between lower- and left-field PRL group and right- and upper-field undesirable PRL group was not statistically significant (F=0.144, P > 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. Key words: Myopia; degenerative/complications; Fixation; ocular/pathophysiology; Perimetry