AIM: To investigate interocular differences in macular ganglion cell complex(mGCC)thickness in normal healthy subjects, and to determine cutoffs for interocular differences in mGCC thickness in normal healthy subjects.

METHODS: This was a cross-sectional study. mGCC thickness were measured in 236 healthy volunteers(472 eyes)using optical coherence tomography(OCT). The differences and the relationships of mGCC thickness between right and left eyes were analyzed.

RESULTS: For the right eyes, the mean average mGCC thickness was 91.99±6.61μm, and for the left, 91.75±9.93μm, with no significant difference. The mean mGCC thickness among superior and inferior in the right eye were 92.32±6.66μm and 91.27±8.87μm, respectively. The mean mGCC thickness among superior and inferior in the left eye were 92.05±6.55 and 91.51±6.76μm, respectively. It is comparable between the two eyes at different area. The P_2.5 and P_97.5 percentiles of interocular difference for mean average mGCC thickness were -4.82μm and 4.36μm, for superior mGCC thickness, -5.79μm and 6.42μm, and for inferior mGCC thickness, -7.21μm and 6.28μm. There was a strong correlation in the corresponding area between the right and left eyes for the mGCC thickness.

CONCLUSION: mGCC thickness shows significant interocular symmetry in normal subjects. Interocular difference exceeding the normal limits should be considered significantly asymmetrical, and may be indicative of glaucoma.