The electro-oculogram (EOG) was studied in 156 normal patients, 103 patients with Best's disease, and 52 patients with dominant cystoid macular dystrophy (DCMD). Statistical analysis was performed by comparing the distribution of Lp/Dt ratios of the groups. Strength of association between Lp/Dt ratio and age was studied with correlation and regression analysis. In normal patients and in those with Best's disease, there was no significant correlation between age and Lp/Dt ratio. Obviously, the gene defect in Best's disease causes an altered light-sensitive slow oscillation that remains stable throughout life. In DCMD patients, there was a significant negative correlation between age and Lp/Dt ratio for the total sample and for the female subgroup. Likely, the gene defect in DCMD interferes with capillary permeability, that becomes susceptible to changes of the female hormones.