Kinetics of foveal cone photopigment in myopia without chorioretinal degeneration

Purpose: To study the early changes in the outer retina of myopic eyes, we performed fundus reflection foveal cone densitometry in 45 subjects with normal visual acuity and no chorioretinal degeneration (ages: 18-47 years, refraction; +2.0014.50 diopters). Methods: After full bleaching, the density of the photopigment was measured for 7 minutes by using a test spot, 562 nm in wavelength and 1°in diameter, focused on the fovea. We calculated the density difference (DD) and the time constant (TC) of photopigment regeneration. Results: Although we found no correlation between the DD and the refractive error, there was a significant increase in TC as the refractive error increased (r = 0.50, P < 0.01). Conclusions: These findings indicated that the kinetics of cone pigments become abnormal preceding the loss of cone cells or chorioretinal degeneration in high myopia.