Abstract
Purpose :
To investigate changes in cone density in developing eyes with different severity of myopia as a measure of retinal stretch.
Methods :
Fifteen adolescents, 10-18 years of age, with healthy eyes were divided into 4 groups based on refractive error, (1) emmetropes (EM): -0.5 to +1.00 DS with < -0.50 DC, (2) low myopes (LM): -0.75 to -3.00 DS with < -2.00 DC, (3) moderate myopes (MM): -3.25 to -6.00 D DS with < -2.00 DC and (4) high myopes (HM): greater than -6.25 DS with < -2.00 DC. Eight retinal locations, namely, 25° temporal (T), 10° T, fovea, 10° nasal (N), 25° N, 10° superior (S), 21° S and 5° inferior (I) retina were imaged with a custom-built adaptive optics – scanning laser ophthalmoscope (AO-SLO). Axial length and refractive error were measured at the same retinal locations so that direct correlation could be made with the corresponding cone density measurements.
Results :
A strong positive correlation was observed between myopic refractive error and axial length at all 8 retinal locations with the mean R2 value of 0.7. The correlation between the cone density and axial length varied more widely depending on the retinal location and the refractive error group. When cone density was compared between the 4 refractive error groups at the same retinal location, statistically significant reduction in density was observed in myopic eyes at 25° T, 10° T, 10° S and 10° N retina in comparison to emmetropic eyes, while not statistically significant reduction was observed at the 2 most central locations, fovea and 5° I retina and 2 other peripheral locations, 21° S and 25° N retina. At 25° T retina, the cone density difference between EM and all 3 myopic groups was statistically significant (p < 0.001 for LM, MM, HM) while at the 10° locations (T, N and S retina), the significant difference was only observed between EM and higher myopia (10° T: p < 0.01 for EM vs HM, 10° N: p < 0.06 for EM vs HM, 10° S: p < 0.003 for EM vs HM). Furthermore, in HM group, the 10° S retinal location showed statistically significant reduction in cone density (p < 0.03) compared to other 10° locations (N and T retina).
Conclusions :
It appears that near-peripheral and temporal aspect of mid-peripheral retina maybe more susceptible to retinal stretching (as indicated by reduced cone density) in response to myopia associated axial elongation than the central and superior - nasal aspects of the mid-peripheral retina.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.