Foveal and Macular Thickness Evaluation by Spectral OCT SLO and Its Relation with Axial Length in Various Degree of Myopia.

PURPOSE To evaluate the foveal and macular thickness in various degrees of myopia and its association with axial length in low, moderate and high degrees of myopia. DESIGN A cross-sectional study was done in the Department of Ophthalmology, MGMCRI, Pondicherry, India. MATERIALS AND METHODS One hundred and twenty five eyes eyes of 64 myopic subjects between the age group of 20-40 who fulfilled the inclusion criteria were selected and complete ophthalmic examination was done. Cycloplegic refraction was done and the subjects were categorized into low (n=43 eyes), moderate (n=43 eyes) and high (n=36) degrees of myopia. The foveal and macular thickness was assessed using spectral OCT- SLO and axial length was measured by A-scan biometry. RESULTS The foveae minimum of high myopia (178 ± 26.4 microns) was significantly thicker compared to moderate myopia (p= 0.028). There was no significant intergroup difference in the thickness significance of the outer and inner macular between mild, moderate and high degree of myopia. The mean axial length of high myopia (26.7±0.97mm) was significantly higher compared to moderate (24.6±0.81mm) and low myopia (23.5±0.81mm) with a p-value of p = 0.001. There was a positive correlation of axial length with foveae minimum, fovea and superior inner macula in respect to myopia (p<0.05). CONCLUSION The foveal and macular thickness in myopia is influenced by the axial length. Early detection of such changes in macular thickness by using OCT is helpful in understanding the mechanism and factors affecting the structural changes of myopic eyes. Also it implicates the importance of refractive error induced retinal macular changes while interpreting OCT.