Anatomical and electrophysiological evaluation of macular function in myopic patients

The aim of this study is to evaluate the posterior segment parameters, the anatomical structure of macula with Spectral Domain Optic Coherence Tomography (SD-OCT) and electrophysiological function of the macula with pattern electroretinography (PERG) in myopic cases and to determine the correlation between them. The study group included 118 subjects (78 female, 40 male). Cases were divided into four groups according to the degree of refractive errors. The first group was between 0.00 / -0.75 D (control group), the second group between -1.00/ -2.75 D, the third group between -3.00 / -5.75 D and the fourth group as -6.00 D and higher. Peripapillary RNFL thickness, macular thickness, thickness of the retinal layers and choroidal thickness were measured using SD-OCT in all cases and then PERG test was applied. It was found that there was a decrease in RNFL thickness except T quadrant with the increase in degree of myopia. There was no correlation between macular thickness and the thickness of retinal layers (except the outer plexiform layer) and the degree of myopia. Negative correlation was found between macular thickness and N95 amplitude in high myopia group. It was found that subfoveal choroidal thickness decreased with increased degree of myopia and increase in AL. There was a negative correlation between AL and subfoveal choroidal thickness. There was a statistically significant difference between the high myopia group and the control group in the amplitudes of P50 and N95 waves. The decrease in P50 and N95 amplitude was observed to be associated with the increase in the degree of myopia. The decrease in N95 amplitude correlated with the increase in axial length. The decrease in P50 amplitude without an anatomical change in macular retinal layers and without reduction of BCVA is suggestive that macula can be affected in high myopia cases in terms of function. The decrease in N95 amplitude was thought to be related with increase in AL and decrease in global peripapillary RNFL thickness. Keywords: Spectral Domain Optical Coherence Tomography, pattern electrography, myopia.