Peripapillary retinal nerve fiber layer thickness distribution in myopia patient measured by 3D-OCT

Background As assessment of the peripapillary retinal nerve fiber layer (RNFL) has been an important approach for detecting structural damage in patients with glaucoma and myopia is a vital risk factor of primary open glaucoma,it is urgent to establish the correlation between RNFL thickness and myopia,not only for understanding the characteristics of RNFL with the change of the degree of myopia,but also for identifying those myopic patients with the early stage of glaucoma.Objective This study was to assess the influence of myopia for the thickness of RNFL measured by 3D optical coherence tomography (3D-OCT).Methods Two hundred and fifty-eight eyes of 258 myopic subjects from General Hospital of Ningxia Medical University were recruited.The myopic eyes were divided into low myopia group (42 eyes,-0.5 D ≤ SE ≤-3.0 D),middle myopia group (120 eyes,-3.0 D＜SE≤-6.0 D),high myopia group (58 eyes,-6.0 D＜SE≤-8.0 D) and extreme high myopia group (38 eyes,SE ＞-8.0 D).The peripapillary RNFL thickness profile including temporal,superior,nasal and inferior quadrants and each of the 12 clocks was measured by 3D-OCT.The measured values were compared among different degrees of myopia,and the correlations between spherical equivalent (SE) and axial length with RNFL thickness were analyzed using linear regression equation.Results The RNFL thickness was gradually declined with the increase of SE and elongation of axis,showing significant differences among the 4 groups in the superior,nasal and inferior quadrants and mean RNFL thickness (F=10.48,15.60,3.31,8.98,all at P＜0.05),but temporal RNFL thickness was increased with the SE rise,with markedly difference among the 4 groups (F =2.92,P =0.03) ; and RNFL thicknesses in the superior,nasal,inferior quadrants and mean RNFL thickness were evidently declined in the high and extreme high myopia group in comparison with low myopia group (all at P＜0.05).The overall RNFL parameters at 1:00,2:00,3:00,4:00,5:00,6:00,8:00,12:00 o'clock sectors were thinning as the increase of SE (all at P＜0.05) and unchanged at the 7:00,9:00,10:00,11:00 sectors in different SE groups (all at P＞ 0.05).Negative correlations were found between axial length or SE with the RNFL thicknesses at superior,nasal and inferior quadrants,average thickness as well as 1:00,2:00,3:00,4:00,5:00,6:00,11:00,12:00 o 'clock,and positive correlation was seen between the axial length or SE with the RNFL thicknesses at temporal quadrant.Conclusions The thickness of RNFL varys with the different degree of myopia and axial length. Key words: Optical coherence tomography;  Myopia;  Retinal nerve fiber