Analysis of peripapillary retinal nerve fiber layer thickness and papillary parameters in different degrees of myopic eyes / 中华实验眼科杂志

ABSTRACT

Background Myopia is an important risk factor of glaucoma.Investigation of the characteristics of retinal nerve fiber layer thickness (RNFLT) and optical head morphology in myopia patients was helpful for differentiating myopic change and glaucomatous change in myopic eye.Objective This study was to investigate the peripapillary RNFLT and papillary parameters in different degrees of myopic eyes.Methods A 5-year case series study was retrospectively analyzed.Total 168 eyes of 168 myopic patients without visual field defect were recruited and divided into three age matched groups according to spherical equivalent (SE)low myopia group (SE-0.25 ～-0.75 D) (57 eyes),moderate myopia group (SE-3.0 ～-5.75 D) (57 eyes) and high myopia group (SE-6.0～-12.0 D) (54 eyes).The RNFLT was measured with scanning laser polarmetry (GDxVCC) and papillary parameters measured with confocal scanning laser ophthalmoscope (HRT Ⅱ).Intergroup difference of parameters from GDxVCC and HRT Ⅱ were analyzed using one-way analysis of variance and SNK-q test.The correlations between spherical equivalent and RNFLT or papillary parameters was evaluated with multiple linear regression analysis.Results The global average,superior and inferior average,standard deviation,inter-eye symmetry of RNFLT were gradually reduced as the increase of SE with significant differences among the three groups (F=6.193,7.127,3.874,4.098,3.128,P ＜ 0.05).Global average,superior average,standard deviation,inter-eye symmetry of RNFLT were significantly lower in the high myopia group than those in the low myopia group (q =5.334,4.526,4.586,20.679,P＜0.05).An statistically significant reduce in inter-eye symmetry was seen between the high myopia group and the moderate myopia group (q =6.225,P＜0.05) as well as between the moderate myopia group and the low myopia group (q =10.035,P＜0.05).The multiple regression analysis showed that global average,superior average,inferior average,standard deviation,inter-eye symmetry of the R NFLT decreased with the increase of SE (β=0.441,t=6.329,P=0.000;β=0.471,t=6.880,P=0.000;β=0.339,t=4.641,P=0.000;β=0.389,t=5.445,P =0.000 ; β =0.338,t =4.621,P =0.000).Cup volume,linear cup/disk ratio,mean cup depth and maximum cup depth in the high myopia group were significantly lower than those of the moderate myopia groups (q =2.603,P =0.0l 1 ;q =2.105,P =0.037 ; q =2.825,P =0.006 ; q =2.495,P =0.014).Mean cup depth and height variation contour were significantly decreased in the high myopia group compared with the low myopia group (q =2.562,P =0.013 ;q =2.203,P =0.030).Rim area,rim volume,height variation contour were positively correlated with the degree of myopia (β=0.195,t=-2.565,P=0.011 ;β=0.199,t=-2.611,P=0.010;β=0.177,t =-2.311,P=0.022) ; while mean cup depth were negatively correlated with the degree of myopia (β =0.153,t =1.997,P =0.047).Conclusions As the increase of myopia degree,superior and inferior quadrants of RNFLT and cup depth are declined,but rim volume is elevated.Myopia is a confounding factor when RNFL data is interpreted by GDxVCC and papillary parameter by HRT Ⅱ.