ABSTRACT
@#AIM:To investigate the influence of myopia on peripapillary retinal nerve fiber layer thickness(RNFLT)using Cirrus optical coherence tomography(OCT)in myopic juveniles aged 12-18 years.<p>METHODS: Cross-sectional observational study. High-definition(HD), spectral-domain Cirrus OCT(Cirrus HD-OCT; Carl Zeiss, Dublin, CA)was used to analyze RNFLT in 145 healthy juveniles(145 eyes). The data for left eye were selected for analysis. The magnification effect was adjusted by the modified axial length method. The subjects were divided into four groups by spherical equivalent(SE): normal group(52 eyes, -0.25-+0.25D), low myopia group(60 eyes, -0.5--3.0D), moderate myopia group(25 eyes, -3.25--6.0D)and high myopia group(8 eyes,-6.25--12.0D). The correlations between RNFLT and axial length(AL)or SE was tested with linear regression analysis.<p>RESULTS: The older the age, the longer the eye axis length, the higher the degree of myopia. Comparison of adjusted RNFLT among the four groups: after adjustment, the average RNFLT of the low myopia group and the moderate myopia group were thicker than those of the normal control group(<i>P</i><0.05). The adjusted RNFLT of temporal quadrant in the moderate myopia group and the high myopia group were significantly thicker than those in the normal group and the low myopia group, as well as the adjusted RNFLT of nasal quadrant in the low, moderate myopia group were significantly thicker compared with those in the normal group(<i>P</i><0.05). There were statistically significant difference of adjusted RNFLT at 1-4 o'clock, 6 o'clock, 7 o'clock and 9 o'clock among multiple groups(<i>P</i><0.05). The adjusted values of RNFLT at 1-4 o'clock all showed positively correlated with AL(<i>r</i>=0.220, 0.259, 0.356, 0.237, 0.335, all <i>P</i><0.01)and negatively correlated with SE(<i>r</i>=-0.386, -0.276,-0.307, -0.254, -0.260, all<i> P</i><0.01); The adjusted RNFLT at 6, 7 o'clock showed negatively correlated with AL(<i>r</i>=-0.296,-0.327, all<i> P</i><0.01)and positively correlated with SE(<i>r</i>=0.245,0.295, all<i> P</i><0.05).<p>CONCLUSION: Teenagers' eyeballs are still in the shaping stage. When judging RNFLT in myopic juveniles, effects of ocular magnification effect, AL and SE should be considered. When adjusted temporal RNFLT at 1-4 o'clock are thinner than normal, glaucoma should be considered.
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.