不同程度近视眼视网膜神经纤维层厚度和视盘形态的分析

Analysis of peripapillary retinal nerve fiber layer thickness and papillary parameters in different degrees of myopic eyes

背景近视是原发性开角型青光眼发病的危险因素，了解不同程度近视眼视网膜神经纤维层厚度（RNFLT）及视盘形态特征对于鉴别近视与青光眼造成的RNFL与视盘改变具有重要意义。目的探讨近视眼RNFLT和视盘形态特征及其与近视程度的关系。方法将在北京协和医院眼科就诊的单纯近视患者168例168眼根据等效球镜度（sE）分为低度近视组（SE：-0．25～-2．75D）、中度近视组（SE：-3．0～-5．75D）和高度近视组（SE：-6．0～-12．0D），3个组患者年龄匹配，但sE和眼轴长度问差异均有统计学意义（SE：F=302．630，P：0．000；眼轴长度：F=166．410，P=0．000）。选择OCTOPUSl01型自动视野计的tG，程序检查受试眼视野，无视野缺损的眼纳入研究。应用GDxVCC测量受试眼的RNFLT，应用HRT—Ⅱ检测受试眼的视盘形态和参数，采用单因素方差分析比较3个组间测量参数的差别，组间比较采用SNK—q检验，采用多元回归法检测屈光度与RNFL相关参数间及视盘相关参数间的关系。结果随着近视度数的增加，RNFLT总平均值、上方平均值、下方平均值、标准差、眼间对称性检测值均逐渐下降，低、中、高度近视组组间比较差异均有统计学意义（F=6．193、7．127、3．874、4．098、3．128，P〈0．05），其中高度近视组、低度近视组比较，RNFLT总平均值、颞上方平均值、标准差、眼间对称性差异有统计学意义（q=5．334、4．526、4．586、20．679、P〈0．05），高度近视组、中度近视组以及中度近视组、低度近视组比较眼问对称性差异有统计学意义（q=6．225、10．035，P〈0．05）。3个组间神经纤维指数（NFI）值差异无统计学意义（F=1．029，P=0．175）。低度近视组与中度近视组比较，视杯容积、杯盘直径比值、平均视杯深度和最大视杯深度随近视屈光度的增加而降低，差异均有统计学意义（q=2．603，P：0．011；q=2．105，P=0．037；q=2．825，P=0．006；q=2．495，P=0．014）。低度近视组与高度近视组比较，平均视杯深度和高度变异轮廓差异均有统计学意义（q=2．562，P=0．013；q=2．203，P=0．030）。RNFLT总平均值、颞上平均值、颞下平均值、标准差、眼间对称性均随着近视度的增加而变薄（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）。视杯容积、平均视杯深度、最大视杯深度3个组比较差异均有统计学意义（F=3．491、4．933、3．357，P〈0．05），其中低度近视组与中度近视组比较，视杯容积、杯盘直径比、平均视杯深度、最大视杯深度差异均有统计学意义（P〈0．05）；低度近视组与高度近视组比较，平均杯深、变异轮廓差异均有统计学意义（P〈0．05）。盘沿面积、盘沿容积、高度变异轮廓随着屈光度的增加而增加（β=0．195，t=-2．565，P=0．011；8：0．199，t=-2．611，P=0．010；β=0．177，t=-2．311，P=0．022），平均视杯深度随着屈光度的增加而减少（β=0．153，t=1．997，P=0．047）。结论随着近视程度的增加，近视眼上方RNFLT、下方RNFLT均变薄，盘沿容积加大，视杯深度减少。对中度、高度近视眼通过GDxVCC获得的RNFL数据以及通过HRTⅡ获得的视盘参数进行分析和对早期青光眼患者进行诊断时均应考虑近视度数的影响。

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 bigh 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 seanning 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〈O. 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 RNFLT decreased with the inerease 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=O. 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 O. 011;q =2. 105,P=0.037;q =2.825,P=0.006;q =2.495,P=0.014）. Mean cup depth and contour were significantly decreased in the high myopia group compared with the low myopia group q=2.603,P= height variation q=2.562,P= 0. 013 ;q = 2. 203, P = O. 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. O10;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 .