角膜塑形镜停戴1个月后角膜形态改变及上皮和基质重分布的观察研究

Observation of corneal morphology and redistribution of corneal epithelium and stroma after orthokeratology cessation

目的观察长期配戴角膜塑形镜患者停戴1个月后角膜形态及上皮和基质重新分布的情况。方法配戴角膜塑形镜1年以上儿童近视患者20例,取右眼纳入连续性研究。分别于停戴当天和停戴后1个月采用傅里叶域光学相干层析成像(FD-OCT)测量直径为6 mm的中央角膜上皮地形图,并按中央区(2 mm),旁中央区(2~5 mm),周边区(5~6 mm),上、下、鼻、颞、鼻上、鼻下、颞上、颞下共分17个区域进行统计分析。角膜厚度减去上皮厚度得到基质厚度。运用Munnerlyns公式t=S2×D/8(n–1)计算预测塑形度数,并与实际矫正屈光度比较分析。同时常规测量停戴前后屈光度、视力、角膜地形图。结果停戴1个月后与停戴前相比,角膜中央厚度(t=-4.288,P<0.001)、角膜最薄点厚度(t=-4.457,P<0.001)、角膜中央2 mm上皮厚度(t=-4.807,P<0.001)显著增厚,中央基质厚度无明显变化。旁中央区整体上皮厚度停戴前后差异无统计学意义,但颞上(t=-2.629,P=0.017)及颞侧(t=-2.428,P=0.025)上皮显著增厚;整体基质(t=2.656,P=0.016)和角膜(t=18.027,P<0.001)厚度变薄,尤以鼻下方和颞上方基质显著变薄(t=-3.237,P=0.004;t=8.539,P<0.001)。周边区上皮变化差异无统计学意义,基质和角膜厚度明显变薄(t=2.635,P=0.016;t=3.435,P=0.003)。预测塑形度显著低于实际矫正屈光度(2.80 D vs 3.72 D,P<0.001)。结论角膜塑形镜停戴1个月后,上皮和基质发生重新分布,角膜上皮增厚主要在中央2 mm区域,旁中央区的上皮增厚集中在颞侧和颞上,中周部(2~6 mm)基质变薄。

Objective To observe the corneal morphology and the redistribution of corneal epithelium and stroma one month after cessation of long-term orthokeratology.Methods Twenty children with myopia who had worn orthokeratology(OK)lens for more than one year were enrolled and the right eye was included into the study.Fourier domain optical coherence tomography(FD-OCT)was used to measure the topography of the corneal epithelium within the central 6 mm diameter zone on the day of cessation and one month after cessation.The area of measurement was divided into 17 areas for analysis:the central 2 mm area,the paracentral 2~5 mm,and the peripheral 5~6 mm at the superior,inferior,nasal,temporal,supranasal,inferonasal,supratemporal and inferotemporal areas.Stromal thickness maps were generated by subtracting the epithelial thickness from the corneal thickness.Munnerlyn formula t=S2×D/8(n–1)was used to calculate the predicted diopter of reshaping,which was compared with the actual corrected refractive power.Routine measurement of refractive power,visual acuity,and corneal topography before and after cessation was conducted.Results The central corneal thickness(CCT;t=-4.288,P<0.001),the thinnest corneal thickness(TCT;t=-4.457,P<0.001)and the central epithelial thickness(CET;t=-4.807,P<0.001)increased significantly after one month of cessation.No obvious change was observed in the central corneal stromal thickness(CCST).In the paracentral area,there was no significant difference in the overall epithelial thickness before and after cessation,but the epithelium on the supratemporal(t=-2.629,P=0.017)and temporal(t=-2.428,P=0.025)area was significantly thickened;the overall stroma(t=2.656,P=0.016)and cornea thickness(t=18.027,P<0.001)was thinner,especially for the stroma in the inferonasal(t=-3.237,P=0.004)and supratemporal areas(t=8.539,P<0.001).There was no statistically significant changes of epithelial thickness in the peripheral area,but the stroma and cornea were significantly thinner(t=2.635,P=0.016;t=3.435,P=0.003).The predicted reshaping diopter was significantly lower than the actual refractive power(2.80 D vs 3.99 D,P<0.001).Conclusions The epithelium and stroma were redistributed after one month of the cessation of orthokeratology.The corneal epithelium thickened mainly in the central 2 mm area,the epithelial thickening in the paracentral area mainly occurred in the temporal and supratemporal areas,and the CST in middle periphery(2-6 mm)area became thinner.