| ObjectiveTo evaluate the short-time effect on corneal tissue in Young with myopia at different time of wearing rid gas permeable contact lens(RGPCL) by the application of confocal microscopy.MethodsA total of 45 young patients(90 eyes) who underwent RGPCL orthodontic treatment in Cangzhou Eye Hospital were collected from March 2009 to July 2010. They were divided into two groups according to the refractive degree of myopia: groupⅠ27 cases wearing RGPCL ovenight, refraction≤-5.00D and astigmatism<-1.25D; groupⅡ18 cases wearing RGPCL daily, refraction>-5.00D and astigmatism <-1.75D. All the patients received regular confocal microscopy examination and other eye examinations within 6 months. The patients wearing RGPCL previous were the control group, patients wearing RGPCL later were the experimental group. We observed the changes of uncorrected visual acuity, corrected visual acuity and refraction in patients. All patients had their corneas examined with the confocal microscopy. Central cornea and within 2mm above the limbal cornea were chosen as the examination points. The epithelial wave, nerve fiber wave, matrix wave, endothelial wave, and complete Z-SCAN images were analyzed. Scanned images of the corneal layers displayed by the liquid crystal display were recorded simultaneously. The changes in cells density of corneal layers and thickness of corneal layers were calculated using the built-counting software.Results(1) Uncorrected visual acuity and refraction:In group I, the differences of uncorrected visual acuity, refraction between before and after wearing RGPCL 6 months were statistically significant. The uncorrected visual acuity improyed(t=30.604; p=0.000) while refraction decreased(t=18.324; p=0.000). In groupⅡ, the differences of uncorrected visual acuity(t=1.414; p=0.162), refraction(t=0.476; p=0.636) between before and after wearing RGPCL 6 months were not statistically significant.(2) Cells density of corneal layers:①Epithelium: In group I, the differences of central and peripheral corneal epithelial cells density between before and after wearing RGPCL 2 to 6 months were statistically significant(F=3.597,p=0.001; F=3.803,p=0.001). The central corneal epithelial cells density decreased (q=4.189,4.473,4.642; p=0.042,0.031,0.029)while peripheral cells increased (q=4.229,4.505,4.844; p=0.039,0.030,0.019)at 2 to 6months after wearing RGPCL. However, the differences of central and peripheral corneal epithelial cells density between before and after wearing RGPCL were not statistically significant in groupⅡ(F=0.736,0.464; p=0.642,0.860).In group I, the differences of central and peripheral corneal epithelial Langerhans cells density between before and after wearing RGPCL were statistically significant(F=3.733,3.486; p=0.001,0.001). The central and peripheral corneal epithelial Langerhans cells density increased at 3 to 6months after wearing RGPCL(central q=4.410,4.991; p=0.036,0.013; peripheral q=4.439,4.951; p=0.034,0.015). The differences of central and peripheral corneal epithelial Langerhans cells density between before and after wearing RGPCL were not statistically significant in group II(F=1.667,1.381; p=0.117,0.213).②Anterior stroma: In group I, the differences of central and peripheral corneal anterior stromal cells density between before and after wearing RGPCL were statistically significant(F=3.230,3.409; p=0.002,0.002). The central and peripheral corneal anterior stromal cells density decreased at 2 to 6months after wearing RGPCL (central q=4.203,4.373,4.876; p=0.041,0.039,0.017; peripheral q=4.284,4.682,4.981; p=0.035,0.021,0.014). The differences of central and peripheral corneal anterior stromal cells density between before and after wearing RGPCL were not statistically significant in groupⅡ(F=1.083,0.632; p=0.374,0.729).③Posterior stroma:In group I, the differences of central and peripheral corneal posterior stromal cells density between before and after wearing RGPCL were not statistically significant(F=1.176,1.867; p=0.316,0.074). The differences of central and peripheral corneal posterior stromal cells density between before and after wearing RGPCL were not statistically significant in group II too(F=0.746, 0.674; p=0.633,0.694).④Endothelium: In group I, the differences of central and peripheral corneal endothelial cells density between before and after wearing RGPCL were statistically significant(F=3.351,3.080; p=0.002, 0.004). The differences of average cells area of central corneal and percentage of hexagonal cells between before and after wearing RGPCL were statistically significant(F=3.577,3.911; p=0.001, 0.001). The average cells area was significantly increased(q=4.302,4.467,4.727; p=0.034,0.032, 0.024)and percentage of hexagonal cells was significantly reduced (q=4.267,4.664,5.359; p=0.036, 0.021,0.006) at 2 to 6months after wearing RGPCL. The differences of central and peripheral corneal endothelial cells density between before and after wearing RGPCL were not statistically significant in group II(F=0.915,0.658; p=0.495,0.708). The differences of average cells area of central corneal and percentage of hexagonal cells between before and after wearing RGPCL were not statistically significant in group II too(F=0.710,0.793; p=0.663,0.594).(3)Changes in corneal thickness:①Epithelial thickness: In group I, the central corneal epithelial thickness between before and after wearing RGPCL were statistically significant(F=3.339, p=0.002). The epithelial thickness were significantly reduced (q=4.420,4.577; p=0.035,0.033) at 3 to 6months after wearing RGPCL. The differences of peripheral corneal epithelial thickness between before and after wearing RGPCL were not statistically significant in group I (F= 1.096, p=0.365). The differences of central and peripheral corneal epithelial thickness between before and after wearing RGPCL were not statistically significant in group II (F= 1.024,0.727; p=0.414,0.649).②Stromal thickness:In group I, the central and peripheral corneal stromal thickness between before and after wearing RGPCL were not statistically significant(F=0.929,0.729; p=0.484,0.648). The differences of central and peripheral corneal stromal thickness between before and after wearing RGPCL were not statistically significant in groupⅡtoo(F=0.859,0.461; p=0.540,0.862).③Corneal thickness: In group I, the central and peripheral corneal thickness between before and after wearing RGPCL were not statistically significant(F= 1.359,0.408; p=0.221,0.897). The differences of central and peripheral corneal thickness between before and after wearing RGPCL were not statistically significant in groupⅡ(F= 1.066,0.577; p=0.386,0.775).Conclusion1. Young patients with myopia of re fraction≤-5.00D and astigmatism<-1.25D can have improved uncorrected visual acuity and reduced refraction degree after wearing RGPCL ovenight in short time. However, RGPCL can cause significant effect on corneal morphology. 2. Young patients with myopia of refraction >-5.00D and astigmatism≤-1.75D can not have improved uncorrected visual acuity and reduced refraction degree after wearing RGPCL daily in short time. RGPCL can not cause significant effect on corneal morphology.3. Application of confocal microscopy can assess the effect of wearing RGPCL on corneal tissue morphology. |
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