• Feng-Ju Zhang, Li-Na Chen, Ning Guo, Fang-Lei Yu, and Zhi-Li Lu.
• Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing 100730, China. wxw93@hotmail.com
• Zhonghua Yan Ke Za Zhi. 2009 Jul 1; 45 (7): 587-93.

ObjectiveTo investigate morphologically the different changes of cornea tissue between thick and thin cornea flap with confocal microscope, and to compare visual function between thick and thin cornea flap after LASIK.Methods70 cases (70 eyes) who had received LASIK were divided into the thin cornea flap group (36 eyes, group A) and the thick cornea flap group (34 eyes, group B). The age was (23 +/- 5) years old, spherical equivalent diopter (SE) were ( - 4.76 +/- 2.30) D and (- 3.03 +/- 2.20) D. Inspection items included visual acuity (VA), refraction, wave-front analysis, contrast sensitivity analysis (KONTRASTOMETER BA4, Germany) during pre-and post-LASIK, at the same time, all eyes were examined by confocal microcopy (HRT III, Germany). Using Moria 90 microm and 130 microm keratome with Allegretto Excimer laser machine.ResultsRefraction: there was no difference between the two groups. Post-LASIK 3 to 6 months: group A (0.35 +/- 0.21) D; group B (0.45 +/- 0.69) D (P > 0.05). Comparison results by confocal microscope. The thickness of cornea flap: group A (107.37 +/- 20.5) microm, group B (149 +/- 25.2) microm (P < 0.05). The thickness of wrinkle: group A (63.71 +/- 15.8) microm; group B (48.16 +/- 20.7) microm (P < 0.05). The thickness of acellular area: group A (69.93 +/- 15.8) microm; group B (55.63 +/- 23.7) microm (P < 0.05). The thickness of activation cornea cells: group A (60.15 +/- 30.9) microm; group B (51.86 +/- 27.9) microm (P < 0.05). The density of anterior stromal: group A (825.14 +/- 156.9) mm2; group B (853.54 +/- 126.8) mm2 (P < 0.05). There were significant differences on the thickness of cornea flap, the thickness of wrinkle, the thickness of acellular area, the thickness of activation cornea cells, the density of anterior stromal, but there was no difference on posterior stromal (P > 0.05). Wavefront analysis:there was no difference between two groups in Z3(-3), Z3(-1), Z3(1), Z3(3), Z4(0), RMS3, RMS4, RMS5, RMS6, RMSh (P > 0.05) pre-and post-operation. Contrast sensitivity analysis: there was also no difference between two groups (P > 0.05) pre-and post-LASIK 1-6 month.ConclusionsFrom the point of confocal microscope view, morphologic changes of cornea was significant with different thick flap. It is not cicatricial healing between the cornea flap and stromal. The cell injury of cornea tissue in the thin cornea flap was severe than that of in the thick cornea flap even though there was no significant difference between thin and thick cornea flap group in clinical refraction correction, wavefront and contrast sensitivity.

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