作者：周俊　何湘珍　刘嘉毅　彭辉灿　袁满红

    【摘要】目的：评价准分子激光原位角膜磨镶术(LASIK)和准分子激光角膜切削术(PRK)治疗高中度远视的预测性、安全性及有效性。方法：选择新西兰大白兔20只，随机分为LASIK和 PRK 2组，设计每组兔右眼为+5.00D，左眼为+8.00D，应用LASIK和 PRK 进行预期矫正度的激光切削。分别于术前、术后3，14，30，60，90，180d对术眼进行角膜地形图和裂隙灯检查和记录，同时每组随机处死 1 只兔子，取角膜标本进行光镜和电镜的病理学检查。结果：所有术眼均无并发症，LASIK组右眼和左眼术后180d的角膜中央曲率变化为(+4.56±0.67)D和(+8.59±0.83)D, PRK组右眼和左眼术后180d的角膜中央曲率变化为 (+4.56±0.80)D和(+7.33±0.98 ) D。术后3~30d均有回退现象(P <0.05) , 180d时已基本稳定(P <0.05)。LASIK组和 PRK组比较，在+5.00D范围内的差异无显著性(P <0.05) ，在+8.00D范围内的差异有显著性(P < 0.05)。病理学观察显示病理损伤后LASIK与PRK的愈合过程相同。 结论：LASIK与PRK治疗远视均具有安全性。LASIK对高度远视治疗的效果与可预测性优于PRK。

    【关键词】  远视眼　准分子激光原位角膜磨镶术　准分子激光角膜切削术　病理学检查

    Experimental study on excimer laser for hyperopia

    Abstract AIM: To evaluate the efficacy, predictability and safety of laser in situ keratomileusis (LASIK) and photorefractive keratectomy(PRK) for the correction of moderate and high hyperopia. METHODS: We chose 20 white rabbits as animal model. The rabbits were divided into two groups according to operation method. Operations were performed with Mulit Scan KERATOM excimer laser. The subjects were randomly divided into two groups. One group was preformed LASIK, the other was preformed PRK. Surgery was performed on the right eye of the rabbit to attempt a correction of +5.00D, and the left eye of the rabbit to attempt a correction of +8.00D. The rabbits were examined with videokeratoscope and slit-lamp microscope preoperation and in 3 days, 2 weeks, 1, 2, 3, and 6 months postoperation, respectively. At each time of the postoperation examination, one rabbit of each group was killed randomly, both corneas were removed for histopathological observation of transmission electron microscopy and light microscopy. RESULTS: No complication was observed. At the 6th month postoperation, the increase of the LASIK group which to attempt +5.00D and +8.00D was +4.58±0.67D and +8.59±0.83D, respectively, the PRK group was +4.56±0.80D and +7.33±0.98D respectively. Compared with peroperation, the central astigmatism increased. The statistical significant regression (P <0.05) of both groups occurred during the period of 3 days to 1 month postoperation. At the 6th month, there was no statistically significant regression (P>0.05) of both groups. Comparing PRK group with LASIK group, there was no statistical difference in the range of +5.00D and statistical difference in the range of +8.00D. The histopathological investigations showed that the healing response of LASIK group was similar to that of PRK group. CONCLUSION: Both LASIK and PRK are safe. LASIK is superior to PRK in efficacy and predictability in treating high hypermetropia.

    · KEYWORDS: hyperopia; laser-in situ keratomileusis; photorefractive keratectomy; histopathological observation

    0引言

    近年来，准分子激光治疗远视已在临床上得到了应用，由于角膜的形态结构及生物学特点，治疗远视的可预测性和稳定性仍有不足。LASIK手术是近几年来广泛开展的术式，它保留角膜上皮层和前弹力层，具有许多其它屈光性手术无法比拟的优点[1], 国内外对其临床研究的报道较多[1-5]，而对于LASIK的实验研究报道相对较少。兔眼的结构与人眼的结构相似，故我们应用LASIK在兔眼角膜基质的旁中央区切削治疗高中度远视的实验研究并与传统的PRK手术进行了比较，同时进行光学和电镜的病理学观察，对LASIK手术的效果、安全性和可预测性进行全面的评估如下。

    1材料和方法

    1.1材料 选用出生日期相近的健康纯种新西兰大白兔 20 只，雌雄不限，质量2.5～3.0kg。按随机的原则将20只兔子分为LASIK和PRK两手术组，根据预期的远视矫正度数的不同，设计每组兔右眼为+5.00D，左眼为+8.00D，应用LASIK和PRK进行预期矫正度的激光切削。术前全部实验兔眼术前通过裂隙灯检查，以排除眼部病变，并采用角膜地形图检测进行记录及分析。

    1.2方法 采用德国视明公司生产的Mulit Scan KERATOM舒荣TM多光束智能扫描准分子激光系统及法国Moria公司生产的LSK-One气动板层角膜成形刀，使用激光制造厂家提供的治疗远视的软件。术前经耳静脉注射30g/L戊巴比妥钠进行全身麻醉（约1mL／kg），常规消毒铺巾，开睑器开睑，颞侧角膜上皮划痕作角膜瓣定位标记，确定角膜中心，放置1号负压环固定眼球，使眼压达65mmHg，启动气动式板层成形刀，做直径8.0~9.0mm带蒂角膜瓣，蒂位于鼻侧，蒂的宽度约30°，角膜瓣厚度130μm。翻转角膜瓣，将术眼参数输入电脑，确定角膜中心后开启准分子激光在基质层行激光切削，每组兔右眼预期矫正度数为+5.00D，切削直径参数5.5mm，切削深度为74μm，每组兔左眼预期矫正度数为+8.00D，作分区域切削，切削直径参数5.5~6.5mm，切削深度为64~152μm。激光切削后将角膜瓣复位，以BSS在瓣下冲洗，清除杂质，然后将角膜瓣仔细对位、吸干。去除开睑器，检查确认角膜瓣无移位，滴泰利必妥眼液。术后LASIK组泰利必妥滴眼，4次d，连续1wk；氟美瞳眼液滴眼，1wk，4次/d，以后每周递减1次，共滴4wk停药。PRK组泰利必妥滴眼，4次/d，连续30d；氟美瞳眼液滴眼，1mo，4次/d，以后每个月递减1次，共滴90d停药。术后3，14，30，60，90，180d定期作角膜地形图及裂隙灯检查，采用美国FDA分级标准进行Haze分级。并随机选1只兔子，用30g/L戊巴比妥钠全身麻醉后摘除眼球，完整剪下角膜平分两半，一半无水酒精固定24h，石蜡包埋、切片等，常规苏木素－伊红染色进行光镜检查；一半用25g/L的戊二醛固定，送电镜室处理，进行透射电镜检查。

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