Gartry D S, Larkin D F, Hill A R, Ficker L A, Steele A D
Cornea Service, Moorfields Eye Hospital, London, England.
Ophthalmology. 1998 Jan;105(1):131-41. doi: 10.1016/s0161-6420(98)91715-8.
Regression, a gradual partial or complete return to the myopic state, remains a common complication of excimer laser photorefractive keratectomy (PRK) and limits the predictability of refractive outcome, especially in high myopia. An estimated 10% to 20% of patients, therefore, request a repeat PRK procedure. This study was designed to provide patient selection criteria and guidelines for successful retreatment.
One hundred six patients who had regressed were randomized to 1 of 4 retreatment groups comprising (1) those with minimal haze after their first PRK who received an exact retreatment; (2) those with minimal haze treated with a 50% deliberate overcorrection; (3) those with significant haze (> or = 2+ haze) given an exact retreatment; and (4) those with significant haze who received a 50% overcorrection. A Visx 20/20 laser was used in each case. Mean follow-up after retreatment was 12 months (range, 6-18 months).
Deliberate overcorrection (groups 2 and 4) resulted in a statistically significantly better refractive outcome (P = 0.026 at 6 months). Analysis of variance showed that significant haze after the first PRK was the most important predictor of a poor outcome after retreatment, other factors being high original myopia, marked regression, and loss of best-corrected visual acuity.
A retreatment PRK procedure for significant regression will reduce residual myopia significantly in the majority of patients, and a deliberate overcorrection (50%) reduces the chance of further regression. However, patients with high myopia who have regressed beyond approximately -3.50 diopters originally and who show significant anterior stromal haze (> 2+) should be retreated only with great caution, because of the risk of further regression, haze, and loss of visual acuity.
回退是准分子激光屈光性角膜切削术（PRK）常见的并发症，表现为近视状态逐渐部分或完全恢复，这限制了屈光结果的可预测性，在高度近视患者中尤为明显。因此，估计有10%至20%的患者需要再次进行PRK手术。本研究旨在提供患者选择标准及成功再次手术的指导原则。
106例发生回退的患者被随机分为4个再次手术组之一，包括：（1）首次PRK术后角膜 haze 最小的患者接受精确再次手术；（2）角膜 haze 最小的患者接受50%的有意过度矫正；（3）角膜 haze 显著（≥2+ haze）的患者接受精确再次手术；（4）角膜 haze 显著的患者接受50%的过度矫正。每组均使用威视20/20激光。再次手术后平均随访12个月（范围6 - 18个月）。
有意过度矫正（第2组和第4组）在统计学上显著改善了屈光结果（6个月时P = 0.026）。方差分析表明，首次PRK术后显著的角膜 haze 是再次手术后效果不佳的最重要预测因素，其他因素包括初始高度近视、明显回退和最佳矫正视力下降。
对于明显回退的再次PRK手术，大多数患者的残余近视将显著降低，有意过度矫正（50%）可降低进一步回退的几率。然而，初始近视度数超过约-3.50屈光度且出现显著前基质 haze（> 2+）的高度近视回退患者再次手术时应格外谨慎，因为存在进一步回退、haze 和视力丧失的风险。
