George S P, Johnson D G
London Place Eye Centre, Inc., New Westminster, British Columbia, Canada.
Ophthalmology. 1999 Aug;106(8):1469-79; discussion 1479-80. doi: 10.1016/S0161-6420(99)90439-6.
Regression and undertreatment after initial photorefractive keratectomy (PRK) in higher myopes is not unusual. Patients frequently desire 20/20 uncorrected vision, which necessitates retreatments or enhancements. However, the safest and most efficacious way to treat these patients has not yet been established. This study evaluates two techniques of PRK enhancements, comparing two different methods of laser epithelial removal.
Retrospective, nonrandomized, comparative trial.
A total of 224 eyes.
Eyes were identified that had 6-month follow-up after a PRK enhancement from February 1995 through February 1997. Two methods of treatment were identified. The same VISX 20/20B laser in the same clinic was used for all retreatments. Group I patients had a total removal of the epithelium in a mode phototherapeutic keratectomy (PTK) prior to the refractive ablation. Group II patients had a total laser epithelial removal in two steps prior to the refractive ablation. The first step was a PRK and then a PTK.
The disappearance of epithelial fluorescence was the end point for the PTK ablation in groups I and II.
There were 131 eyes in group I and 93 eyes in group II. The mean spherical equivalent (SE) prior to the original PRK in group I was -7.5 diopters (D) +/- 3 D and in group II was -7.75 D +/- 2.34 D. The mean SE prior to the PRK retreatment in group I was -2.22 D +/- 1.29 D and in group II was -1.89 D +/- 0.83 D. The mean postoperative 6-month SE after the PRK enhancement in group I was -0.05 D +/- 0.80 D and in group II was 0.01 D +/- 1.08 D. A greater proportion of group I eyes (7.8%) had arcuate haze and a hyperopic shift from the 1- to 6-month postoperative visit (P = 0.03).
A two-step laser epithelial removal compared with a one-step PTK epithelial laser removal in PRK retreatments provides a more even and confluent epithelial removal, less risk of arcuate haze development, and less risk of a hyperopic shift from 1 to 6 months after the retreatment.
高度近视患者初次准分子激光角膜切削术（PRK）后出现回退和治疗不足的情况并不罕见。患者通常期望获得20/20的裸眼视力，这就需要再次治疗或增效治疗。然而，治疗这些患者最安全、最有效的方法尚未确定。本研究评估了PRK增效治疗的两种技术，比较了两种不同的激光上皮去除方法。
回顾性、非随机、对照试验。
共224只眼。
确定1995年2月至1997年2月期间接受PRK增效治疗并随访6个月的眼睛。确定了两种治疗方法。所有再次治疗均在同一诊所使用同一台VISX 20/20B激光。I组患者在屈光性消融术前以模式光治疗性角膜切削术（PTK）完全去除上皮。II组患者在屈光性消融术前分两步完全去除激光上皮。第一步是PRK，然后是PTK。
I组和II组中，上皮荧光消失是PTK消融的终点。
I组有131只眼，II组有93只眼。I组初次PRK术前平均等效球镜度（SE）为-7.50屈光度（D）±3 D，II组为-7.75 D±2.34 D。I组PRK再次治疗术前平均SE为-2.22 D±1.29 D，II组为-1.89 D±0.83 D。I组PRK增效治疗术后6个月平均SE为-0.05 D±0.80 D，II组为0.01 D±1.08 D。I组中更大比例的眼睛（7.8%）出现了弓形 haze，并且从术后1个月至6个月出现了远视偏移（P = 0.03）。
在PRK再次治疗中，与一步式PTK上皮激光去除相比，两步式激光上皮去除可提供更均匀、更融合的上皮去除效果，减少弓形 haze形成的风险，以及再次治疗后1至6个月远视偏移的风险。
