McGhee C N, Bryce I G
Corneal Diseases and Excimer Laser Unit, Sunderland Eye Infirmary, United Kingdom.
J Cataract Refract Surg. 1996 Nov;22(9):1151-8. doi: 10.1016/s0886-3350(96)80063-0.
To assess the incidence and natural history of central corneal topographic islands following excimer laser photorefractive keratectomy (PRK) and photoastigmatic refractive keratectomy (PARK).
A dedicated corneal diseases and refractive surgery unit within a National Health Service Trust ophthalmology unit in the United Kingdom.
Corneal topographic analysis was performed in a prospective study of 100 eyes of 75 consecutive patients who had PRK. All PRK/PARK excimer laser photorefractive procedures were performed by two surgeons observing a standardized protocol using a VISX 20/20 excimer laser. Mean preoperative myopic error was 5.54 diopters (D) +/- 3.44 (SD). Corneal topographic analysis was performed on all eyes preoperatively, 1 week postoperatively, and monthly thereafter for a minimum of 6 months or until central islands, if present, resolved. All patients had a minimum 12 months follow-up.
Postoperatively, 29 eyes (29%) demonstrated central corneal topographic islands of greater than 3.00 D topographic power by computerized videokeratography (CVK). All central islands were identified in the first 4 weeks postoperatively. In all cases the differential dioptric power, created by the central islands within the ablation zone, decreased rapidly; within 6 months, 26 (90%) central islands had fully resolved without further treatment, and the remaining 3 (10%) resolved within 1 year of photorefractive surgery. The occurrence of central islands was related to higher preoperative myopic spherical equivalent (P = .01), greater attempted laser correction (P = .01), and greater projected depth of ablation (P = .01) (Student's two-tailed t-test).
Central corneal topographic islands occurred in a significantly higher proportion of eyes having excimer laser photorefractive surgery than previously believed. The islands were associated with decreased unaided vision, reduced best spectacle-corrected acuity, and other troublesome visual symptoms; however, the central islands, along with their associated visual effects, usually resolved without surgical intervention within 6 months postoperatively.
评估准分子激光屈光性角膜切削术（PRK）和光性散光性屈光性角膜切削术（PARK）后中央角膜地形图岛的发生率及自然病程。
英国国民健康服务信托眼科部门内一个专门的角膜疾病与屈光手术科室。
对75例连续接受PRK手术的患者的100只眼进行前瞻性角膜地形图分析。所有PRK/PARK准分子激光屈光手术均由两名外科医生按照标准化方案使用VISX 20/20准分子激光进行。术前平均近视度数为5.54屈光度（D）±3.44（标准差）。术前、术后1周以及此后每月对所有眼睛进行角膜地形图分析，至少持续6个月，或直至中央岛（若存在）消退。所有患者至少随访12个月。
术后，通过计算机化角膜地形图仪（CVK）检查发现，29只眼（29%）出现了中央角膜地形图岛，其地形图屈光度大于3.00 D。所有中央岛均在术后4周内被发现。在所有病例中，消融区内中央岛产生的屈光度差异迅速减小；6个月内，26只眼（占90%）的中央岛未经进一步治疗完全消退，其余3只眼（占10%）在屈光手术后1年内消退。中央岛的出现与术前较高的近视等效球镜度数（P = 0.01）、更大的激光矫正量（P = 0.01）以及更大的预计消融深度（P = 0.01）相关（学生双尾t检验）。
接受准分子激光屈光手术的眼睛中，中央角膜地形图岛的发生率比之前认为的要高得多。这些岛与裸眼视力下降、最佳矫正视力降低以及其他令人困扰的视觉症状有关；然而，中央岛及其相关的视觉影响通常在术后6个月内无需手术干预即可消退。
