准分子激光治疗性角膜切削术治疗角膜浅层病变的实验和临床研究

目的：观察准分子激光治疗性膜切削术（photo-therapeutic keratectomy,PTK)后兔角膜组织的修复情况,探讨PTK的临床疗效,适应证和治疗参数。方法：（1）实验组采用8．17％硫酸烧灼法制作兔角膜浅层瘢痕模型,2周后行PTK;于术后不同时间进行角膜活体共焦显微镜,神经染色,光镜和透射电镜检查,并与对照组进行比较。（2）根据临床治疗组26例（30只眼）角膜浅层病变患者的病变种类,分别行去除上皮和非去除上皮PTK。观察术后不同时间患者的视力,屈光状态和角膜曲率变化情况,以及角膜雾状混浊（haze)的程度,随访时间6个月。结果：（1）实验组兔角膜切削区PTK术后早期多形 性粒细胞和巨噬细胞浸润。浅基质成纤维细胞增生活跃,新生胶原纤维排列紊乱,疏松;术后6个月趋于正常,组织修复稳定。（2）临床治疗组PTK术后6个月最佳矫正视力与术前比较,21只眼提高,5只眼不变,4只眼下降;其中PTK治疗角膜营养不良和角膜带状变性的效果最佳;术后6个月haze 0级23只眼,0．5级5只眼,1级2只眼,平均远视移动度数＋1．52D。结论：兔角膜PTK术后6个月组织修复趋于稳定;临床PTK治疗角膜浅层病变患者,方法简便,安全,有效,其中以治疗角膜营养不良和角膜带状变性的效果最佳,采用PTK治疗的角膜病变以不超过角膜前1／3厚度为宜。     

准分子激光术治疗近视眼164例术后远期疗效观察

目的观察评价准分子激光角膜切削术(photorehaefive keratectomy，PRK)和准分子激光原位角膜磨镶术(excimer laser insitu keralcmileusis，LANK)治疗近视眼术后的远期疗效。方法对。164例328眼，按手术方法，近视屈光度分为两组，一组行PRK手术，屈光度-1．25DS～-7．00DS，二组行LASIK手术，屈光度-2．50DS～一12．00DS，对行准分子激光治疗后1～6年患者的视力、并发症角膜上皮下基质混浊、眼压进行观察分析。结果裸眼视力达到术前最佳矫正视力(≥5．0)，PRK组为75％(114眼)，LASIK组为78．4％(138眼)，角膜下基质混浊，影响视力，PRK组6％，LASIK组未见角膜混浊，眼压平均12mmHg。结论准分子激光治疗近视安全有效，大部分远期疗效较好，PRK组个别患者发生角膜混浊，应引起重视。     

准分子激光治疗性角膜切削术治疗浅层角膜病变

目的评价准分子激光治疗性角膜切削术（PTK）治疗浅层角膜病变的临床效果。方法采用PTK治疗10例（12只眼）角膜浅层病变,术后随访观察1年并对结果进行分析。结果术前及术后1、3、6、12个月最佳矫正视力均值作配对t检验,对数视力平均提高0.16（P〈0.001）。术后6个月,远视漂移度数平均为＋1.6D。结论 PTK治疗浅层角膜病变安全有效,术后存在远视化和原有疾病复发等问题。     

PRK和LASIK偏中心切削分析

目的　分析准分子激光屈光性角膜切削术 (photorefractivekeratectomy ,PRK)和准分子激光原位角膜磨镶术 (laserinsitukeratomileusis ,LASIK)治疗近视偏中心切削及其与临床效果的关系。方法　对术前屈光度为 -3 0 0D～ -10 0 0D ,平均 (-6 0 8± 1 2 1)D76例 (15 0眼 )行PRK ,75例 (15 0眼 )行LASIK ,分为PRK和LASIK组。术后 1、3、6、12月行角膜地形图检查。结果　两组偏中心距离大部分≤ 0 5 0mm ,偏中心方位大多位于鼻上象限 ,差异无显著意义 (P >0 0 5 )。偏中心距离 >0 5 0mm时 ,裸眼视力较术前最佳矫正视力下降≥ 2行所占比例明显高于偏中心距离≤ 0 5 0mm者 (P <0 0 0 1)。结论　偏中心切削与PRK和LASIK的手术方式无关。偏中心距离≤ 0 5 0mm ,对视力的影响不大 ,偏中心距离 >0 5 0mm时 ,术后裸眼视力较差。     

伴眼球震颤的近视准分子激光屈光手术的观察

目的　探讨对伴有先天性眼球震颤的近视施行准分子激光角膜屈光手术的方法及疗效。方法　对16例(3 2眼)以水平震颤为主的先天性运动性眼球震颤的近视(矫正视力>0 .5 )施行准分子激光PRK13例(2 6眼) ,LASIK 3例(6眼) ,术中采用2 %利多卡因球周麻醉。术后随访时间6月。结果　视力:PRK 2 4眼、LASIK 5眼共2 9眼术后裸眼视力达到术前最佳矫正视力。屈光度:PRK 2 6眼术前平均为(-4 .86±0 .5 5 )D ,术后6月平均为( 0 . 5 2±0 . 46)D ;LASIK 6眼术前平均为(-6 . 72±0 . 76)D ,术后6月平均为(-0 .75±0 .87)D。结论　对矫正视力较好的伴有先天性眼球震颤的近视施行准分子角膜屈光手术和普通的近视一样可获得良好的临床效果。     

准分子激光治疗性角膜切削术在角膜浅层病变治疗中的临床应用

目的 评价准分子激光治疗性角膜切削术 （ PTK ）在浅层角膜病变治疗中的临床效果.方法 采用 PTK治疗 8例 （ 10只眼 ）角膜浅层病变,术后随访观察6~12月并对结果进行分析.结果 术前及术后 1、3、6个月最佳矫正视力均值作配对t检验,对数视力平均提高0.15 （ P ＜ 0.001）.术后 6个月,远视漂移度数平均为 ＋ 1.6 D.结论 PTK治疗浅层角膜病变安全有效,术后存在远视化和原有疾病可能复发等问题.     

激光治疗性角膜切削术治疗LASIK术后角膜上皮内生

目的 探讨激光治疗性角膜切削术(PTK)治疗LASIK术后角膜上皮内生的方法和效果,方法 LASIK术后较严重的角膜瓣下角膜上皮内生4例(4眼),进行内生的上皮刮除和PTK治疗后戴接触镜3～5天,随访10～24个月,结果 4例均治愈,随访期内无复发,视力均恢复至术前最佳矫正视力.眼部刺激症状、眩光消失.结论 LASIK术后瓣下角膜上皮内生,进行角膜瓣后面和角膜床表面的角膜上皮刮除及PTK术,术后戴角膜接触镜,是治疗LASIK术后瓣下角膜上皮内生的有效方法.     

准分子激光角膜切削术治疗圆锥角膜行角膜表层镜片术后的屈光不正

目的探讨角膜表层镜片术（EP）联合Ⅱ期准分子激光角膜切削术（PRK）治疗圆锥角膜完成期的临床疗效。方法（1）病例入选标准：①EP入选标准：圆锥角膜完成期患者,角膜中央区无瘢痕,最佳矫正视力（BCVA）≤0．3,角膜曲率≤60．0D;②Ⅱ期行PRK入选标准：角膜拆线后3个月内散光变化〈0．5D,年龄〉18岁,无其他眼部疾病。（2）手术治疗：对进入手术入选标准的患者常规Ⅰ期行EP,Ⅱ期行PRK。（3）术后随访：观察术后植片情况,记录视力、散光变化及并发症发生情况。结果8例（10只眼）患者接受了Ⅰ期EP联合Ⅱ期PRK,术后平均随访时间为40．6（30～94）个月。（1）视力：EP术后12～18个月（角膜全拆线行PRK术前）,10只眼BCVA均〉0．3,其中0．3～0．5者1只眼,≥0．5者9只眼;行PRK术后〉12个月,10只眼BCVA均≥0．5,其中5只眼BCVA达到1．0。（2）角膜散光：EP术前平均角膜散光为（7．3±1．8）D,EP术后12～18个月平均角膜散光为（3．8±1．6）D,PRK术后24个月以上,平均角膜散光为（1．6±0．9）D。（3）植片情况：EP术后所有植片透明,无免疫排斥反应发生。PRK术后1只眼发生0．5级的角膜上皮下雾状混浊,未见圆锥角膜复发。（4）术后并发症与处理：1例（1只眼）患者EP术后当天继发青光眼,前房消失,急诊行前房重建后缓解;1例（1只眼）患者EP术后植床出现较大皱褶,1例（1只眼）患者EP术后3个月内缝线松动,行植片重缝后缓解。结论Ⅰ期EP联合Ⅱ期PRK可能是治疗圆锥角膜完成期的有效方法,行PRK术后视力长期稳定。     

准分子激光治疗性角膜切削术在复发性角膜糜烂中的应用

目的:评价早期实施准分子激光治疗性角膜切削术(PTK)对复发性角膜糜烂(RCE)的临床治疗效果。方法:筛选经常规治疗方法无效,但未经基质穿刺及角膜接触镜治疗的RCE临床连续病例23例(25眼),平均病程为9.3mo(2mo～3a),经全面眼科检查后行PTK治疗,切削深度为10μm,光学区为4～8mm。对比PTK手术前后裸眼视力(UCVA)、最佳矫正视力(BCVA)、等效球镜(SE)以及散光度数(RC)。结果:术后平均随访10.1±5.5mo(4.2～19.2mo),免于复发率为96%,平均BCVA显著提高(术前为0.69±0.30,术后为0.90±0.23,P<0.001),平均SE变化不明显(术前0.41±1.67DS,术后0.35±1.63DS,P=0.26),但平均RC显著降低(术前-1.22±0.90DC,术后-0.57±0.57DC,P<0.001)。结论:对于早期RCE患者,PTK是一种安全有效的治疗方法,它可使绝大多数患者的角膜上皮快速愈合而迅速减轻症状,并可显著提高最佳矫正视力。     

乙二胺四乙酸螯合联合PTK及羊膜移植术治疗眼内硅油填充术后带状角膜变性的临床疗效观察

目的评估乙二胺四乙酸(EDTA)螯合联合激光治疗性角膜切削术(PTK)及羊膜移植术治疗眼内硅油填充术后带状角膜变性的临床疗效。方法收集2009年至2011年EDTA螯合联合PTK及羊膜移植术治疗眼内硅油填充术后并发带状角膜变性的6例(7只眼)患者临床资料,对手术前后最佳矫正视力、症状有无改善、上皮重建时间、外观、并发症进行回顾性分析。结果视力提高2只眼(28.5%),视力无提高5只眼(71.5%),所有患者症状均有改善,平均上皮重建时间为(10.6±2.4)d,外观较好5只眼(71.5%),外观改善一般的2只眼(28.5%),术后追踪随访时间平均为(11.1±4.0)个月,没有发现术后并发症以及复发。结论 EDTA螯合联合PTK及羊膜移植术对于治疗眼内硅油填充术后带状角膜变性是有效的。     

Phototherapeutic keratectomy with mitomycin C for corneal haze following photorefractive keratectomy for myopia

PURPOSE: To evaluate the safety and efficacy of phototherapeutic keratectomy (PTK) with single application of mitomycin C for patients with severe corneal haze following photorefractive keratectomy (PRK) for high myopia. METHODS: Eight eyes of seven patients were treated with PTK and intraoperative topical application of mitomycin C (0.02%) for severe corneal haze (grade 3) following PRK for myopia. RESULTS: All patients' visual performance improved significantly. Mean preoperative visual acuity (20/200 for both UCVA and BSCVA) improved significantly to 20/33 (0.6) and 20/30 (0.7) for UCVA and BSCVA, respectively. Six eyes (85.7%) had improved UCVA to 20/40 or better and gained five or more lines of UCVA. The corneal haze score decreased from grade 3 initially (for all eyes prior to PTK and mitomycin C) to a final mean haze score of 0.3 (range 0 to 0.5). Mean final spherical equivalent refraction achieved was -1.30 +/- 1.60 D (range -3.75 to +1.25 D). One eye gained only three lines of visual acuity due to regression and residual haze. No adverse effects related to the use of mitomycin C were recorded. CONCLUSION: PTK with a single intraoperative application of mitomycin C was safe and effective in reducing corneal haze and improving visual acuity in patients with severe corneal haze following PRK.     

Fourier-domain optical coherence tomography-guided phototherapeutic keratectomy for the treatment of anterior corneal scarring

AIM: To evaluate the safety, visual and anatomic outcomes of fourier-domain optical coherence tomography (FD-OCT)-guided excimer laser phototherapeutic keratectomy (PTK) combined with photorefractive keratectomy (PRK) surgery in treating anterior corneal scarring. METHODS: Clinical data of 23 eyes of 21 patients with anterior corneal scarring underwent FD-OCT-guided PTK and PRK from Dec. 2014 to Jul. 2016 were reviewed. Patients were assessed for preoperative and postoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), contrast sensitivity (CS), FD-OCT, corneal topography and colour figures of anterior segments. RESULTS: The preoperative corneal pathologic conditions included viral keratitis (7 patients, 7 eyes), band keratopathy (2 patients, 4 eyes), corneal dystrophy (4 patients, 4 eyes), traumatic corneal disease (2 patients, 2 eyes) and corneal chemical injury (6 patients, 6 eyes). Mean follow-up time was 10.65 (range, 3-19)mo. UCVA (in logMAR) improved from a mean of 0.79 (95%CI, 0.28-1.29) preoperatively to a mean of 0.45 (95%CI, 0.29-0.62) postoperatively (P=0.021). BSCVA (in logMAR) improved from 0.57 (95%CI, 0.26-0.88) preoperatively to a mean of 0.28 (95%CI, 0.15-0.41) postoperatively (P=0.001). Corneal topographic indices postoperatively showed significant improvement in corneal cylinder (P=0.009), the surface regularity index (P=0.001) and surface asymmetry index (P=0.007). Postoperative spherical equivalent averaged -0.53 diopters (-1.49-0.42). No complications were associated with the treatment. CONCLUSION: FD-OCT-guided PTK combined with PRK is safe and effective for the treatment of anterior corneal scarring by eliminating or reducing corneal opacities.     

Phototherapeutic keratectomy in children: 5-year results

PURPOSE: To evaluate the efficacy and safety of phototherapeutic keratectomy (PTK) for the treatment of superficial corneal opacities, surface irregularities, epithelial instability, and reepithelialization failure in pediatric patients and study the visual and refractive changes after combined PTK and photorefractive keratectomy (PRK). SETTING: Department of Ophthalmology, Masaryk University Hospital, Brno, Czech Republic. METHODS: This retrospective clinical study comprised children who had PTK or PTK combined with PRK from September 1996 to January 2000. The goals of treatment were to improve visual acuity and reduce or eliminate subjective ocular discomfort (eg, pain, lacrimation, and photophobia). A Nidek EC-5000 excimer laser was used in PTK mode with a 3.0 to 6.0 mm optical zone and a 4.0 to 7.5 mm transition zone. RESULTS: Forty-one pediatric patients (41 eyes) were included. Twenty-three eyes had PTK only, and 18 eyes had PTK combined with PRK to reduce preoperative myopia (11 eyes) or hyperopia (7 eyes). The mean patient age was 11.4 years (range 8 to 18 years) and the mean follow-up, 4.8 years (range 3 to 6 years). The best spectacle-corrected visual acuity (BSCVA) improved in all patients, and episodes of ocular pain or discomfort, lacrimation, and photophobia diminished. The mean preoperative BSCVA of 6/38 (range 6/10 to 1/60) improved to 6/12 (range 6/6 to 6/38) at the last postoperative examination. Eight eyes gained 5 or more Snellen lines of BSCVA; 11 gained 4 lines, 9 gained 3 lines, 7 gained 2 lines, 5 gained 1 line, and 1 eye was unchanged. No eye lost a line of BSCVA. The mean preoperative spherical equivalent (SE) decreased from -5.32 to -1.16 diopters (D) in the 11 myopic eyes and from +4.72 to +1.51 D in the 7 hyperopic eyes within 3 years of the combined procedure. CONCLUSIONS: Phototerapeutic keratectomy is an effective and safe procedure for the treatment of various surface corneal disorders in children. It can improve best corrected visual acuity and eliminate ocular pain and irritation. Preoperative myopia and hyperopia were effectively reduced by a combination of PTK and PRK.     

Wavefront-supported photorefractive keratectomy with the Bausch & Lomb Zyoptix in patients with myopic astigmatism and suspected keratoconus

PURPOSE: To evaluate the safety, efficacy, and visual outcome of wavefront-supported photorefractive keratectomy (PRK) for the correction of myopia and myopic astigmatism in patients with suspected keratoconus. METHODS: Forty eyes of 20 patients with myopia -4.0 to -8.0 diopters (D) (mean: -6.25 +/- 1.04 D), cylinder -1.0 to -2.50 D (mean: -1.61 +/- 0.71 D), and corneal thickness 440 to 488 microm were treated with wavefront-supported PRK. Corneal topography evaluation revealed a significantly irregular cylinder (inferior-superior difference > 1.5 D) with possible mild or forme fruste keratoconus. Aberrometry was performed with the Hartmann-Shack aberrometer, and corneal data were evaluated with the Orbscan system. Eyes were treated with the Technolas 217z Bausch & Lomb excimer laser and followed for a minimum of 40 months. RESULTS: Following surgery, mean spherical equivalent refraction was +0.33 +/- 0.8 D. It was within +/- 0.5 D of the intended refraction in 95% of eyes and within +/- 1.0 D in 100% of eyes. Mean uncorrected visual acuity improved from 20/400 preoperatively to 20/25 postoperatively. Mean best spectacle-corrected visual acuity (BSCVA) remained unchanged (20/20) or improved to 20/20 in 92.5% of eyes and to 20/25 in 7.5% of eyes. Individually, BSCVA did not change in 28 (70%) eyes and increased by > or = 2 Snellen lines in 9 (22.5%) eyes; 3 (7.5%) eyes lost 1 Snellen line because of corneal haze. Laser treatment induced a significant flattening of the preoperative inferior corneal steepness in all eyes. Wavefront analysis demonstrated a significant decrease in high order aberrations (total root-mean-square and coma). CONCLUSIONS: Wavefront-supported PRK appears to be effective for the treatment of myopia and astigmatism in patients with suspected keratoconus and thin, irregular corneas. Longer follow-up is needed to prove the safety of the procedure in this patient population.     

准分子激光屈光性角膜切削术后的再治疗

目的 评价准分子激光屈光性角膜切削术（ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅ ｋｅｒａｔｅｃｔｏｍｙ,ＰＲＫ）术后因屈光回退,欠矫出现的残留近视及严重角膜上皮下雾状混沌（ｈａｚｅ）而再次手术治疗的疗效及安全性。方法 采用准分子激光仪对－１．００～－１６．５０Ｄ的近视眼及近视散光患者进行治疗。ＰＲＫ术后３５例（５１只眼）患者出现残留近视及严重ｈａｚｅ。结合ＰＲＫ手术及准分子激光治疗性角膜切削术（ｐｈｏｔｏｐ     

准分子激光角膜切削术前后的角膜地形图分析

了解准分子激光角膜切削术（ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅｋｅｒａｔｅｃｔｏｍｙ，ＰＲＫ）前、后角膜表面形态变化并对切削区偏中心进行分析。方法应用计算机辅助的角膜地形图仪对８０例（１２２只眼）ＰＲＫ前、后角膜地形图进行检测和分析。结果术前角膜地形图的形态呈对称或非对称性蝴蝶结形者占７５．４％；术后圆形或近似圆形者占６３．９％。切削区偏离瞳孔中心的距离与术前屈光度无关。切削区偏中心距离越大，术后角膜散光增加及术后最佳矫正视力下降越明显。结论ＰＲＫ前、后角膜地形图检查和分析能清楚地显示角膜表面形态变化及定量评估切削区偏中心问题。     

Phototherapeutic keratectomy for epithelial irregular astigmatism: an emphasis on map-dot-fingerprint degeneration

PURPOSE: To study the changes in irregular astigmatism in patients with recurrent corneal erosion syndrome due to map-dot-fingerprint degeneration and to demonstrate that both symptomatic and asymptomatic map-dot-fingerprint degeneration/recurrent corneal erosion syndrome may be related to irregular astigmatism, which can effectively be corrected by phototherapeutic keratectomy (PTK) or standard spherical photorefractive keratectomy (PRK). METHODS: Eleven eyes with irregular astigmatism related to map-dot-fingerprint degeneration/recurrent corneal erosion syndrome with and without changes at the slit-lamp microscope were treated with PTK or spherical PRK, which was performed with a VISX S2 or S4 excimer laser. All eyes underwent videokeratography performed pre- and postoperatively using either the Tomey TMS-2N Topographic Modeling System or EyeSys Technologies Corneal Analysis System 2000. RESULTS: Mean pre- and postoperative best spectacle-corrected visual acuity (BSCVA) was -0.18 +/- 0.14 logMAR and 0.04 +/- 0.04 logMAR, respectively. This improvement in BSCVA was statistically significant. The mean gain in Snellen lines was 2.4 +/- 2.1. Preoperative corneal videokeratography showed irregular astigmatism with an elevation pattern that was corrected in all eyes despite the fact that no astigmatic photorefractive correction was performed. CONCLUSIONS: Following PTK, eyes with irregular astigmatism related to map-dot-fingerprint degeneration showed significant improvement in BSCVA and correction of irregular astigmatism as revealed by videokeratography. This study shows that irregular astigmatism can be exclusively of epithelial origin and in some eyes abnormal corneal epithelium may create optical aberrations. This possibility should be taken into account when, for example, wavefront-guided stromal photoablation procedures are being planned.     

LASEK and photorefractive keratectomy for myopia: clinical and confocal microscopy comparison

PURPOSE: To compare postoperative visual acuity and corneal morphology after laser epithelial keratomileusis (LASEK) versus photorefractive keratectomy (PRK) in the correction of low to moderate myopia. METHODS: In a double-blind, randomized clinical trial, 50 myopic patients (mean: -4.5 +/- 1.35 diopters) were randomized to receive LASEK in one eye and PRK in the fellow eye. No mitomycin C eye drops were used in this study. Patients were observed daily for 4 days, then at 1 month and every 3 months up to 1 year. Uncorrected and best-corrected visual acuity (UCVA and BSCVA), manifest refraction, corneal epithelium healing time, postoperative pain, and corneal haze were evaluated. Corneal wound healing was quantified with corneal confocal microscopy. RESULTS: Refractive error, UCVA, and BSCVA were not statistically different between eyes treated with LASEK and PRK. Corneal epithelium healing time was 2.52 +/- 0.99 days in the eyes treated with PRK and 2.29 +/- 0.52 days in the eyes treated with LASEK (P=.22). The postoperative pain score was 2.17 +/- 0.87 in the eyes treated with PRK and 2.62 +/- 0.60 (P=.02) in the eyes treated with LASEK. Corneal confocal microscopy showed fewer stromal activated keratocytes and less extracellular matrix deposition in the eyes treated with LASEK than in the eyes treated with PRK at 1 month postoperatively (P=.003). CONCLUSIONS: LASEK is an effective and safe procedure for low to moderate myopia, but it seems more painful until full corneal reepithelization. In the early postoperative period, the corneal wound healing process is significantly less intense in eyes treated with LASEK than in eyes treated with PRK. The role of LASEK in corneal wound healing modulation remains controversial.     

Combination of photorefractive and phototherapeutic keratectomy in the treatment of keratoconus

Twenty patients (28 eyes) with primary keratoconus of stages I-II (Amsler) were operated using photorefraction keratectomy (PRK) supplemented by phototherapeutic keratectomy (PRK). Mean UCVA before surgery was 0.04 +/- 0.004, BCVA 0.68 +/- 0.03. Eximer laser EC-5000(NIDEK) was used in the treatment. PRK included spherical, cylindrical ablations, or both. The diameter of ablation zone in PRK was 6 mm. in PTK the diameter of ablation zone was 8 mm, transition zone 9 mm. In PTK the ablation zone was decentered towards the cone apex (according to corneal computer topography). The method is patented in the Russian Federation. Visual acuity without correction notably improved in all 20 patients and its mean value after the operation was 0.73 +/- 0.03, 68% eye having visual acuity of 1.0. In one female patient keratoconus progressed 6 months after the operation. Haze was observed in 1 patient as a result of delayed reepithelialization. No progress of keratoconus was observed in other patients (period of observation 17.3 +/- 1.5 months). Hence, the new PRK-PTK method is an effective method for treating primary keratoconus of the first-second stage according to Amsler; the method arrests the progress of the condition in 96% cases.     

Late natural history of corneal topography after excimer laser photorefractive keratectomy

PURPOSE: To investigate the 3 month to 1 year natural history of corneal topography after excimer laser photorefractive keratectomy (PRK). DESIGN: A prospective, multicenter, nonrandomized comparative study. PARTICIPANTS: A total of 75 eyes of 68 patients with myopia were studied. INTERVENTION: Excimer laser photorefractive keratectomy and computer-assisted videokeratography were performed. MAIN OUTCOME MEASURES: Preoperative and 3, 6, and 12 month postoperative topography patterns were compared and changes assessed by averaging defined sectors of the ablation zone in individual maps to produce composite "average" topography maps. RESULTS: Corneal topography was relatively smooth 3 months after PRK. By 12 months, the corneal contour in general had become even more uniform. No "central island" effect was observed. When looking at right and left eyes independently, there was a tendency toward maximum flattening nasally. CONCLUSIONS: Corneal topography in general continues to smooth from 3 to 12 months after PRK, possibly as a result of epithelial and stromal healing and remodeling. Right and left eyes on average show mirror-image, spatially oriented topography patterns.