Excimer laser photorefractive keratectomy for high myopia and myopic astigmatism.

BACKGROUND AND OBJECTIVE: To determine the efficacy, safety, and predictability of excimer laser photorefractive keratectomy of high myopia and myopic astigmatism. PATIENTS AND METHODS: 76 eyes of 52 patients with myopia from -8.00 to -23.50 diopters (D) with or without astigmatism up to -5.50D were treated with the VISX 20/20 excimer laser (VISK, Santa Clara, CA) and a multi-zone ablation technique. Visual acuity, manifest refraction, corneal haze, and topography were evaluated at 1 week and 1, 3, 6, 12, and 18 months postoperatively. RESULTS: Postoperative refractions were generally stable after 12 months. At the last follow-up all patients were within - 1.96 D of the intended correction. Eighteen months postoperatively, 68% of patients undergoing photorefractive keratectomy (PRK), and 65% of patients undergoing photo astigmatic refractive keratectomy (PARK), were within 1 D of planned refraction. Furthermore, 87% of patients after PRK and 80% of patients after PARK had a visual acuity of 20/40 or better. CONCLUSIONS: High myopia with or without astigmatism was successfully treated in most of the patients using PRK. The stability of the postoperative refraction during the first 18 months seems to be good. The incidence of adverse effects was low but improvements in the future should further reduce complications, thus increasing the safety of refractive procedures.     

多光区准分子激光角膜切削术治疗高度近视眼

目的研究多光区准分子激光角膜切削术（multizonephotorefractivekeratectomy,PRK－MZ）治疗高度近视眼的疗效。方法229眼高度近视（－6．25～－9．00D）经PRK－MZ治疗后随访1a，观察视力、屈光稳定性和角膜Haze，用角膜地形图对PRK－MZ术后角膜形态及平均角膜屈光力（ACP）进行研究。结果PRK-MZ治疗1a后．197（86.03％）眼裸眼视力≥0．8，37（16．16％）眼屈光回退≥－1．00D，角膜Haze0．5～1级者5眼（2．18％），ACP值在PRK－MZ治疗后1mo、6mo及1a时较术前显著下降（P＜0.01），术后1a时ACP值较术后1mo和6mo时增加（P＜0．05）；角膜表面规则指数（SAI）在PRK-MZ术后无明显变化．角膜表面不规则指数（IAI）亦无变化。结论PRK-MZ治疗－6．25～－9．00D范围的高度近视仍有较好疗效，不影响角膜表面形态，但屈光稳定性降低，角膜Haze在随访1a中逐渐减退或消失。     

准分子激光角膜切削术治疗高度近视远期疗效分析

目的:评价准分子激光角膜切削术(photorefractive keratectomy, PRK)治疗高度近视的远期疗效.方法:将104例183眼屈光度>-6.00D患者分两组,Ⅰ组-6.25～-10.00D,Ⅱ组≥-10.25D,对PRK术后3年患者的视力、屈光度、角膜上皮下基质混浊进行随访分析.结果:3年时Ⅰ组裸眼视力达到术前最佳矫正视力的为73.3%(96眼),Ⅱ组为38.5%(20眼);屈光度在预期矫正度±1.00D以内者,Ⅰ组为76.3%(100眼),Ⅱ组为42.3%(22眼);角膜上皮下基质混浊,3年时0～0.5级的Ⅰ组为100%,Ⅱ组为90.4%.结论:PRK治疗-6.25～-10.00D的高度近视远期疗效较好,大于-10.00D的远期疗效不理想.     

准分子激光角膜切削术治疗高度近视的并发症

评价准分子激光角膜切削术治疗高度近视的手术并发症。对PRK治疗的104例136眼高度近视散光术后12－18月随访，对手术并发症进行统计分析。近视回退90眼占66％；角膜上皮下混浊95眼占69.8％；低矫21眼占15.4％；最佳矫正视力下降2行以上14眼占11．1％。本组病例近视回退，角膜上皮下混浊和低矫的发生与试图矫正的屈光度有关，并发症的发生率远高于中低度近视。     

PRK治疗高度近视的临床分析

目的探讨准分子激光角膜切削术对高度近视的疗效及其并发症。方法采用UV200型准分子激光机,对183例（330眼）—6．00D以上近视患者施行准分子激光角膜切削术,对随诊1a以上的患者进行观察。术前等值球面镜屈光度为—6．00～—26．00D（—10．27±—3．87D）,按屈光度分为3组：A组—600～—10．00D,199眼;B组—10．00～—15．00D,87眼;C组＞—15．00D,44眼。结果术后1a时裸眼视力＞0．5者276眼,占83．64％,M1．0者144眼,占43．64％;术后类固醇高眼压37眼,占11．21％;23眼（6．97％）的患眼有严重的角膜混浊,发生视网膜脱离3眼,眼底出血2眼。角膜曲率和中央角膜厚度在术后各时期无明显变化。结论PRK手术对高度近视是有效的．安全的。部分患者可获得良好的裸眼视力,大部分患者可明显减轻眼镜度数。     

Contrast sensitivity after excimer laser photorefractive keratectomy for myopia

AIM: To evaluate contrast sensitivity in patients who had undergone uncomplicated excimer laser photorefractive keratectomy (PRK) for myopia. · METHODS: Monocular contrast sensitivity function was measured with the CSV-I000E chart in 41 patients who had received PRK by the Nidek EC-5000 excimer laser system. Mean preoperative refractive error was -2.62±1.33 D (range, -0.75 to -4.00 D). Contrast sensitivity function was measured preoperatively, 1week, 1, 3 and 6 months after surgery through the CSV-1000E contrast sensitivity unit (VectorVision). · RESULTS: Logarithmic values of contrast sensitivity at each spatial frequency were used for statistical analysis and normalized values were used for graphical representation. Contrast sensitivity decreased 1 week and 1 month postoperatively. Starting from the first month, there was rapid recovery of contrast sensitivity especially at low spatial frequencies, and at the third month, only at 6 and 12 cycles per degree (cpd) statistically significant decrease was seen. Six months after surgery, there was an increase in contrast sensitivity values at all spatial frequencies. · CONCLUSION: Photorefractive keratectomy can induce significant reductions in contrast sensitivity in the first month after surgery; these values returned to the preopereative values at 6 months after surgery.     

近视眼准分子激光角膜切削术后的对比敏感度评价

目的:评价近视患者PRK术后的对比敏感度变化.方法:应用CSV-1000E图表对41例接受Nidek EC-5000型准分子激光仪行PRK手术的患者,行单眼对比敏感度测量.患者术前平均屈光度为-2.62±1.33D(范围从-0.75至-4.00D).应用CSV-1000E对比敏感度仪分别在术前,术后1wk;1,3,6mo行对比敏感度检查.结果:将每个空间频率的对比敏感度对数值进行统计学分析,并应用图表与正常值进行比较.结果显示对比敏感度在术后1wk及术后1 mo时明显降低,从第1 mo开始,对比敏感度尤其是低空间频率的对比敏感度快速恢复,在第3mo,只有6和12cpd两种空间频率的对比敏感度明显降低,在术后6mo时,所有频率的对比敏感度功能都明显增加.结论:PRK术后患者第1 mo对比敏感度功能明显降低,但在术后6mo时对比敏感度功能即恢复至术前水平.     

PRK治疗高度、超高度近视眼二年观察

目的　评价PRK 治疗高度、超高度近视眼的临床效果。方法　应用日本NIDEK EC—5000型准分子激光仪治疗高度近视眼214 例(343 只眼),按术前等值球镜度分为二组,Ⅰ组:- 6.25～- 10.00D,254 只眼;Ⅱ组:- 10.25～- 24.00D,89 只眼。术后随访2 年。结果　术后2 年,裸眼视力大于或等于术前最佳矫正视力者,Ⅰ组为59.4% ,Ⅱ组为31.5% ;裸眼视力≥0.5 和≥1.0 者,Ⅰ组为84.3% 和46.9% ,Ⅱ组为36.0% 和4.5% ;屈光度在±1.00D 以内者,Ⅰ组为82.6% ,Ⅱ组为27.0% ;术后最佳矫正视力较术前最佳矫正视力不变或上升者,Ⅰ组为94.1% ,Ⅱ组为91.0% 。角膜混浊度小于或等于1 级者,Ⅰ组为93.7% ,Ⅱ组为81.0% 。结论　PRK 矫治高度、超高度近视眼是安全有效的屈光手术,高度近视眼的稳定性和预测性比超高度近视眼高,而超高度近视眼术后可明显减少屈光度数,更远期的疗效需要更长时间观察     

准分子激光屈光性角膜切削术治疗高度近视的疗效分析

目的探讨准分子激光角膜切削术治疗高度近视的疗效。方法应用德国Ｋｅｒａｃｏｒ１１６型准分子激光仪，采用多步分区切削法治疗高度近视。按屈光度分为二组，Ⅰ组：－６．００～－９．７５Ｄ，２３３只眼；Ⅱ组：－１０．００～－１４．００Ｄ，５５只眼。术后随访１年，并对结果进行分析。结果本组患者术后１年裸眼视力≥０．５者占７９．４％，≥１．０者占３１．６％（其中Ⅰ组≥０．５者占９２．３％，Ⅱ组≥０．５者占５８．３％）。术后最佳矫正视力大于术前者占３７．１％，小于术前者占６．２％，９３．８％术后最佳矫正视力不变或上升。术后１个月时角膜上皮下混浊最重；１年时最轻，８７．４％的术眼混浊度为０。术后１年实际矫正度在预测矫正度±１．００Ｄ内者占５２．０％，±２．００Ｄ内者占８０．９％。激素性高眼压占１４．９％。结论准分子激光多步分级切削法治疗高度近视是一种安全、有效且稳定性较好的方法，对于超高度近视其安全性较高，但预测性略差。     

多区域准分子激光角膜切削术治疗近视

本文报导了多区域准分子激光角膜切削术治疗近视的疗效。１５０眼随访满６月，中低度近视组（≤－６．０Ｄ）８４眼，高度近视组（－６Ｄ～－１２Ｄ）６６眼。术后半年总体平均裸眼视力达到１．０７±０．２８；１４４眼（９６．０％）最终屈光度在±１．０Ｄ以内，其中中低度近视组８４眼（１００％）、高度近视组６０眼（９０．９％）。术后疗效高于单区域ＰＲＫ文献报导，尤其是高度近视术后稳定性及预测性明显提高     

固体激光治疗高度近视的疗效分析

目的：评价固体激光光学角膜切削术治疗高度近视的疗效。方法：应用Ｌｉｇｈｔ ＢｌａｄｅＴＭⅡ固体激光手术系统进行光学角膜切削术治疗高度近视－６．１２～－１６．００Ｄ１０６ 例１８０ 眼,随访１２ ～２４ 月,回顾性评价疗效和并发症。结果：１８０ 眼术前平均球镜屈光度－８．１９±０ ．５３Ｄ,术后１ 年－ ０．４７ ±０．４２Ｄ。术前平均角膜屈光力４３ ．２４ ±０ ．２６Ｄ,术后３９ ．８９ ±０ ．５０Ｄ。在１２ 个月时,试矫和实矫屈光度相差０ ．５０Ｄ内５８ ．９５ ％ ,１ ．００Ｄ内９３．３３％ ,２．００Ｄ内９８ ．３３％ 。术后１ 年裸视力１ ．０ 占５７．２２％ ,裸视力０ ．５ 占９５％ ,最好矫正视力达到术前水平８０％ ,超过１ 行６ ．６７ ％ ,超过２ 行３．３３％ ,下降１ 行８．８９％ ,下降２ 行１．１１ ％ 。术后角膜Ⅰ级ｈａｚｅ１ ,３,６,１２ 月分别是５２ ．２２ ％ ,４２ ．７８ ％ ,４５ ％ ,４５ ．５６ ％ ,Ⅱ级ｈａｚｅ 分别是１９ ．４４ ％ 、１５ ％ 、１２ ．７８ ％ 、８ ．３３ ％ ,Ⅲ级ｈａｚｅ１ 眼０ ．５６％ 。１０ 眼屈光回退６～１７ 月再手术。４ 眼激素性眼压升高,用药后恢复。结论：固体激光治疗高度近视安全有效,     

Laser-assisted subepithelial keratectomy versus photorefractive keratectomy for the correction of myopia. A prospective comparative study

PURPOSE: To compare the early postoperative visual rehabilitation after laser-assisted subepithelial keratectomy (LASEK) and photorefractive keratectomy (PRK) for the correction of myopia. SETTING: CODET Aris Vision Institute, Tijuana, Mexico. METHODS: This prospective study included 50 eyes of 25 patients with myopia who received LASEK in 1 eye and PRK in the contralateral eye. Excimer laser corneal ablation was done using the Nidek EC-5000 excimer laser. Patients were seen at 1 and 3 days, 1 week, and 1 month. Discomfort, subjective uncorrected visual acuity (UCVA), objective UCVA, best corrected visual acuity (BCVA), corneal clarity (haze), and time for corneal reepithelialization were analyzed. RESULTS: Seventy-two percent and 80% of the LASEK eyes had more discomfort at 1 day and 3 days, respectively. Eighty percent and 96% of the PRK eyes had better subjective UCVA at 1 day and 3 days, respectively. Corneas were fully reepithelialized at a mean of 3.3 days +/- 0.5 (SD) and 3.6 +/- 0.5 days in the PRK and LASEK groups, respectively. At 1 month, the UCVA was similar in both groups; no eye had lost lines of BCVA or developed haze. CONCLUSIONS: Both LASEK and PRK were effective and safe procedures in the surgical correction of myopia at the 1-month postoperative visit. Patients reported less discomfort and better visual acuity in their PRK eye during the early postoperative period. Patients should be informed that LASEK, whose acronym is similar to that of laser in situ keratomileusis, has a recovery speed that is similar to that of surface laser refractive procedures such as PRK.     

Technical improvements in photorefractive keratectomy for correction of high myopia

PURPOSE: To evaluate the effects of hardware and software improvements in photorefractive keratectomy (PRK) for the treatment of highly myopic eyes. METHODS: A retrospective study was carried out in 554 patients (582 eyes) with myopia between -7.00 and -17.00 D (mean -11.20 +/- 3.60 D) who had undergone PRK using the Aesculap Meditec laser. Group 1 with a 5-mm-diameter single ablation zone; Group 2 with a 5-mm-diameter single zone surrounded by a 2-mm tapered transitional zone; Group 3 and Group 4, same as Group 2 but with the laser upgraded with a smoke aspiration control system (Group 3), and with a computer-controlled fluence (Group 4). RESULTS: In Group 1 at 2 years after PRK (50 eyes), 10 eyes (20%) were within +/-1.00 D of attempted correction and 13 eyes (26%) were within +/-2.00 D. In Group 2 at 2 years (118 eyes), 42 eyes (36%) were within +/-1.00 D of attempted correction and 65 eyes (55%) were within +/-2.00 D. In Group 3 at 2 years (43 eyes), 18 eyes (42%) were within +/-1.00 D of attempted correction and 28 eyes (65%) were within +/-2.00 D. In Group 4 at 2 years (47 eyes), 25 eyes (53%) were within +/-1.00 D of attempted correction and 29 eyes (62%) were within +/-2.00 D. CONCLUSIONS: Software and hardware improvements facilitated PRK correction of high myopia with reasonable predictability, especially if a tapered transition zone was used. At 12 and 24-month follow-up, only the use of a tapered transition zone was associated with a statistically significant improvement in predictability.     

准分子激光角膜切削术治疗近视的并发症

为分析准分子激光角膜切削术（ＰＲＫ）治疗近视的并发症，对１３９例（２５７眼）ＰＲＫ术后随访半年至一年。结果表明：术后一年，低中度和高度组各有１眼最佳矫正视力丢失二行，分别占２．５％和３．３％；低中度和高度组的角膜上皮下１级混浊分别为１０．８１％和１５．１６％，２级混浊分别为２．７３％和０％；激素性高眼压，在发生率最高的３个月时，可分别达２４．３７％和２５．３２％，但这种反应性的眼压升高只是暂时的，容易控制；过矫和散光增加的发生率均较低，主要与术者的经验有关。随着术者经验的提高、手术设计的完善及术后用药的研究，这些并发症会降到最低水平。ＰＲＫ是安全、有效的。     

Endothelial cell density after photorefractive keratectomy for moderate myopia using a 213 nm solid-state laser system

PURPOSE: To evaluate whether photorefractive keratectomy (PRK) for moderate myopia using a solid-state laser with a wavelength of 213 nm alters the corneal endothelial cell density. SETTING: University refractive surgery center. METHODS: The corneal endothelium was analyzed preoperatively and 1, 6, and 12 months postoperatively using corneal confocal microscopy (modified HRT II with a Rostock Cornea Module, Heidelberg Engineering) in 60 eyes (30 patients). Patients were randomized to have myopic PRK using a 213 nm wavelength solid-state laser (study group) or a conventional 193 nm wavelength excimer laser (control group). Three endothelial images were acquired in each of 30 preoperative normal eyes to evaluate the repeatability of endothelial cell density measurements. Repeated-measures analysis of variance was used to compare the variations in endothelial cell density between the 2 lasers and the changes in endothelial cell density over time. RESULTS: There were no statistically significant differences in sex, age, corneal pachymetry, attempted correction, preoperative endothelial cell density, or postoperative refractive outcomes (uncorrected visual acuity, best spectacle-corrected visual acuity, and spherical equivalent refraction) between the 2 groups (P>.05). The coefficient of repeatability of endothelial cell density was 131 cells/mm(2). The measured endothelial cell count per 1.0 mm(2) did not significantly change up to 1 year postoperatively in either group (both P>.05). No statistically significant difference was found between the 2 groups in any postoperative interval (P>.05). CONCLUSION: Photorefractive keratectomy for moderate myopia using a 213 nm wavelength solid-state laser or a conventional 193 nm wavelength excimer laser did not significantly affect corneal endothelial density during the 1-year postoperative period.     

PRK与LASIK治疗高度近视的疗效比较

为比较准分子激光原位角膜磨镶术与准分子激光角膜切削术治疗高度近视的疗效，对２８８眼行ＰＲＫ手术及２９眼行ＬＡＳＩＫ手术，分别分为两组，观察１～１２月。结果：ＰＲＫ组术后一年裸视大于等于０５占７９４％，大于等于０８占６３２％，其中二组大于等于０５占５８３％，大于等于０８占３１６％。ＬＡＳＩＫ组术后一年裸视大于等于０５占６９２％，大于等于０８占５３１％，其中，二组大于等于０５占６６７％，大于等于０８占５０％。最佳矫正视力大于等于术前者ＰＲＫ组占９３７％，ＬＡＳＩＫ组占９２％。ＰＲＫ组角膜混浊一月时最重，一年时最轻。ＬＡＳＩＫ组无角膜混浊发生。实际矫正度在预计矫正度＋／－１Ｄ内者ＰＲＫ和ＬＡＳＩＫ分别占５２％和５１８％。结论：ＬＡＳＩＫ虽然由于微角膜切开刀的使用而较复杂，但对于大于－１００Ｄ的近视，是一种较ＰＲＫ好的手术方法。     

LASIK与PRK治疗高度近视的对比

为比较激光原位角膜磨镶术与准分子激光角膜切削治疗高度近视的临床效果。方法随机选择随访半且且资料完整的ＬＡＳＩＫ（１４３只眼）和ＰＲＫ（１２９只眼）两组治疗高度近 虱,并按屈光度分为Ａ、Ｂ、Ｃ３个组,对两种术式在不同度数,不同治疗时期的术后视力,屈光度,并发症等进行系统的的对比分析和统计学处理。结果Ｌ式和Ｐ式术后６个月的裸眼视力≥０．５者分别为９５．８％和７９．８％;裸眼视力≥１．０者为７４．１％和     

准分子激光角膜切削术治疗高度、超高度近视眼术后角膜上皮下混浊的远期观察

目的:探讨准分子激光角膜切削术(PRK)治疗高度、超高度近视眼术后角膜上皮下雾状混浊(Haze)的发生情况及影响因素。方法:应用日本NIDEKEC-5000型准分子激光仪治疗高度、超高度近视眼143例(245眼),I组:-6.25～-10.00D,167眼;Ⅱ组-10.25～-24.00D,78眼。观察术后不同时期Haze的发生情况,随访7a以上。结果:术后3mo,0.5,1,4,7a,Haze的发生率,I组分别为74.8%,44.3%,24.5%,11.9%,7.8%;Ⅱ组为80.7%,52.1%,33.3%,24.3%,19.2%。7a时I组屈光度-0.57±1.84D,Ⅱ组-5.02±4.26D。有3级Haze7眼,I组2眼,为RK术后者;Ⅱ组5眼,4眼为年龄>40岁者。≥3级Haze者多出现在Ⅱ组,3～6mo达到高峰,持续时间达1a以上。结论:Haze为高度、超高度近视眼PRK术后的主要并发症。预矫屈光度越高,切削越深,则混浊程度越重;部分患者Haze逐渐减轻,角膜组织创伤修复时间长,部分重度Haze日后可能成为永久性瘢痕。