准分子激光原位角膜磨镶术矫正近视的初步研究

目的探讨准分子激光原位角膜磨镶术（LASIK）治疗低、中、高度近视的疗效。方法应用波长193nm的ArF准分子激光对147例（289眼）屈光度在－1．00D～－20．00D的近视及近视散光行LASIK治疗。结果对289眼随访6－10月，92％术后探视达到或超过术前最好矫正视力，10％的裸视达2．0，89．6％的术后屈光度在±1．00D之间，欠矫25眼，欠矫率仅为8．7％，术中术后无严重并发症。结论LASIK手术矫正近视及近视散光优于PRK手术，是一种更加准确、有效和安全的屈光手术方法。     

表层切削的适应证和技术规范

准分子激光在角膜方面的应用主要涉及屈光矫正（矫正近视、远视、散光,并能补偿老视）。这类屈光性手术在表层切削中的术式包括屈光性角膜切除术（photorefractive keratectomy,PRK）、乙醇法准分子激光上皮瓣下角膜切削术（laser subepithelial keratectomy,LASEK）、机械法准分子激光角膜原位磨镶术（epipolis laser in situ keratomileusis,Epi—LASIK）等表层切削术及前弹层下角膜磨镶术（sub—Brownmn’s layer keratomileusis,SBK）或薄瓣LASIK。准分子激光切削也能清除前中基质的混浊,治疗部分基底膜异常,这类治疗性手术包括（photothera keratectomy,PTK）及治疗性基质透镜切除等。     

PRK治疗眼外伤后散光10例

目的观察PRK治疗眼外伤后散光的疗效方法用准分子激光屈光性角膜切削术(PRK)治疗眼外伤散光10例10眼，随访时间1年：结果术后视力均明显提高，散光度明显下降术中及术后无严重并发症发生：结论准分子激光屈光性角膜切削术治疗眼外伤后散光的预测忡好，疗效稳定，安全可靠。     

LASIK治疗复性近视散光疗效分析

目的：探讨准分子激光原位角膜磨镶术（laser in situkeratomileusis,LASIK)治疗复性近视散光的临床疗效。方法：按照术前散光度将复性近视散光220例316眼分为3组：A组，－0．50－－1．50DC,173眼；B组，－1．75－－2．50DC，89眼；C组，－2．75－－5．0DC，54眼。回顾性分析LASIK术后3－24月（平均6．7月）的裸眼视力、最佳矫正视力、残留散光度及并发症。结果：术后裸眼视力均较术前明显提高（P＜0．001），对近视与散光的矫正均有确切效果，术后矫正视力与术前最佳矫正视力一致，差异无显著性（P＞0．05）。术后散光残留度在3组中差异具有显著性（P＜0．05），而并发症发生率无明显增加。结论；LASIK治疗复性近视散光安全有效。     

治疗性准分子激光原位角膜磨镶术手术疗效分析

目的分析准分子激光原位角膜磨镶术（LASIK）治疗超高度近视、近视性屈光参差及混合性散光的临床疗效。方法2002年8月～2007年8月在我科接受LASIK治疗的非单纯近视患者532例（972眼），根据屈光状态不同分为3组：A组超高度近视336例（672眼）；B组近视性屈光参差107例（170眼）；C组混合性散光89例（130眼），并对其进行回顾性分析。结果术后第一天裸眼视力即有明显提高；术后1周达到或接近术前最佳矫正视力；术后3个月时视力趋向稳定，裸眼视力与预期矫正视力符合率A组为632眼（94．05％），B组为164眼（96．47％），C组为121眼（93．08％）。术后3个月时，实际矫正屈光度与预期矫正屈光度差值在0．75D左右范围内者，三组分别为94．2％、96．47％及91．54％，屈光回退者三组分别为16眼（2．53％）、6眼（3．66％）及4眼（3．36％）。结论LASIK在治疗超高度近视、近视性屈光参差及混合性散光中是安全、有效和可预测的。疗效的提高有赖于设备与方法的改进、手术技巧的熟练及经验的积累。     

准分子激光角膜屈光手术治疗近视及近视散光的疗效观察

目的评价准分子激光角膜屈光手术治疗近视的疗效。方法采用准分子激光角膜切削仪和自动报层角膜刀对332例628只眼近视及散光患者行PRK或Lasik手术，术前球镜屈光度-1．00～－23．00D（-6．12±4．05D），柱镜屈光度0～－5．00D，角膜屈光力43．35±1．31，术后随访一年。结果术后1年裸眼视力≥0．8占90．76％，实际矫正屈光度与预测矫正度绝对值差在±1．50D范围内达91％，术后半年角膜屈光力38．14±2．63。结论该手术具有安全、准确、可预测性强、矫正近视范围大等优点，低中度近视可选PRK手术，高度近视尤为-8．00D以上者，应选择Lasik手术，强调长期观察的重要性。     

Epi-LASIK-准分子激光角膜屈光手术发展的新方向

自80年代初Trokel等首先介绍准分子激光角膜切削术（photorefractive keratectomy，PRK）矫治近视以来，准分子激光角膜屈光手术在不长的时间内得到变革与突破，目前准分子激光原位角膜磨镶术（laser in—situ keratomileusis，LASIK）占据主流地位，但其它术式如准分子激光上皮瓣下角膜磨镶术（laser subepithelial keratomileusis，LASEK）、角膜微型刀上皮瓣下准分子激光原位角膜磨镶术（epipolis laser in—situ keratomileusis，Epi-LASIK）、全激光准分子激光原位角膜磨镶术（femotscend laser asisted laser in-situ keratomileusis，Intra-LASIK）等也得到快速发展，这意味着准分子激光屈光手术在不断的丰富、完善，同时也为医师和患者提供更多的选择。诸多的准分子激光角膜屈光手术中，可将之划分为两大类：即深部角膜屈光手术和表面角膜屈光手术，行准分子激光前制作了一个带有部分角膜基质的角膜瓣的手术属于前者；而不制瓣或仅制作上皮瓣的一类手术属于后者。     

LASEK与PRK矫正近视及近视散光的疗效比较

目的 比较LASEK与PRK手术矫正不同程度近视及近视散光的有效性、安全性及稳定性。方法 70名患者(140眼)，分为中低度近视组39人(78眼)、高度近视组31人(62眼)。患者一眼行LASEK手术，对侧眼行PRK手术，术后观察术眼疼痛情况、上皮愈合时问、角膜上皮下雾状混浊(haze)、术后裸眼视力6个月。结果LASEK与PRK术后上皮愈合时间及术眼疼痛指数无明显差异；中低度近视组两种手术后裸眼视力无显著差异；高度近视组裸眼视力及角膜haze程度差异显著。结论 LASEK矫正不同程度近视均能取得较好的临床效果，术后裸眼视力及视力稳定程度优于PRK，特别表现在高度近视组。     

准分子激光屈光性角膜切削术矫正散光的准确性及预测性

目的 探讨准分子激光屈光性角膜切削术（ｅｘｃｉｍｅｒ ｌａｓｅｒ ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅ ｋｅｒｅｃｔｏｍｙ,ＰＲＫ）矫正散光的准确性及预测性。方法 根据角膜地形图提供的角膜屈光力数值,用Ｈｏｌｌａｄａｙ法计算复性近视散光３０例（５３只眼）和单纯近视２３例（３３只眼）患者术前与术后６个月角膜屈光力的差值,确定实际矫正散光度及轴位,及预期矫正散光度及轴位进行对比分析。结果 复性近视散光组５３     

初学LASIK的并发症及其预防

准分子激光角膜切削术(PRK)治疗中低度近视以其安全可靠,预测性好,并发症少等优点得到广泛地认可。然而,PRK手术尚不能解决激光矫正高度近视的问题。激光角膜磨镶术(LASIK)弥补了这一不足。但LASIK手术技术难度大,要熟知仪器性能和操作,同时对术者和患者也有一定的要求,稍...     

Comparison of photorefractive keratectomy and laser in situ keratomileusis for the treatment of compound hyperopic astigmatism

PURPOSE: To compare photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for compound hyperopic astigmatism. SETTING: University laser center. METHODS: This prospective nonrandomized study evaluated 41 consecutive eyes (27 patients) that had PRK and 24 consecutive eyes (15 patients) that had LASIK to correct compound hyperopic astigmatism. RESULTS: The mean preoperative error was +3.06 diopters of sphere (DS) +/-1.73 (SD)/+1.31 +/- 0.60 diopters of cylinder (DC) in the PRK eyes and +2.86 +/-1.28 DS/+1.55 +/- 0.96 DC in the LASIK eyes. The mean maximal pain score in PRK eyes was 1.95 +/- 1.19 (range 0.0 to 3.0) in PRK eyes and 0.84 +/-1.12 in LASIK eyes (P=.0014). The uncorrected visual acuity was 20/20 or better in 7.7% of the PRK eyes and 58.3% of the LASIK eyes at 1 month (P<.001) and 57.9% and 66.7%, respectively, at 9 months (P=.586). The mean postoperative spherical error was -0.95 +/- 0.92 D in PRK eyes and +0.33 +/- 0.56 D in LASIK eyes at 1 month (P<.001) and +0.64 +/- 1.01 D and +0.44 +/- 0.57 D, respectively, at 9 months (P=.375). There was no statistically significant between-group difference in the mean residual astigmatic error. Mild peripheral haze (grade 0.5 to 1.0) occurred in 19.5% of PRK eyes and no LASIK eye. No eye in either group lost more than 2 lines of best spectacle-corrected visual acuity. CONCLUSIONS: Photorefractive keratectomy was more painful than LASIK and led to a slower visual recovery, a higher incidence of peripheral haze, and an initial myopic overcorrection, which self-corrected by 3 to 6 months. Efficacy and stability of the astigmatic correction were similar in both groups. Long-term stability of both procedures requires further study.     

近视眼全眼散光及角膜散光对LASIK术矫正近视散光的影响

目的:探讨全眼散光和角膜散光对LASIK手术矫正散光的影响。方法:回顾性分析84例162眼行LASIK手术矫正的近视散光患者,根据全眼散光与角膜散光轴向相差<15°,全眼散光度数<2倍角膜散光度数和全眼散光与角膜散光轴向相差≥15°,全眼散光度数≥2倍角膜散光度数分为A(112眼)、B(50眼)两组,分析术后视力、散光矫正效果。结果:患者中69%的全眼散光轴与角膜散光轴向相关,差异在15°以内,术后两组眼散光度数分别为-0.39±0.43,-0.73±0.21D,差异有统计学意义(P<0.05)。B组有4例患者主诉夜晚有眩光,近视力差、疲劳。结论:近视眼全眼散光与角膜散光有高度相关性。LASIK矫正散光术前应根据验光和角膜地形图结果分析,合理设计散光的切削量和轴位,选择个性化治疗方案。     

LASIK versus PRK for high astigmatism

Purpose

To compare the refractive outcomes of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for myopic astigmatism of 3 diopters (D) or more.

Study design

Retrospective matched comparative study.

Methods

This study include consecutive myopic patients (SE 0 to –10 D) undergoing LASIK or PRK between 2007 and 2016 with astigmatism of 3 to 6 D, and postoperative follow-up of at least 30 days for LASIK and 60 days for PRK, compared outcomes of LASIK and PRK eyes.

Results

The LASIK and PRK groups comprised 175 eyes of 175 patients each, with median follow-up of 39 and 139 days, respectively (P?<?0.001). Mean preoperative manifest astigmatism was –3.35?±?0.46 and –3.42?±?0.51 D (P?=?0.92), postoperative SE was –0.43?±?0.55 and –0.16?±?0.64 D (P?<?0.001), and arithmetic astigmatism was –0.59?±?0.46 and –0.88?±?0.60 D (P?<?0.001), for the LASIK and PRK groups, respectively. Fifty-seven and 64.0% eyes had postoperative SE within?±?0.5 D of emmetropia (P?=?0.19), and 57.7 and 38.8% eyes were within 0.5 D of attempted astigmatic correction (P?<?0.001) for the LASIK and PRK groups, respectively. More PRK eyes were overtreated regarding both SE and astigmatism than LASIK eyes (P?<?0.001). The efficacy and safety indices were close to 1.0 in both groups. The surgically induced astigmatism, magnitude of error, index of success, correction index and flattening index were all better in the LASIK group.

Conclusion

Both LASIK and PRK achieve good outcomes in high astigmatism. LASIK achieved mild superiority over PRK.

     

Comparison of ocular higher-order aberrations and visual performance between photorefractive keratectomy and laser in situ keratomileusis for myopia

The purpose was to compare the ocular higher-order aberrations and the visual performance between photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). Ocular aberrations and visual performance were measured after PRK in 26 eyes, after LASIK in 39 eyes, and in 29 normal myopic control eyes. Ocular aberrations were measured with a Hartmann-Shack aberrometer. Visual performance was evaluated with grating contrast sensitivity, high and low contrast visual acuity, and letter contrast sensitivity under full correction with spectacles. The results were that the root mean square (RMS) values of ocular higher-order aberrations after PRK or LASIK were significantly greater than that of normal controls for both 4-mm and 6-mm zones (PRK; 0.22 +/- 0.09 and 0.85 +/- 0.24 microm, LASIK; 0.20 +/- 0.06 and 0.82 +/- 0.24 microm, normal; 0.10 +/- 0.03 and 0.33 +/- 0.11 microm. P < 0.05 between PRK and normal, LASIK and normal, One Way ANOVA on Ranks). There were no significant differences between PRK and LASIK. The ocular higher-order aberrations increased in proportion with the attempted refractive correction by PRK and LASIK. The ocular higher-order aberrations correlated better with grating contrast sensitivity, low contrast visual acuity, and letter contrast sensitivity than with high contrast visual acuity. There was no difference among normal, PRK and LASIK in all the visual function tests, except between normal and PRK, or between normal and LASIK with letter contrast sensitivity. In conclusion, there was no difference in both ocular higher-order aberrations and visual performance between PRK and LASIK. The result suggests that surgeons can choose refractive procedures according to the corneal conditions or daily activities of patients.     

Comparison of laser in situ keratomileusis and photorefractive keratectomy results: long-term follow-up

PURPOSE: To compare the results of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) over a 4-year follow-up. SETTING: Miyata Eye Hospital, Miyazaki, Japan. METHODS: This comparative retrospective study comprised 22 eyes (22 patients) that had PRK and 18 eyes (18 patients) that had LASIK. To be included, the patient had to have completed a 4-year follow-up. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), percentage of eyes within +/-0.5 diopter (D) of the targeted refraction, central corneal thickness, and the anterior and posterior corneal elevations were compared between the PRK and LASIK groups. RESULTS: The mean UCVA was significantly better in the LASIK group than in the PRK group at 6 months (P = .0043) and 1 year (P = .0044). At 2 years, there was no significant difference in the mean UCVA between the 2 groups. The mean BSCVA was significantly better in the LASIK group than in the PRK group at 6 months (P<.0001), 1 year (P<.0001), and 2 years (P = .0083). At 3 and 4 years, there was no significant difference in the mean BSCVA between the 2 groups. The percentage of eyes within +/-0.5 D of the targeted refraction was not significantly different between groups at any time. CONCLUSIONS: The superiority of LASIK over PRK in short-term efficacy was not retained 4 years after surgery. The main reasons were a myopic shift and a decline in UCVA at the last follow-up in the LASIK group.     

Photorefractive keratectomy for residual myopia after cataract surgery

PURPOSE: To evaluate the effectiveness, predictability, and safety of photorefractive keratectomy (PRK) for correcting residual myopia and myopic astigmatism after cataract surgery with intraocular lens implantation. SETTING: Refractive Surgery and Cornea Unit, Instituto Oftalmológico de Alicante, Alicante, Spain. METHODS: Thirty consecutive eyes (30 patients) had PRK for residual myopia after cataract surgery. Surface PRK with a VISX Twenty-Twenty excimer laser was used in all patients. Follow-up was 1 year. RESULTS: Before PRK, no eye had an uncorrected visual acuity (UCVA) of 20/40 or better. Twelve months after PRK, 16 eyes (53.33%) had a UCVA of 20/40 or better. After PRK, best corrected visual acuity (BCVA) improved 1 line or more in 14 eyes (46.66%) over the preoperative values, and 15 eyes (50.00%) had the same BCVA as before PRK. Mean pre-PRK refraction of -5.00 diopters (D) +/- 2.50 (SD) decreased significantly to -0.25 +/- 0.50 D at 12 months (P < .001). At 12 months, the spherical equivalent was within +/- 1.00 D of emmetropia in 27 eyes (90.00%). No vision-threatening complications occurred. CONCLUSION: Photorefractive keratectomy was an effective, predictable, and safe procedure for correcting residual myopia and myopic astigmatism after cataract surgery.     

Recovery of uncorrected visual acuity after laser in situ keratomileusis or photorefractive keratectomy for low myopia

PURPOSE: To compare uncorrected visual acuity and refractive error in patients undergoing photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) between 1 week and 6 months after surgery. METHODS: All eyes underwent PRK or LASIK with the VisX StarS2 excimer laser. We retrospectively analyzed data from 77 random eyes of 77 patients in the PRK group and 76 eyes of 76 patients in the LASIK group. All eyes had a low myopic refractive error (spherical equivalent range, -0.88 diopters (D) to -5.13 D; mean PRK. -2.8 +/- 0.20 D: LASIK, -2.5 +/- 0.22 D). Uncorrected visual acuity and manifest refractive error were evaluated 1 week, 1 month, and 6 months after surgery. RESULTS: Each eye undergoing PRK was paired with an eye undergoing LASIK for a similar level of spherical equivalent. Mean uncorrected visual acuity after 1 week was 0.85 +/- 0.06 (20/25, logMAR 0.12 +/- 0.04) for the PRK group and 1.01 +/- 0.06 (20/20, logMAR 0.01 +/- 0.03) for the LASIK group (p < 0.001). Mean spherical equivalent after 1 week was 0.23 +/- 0.12 D for the PRK group and -0.02 +/- 0.07 D for the LASIK group (p = 0.02). Mean uncorrected visual acuity after 1 month was 1.03 +/- 0.05 (20/20, logMAR 0.02 +/- 0.03) for the PRK group and 1.05 +/- 0.05 (20/20. -0.02 +/- 0.03) for the LASIK group (p = 0.16). Mean spherical equivalent after I month was 0.19 +/- 0.10 D for the PRK group and -0.02 +/- 0.09 D for the LASIK group. This difference was statistically significant (p = 0.02), but was unlikely to be clinically significant. Mean uncorrected visual acuity after 6 months was 1.05 +/- 0.06 (20/20, logMAR -0.01 +/- 0.03) for the PRK group and 1.06 +/- 0.05 (20/20, logMAR -0.14 +/- 0.03) for the LASIK group (p = 0.41). Mean spherical equivalent after 6 months was 0.02 +/- 0.08 D for the PRK group and 0.00 +/- 0.08 D for the LASIK group (p = 0.35). CONCLUSION: Uncorrected visual acuity 1 week after surgery is significantly better in eyes undergoing LASIK than in eyes undergoing PRK. Both procedures provide functional vision by 1 week after surgery. The difference does not relate to refractive error, which was similar between the two groups, but to differences in healing of the epithelium. By 1 month after surgery, there is no difference in mean uncorrected visual acuity between eyes that undergo PRK or LASIK for low myopia.     

Keratectasia after LASIK but not after PRK in one patient

PURPOSE: To report a case of keratectasia in a patient who underwent LASIK in the right eye and photorefractive keratectomy (PRK) in the left eye for correction of compound myopic astigmatism. METHODS: A 30-year-old man underwent LASIK in the right eye and PRK in left eye for refraction of -1.75 -1.50 x 48 degrees and -1.00 -1.75 x 100 degrees, respectively. Preoperative corneal thickness was 447 microm in the right eye and 446 microm in the left eye. RESULTS: Postoperative corneal thickness decreased to 341 microm and 384 microm in the right and left eye, respectively. Uncorrected visual acuity in the left eye was 20/20, but the right eye developed keratectasia, which led to severe visual loss (20/400). CONCLUSIONS: Photorefractive keratectomy may be better than LASIK for ablative refractive surgery for low myopic astigmatism in eyes with low central corneal thickness.     

The safety and efficacy of photorefractive keratectomy after laser in situ keratomileusis

PURPOSE: To determine the safety and efficacy of performing photorefractive keratectomy (PRK) in corneas previously treated with laser in situ keratomileusis (LASIK) surgery. METHODS: Fifteen eyes of 14 patients who had initially received LASIK for the treatment of myopia and compound myopic astigmatism were evaluated. Variables included existence of and/or type of flap complication associated with the original LASIK procedure, refractions before and after (3 and 6 months) PRK, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and the development of complications after PRK such as haze, scarring, double vision, or ghosting. RESULTS: All 15 eyes were available for analysis at 6 months. Eleven eyes had experienced flap complications during the initial LASIK procedure and 4 eyes had experienced complications in the LASIK postoperative period. Characteristics prior to performing PRK included 11 myopic and 4 hyperopic eyes. By 6 months after PRK treatment, 87% of eyes had UCVA > or = 20/40, 53% had > or = 20/25, and 40% had > or = 20/20. All eyes had BSCVA of > or = 20/30, with 73% being > or = 20/20. No eye had lost 2 lines of BSCVA and only 1 eye lost 1 line of BSCVA. Sixty percent of eyes were within 1.0 diopters (D) of emmetropia, and 40% were within 0.5 D of emmetropia. A trend towards undercorrection and surgical induction of astigmatism as confirmed by vector analysis was noted. No eye developed significant haze or scarring. CONCLUSIONS: Photorefractive keratectomy may be a safe procedure to perform in corneas previously treated with LASIK surgery. Results show good reduction of refractive error and improvement of UCVA and BSCVA. A significant undercorrection of astigmatism was attributed to surgically induced astigmatism. Further studies are necessary to determine the long-term safety and stability of outcomes.     

Surgically induced astigmatism after photorefractive keratectomy and laser in situ keratomileusis. Summit PRK-LASIK Study Group

PURPOSE: To compare the axis and magnitude of surgically induced astigmatism in photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). SETTING: Multicenter clinical trial. METHODS: In this prospective randomized trial, 220 eyes of 220 patients entered the study cohort: 105 randomized to PRK and 115 to LASIK. All patients received a single-pass, multizone excimer laser ablation as part of a PRK or LASIK procedure. Attempted corrections ranged from -6.00 to -15.00 diopters (D). The LASIK procedures were performed with nasal hinges. Absolute changes in astigmatism and axis and magnitude of surgically induced astigmatism were analyzed. Patients were followed for up to 6 month. RESULTS: In the PRK group, the mean change in absolute astigmatism was +0.14, +0.16 and +0.32 D at 1, 3, and 6 months, respectively; in the LASIK group, the mean change was -0.15, -0.08, and -0.03 D, respectively. At all time points, a greater proportion of PRK than LASIK eyes had an increase in absolute magnitude of astigmatism. In the PRK group, the axis of vectoral-induced astigmatism was significantly different from random at 3 and 6 months (P = .01, P < .001), respectively) with a tendency for induced with-the-rule shifts postoperatively. In the LASIK group, the axis of vectoral-induced astigmatism was significantly different from random at only 1 month (P = .04), and there was no preponderant direction of axis shift. Despite these findings, other analyses showed no statistically significant between-group differences in vectoral axis or magnitude of surgically induced astigmatism. CONCLUSIONS: Induced astigmatism was generally less and more random in axis in LASIK than in PRK; a general trend for induced with-the-rule astigmatism in PRK was not seen in LASIK. Hypothetically, the lamellar corneal flap in LASIK may counteract the tendency toward steepening at 90 degrees seen in PRK by retracting toward the hinge, by masking underlying induced astigmatism in the ablation zone, or by its mitigating influence on postoperative corneal healing.