准分子激光角膜切削术后的屈光回退

目的通过准分子激光角膜切削术（ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅｋｅｒａｔｅｃｔｏｍｙ,ＰＲＫ）术后屈光回退的分析,以期探讨可能影响回退的因素。方法经ＰＲＫ手术治疗近视于术后发生回退（≥－１．００Ｄ）１０３只眼,术前屈光度－４．００～－１４．５０Ｄ（－８．７５±２．６５Ｄ）。分为二组进行比较,Ⅰ组为中度近视（－４．００～－７．９０Ｄ）,Ⅱ组为高度近视（≥－８．００Ｄ）。结果中度近视回退率１．１７％,高度近视回退率６．９３％（Ｐ＜０．００１）。高年龄组回退率较低年龄组高（Ｐ＜０．０１）。较严重的角膜上皮下雾状混浊（ｈａｚｅ）多与回退伴行。因激素性高眼压减少或停止局部糖皮质激素的应用可导致回退,屈光的稳定性与性别无关,回退常伴Ｋ值增大。结论回退与预期矫正度、年龄以及ｈａｚｅ有明显相关     

准分子激光二次切削治疗近视性角膜切削术后欠矫

目的探讨准分子激光二次切削对近视性角膜切削术欠矫的疗效。方法对23例（30眼）准分子激光角膜切削术后欠矫而采用光学性角膜切削术，术前平均屈光度为－8．888D（－3．5—－15．5D），其中4眼为中度近视（－3．25～－6．00D），8眼为高度近视（－6．25～－9．00D），18眼为超高度近视（≥－9．25D）。结果术后平均随访13．4月表明，70％的裸眼视力≥1．0。0．5≤9眼（30％）的裸眼视力＜1．0，平均屈光度－0．333±0．603D。角膜混浊与一次术后相近。结论　准分子激光二次切削治疗近视性角膜切削术后欠矫有效。     

准分子激光术后近视回退和欠矫原因分析

目的：探讨准分子激光近视治疗术后屈光回退和欠矫的原因,为临床提供理论依据。方法：将我院近视中心准分子激光术后发生屈光回退并行二次手术的45例70眼,按〈-6．00D为Ⅰ组,〉-6．00D度为Ⅱ组,将两组患者两次治疗前后屈光度、术后不同时间的视力、术式、切削光斑直径、角膜切削量及残留厚度等相关资料进行了对比分析。结果：两组未手术时屈光度差别显著（P〈0．05）。屈光回退后两组屈光度差别无意义（P〉0．05）。Ⅰ,Ⅱ两组首次激光术后6mo内,不同时间点裸眼视力与术前矫正视力有明显差别（P〈0．05）。二次手术后,1wk内裸眼视力与矫正视力差别明显（P〈0．05）,1～3mo无差别（P〉0．05）;Ⅰ组于6mo时裸眼视力与矫正视力出现差别（P〈0．05）,Ⅱ组差别不显著（P〉0．05）;两组激光切削光斑的直径及角膜切削量有明显差别（P〈0．05）。结论：准分子激光近视治疗术后,屈光度回退程度与术前屈光状态无关。不同屈光度屈光回退程度相同。高度近视、LASIK多区切削和切削光斑直径小是发生屈光回退和欠矫的主要原因。     

准分子激光屈光性角膜切削术治疗近视的临床分析

目的：评价准分子激光屈光性角膜切削术（PRK）治疗不同程度近视的疗效。方法：应用SchwindKeratomF准分子激光机对1995眼不同程度近视（－0．75～15．50D）行PRK治疗。按屈光度分三组：组Ⅰ≤－6．00D,873眼;组Ⅱ－6.25D—－10．00D,774眼;组Ⅲ＞－10．00D,348眼。术后12个月,对三组术后的视力、屈光度及Haze进行随访比较。结果：术后12个月Ⅰ、Ⅱ、Ⅲ组裸眼视力≥0．5者分别为986%,94．2％和60.04％;≥1.0者分别为85．5％,71.3％和25.9％;屈光度在±1．00D以内分别为90．5％,68．8％和29．3％。角膜雾状混浊（Haze）≥2级者分别为0.8％,11．5％和13．7％。结论：PRK治疗中低度近视疗效较好,对高度和超高度近视由于术后Haze和屈光度回退发生率增高,疗效受到明显影响,有待进一步完善手术方法和术后用药等问题。     

Epi—LASIK术后泪膜和眼表变化对haze及屈光回退的影响

目的 观察机械法准分子激光上皮瓣下角膜磨镶术（Epi-LASIK）后泪膜和眼表的变化,探讨其与haze及屈光回退的关系.方法 低中度近视214眼和高度近视154眼行Epi-LASIK手术,分别于术前和术后行泪膜破裂时间（BUT）、泪液分泌量（Schirmer Ⅰ试验）和角膜荧光素染色检查,并观察术后haze和屈光回退情况,对相关数据进行t检验和相关统计分析.结果 术后1个月87跟（23.6%）出现0.5级或1级haze,术后3个月69眼（18.8%）,术后6个月48眼（13.0%）.术后6个月37眼（10.1%）出现屈光回退.出现haze和屈光回退的病例均属于高度近视组.低中度近视组和高度近视组术后BUT值均有不同程度减小.术后1、3、6个月,高度近视组的BUT下降程度较低中度近视组明显,差异有统计学意义（t=6.82、7.51、6.73,P均＜0.05）.低中度近视组和高度近视组泪液分泌量术后与术前相比差异均无统计学意义,术后两组之间泪液分泌量差异亦无统计学意义.术后1、3、6个月,高度近视组角膜荧光素染色点的数量明显多于低中度近视组（t=5.48、5.23、7.67,P均＜0.05）.术后1、3、6个月,高度近视组中haze的发生与BUT下降幅度和角膜荧光素染色点的数量呈正相关（r=0.892、0.881,P均＜0.05）.术后6个月,高度近视组屈光回退眼的BUT值下降幅度较无屈光回退眼更明显,差异有统计学意义（t=5.50,P＜0.05）;屈光回退眼角膜荧光素染色点的数量明显多于无屈光回退眼（t=5.27,P＜0.05）.结论 Epi-LASIK术后泪膜和眼表变化与haze及屈光回退密切相关.     

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。     

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     

PRK后角膜混浊与屈光回退分析

为探讨准分子激光屈光性角膜切削术（ＰＲＫ）后,角膜上皮下雾状混浊（ｈａｚｅ）和屈光回退的相关因素,对３５６例（６２５眼）近视施ＰＲＫ随访１２个月后,按术前等值球镜屈光度分为Ａ组（≤—３．００Ｄ）,Ｂ组（－３．２５～－６．００Ｄ）,Ｃ组（－６．２５～１０．００Ｄ）和Ｄ组（＞－１０．００Ｄ）。观察各组术后视力恢复,角膜ｈａｚｅ和屈光回退情况。结果：术后裸眼视力在１．０以上的Ａ、Ｂ、Ｃ、Ｄ各组分别是８３．３３％、７４．３１％、４９．６２％和１３．７５％（Ｐ＜０．００１）;在０．８以上的各组是９５．０８％、９３．１２％、７７．０６％和３１．２５％（Ｐ＜０．００１）。屈光回退在－１．００Ｄ以上的分别是３．２８％、５．９６％、２２．９３％和４９．７５％（Ｐ＜０．００１）。角膜ｈａｚｅ在２级以上的仅在Ｃ组和Ｄ组中出现,分别为１０．５２％和１７．５０％（Ｐ＜０．００１）。结论：术后视力提高,角膜ｈａｚｅ和屈光回退与术前屈光度有关。ＰＲＫ治疗低中度近视,术后并发症轻、预测性和稳定性好,而用于治疗高度近视则应慎重。     

准分子激光原位角膜磨镶术后屈光回退与术中角膜床厚度的关系

目的　探讨准分子激光原位角膜磨镶术（ｅｘｃｉｍｅｒ ｌａｓｅｒ ｉｎｓｉｔｕ ｋｅｒａｔｏｍｉｌｅｕｓｉｓ ＬＡＳＩＫ） 矫治高度近视后屈光回退与术中角膜床厚度的关系。方法　对４７６ 例９３８ 只眼在我院接受Ｌａｓｉｋ 治疗的患者中,发生屈光回退的病例９６ 例,１８９ 只眼与未发生屈光回退的病例３８０ 例７４９ 只眼术中角膜床厚度及术前、术后１ ｗ ｋ 、１ 、３ 、６ ｍ ｏ 屈光状态的资料进行对比分析。结果　有屈光回退眼组比无屈光回退眼组平均角膜床厚度小;屈光回退眼组屈光回退程度（ 术后６ ｍｏ 时） 与角膜床厚度呈负相关系,上述结果经统计学检验均有显著性差异（ Ｐ ＜ ００１） ;有屈光回退眼组术后早期（１ ｗｋ） 屈光状态略成过矫,但其后屈光回退程度在０ ．５ａ 内呈加重趋势。结论　高度近视准分子激光原位角膜磨镶术中的角膜床厚度是影响术后屈光稳定性的重要因素     

PRK后视力回退与屈光度的关系

为研究不同屈光度患者准分子激光角膜切削术（ＰＲＫ）后的视力稳定性，对３６１例６１５眼行ＰＲＫ手术并随访６～１８个月，对术后视力回退情况分组统计分析。结果：近视回退率中低度近视组为３．２％，高度近视组为１４．４％，超高度近视组为５６．９％。结论：等值球镜－７．００Ｄ以下的近视患者视力稳定性较好，ＰＲＫ手术应该严格控制手术适应证来减少手术风险     

影响准分子激光屈光性角膜切削术疗效的多因素分析

目的:观察准分子激光屈光性角膜切削术(PRK)治疗近视、散光的疗效,探讨影响疗效的相关因素。方法:采用VISX20/2O型准分子激光仪对306例(529眼)近视、散光患者进行PRK手术。术前等值球镜屈光度为-1.00～16.00D(-6.55±3.19D),分为两组:Ⅰ组:-1.00～6.00D,294眼;Ⅱ组:-6.25～16.00D,235眼。随访3～12个月。结果:术后12个月,裸眼视力≥0.5、1.0者在Ⅰ组分别为97.5％、77.5％,在Ⅱ组分别为80.3％、32.8％;实际矫正度在预测矫正度±1.00D内者在Ⅰ、Ⅱ组分别为92.5％、42.6％。影响术后屈光度变化的因素:术后角度上皮下雾状混浊(Haze)程度、去上皮的方法、眼压、术前中央角膜厚度。结论:PRK治疗-6.00D以内的近视是一种安全、稳定、预测性强、有效的方法。术前应根据屈光度、年龄、角膜厚度、眼压、设计手术方案,术中强调采用激光去除上皮。眼科学报1997;13:75～78     

Repeated photorefractive keratectomy for undercorrection and regression

PURPOSE: Regression (often combined with significant haze) and undercorrection are the most frequent complications after photorefractive keratectomy (PRK) for myopia. PRK retreatment has been used to treat both of these complications. METHODS: Sixty-three eyes (55 patients) were reoperated (PRK) because of initial regression or undercorrection. The mean interval between the operations was 17.2 months (range 5 to 37 mo). Residual myopia before retreatment was less than -5.00 D in 62 eyes (mean -2.21 +/- 0.99 D) and was -10.50 D in one eye. The same surgical PRK technique (Aesculap-Meditec MEL 60 excimer laser with 5 or 6-mm ablation zone) was used in both operations. RESULTS: One-year results were available for 51 eyes. In the group of eyes with low residual myopia (<-5.00 D), mean refraction 1 year after retreatment was -0.42 +/- 0.96 D and 43 eyes (86%) were within +/-1.00 D of emmetropia. Uncorrected visual acuity of 20/40 or better was achieved in 43 eyes (86%) after 1 year. One eye lost two lines of best spectacle-corrected visual acuity after two procedures because of haze. Mean haze was the same before and 12 months after reoperation (grade 0.39 vs. 0.38). Significant haze (>2) and high regression after the first PRK occurred after reoperation. The one eye with -10.50 D residual myopia after the first PRK showed high regression, and 1 year after the reoperation refraction was -9.50 D with grade 2 haze. CONCLUSIONS: Repeated PRK was safe and in most cases effective in treating regression and undercorrection in eyes with low residual myopia after initial PRK. High regression and especially haze after the initial PRK often reappeared after reoperation.     

Cooling effect on excimer laser photorefractive keratectomy.

PURPOSE: To evaluate the effect of cooling on pain, corneal haze, and refractive outcome after excimer laser photorefractive keratectomy (PRK). SETTING: Tokyo Medical and Dental University Hospital, Tokyo, Japan. METHODS: The corneal surface was cooled before, during, and after laser ablation using a method called cooling PRK. Thirty-eighty highly myopic eyes of 38 patients whose spherical errors ranged from -8.00 to -18.75 diopters (D) were randomized into 2 groups: 16 eyes with conventional PRK and 22 eyes with cooling PRK. Postoperative pain was measured using the Visual Analogue Scale (VAS). Refraction, visual acuity, and complications were followed for up to 2 years. All data were analyzed and compared between groups to evaluate the cooling effect on PRK. RESULTS: One day postoperatively, patients in the cooling PRK group had significantly less pain (P < .01). At 3 months, the haze score in the cooling PRK group was significantly less than in the conventional PRK group (P < .01). The residual refractive error was not significantly different between the 2 groups until 2 years, when it was greater in the conventional PRK (mean -5.09 D +/- 2.11 [SD]) than the cooling PRK group (-4.64 +/- 2.27 D). Ten eyes (62.5%) in the conventional PRK group and 15 eyes (68.2%) in the cooling PRK group were within +/- 1.00 D of the intended refraction. There were no serious complications in the cooling PRK group. Two eyes in the conventional PRK group had severe corneal haze and lost 2 Snellen lines of best corrected visual acuity. CONCLUSION: Corneal cooling on PRK effectively reduced postoperative pain, corneal haze, and myopic regression.     

Late-onset corneal haze and myopic regression after photorefractive keratectomy (PRK)

OBJECTIVE: To report the incidence and clinical course of a series of patients who developed both delayed-onset, clinically significant progressive haze and myopic regression after photorefractive keratectomy (PRK). METHODS: In this retrospective case series, the charts of 542 consecutive patients who had undergone PRK with the VISX Star Excimer or Nidek EC-5000 laser between July 1996 and October 1998 and who had a minimum of 6 months of follow-up were reviewed. Ten eyes of 8 patients developed progressive haze to greater than 1+ and myopic regression equal to or more than -1 D 3 months or more after PRK. The historical and clinical features were reviewed. RESULTS: The incidence of combined progressive haze and myopic regression was 1.8%. The average age was 40.5 years. Three of the 8 patients were female. The median spherical equivalent (SE) attempted correction was -6.69 D (range -4.00 to -12.25 D). Five patients who underwent bilateral PRK had unilateral involvement. The mean SE regression was -2.01 +/- 0.79 D (range -1.00 to -3.00 D). Regression plateaued at a mean of 9.8 months. Haze ranging up to 4+ peaked at a mean of 7.4 months. Topical steroid treatment and/or epithelial scraping was attempted in 3 eyes but was ineffective. CONCLUSIONS: Combined delayed-onset progressive haze and myopic regression can occur after PRK. In such cases, the amount of haze appears to correlate with the magnitude of attempted initial correction (r = 0.639, P = 0.046) although not with the magnitude of subsequent regression. Patients may need at least 10 months of follow-up to achieve a stable refraction and level of haze. These observations suggest a need for improved understanding of corneal wound healing following PRK and of biologic factors that may contribute to variability in outcomes.     

Eight-year follow-up of photorefractive keratectomy for myopia

PURPOSE: We evaluated 8-year results of excimer laser photorefractive keratectomy (PRK) for myopia in terms of stability and late complications. METHODS: Ninety-two myopic eyes of 55 patients were treated with a single-step method using an Aesculap-Meditec MEL 60 excimer laser with a 5.0-mm ablation zone. Treated eyes were divided into three groups according to preoperative refraction: low myopes (< or = -6.00 D), medium myopes (-6.10 to -10.00 D), and high myopes (>-10.00 D). RESULTS: Change in myopic regression stabilized in all myopia groups within 12 months, although a small myopic shift occurred up to 8 years after PRK. Mean change in refraction between 2 and 8 years was -0.42 +/- 0.48 D for low myopes, -0.37 +/- 0.34 D for medium myopes, and -0.41 +/- 0.50 D for high myopes. The percentage of eyes within +/- 1.00 D of emmetropia 8 years after PRK was 78.3% in the low myopia group, 68.8% in the medium myopia group, and 57.1% in the high myopia group. One eye lost 2 lines of best spectacle-corrected visual acuity due to irregular astigmatism. In 13.0% of eyes, a residual trace corneal haze was observed, which had no effect on visual acuity. Apart from the loss of 2 lines of BSCVA in one eye, there were no other late complications during the study period. CONCLUSIONS: The mean change in refraction between 2 and 8 years was less than -0.50 D, regardless of preoperative refraction, and may be attributed to natural age-related refractive change. The appearance of residual corneal haze after 8 years correlated with the amount of myopic correction. PRK was a safe and stable surgical procedure in this group of patients.     

Scraping and mitomycin C to treat haze and regression after photorefractive keratectomy for myopia

PURPOSE: To evaluate the efficacy, safety, and predictability of therapeutic scraping and application of a diluted 0.02% mitomycin C solution to treat haze and regression after photorefractive keratectomy (PRK) for myopia. METHODS: We performed a non-comparative, non-randomized retrospective study of 35 eyes of 30 patients who had previously undergone PRK for myopia and developed haze and regression after treatment. The range of refractive error after regression was -0.75 to -5.50 D (mean -2.92 D). Haze, ranging from grade 3 to 4 (scale: 0 to 4) caused a best spectacle-corrected visual acuity loss of 1 to 6 Snellen lines. All eyes were treated 6 to 12 months after PRK by scraping the stromal surface and application of a 0.02% mitomycin C solution for 2 minutes using a soaked merocel sponge. No laser ablation was performed. Corneal transparency, refractive error, and visual outcomes were evaluated over a 12-month follow-up period. RESULTS: All eyes had significant improvement in corneal transparency. Thirty-one eyes had haze grades lower than 1, which were maintained over time. Only four eyes showed haze grades 1 to 2 and two of them needed further treatment using the same technique. At 12 months after treatment, all eyes were within +/-1.50 of original intended correction (mean 0.04 +/- 0.63 D). BSCVA improved in all eyes. No toxic effects were observed during re-epithelialization or during follow-up. CONCLUSION: Single application of diluted mitomycin C 0.02% solution following scraping of the corneal surface was effective and safe in treating haze and regression after PRK.     

Corneal haze among blue eyes and brown eyes after photorefractive keratectomy

BACKGROUND: To compare the incidence and severity of corneal haze after photorefractive keratectomy (PRK) among white patients with blue eyes and Saudi patients with brown eyes. DESIGN: Retrospective, nonrandomized, comparative trial. PARTICIPANTS: A total of 150 patients (71 females and 79 males) were included in this study. Two hundred sixty-six eyes of 150 patients were subjected to PRK. One hundred blue eyes of 50 white patients and 166 brown eyes of 100 Saudi patients were included in this study. METHODS: Two hundred sixty-six eyes of 150 patients were subjected to PRK with the Chiron Technolas Keracor 117C for the correction of myopia and astigmatism. MAIN OUTCOME MEASURES: All patients had complete ophthalmologic examinations, visual acuity testing, intraocular pressure, pachymetry, corneal haze assessment (0-4+), and computerized corneal topography. RESULTS: There were 266 eyes of 150 patients with 100 blue irides and 166 brown irides. The spherical equivalent was -0.50 diopter (D) to -8.75 D. The mean postoperative spherical equivalent at 6 months was -0.063 D (standard deviation [SD], +/-0.595) in blue eyes compared to -0.28 D (SD, +/-0.683) in brown eyes (P = 0.006). Ninety-five (95%) of 100 of the blue eyes achieved +/- 1 D of attempted correction compared to 148 (89.2%) of the 166 brown eyes. All patients with blue eyes had a visual acuity of 20/30 or better compared to 153 (92.2%) of the 166 brown eyes (P = 0.009). Forty-eight (18.04%) eyes had minimal to mild haze, 3 (1.12%) eyes had moderate haze, and 2 (0.75%) eyes had severe haze. The incidence of corneal haze among brown eyes was 48 (28.9%) of 166 eyes compared to 5 (5%) of 100 in blue eyes (P < 0.001). The difference remained significant after adjustment for age and gender with a P value of 0.0283. The relative risk for developing haze in brown eyes was found to be 7.72. CONCLUSION: The incidence of corneal haze after PRK was significantly higher among Saudi patients with brown irides than among white patients with blue irides. This suggests that racial factors may play a role in the development of corneal haze.     

Photorefractive keratectomy in children

PURPOSE: To evaluate photorefractive keratectomy (PRK) in pediatric patients who fail traditional methods of treatment for myopic anisometropic amblyopia and high myopia. SETTING: Nonhospital surgical facility with follow-up in a hospital clinic setting. METHODS: Photorefractive keratectomy was performed in 40 eyes of 27 patients. The patients were divided into 4 groups based on the type of myopia: myopic anisometropic amblyopia (15 eyes/13 patients), bilateral high myopia (20 eyes/10 patients), high myopia post-penetrating keratoplasty (3 eyes/2 patients), and combined corneal scarring and anisometropic amblyopia (2 eyes/2 patients). All procedures were performed under general anesthesia using the VISX 20/20 B laser and a multizone, multipass ablation technique. Appropriate corneal fixation was achieved with appropriate head positioning (turn and tilt) and an Arrowsmith fixation ring. Myopia was as high as -25.00 diopter (D) spherical equivalent (SE), but no treatment was for more than -17.50 D SE. RESULTS: The mean SE decreased from -10.68 D to -1.37 D at 1 year, a mean change of -9.31 D. At 1 year, the mean best corrected visual acuity improved from 20/70 to 20/40 in the entire group. Forty percent of eyes were within +/-1.0 D of the targeted refraction. There was no haze in 59.5% of eyes. Three eyes initially had 3+ haze; 1 improved to 2+ and 2 required repeat PRK with significant haze reduction. Five eyes (3 patients) with greater than -17.00 D SE myopia before PRK (range -17.50 to -25.00 D) had 3.42 D more effect than predicted (range 0.50 to 5.50 D). A functional vision survey demonstrated a positive effect on the children's ability to function in their environments after the laser treatment. CONCLUSION: Photorefractive keratectomy in children represents another method of providing long-term resolution of bilateral high myopia and myopic anisometropic amblyopia.