准分子激光角膜切削深度与术后角膜上皮下雾状混浊的关系

目的研究准分子激光角膜切削术（ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅｋｅｒａｔｅｃｔｏｍｙ，ＰＲＫ）后角膜上皮下雾状混浊（ｈａｚｅ）与角膜切削深度之间的关系。方法选择治疗条件基本相同，对双眼同时接受ＰＲＫ治疗的３１例（６２只眼）近视性屈光参差（平均４．９７Ｄ）患者进行前瞻性自身对照研究，将高近视度数眼（－１４．１０±４．１７Ｄ）作为治疗组，低近视度数眼（－９．１３±３．５３Ｄ）作为对照组，术后随访６～１２个月，平均１０个月。结果术后两组的角膜上皮下雾状混浊程度经统计学分析差异有显著性（Ｐ＜０．０５）。结论准分子激光角膜切削术治疗近视，矫正度数越高，角膜切削越深，术后发生角膜上皮下雾状混浊的危险性则越大。     

准分子激光二次切削治疗近视性角膜切削术后欠矫

本研究共１５人（２３眼）于准分子激光角膜切削术后因欠矫而实施二次切削。术前平均屈光度为－９．８６Ｄ（－５．００—－２０．００Ｄ），其中２眼为中度近视（－３．２５—－６．００Ｄ），６眼为高度近视（－６．２５—－９．００Ｄ），１５眼为超高度近视（≥－９．２５Ｄ）。准分子激光二次切削采用治疗性角膜切削术（ＰＴＫ）和光学性角膜切削术（ＰＲＫ）相结合的方法。术后６个月随访结果表明：９１％的裸眼视力≥０．５，７０％的裸眼视力≥１．０，７０％的屈光度在±１．００Ｄ，角膜无明显混浊。由此证明：准分子激光二次切削治疗近视性角膜切削术后欠矫及角膜混浊是有效的。     

准分子激光屈光性角膜切削术后屈光回退的多因素分析

目的：探讨准分子激光屈光性角膜切削术后屈光回退的主要因素。方法：采用VISX20／20型准分子激光仪对121例214眼近视患者行准分子激光角膜切削术,术后随访2年。分二组进行比较,Ⅰ组为低中度近视（－1．00D－－6．00D）124眼,Ⅱ组为高度近视（－6．25D－－16．00D）90眼。结果：术后2年低中度近视回退率9．7％,高度近视回退率27．8％（P＜0．005）,高度近视中高龄组较低龄组回退率高（P＜0．005）,较严重的角膜上皮下雾状混浊与回退伴行。结论：准分子激光角膜切削术后屈光回退的主要因素有预期矫正屈光度,角膜Haze及年龄。     

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。     

准分子激光角膜原位磨镶术后角膜内皮细胞的观察

目的 活体观察准分子激光角膜原位磨镶术（ＬＡＳＩＫ）治疗近视后角膜内皮细胞密度和形态学的变化。方法 对９２例（１７６眼）接受ＬＡＳＩＫ矫治了－２．４０～－２５．００Ｄ的近视患者，分别于术前、术后用角膜内皮镜检查角膜中央区皮细胞，并对资料进行分析，又对其中２９例（５４眼）术前接触镜配戴者单独立组分析。结果 ＬＡＳＩＫ治疗殂膜内皮细胞密度无显著性差异（Ｐ〉０．０５），术后内皮细胞密度与角膜切削深度无显     

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。     

激光角膜切削术后发生雾状混浊的研究

目的;了解角膜雾状混浊的程度与屈光度、角膜切削深度以及角膜切削相对深度之间的关系。方法：对１４８例近视患者行准分主光治疗,观察术后３个月时视力及昆浊的情况。结果：术后中你蔗近视患者效果较好,高度近视我有欠矫现象,角膜混浊程度随近视度数及切削深度的增加有逐渐增加的趋势,同时角膜切削时相对深度超过９％者角膜混浊的发生率明显升高,Ⅱ级以上混浊更为明显。结论：激光角膜切削术治疗中低度近视效果理想。屈光度、     

PRK术中角膜切削深度与Haze形成的关系

目的：不同屈光度近视进行光学屈光性角膜切削术（PRK），探讨术中角膜切削深度与角膜雾状浑浊（haze)形成的关系。方法：220眼分为轻度和中度近视两组进行PRK治疗，术前及术后1、3、6、12和24月用A超测量角膜中心厚度，及观察角膜haze的情况。结果：中度近视组术中角 膜切削深度较深，haze形成比率较高；两组角膜中心厚度术后３月时最厚，以后逐渐平稳，haze均在１级以下，且多见于术后１、3月，3月时最重，以后逐渐减轻甚至消失。结论：在中低度近视的PRK治疗中，角膜切削深度与屈光度的高低成正比，haze形成与角膜切削深度呈正相关，且术后角膜中心厚度的变化与haze的变化呈现一定的相关性。     

准分子激光原位角膜磨镶术与准分子激光角膜上皮瓣下磨镶术后角膜知觉恢复的研究

目的 比较准分子激光原位角膜磨镶术（LASIK）和准分子激光角膜上皮瓣下磨镶术（LASEK）后角膜知觉的恢复情况。方法 本研究观察在我院行LASIK或LASEK近视矫正的患者59例（59只眼）,包括低、中度近视行LASEK者20只眼,高度近视行LASEK者30只眼,以及低、中度近视行LASIK者9只眼。分别在术前、术后2周、1、3、6个月时测量角膜中央知觉,并和切削深度进行相关性检验。结果 LASIK和LASEK术后角膜知觉均下降,但LASIK术后下降更明显。在各观察时间点,LASEK术后的角膜知觉均好于LASIK术后2周、1个月和3个月时差异均有统计学意义（P〈0．01）,6个月时P=0．031。低、中度近视LASIK术后6个月时角膜知觉仍未恢复（P=0．023）;而LASEK术后3个月时角膜知觉已恢复（P〉0．05）。高度近视LASEK术后6个月时角膜知觉基本恢复（P〉0．05）。LASEK术后1、3及6个月的角膜知觉和切削深度有相关性（r=0．419,0．433,0．413;P〈0．05）,其余观察时间点两者无相关性。LASIK术后各时间点的角膜知觉和切削深度无相关性（P〉0．05）。结论 LASEK术后角膜知觉的恢复较LASIK术后快,LASEK术后角膜知觉的恢复和切削深度有关。     

高度近视PRK后重度角膜上皮下浑浊5年随访

目的 了解高度近视PRK后重度角膜上皮下浑浊长期变化情况。对象与方法 95年3月－8月在我院眼科激光中心行PRK手术的高度超高度近视患者中,有部分患眼发生了Ⅲ级角膜上皮下浑浊,对其中7例7眼随访5年。结果 全部7眼在3月时角膜上皮下浑浊达到高峰,3－12月虽经局部滴用皮质类固醇,角膜浑浊也无改善,随访至3年时角膜上皮下浑浊开始出现变化,4年时全部7眼均有不同程度的减轻,无1眼保持在Ⅲ级,其中4眼降至Ⅱ级,角膜渐显透明,5年时4眼降至Ⅰ级。结论 PRK术后重度角膜上皮下浑浊有随着时间的推移而逐渐减轻的趋势。     

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     

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.     

Ascorbate prophylaxis for corneal haze after photorefractive keratectomy

PURPOSE: To evaluate whether prophylactic systemic ascorbic acid influences the average level of haze and the incidence of late onset corneal haze after photorefractive keratectomy (PRK). METHODS: Two consecutive groups of eyes treated with PRK for myopia with or without astigmatism were retrospectively compared. The patients had been treated similarly, with the exception that systemic ascorbate had been supplied orally in one of the groups. Haze intensity was quantified on a scale from 0 (clear cornea) to 4 (anterior chamber not visible). The diagnostic criterion for late onset corneal haze was a haze grade 2 or higher, occurring 4 to 12 months after surgery. RESULTS: One week, 1, 3, 6, and 12 months after surgery, the group without ascorbate (314 eyes) showed haze of average levels 0.61, 0.51, 0.50, 0.32, 0.10, respectively, and the group with ascorbate (201 eyes) showed haze of average levels 0.38, 0.18, 0.16, 0.09, 0.06, respectively. Comparison of the respective values showed a statistically significant difference between the two groups (P<.01) at 1 week, 1, 3, and 6 months. Late onset corneal haze was observed in 11 eyes in the group without ascorbate, and none was observed in the group with ascorbate (P<.02). CONCLUSION: This retrospective nonrandomized clinical study suggests that oral ascorbic acid supplementation may have a prophylactic effect against haze development after PRK. However, routine prophylactic use of ascorbate can be recommended only after a randomized, prospective clinical trial substantiates its efficacy.     

准分子激光角膜上皮瓣下磨镶术与准分子激光屈光性角膜切削术治疗近视的比较

目的　研究准分子激光角膜上皮瓣下磨镶术 (LASEK)与准分子激光屈光性角膜切削术(PRK)在治疗 - 8 0 0D以下近视的异同。方法　 4 6例近视度数在 - 1 75～ - 8 0 0D的患者在双眼同时治疗时 ,其中一只眼行PRK治疗 ,另一只眼行LASEK治疗 ,观察上皮愈合时间 ,记载疼痛程度 ,对比术后 6个月内视力、屈光状态及角膜上皮下雾状混浊 (Haze)程度。结果　LASEK组上皮愈合时间平均为 3 4 9d ,PRK组为 2 87d ,两者差异有显著意义 (P <0 0 5 ) ;平均疼痛指数LASEK组为 2 0 4 ,PRK组为 2 4 5 ,差异有显著意义 (P <0 0 5 ) ;术后 6个月内两组间视力及屈光度恢复的差异无显著意义 (P>0 0 5 ) ,并发症的发生无差异。LASEK组术后Haze程度明显低于PRK组 (P <0 0 5 )。结论　LASEK可以和PRK一样安全有效地治疗低于 - 8 0 0D的近视 ,并且与PRK相比 ,可以降低早期疼痛水平 ,减少Haze并发症的发生。     

Corneal haze after photorefractive keratectomy for myopia: role of collagen IV mRNA typing as a predictor of haze

PURPOSE: To develop a test based on the individual expression of collagen type IV synthesis in corneal epithelial cells to identify patients who have the potential for significant corneal haze after myopic photorefractive keratectomy (PRK). SETTING: Department of Ophthalmology and the Institute of Microbiology, University of Regensburg, Germany. METHODS: The individual synthesis of collagen type IV alpha3 mRNA was quantitatively measured in corneal epithelial cells of 34 eye (34 patients) with myopia ranging from -1.5 to -10.0 diopters (D) by a polymerase chain reaction (PCR) test. The corneal epithelial cells were collected before the PRK procedure. Collagen type IV alpha3 mRNA levels were correlated to postoperative haze and regression at 12 months. RESULTS: In all samples, collagen type IV alpha3 mRNA was detected; the mean was 1.47 (range 0.11 to 6.42). There was a correlation between haze and the amount of collagen type IV alpha3 mRNA; that is, eyes with haze had more collagen IV expression. In contrast, no correlation was observed between regression and the amount of collagen type IV alpha3 mRNA. CONCLUSIONS: The results show that collagen type IV alpha3 is an important factor in the development of corneal haze after PRK. Based on a quantitative PCR test, the individual collagen IV mRNA concentration in corneal epithelial cells could be measured. Further development could establish a screening test by which eyes with pronounced synthesis of collagen IV could be identified as being at high risk for haze after PRK.     

Plasminogen activator activity and inhibition in rabbit tears after photorefractive keratectomy

Plasminogen activator is a normal component of tear fluid that plays a role in corneal wound healing processes. This work examines whether inhibitor-induced low levels of plasminogen activator activity (PAA) during corneal re-epithelialization after excimer laser photorefractive keratectomy (PRK) correlates with the eventual occurrence of haze in rabbit eyes. Tear samples were collected with glass capillaries from 16 eyes of eight New Zealand rabbits, using i.m. injection of pilocarpine hydrochloride for stimulation. Tears were collected before and after PRK surgery, and then daily for 5 days, and every fourth day thereafter for 3 months. Both eyes underwent PRK treatment. One eye of each rabbit was treated as a control while the contralateral eye was treated with aprotinin, a serine protease inhibitor, over the first 7 days. PAA in the tear samples was measured by a spectrophotometric method using human plasminogen and chromogenic peptide substrate S-2251. For the eight control eyes after PRK, the PAA values were significantly lower (day 1) and higher (days 2 and 3) than the equilibrium PAA (p<0.001). The corneas remained clear in each of these control eyes. For the eight contralateral aprotinin-treated eyes after PRK, the PAA values on days 1-7 were significantly lower than the equilibrium PAA (p<0.001). All eight of these aprotinin-treated eyes developed corneal haze after 2 months. There was no significant difference (p=0.06) between control and aprotinin-treated eyes for the equilibrium PAA after 19 days. We conclude that a corneal wound healing abnormality (haze) develops in rabbit eyes after PRK when PAA levels are reduced using aprotinin for a week following PRK.     

Effect of nepafenac sodium 0.1% on delayed corneal epithelial healing and haze after photorefractive keratectomy: retrospective comparative study

PURPOSE: To assess delayed epithelialization and corneal haze related to nepafenac ophthalmic suspension 0.1% (Nevanac) use after photorefractive keratectomy (PRK). SETTING: Private practice, Beverly Hills, California, USA. METHODS: This retrospective comparative chart review comprised 69 eyes (44 patients) that were divided into 2 treatment groups that were not statistically significantly different in age or preoperative spherical equivalent. The nepafenac group consisted of 34 eyes (22 patients) that received nepafenac 0.1%, moxifloxacin, and fluorometholone postoperatively. The non-nepafenac group included 35 eyes (22 patients) that received moxifloxacin and fluorometholone only. Patients were seen between 1 day and 5 days postoperatively for evaluation of epithelial healing and haze formation. Delayed epithelialization was defined as healing after day 5. All patients were followed for haze formation for a minimum of 3 months. RESULTS: Statistical analysis showed no difference between the nepafenac and non-nepafenac groups in delayed epithelialization (P = .61, chi-square test). Neither group had significant corneal haze. CONCLUSION: Nepafenac did not appear to delay corneal epithelial healing or contribute to haze formation 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.     

近视眼PRK后角膜上皮延迟愈合及其对视力的影响

目的：了解ＰＲＫ后角膜上皮延迟愈合发生的原因及其对视力、角膜上皮下混浊（ｈａｚｅ）等的影响。方法：统计对比分析角膜上皮去除方法，炎症，屈光度等对上皮延迟愈合的影响，延迟组与非延迟组的视力及发生ｈａｚｅ的差别。结果：１７０５眼ＰＲＫ后２７４眼（１６．１％）发生延迟愈合，最长达６天。炎症是影响愈合的最主要因素（５７．３％）其次为上皮机械刮除范围过大等；近视屈光度高低无明显影响。术后半年，延迟组视力较非