准分子激光角膜切削术与准分子激光原位角膜磨镶术角膜创口愈合的对比实验研究

比较准分子激光角膜切削术(photorefractive keratectomy,PRK)与准分子激光原位角膜磨镶术(1aser in situ keratomileusis,LASIK)后激光对角膜组织的切削效应及角膜的愈合情况,从组织学角度探讨角膜雾状混浊(Haze)及屈光度数回退的成因。方法24只新西兰白兔按预矫屈光度数随机分为-4.00 D组和-8.00 D组,每只兔右眼行PRK,左眼行LASIK。术后10d,1、3及6个月观察Haze情况并验光,每组随机处死3只兔取角膜行光镜、电镜及免疫组化检查,检测胶原Ⅲ、胶原Ⅳ、纤维连结蛋白(fibronectine,FN)及转化生长因子-β(transforming growth factor-β1,TGF-β2)的含量。结果行PRK术的右眼术后出现不同程度的Haze及屈光度数回退,其程度与预矫正屈光度数成正比。行LASIK术的左眼术后除少数角膜瓣周围半环形混浊外,手术区域角膜透明,屈光度数回退较右眼轻。-4.00 D组右眼与左眼术后屈光度数均稳定,-8.00 D组右眼较左眼屈光度数回退明显。右眼术后角膜愈合反应重,恢复慢。6个月时角膜基质仍处于修复阶段。左眼术后除形成角膜上皮栓及对应处基质轻度增生外,手术区域角膜瓣与基质床间界面清晰,无明显增生,角膜基质愈合反应轻、恢复快。术后所有兔眼角膜均有TGF-β1表达及活化,持续时间与角膜愈合时间一致。Haze及屈光度数回退组织学改变为：角膜上皮细胞增生,基底膜不成熟,前基质角膜细胞活化、增殖,新生胶原Ⅲ合成、排列紊乱,细胞外基质FN在角膜上皮下沉积。结论LASIK矫正近视尤其是高度近视优于PRK;角膜伤口愈合特别是基质愈合的反应程度,是。Haze及屈光度数回退的关键;TGF-β1是角膜愈合过程中重要调节因子,可通过介导角膜上皮一基质相互作用,调节胶原Ⅲ及FN的含量,参与瘢痕形成。     

不同切削深度对兔PRK和去瓣Epi—LASIK术后早期角膜愈合反应的观察

背景去瓣准分子激光角膜上皮瓣下磨镶术（Epi—LASIK）术后上皮愈合快,创伤反应轻,受到眼科医师的关注。但去瓣Epi～LASIK术后上皮愈合的机制一直是目前研究的热点。目的研究兔准分子激光角膜切削术（PRK）和去瓣Epi—LASIK对不同屈光度眼切削术后早期角膜基质中炎性细胞、碱性成纤维细胞生长因子（bFGF）、核转录因子（NF—KB）的表达,探讨两种手术方式在不同切削深度时角膜创伤愈合反应的机制。方法将16只新西兰大白兔按随机数字表法分为高度切削组（-10．00D）6只、低度切削组（-3．00D）6只和空白对照组2只。实验组取一侧眼行PRK,对侧眼行去瓣Epi—LASIK,术后每日裂隙灯下观察活体兔角膜愈合情况。术后7d空气栓塞法处死兔,角膜组织用苏木精一伊红染色和免疫组织化学法检测早期角膜上皮及基质中炎性细胞、bFGF和NF—κB的表达。结果裂隙灯检查表明,去瓣Epi-LASIK手术眼术后炎症反应轻于PRK眼。在低度切削组,2种术式间术后角膜炎性细胞的数量以及NF—κB和bFGF在角膜组织中表达的差异均无统计学意义（P〉0．05）,而在高度切削组,PRK手术眼角膜中炎性细胞数量为（12．25±1．22）个／400倍视野,明显高于去瓣Epi—LASIK手术眼的（6．67±0．31）个／400倍视野,差异有统计学意义（t=-8．87,P〈0．01）。角膜中PRK手术眼NF—KB的表达量（A）分别为6．11±1．36、41．82±8．71,较去瓣Epi—LASIK手术眼的3．01±0．81、11．59±4．55明显增加,而角膜中PRK手术眼bFGF的表达量（A）分别为33．59±6．98、123．68±18．81,较去瓣Epi—LASIK手术眼的69．20±8．85、123．68±18．81降低,差异均有统计学意义（P〈0．05）。去瓣Epi-LASIK上皮愈合速度快于PRK组,而随着切削深度的增加,愈合速度减慢。结论在低度切削时,去瓣Epi—LASIK手术眼角膜上皮的愈合速度与PRK手术眼无明显差别,但在高度切削时,去瓣Epi—LASIK术眼角膜上皮的愈合速度稍快于PRK术眼,炎症反应程度轻。     

Effect of exogenous keratinocyte growth factor on corneal epithelial migration after photorefractive keratectomy

PURPOSE: To investigate the effect of topical keratinocyte growth factor (KGF) on wound healing after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). SETTING: Department of Ophthalmology, Rayne Institute, St. Thomas' Hospital, London, United Kingdom, St. Erick's Eye Hospital, Stockholm, Sweden, and the University of Regensberg, Regensberg, Germany. METHODS: In a placebo-controlled trial, 24 New Zealand white female rabbits were divided into 3 equal groups. Group 1 (n=8) had myopic PRK (6.0 diopters [D]) using the Technolas 217z laser (Bausch & Lomb). Group 2 and Group 3 had myopic LASIK (6.0 D) with a flap depth of 140 microm and 180 microm, respectively. Topical KGF (20 microg/mL) was administered to half the treated eyes in each group intraoperatively and postoperatively; the other half received placebo eyedrops. Epithelial closure, corneal haze, and keratocyte activation in the rabbit eyes were analyzed and compared with those in placebo-controlled eyes for 5 weeks postoperatively. RESULTS: In Group 1, the mean reepithelialization after PRK was 0.10 mm2/h +/- 0.02 (SD) in the KGF group and 0.33 +/- 0.05 mm2/h in the control group (P=.001). There was no significant difference in the mean backscatter between the KGF eyes (154 +/- 45.95) and the control eyes (141 +/- 38.45) after PRK (P=.42). Histology revealed reduced epithelial cell layers in the KGF group and comparable keratocyte density as in the control group. In Groups 2 and 3, there was no significant difference in backscatter, epithelial layers, and keratocyte density between KGF and control eyes after LASIK. CONCLUSIONS: Topical KGF (20 microg/mL) delayed reepithelialization after PRK. It had no effect on stromal wound healing in LASIK eyes with an intact epithelial barrier.     

安贺拉眼液在PRK术后的止痛作用

为了评价安贺拉眼液在ＰＲＫ术后的止痛作用。方法随机选择６０只眼,除４只眼外皆为双眼自身对照。分为两组,每组各３０只眼。ＰＲＫ术后分别滴用安贺拉和佳贝眼液,佳贝组作为对照组,记录疼痛程度及观察角膜上皮愈后情况,共随访３天。     

Mitomycin C alters corneal stromal wound healing and corneal haze in rabbits after argon-fluoride excimer laser photorefractive keratectomy.

PURPOSE: To investigate the effects of mitomycin C (MMC) on rabbit cornea wound healing after photorefractive keratectomy (PRK). MATERIALS AND METHODS: Rabbit corneas were stained with dichlorotriazinyl aminofluorescein immediately after PRK. MMC was applied to the right eye and phosphate-buffered salt solution (PBS) to the left. Corneal epithelial wound healing rate and corneal haze were examined. Ultrasound pachymetry was performed. Stromal collagen regeneration was evaluated by fluorescent microscopy. We used terminal deoxyribonucleotidyl transferase-mediated D-uridine 5'-triphosphated-digoxigenin nick-end labeling (TUNEL) assay and transmission electron microscopy (TEM) to evaluate keratocyte apoptosis. RESULTS: In eyes treated with MMC, there was no delay to the healing rate of corneal epithelial wound, and less haze 4 weeks after PRK. Ultrasound pachymetry showed thinner corneal thickness in MMC-treated eyes at week 4. Corneal stromal thickness regression was less in MMC-treated eyes observed by fluorescent microscope at week 4. Keratocyte apoptosis was noted in both MMC- and PBS-treated eyes by TUNEL assay and TEM observation. This study discovered the phenomenon that MMC prolongs keratocyte apoptosis. CONCLUSIONS: Applying MMC after PRK is an effective method to decrease haze formation and corneal stromal thickness regression in rabbit corneas. The effect may be related to MMC prolonging keratocyte apoptosis.     

准分子激光屈光性角膜切削术后兔角膜基质细胞凋亡及其防治的研究

目的：探讨准分子激光屈光性角膜切削术（photorefractive keratectomy,PRK）后凋亡机制介导的角膜创伤愈合反应对屈光度数回退和角膜雾状混浊（haze）的影响,以及局部应用锌制剂的药物效果。方法：对90只新西兰白兔行双眼PRK,将左眼作为实验眼,手术前、后分别给予A组0．1％地塞米松眼液、B组0．5％硫酸锌眼液和C组0．04％丝裂霉素眼液滴眼;右眼作为对照眼。术后定期裂隙灯下观察haze的程度,测量角膜的厚度,进行光镜和透射电镜观察,采用脱氧三磷酸尿苷缺口末端标记法行凋亡细胞检测,并进行对比性分析。结果：（1）PRK术后角膜前基质细胞出现凋亡,实验眼B组凋亡细胞最少（P＜0．01）。（2）术后角膜厚度增加,前基质细胞增多,实验眼haze和增生程度眼B组凋亡细胞最少（P＜0．01）。（3）术后角膜上皮增生,实验眼B组角膜上皮厚度最小（P＜0．01）。结论：PRK术后屈光度数回退和haze的形成是凋亡机制介导的角膜创伤愈合过程,锌制剂可阻止角膜前基质细胞凋亡,最大限度减轻反应性过度增生,有望成为临床防治haze形成和屈光度数回退的理想药物。     

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.     

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.     

Effects of morphine on corneal sensitivity and epithelial wound healing: implications for topical ophthalmic analgesia.

Studies were conducted to examine the analgesic and toxic effects of topical morphine on corneal abrasion. For the toxicity study, rabbits were anaesthetized and epithelial cells were removed from the cornea and limbus. Animals were randomised and treated topically as follows: (1) saline (control); (2) morphine sulphate (MS, 0.5%); and (3) proxymetacaine hydrochloride (proparacaine) (PH, 0.5%). Two drops of the solution were instilled in the eyes at 4 hour intervals for 6 consecutive days and the progression of corneal wound healing was assessed. Results showed that repeated topical MS had no adverse effects on corneal wound closure. The rates of wound healing were similar in both saline and MS treated groups. Eyes treated with MS showed wound closure in a symmetrical fashion starting on day 2 following abrasion. The progression of epithelial wound healing was completed by day 4 in one eye, by day 5 in three eyes, and by day 7 in five eyes. In contrast, repeated topical PH application delayed corneal wound closure. Eyes treated with PH showed signs of corneal wound closure on the third day, but only two eyes out of six had completed wound closure by the eighth day after corneal abrasion. In a subsequent masked study, the analgesic efficacy of topical MS was assessed in seven patients with unilateral corneal abrasion. In all cases, a baseline response was first established. Subsequently, saline was instilled in both eyes and the patient's corneal response to pain pressure was determined 10 and 20 minutes later. Finally, MS was applied and the analgesic effect on the cornea was assessed. Results showed that saline had no effect compared with the baseline response. In contrast, MS showed an analgesic effect as early as 10 minutes after application in the eye with corneal abrasion. MS showed an analgesic efficacy of 4.3-fold and 5.5-fold greater than the baseline or saline on the eye with corneal abrasion. However, MS had no analgesic effect on the intact corneal. Collectively, these data indicate that opioids do have a desirable analgesic property with out irritating or causing any adverse effect on ocular structures.     

Corneal barrier function, tear film stability, and corneal sensation after photorefractive keratectomy and laser in situ keratomileusis

PURPOSE: To compare corneal sensation, corneal barrier function, tear secretion, and tear film stability after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). DESIGN: Prospective, nonrandomized clinical trial. METHODS: In a prospective study, 28 eyes of 15 patients underwent PRK and 115 eyes of 59 patients underwent LASIK to correct myopia. Corneal sensation, corneal epithelial barrier function, tear secretion, and tear film stability were examined preoperatively and 1 week and 1, 3, 6, and 12 months postsurgery. RESULTS: Both PRK and LASIK significantly compromised corneal sensation, increased epithelial barrier function, reduced tear secretion, and deteriorated tear film stability (P < .05, Wilcoxon signed-rank test). Deterioration of corneal sensation was significantly greater after LASIK than after PRK by 3 months postoperatively (P < .05, Wilcoxon rank sum test). Increases in corneal epithelial permeability were more prolonged after LASIK than after PRK. A significant intergroup difference in permeability was observed 1 month after surgery (P < .01). Tear breakup time was significantly shorter in the LASIK group than in the PRK group up to 3 months after surgery (P < .045). CONCLUSIONS: LASIK induces greater and more prolonged damage to corneal sensation, corneal barrier function, and tear film stability than PRK.     

Epithelial healing rates with topical ciprofloxacin, ofloxacin, and ofloxacin with artificial tears after photorefractive keratectomy

PURPOSE: To determine whether corneal epithelial healing differs after the use of topical ciprofloxacin alone, topical ofloxacin alone, or topical ofloxacin with artificial tears in patients having photorefractive keratectomy (PRK). SETTING: Department of Ophthalmology and Visual Science, The University of Texas Health Science Center at Houston, Houston, Texas, USA. METHODS: Eighteen patients (6 women, 12 men) with moderate myopia (-1.50 to -6.00 diopters [D]) had standardized PRK. Patient age ranged from 25 to 62 years. The 28 eyes (16 right, 12 left) were randomized into 3 treatment groups: ofloxacin alone, n = 9 eyes; ciprofloxacin, n = 9 eyes; and ofloxacin with Refresh Plus, n = 10 eyes. The drugs were administered immediately after surgery and then every 6 hours. Video recordings of the corneal wounds stained with fluorescein were performed at 8:00 AM and 4:00 PM using a video slitlamp camera with a cobalt-blue light until the wound completely healed. The videotaped images were recorded and analyzed by a computer planimetry program. Wound areas were recorded and compared among the 3 drugs. The square-root transformation was applied to the wound area to obtain a constant healing rate. Statistical comparisons were analyzed using an analysis of variance test. RESULTS: Mean recovery time was 82.67 hours +/- 14.42 (SD) in the ofloxacin eyes, 120.89 +/- 34.05 hours in the ciprofloxacin eyes, and 76.80 +/- 19.30 hours in the ofloxacin with Refresh Plus eyes. Mean healing rate was 0.66 +/- 0.17 hours, 0.54 +/- 0.16 hours, and 0.67 +/- 0.15 hours, respectively. The healing rate was significantly higher in the ofloxacin with Refresh Plus eyes than in the ciprofloxacin eyes (P < .0001). There was no significant difference between the ofloxacin eyes and the ofloxacin with Refresh Plus eyes (P = .42). CONCLUSION: Ofloxacin with Refresh Plus and ofloxacin alone had a more positive effect on epithelial healing than ciprofloxacin. The ciprofloxacin eyes were significantly more prone to impaired or delayed wound healing and to the development of corneal haze.     

Effects of the COOH-terminal tripeptide alpha-MSH(11-13) on corneal epithelial wound healing: role of nitric oxide

It is known that alpha-melanocyte stimulating hormone (alpha-MSH) may exert anti-inflammatory effects and facilitate reparative processes in different tissues. The effective message sequence of alpha-MSH resides in the COOH-terminal tripeptide alpha-MSH(11-13). This study was undertaken to investigate the effects of topical administration of the COOH-terminal tripeptide sequence of alpha-MSH (alpha-MSH(11-13), KPV) on corneal epithelial wound healing in rabbits and the possible role of nitric oxide (NO) in these effects. The whole corneal epithelium was denuded in both eyes by mechanical abrasion. The area of the corneal epithelial defect was stained with fluorescein, photographed, and then measured before the treatment and every 12 h by a computerized software. The mean epithelial wound area and the mean percent of epithelial defect remaining at each follow-up control were compared between experimental groups. Rabbits were topically treated with KPV 1, 5 or 10 mg/ml (30 microl), two drops four times in a day, for 4 days, starting immediately after corneal abrasion, while control animals received topical phosphate-buffered saline as vehicle. In order to study the role of NO in corneal repair processes, the NO donor, sodium nitroprusside (SP, 10 mg/ml, 30 microl) was administered in both eyes, two drops four times in a day, for 4 days. The effects of KPV or SP were challenged by pre-treatment with the nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME, 10 mg/ml, 30 microl) 30 min prior to KPV or SP instillation. The mean percent epithelial defect remaining each time was significantly smaller in animals treated with KPV or SP in comparison to controls. Sixty hours later, eight out of eight (100%) corneas treated with KPV or SP were completely re-epithelized (P<0.05) while none of the corneas treated with placebo were re-epithelized. Pre-treatment with L-NAME inhibited the facilitating effect of KPV on corneal epithelial wound healing process and totally prevented the effect of SP. Rabbit corneal epithelial cells (RCE) in culture were exposed for 1, 6 and 24 h to different KPV concentrations (0.1, 1 and 10 microM) in medium containing 15% foetal bovine serum (FBS). Cell viability was stimulated by 1 and 10 microM concentrations of the substance. Thus, KPV may facilitate corneal epithelial wound healing in rabbits with a mechanism that may involve NO disposition in corneal tissue. However, it is not known whether this mechanism is likely to depend on a direct stimulating repairing activity shared by the entire molecule of alpha-MSH.     

Mitomycin C, ceramide, and 5-fluorouracil inhibit corneal haze and apoptosis after PRK

PURPOSE: To investigate the effects of mitomycin C (MMC), ceramide, and 5-fluororacil (5-FU) on haze after photorefractive keratectomy (PRK) and exposure to ultraviolet B (UVB) radiation. METHODS: The right eyes of 42 New Zealand white rabbits were treated with PRK to correct -10 diopter with a 5-mm optical zone. Sponges soaked in 0.02% MMC, 10 or 40 micromol/L ceramide, or 0.5% 5-FU were applied to the right eyes of 6 rabbits each, and a tarsorrhaphy was performed. Eight weeks after complete healing, topical 0.02% MMC or 0.5% 5-FU was applied twice daily to the right eyes of 6 rabbits that had previously received PRK but no topical medication. The control group of 6 rabbits was treated only with PRK. Three weeks after PRK, all the laser-treated eyes were exposed to 100 mJ/cm UVB radiation. Corneal haze was assessed biomicroscopically every 2 weeks using the Fantes scale. Eyes were enucleated 2, 7, and 13 weeks after PRK, and tissue specimens were stained with hematoxylin and eosin and with Apostain. RESULTS: Corneal haze was observed in all rabbits after PRK and was aggravated by UVB irradiation. When applied immediately after PRK, MMC induced corneal opacity and apoptosis of keratocytes, but, at later times, this reagent significantly suppressed opacity, Apostain-positive keratocytes and reactivation of keratocytes, even after UVB irradiation. In contrast, ceramide and 5-FU suppressed corneal opacity after PRK, but this effect was not sustained after UVB irradiation. CONCLUSIONS: MMC is a potent inhibitor of haze induced by PRK and UVB irradiation. Throughout the process of corneal wound healing, the severity of apoptosis and reactivation of keratocytes was closely correlated with haze formation.     

Corneal epithelial healing after photorefractive keratectomy: analytical study

PURPOSE: To characterize the velocity of epithelial migration after photorefractive keratectomy (PRK) with 3 different corneal ablation patterns. SETTING: Department of Ophthalmology, Catholic University of Rome, Rome, Italy. METHODS: Fifteen patients (30 eyes) with mild to moderate myopia and with simple to compound myopic astigmatism were enrolled for this study. The surgical procedure consisted of standardized PRK with final smoothing performed using the Technolas Keracor 217C excimer laser. The reepithelialization process was evaluated at 0 hours, 20 hours, 40 hours, and 60 hours after surgery using a digital photo camera and custom software for measurement. Digital analysis of the images was performed. Corneal topographies were taken at 1 month, 3 months, 6 months, and 12 months after PRK. RESULTS: The mean speed of radial migration in the 10 eyes (33%) in the low spherical ablation group was 0.087 mm/h +/- 0.008 (SD). This was significantly higher than that found in the 10 eyes (33%) in the high spherical ablation group (mean speed 0.078 +/- 0.007 mm/h; P<.001) and in the 10 eyes (33%) in the cross-cylinder ablation group (mean speed 0.055 +/- 0.014 mm/h; P<.001). CONCLUSION: Analysis of the data shows that epithelial migration along the photoablated corneal surface depends on the ablation pattern. The epithelial sliding is highly influenced by local variations in the curvature of the stromal surface. The data demonstrate that faster epithelial wound healing after PRK is predictive of optimal visual performance.     

多柔比星对兔眼准分子激光角膜切削术后角膜上皮下混浊（Haze)的影响

目的　通过动物实验初步观察应用多柔比星对准分子激光角膜切削术（photorefractive keratectomy,PRK）术后角膜上皮下混浊(Haze)的影响,评估其抑制PRK术后Haze的有效性和安全性,旨在探讨PRK术中多柔比星替代丝裂霉素C应用的可行性。方法　新西兰白兔10只（20眼）,其中右眼为多柔比星治疗的实验组,左眼为丝裂霉素C治疗的对照组,两组兔眼均行PRK激光切削校正-8.00 D后,分别用0.2 g·L^-1多柔比星或0.2 g·L^-1丝裂霉素C的棉片处理,分别于术后1 d、1周、2周、3周、4周在裂隙灯下观察角膜上皮愈合及Haze情况。结果　术后1周,两组所有兔眼角膜上皮均已完全愈合。实验组3眼术后1 d即出现角膜基质片状炎性浸润灶,其中2眼治疗后角膜基质炎性浸润灶消退,另1眼形成浅层斑翳;实验组其余7眼及对照组10眼均未见Haze。结论　多柔比星虽然可能引起角膜基质非感染性炎症反应,但在抑制PRK术后细胞增殖方面或具有与丝裂霉素C类似效果。     

Concentration-dependent effects of lidocaine on corneal epithelial wound healing.

Local anesthetic toxicity is a recognized clinical problem that has limited the use of topical corneal anesthetics for pain relief after corneal abrasion. Studies have shown clinically administered concentrations (0.5-2%) of local anesthetics impair corneal reepithelialization. Unfortunately, instillation of local anesthetic drops into an eye does not provide a measurable, steady-state concentration of drug. Thus, it has not been possible to evaluate whether there is an analgesic concentration of local anesthetic that does not impair corneal wound healing. Using the new in vitro rabbit cornea wound healing model, the effect of steady-state lidocaine concentrations on epithelial wound healing was examined. At lidocaine concentrations below 100 micrograms/ml, wound healing was not impaired. Higher concentrations (250-1000 micrograms/ml) resulted in dose-dependent impairment of epithelial wound healing. Combined with electrophysiologic evidence that corneal nerve injury discharge can be abolished by lidocaine concentrations less than 100 micrograms/ml, this research suggests that topical lidocaine in low concentration may be a safe topical corneal analgesic.     

羊膜移植对家兔PRK术后伤口愈合作用的研究

目的：观察羊膜对家兔PRK术后角膜伤口愈合反应的影响。方法：对30只家兔常规施行双眼PRK手术（－8．0D切削程序），即行羊膜移植，观察术后早期角膜切削区炎性细胞的浸润和角膜上皮愈合情况，晚期角膜成纤维细胞增生和上皮增生情况，观察haze并评分；早期测量角膜SOD活力和MDA含量，对结果进行统计学分析。结果：早期移植相炎性细胞的数目比对照组少，上皮愈合时间较短，晚期上皮增生较轻，晚期移植组成纤维细胞数目较少；移植组haze评分较低；早期移植组自由基反应产物MDA的含量较低，而SOD含量较高，差异均具有显著性。结论：羊膜能促进术后上皮愈合，减轻炎性反应和自由基反应，减少成纤维细胞增生，减轻haze的形成。     

微型角膜刀法准分子激光上皮下角膜磨镶术后兔角膜愈合的实验研究

目的探讨微型角膜刀法准分子激光上皮下角膜磨镶术（Epi-LASIK）术后角膜的愈合规律,并与准分子激光屈光性角膜切削术（PRK）比较。方法建立兔近视性Epi-LASIK及近视性改良PRK动物模型,用锥虫蓝-茜素红活性染色法观察Epi-LASIK术后角膜上皮细胞活性,裂隙灯显微镜下观察角膜瓣变化、上皮修复过程和上皮下雾状混浊（haze）形成情况,通过角膜组织病理学观察角膜上皮及基质的愈合反应。结果 Epi-LASIK术后角膜上皮愈合时间为（4.67±0.41）d,而PRK术后为（2.75±0.27）d,差异有统计学意义（t=9.550,P=0.000）。PRK术后即刻和3d、5d角膜上皮瓣细胞活性率分别为（85.83±2.07）%、（48.67±3.41）%、（91.33±3.10）%,差异有统计学意义（F=215.060,P=0.000）。Epi-LASIK术后角膜瓣逐渐融解并被新生上皮取代,上皮愈合过程较改良PRK缓慢。PRK术后haze分级高于Epi-LASIK,差异有统计学意义（Z=2.27,P=0.02）。角膜组织病理学检查显示,术后1个月时2组上皮均明显增厚,3个月时上皮细胞排列仍不规则,6个月时上皮细胞形态基本恢复正常,术后3～6个月时Epi-LASIK组角膜上皮厚度已基本接近正常,与PRK组比较差异有统计学意义（P〈0.05）。术后3～6个月时Epi-LASIK组角膜前基质细胞数明显低于PRK组（P〈0.05）。结论 Epi-LASIK术后上皮瓣活性随时间的推移而降低,上皮修复较慢。与改良PRK比较,Epi-LASIK术后上皮细胞形态变化和上皮增厚程度较轻,角膜基质细胞恢复快,haze程度明显减轻。     

Effects of substance P and IGF-1 in corneal epithelial barrier function and wound healing in a rat model of neurotrophic keratopathy

PURPOSE: To establish a rat model of neurotrophic keratopathy and to examine the effects of the combination of substance P (SP) and insulin-like growth factor (IGF)-1 on corneal epithelial barrier function and wound healing in this model. METHODS: Corneal denervation was achieved by thermocoagulation of the ophthalmic branch of the trigeminal nerve. A modified Schirmer test was performed without topical anesthesia. Corneal epithelial barrier function was assessed by measurement of fluorescein permeability with an anterior fluorophotometer. Epithelial wound healing was evaluated by measurement of the area of the defect at various times after removal of the entire epithelium. Eye drops containing both 1 mM SP and IGF-1 (1 micro g/mL) were administered six times daily. RESULTS: The Schirmer test result in eyes subjected to trigeminal denervation was lower than that in control eyes. The fluorescein permeability of the corneal epithelium of denervated eyes was increased relative to that of control eyes. Furthermore, trigeminal denervation induced a delay in corneal epithelial wound healing. Application of eye drops containing SP and IGF-1 to denervated corneas restored the fluorescein permeability of the corneal epithelium to control levels and abolished the delay in epithelial wound healing. CONCLUSIONS: A rat model of neurotrophic keratopathy, characterized by reduced tear secretion, loss of corneal sensation, impaired epithelial barrier function, and delayed epithelial wound healing, was established by trigeminal denervation. Treatment with both SP and IGF-1 improved corneal epithelial barrier function and stimulated corneal epithelial wound healing in this model.     

Nitric oxide levels of aqueous humor after photorefractive keratectomy

PURPOSE: To measure the nitric oxide (NO) levels of aqueous humor in rabbits after photorefractive keratectomy (PRK) and to evaluate the alterations of NO levels according to the PRK surgery steps, ablation depth, and time. METHODS: Fifty eyes of 25 New Zealand white rabbits were included in the study. One eye was later randomly excluded from the study in order to equalize the number of eyes in groups. Eyes were divided into seven groups, each comprising seven eyes: unwounded control (Group 1), epithelial scrape (Group 2; aqueous humor samples taken at the 4th hour), superficial PRK (Group 3; samples taken at the 4th hour), deep PRK (Group 4; samples taken at the 4th hour), epithelial scrape (Group 5; samples taken at the 24th hour), superficial PRK (Group 6; samples taken at the 24th hour), and deep PRK (Group 7; samples taken at the 24th hour). The corneal epithelium was mechanically removed in surgical groups. The authors performed superficial corneal ablation (59 microm) in Groups 3 and 6 and deep corneal ablation (99 microm) in Groups 4 and 7. Aqueous humor samples were taken at the 4th hour (Groups 2-4) or 24th hour (Groups 5-7) after corneal surgeries. NO measurements were performed indirectly by using the Griess reaction with a spectrophotometer. RESULTS: Aqueous humor NO levels 4 hours after corneal surgery were statistically significantly lower than the control group (p<0.05). However, there was no difference among the surgical groups at the 4th hour (p>0.05). At the 24th hour, the deep PRK group had significantly lower NO levels than both the control group and Groups 5 and 6 (p<0.05). NO levels were normalized at the 24th hour in epithelial scrape and superficial PRK groups (p>0.05) but remained stable at lower levels in deep PRK groups (p<0.05). CONCLUSIONS: Corneal surgery caused low NO levels in aqueous humor 4 hours after surgery. However, 24 hours after surgery, NO levels normalized following epithelial scrape and superficial PRK and were stable at lower levels in the deep PRK group. Complications of deep PRK application are possibly induced by low NO existence in the aqueous humor.