胶原交联对兔角膜碱烧伤后基质融解的影响

目的研究角膜胶原交联治疗对兔角膜碱烧伤后基质融解的影响。方法选取25只新西兰大白兔随机分为正常对照组(5只10眼)、模型对照组(10只10眼)、胶原交联治疗组(10只10眼)。正常对照组不做处理,模型对照组和胶原交联治疗组右眼制备角膜中度碱烧伤模型。造模成功后,胶原交联治疗组采用胶原交联治疗后涂红霉素眼膏,模型对照组滴核黄素眼液30min后涂红霉素眼膏;三组均应用抗生素眼液滴眼。观察角膜融解及混浊等情况,28d后处死动物,对兔角膜进行组织病理学检查和免疫组织化学检测。结果正常对照组未发生变化,模型对照组6眼造模后(14±4)d角膜融解,2眼角膜穿孔;胶原交联治疗组1眼造模后23d角膜融解,无角膜穿孔发生;两组角膜融解发生率间比较,差异有统计学意义(P<0.05)。病理检查结果显示胶原交联治疗组角膜水肿程度轻,角膜胶原纤维破坏轻,炎性细胞浸润明显少于模型对照组。免疫组织化学结果显示胶原交联治疗组角膜胶原纤维较模型对照组排列整齐,深层角膜组织影响小。结论胶原交联治疗可抑制和延迟兔角膜碱烧伤后角膜融解的发生和发展,减轻角膜胶原纤维的破坏及减少角膜组织中炎性细胞的浸润。     

GM6001对碱烧伤角膜组织中基质金属蛋白酶表达及活性的影响

目的 检测正常和碱烧伤后不同时间角膜组织中明胶酶(MMP-2，MMP-9)和胶原酶(MMP-1)的表达，探讨在角膜融解发生中的作用．方法 兔角膜碱烧伤20眼，分为对照组和GM600l治疗组，于伤后12、24、48、72h，1、2周和1个月取材，酶谱法检测角膜组织中明胶酶MMP-2、MMP-9的表达，Western blot检测胶原酶MMP-1的表达。结果 在正常兔角膜中，仅检测到微弱的明胶酶原MMP-2，碱烧伤后1周后开始明显升高，至烧伤后1个月维持较高水平，并在2周时出现MMP-2活性酶的表达，并持续至烧伤后1个月。明胶酶MMP-9在正常角膜组织中检测不到，但烧伤后24h开始表达，于烧伤后1周达到最高，然后逐渐下降，至伤后1个月已检测不到。胶原酶MMP-1在正常组织中检测为阴性，从伤后24h开始升高，1个月内无下降。GM6001治疗组角膜组织MMP-2、MMP-9及MMP-1的表达均明显低于对照组。结论 基质金属蛋白酶参与碱烧伤角膜组织的融解，GM6001可抑制MMPs的活性，进而抑制角膜融解的发生。     

结膜下注射Avastin抑制角膜新生血管的实验研究

目的:观察结膜下注射Avastin对实验性兔眼角膜新生血管(neovascularization,NV)的抑制作用,初步探讨作用机制。方法:应用5mm直径的加样器(末端附有棉片)吸入1mol/LNaOH接触新西兰兔右眼(20眼)中央角膜区烧灼30s,制作碱烧伤兔眼角膜NV模型。将实验兔随机分成2组,10眼(A组)碱烧伤后立即结膜下注射Avastin 2.5mg;其余10眼为对照组(B组),结膜下注射等量生理盐水。烧灼后次日每天裂隙灯观察角膜NV、角膜水肿情况,分别于3,7,14,21,28d裂隙灯照相并计算NV面积及NV抑制率。伤后7,28d各组随即处死5只实验兔,取角膜组织做石蜡切片行组织病理学检查及VEGF免疫组织化学检测。结果:两组兔眼伤后第1d角膜缘血管网明显扩张充血,3d时血管开始侵入角膜,7～14d时NV达到高峰,14～21d后NV稳定并逐渐回退。两组角膜NV长度、NV面积及角膜水肿程度存在差异(P<0.05);A组各时间点角膜NV抑制率为44.2%～55%。A组角膜上皮及实质层水肿较轻,NV较少,后弹力层基本完整,VEGF表达明显弱于B组。结论:结膜下注射Avastin对碱烧伤诱导的兔眼角膜NV形成及生长具有明显的抑制作用,可能通过下调VEGF表达发挥作用。     

抗坏血酸治疗实验性硷烧伤

报告兔眼角膜与结膜用0.25当量的氢氧化钠0.5ml接触30秒钟后用20ml盐水冲洗。双眼每天检查,并用广谱抗菌素眼膏治疗。此外,治疗组用抗坏血酸皮下注射(动物每公斤体重给0.5g)。受伤眼表现为结膜水肿、充血及整个角膜糜烂。49只兔眼缺损的角膜上皮平均12.1±0.7天内愈合。31只兔眼未用抗坏血酸治疗。当上皮刚复益基质时,对角膜各层及房水的新陈代谢作了研究。碱烧伤后,角膜基质中的抗坏血酸含量减少。平均从4.8±2.4μmol/g湿重降至1.0±0.08μmol/g湿重。但是在房水及角膜上皮中未见明显降低。抗坏血酸治疗12天后发现50只兔眼房水抗坏血酸含量为正常的2倍(2.0±0.04),但21只兔眼角膜基质的抗坏血酸量仍见减少)1.6±     

兔角膜重度碱烧伤后异种猫前板层角膜移植重建角膜眼表

目的研究猫新鲜前板层角膜移植治疗兔右眼角膜重度碱烧伤的疗效。方法将16只5个月龄的健康雄性新西兰白兔右眼制作重度角膜碱烧伤模型,随机分成A、B两组,每组各8只兔,其中A组为猫(4只)→兔异种前板层角膜移植组,植片直径为11.0mm,植床直径为10.0mm;B组未行手术。A组兔术后及B组造模后用500g.L-1葡萄糖及复方氯霉素滴术眼直至处死,记录两组疗效指数,并分别于术后1个月、2个月、3个月取材进行术眼角膜病理学及扫描电镜检查。结果3个月内A组8只角膜碱烧伤兔经异种猫前板层角膜移植后,7只移植角膜保持透明,1只出现局限性角膜混浊和角膜新生血管;而B组未手术的8只兔中出现角膜白斑、新生血管4只,角膜溃疡、穿孔3只,角膜溶解穿孔1只,并且有4只发生睑球粘连等并发症。A、B两组治疗后1个月、2个月、3个月平均疗效指数差异均有统计学意义(均为P<0.05)。A组透明角膜中组织学及扫描电镜下的结构特征清晰;B组兔角膜中有明显的角膜水肿和炎性细胞浸润,组织学及扫描电镜下的结构特征显示细胞连接混乱、消失。B组扫描电镜还提示随着时间的延长,上皮细胞部分生长、增多,细胞连接差,角膜上皮排列紊乱;角膜内皮细胞数量明显减少或无,...     

基质金属蛋白酶抑制剂GM6001抑制角膜移植排斥反应的实验研究

角膜移植多因角膜新生血管而失败,基质金属蛋白酶(MMPs)及其抑制剂(TIMP)GM6001对角膜新生血管有较强抑制作用。本实验探讨其对排斥反应是否有抑制作用。1材料与方法1.1角膜碱烧伤兔的角膜缘出现新生血管后制作角膜移植模型并分成治疗组(22眼)和对照组(15眼)。治疗组每日结膜下     

重组人kringle 5蛋白滴眼液抑制兔角膜新生血管的研究

目的　观察重组人kringle 5 (K 5蛋白 )滴眼液抑制碱烧伤诱导的兔角膜新生血管(neovascularization ,NV)的效果 ,探讨其作用机制。方法　采用基因重组方法获得K 5蛋白 ,取新西兰白兔 4 0只 ,将浸有 1mol/L氢氧化钠滤纸片置于兔角膜中央 ,制成碱烧伤模型 ,随机均分为A、B、C及D组 ,每组 10只兔 (10只眼 ) ,伤后即分别滴用 5、10及 2 0mg/L的K 5蛋白滴眼液 ,对照 (D)组滴载体溶液 ;均每日 4次 ,共滴 2 8d。裂隙灯显微镜下观察角膜NV生长情况 ,并计算其面积 ,伤后 2 8d处死实验兔 (A、B及C组 ) ,取其角膜片做组织病理学检查。结果　伤后A、B、C及D组角膜NV开始出现的时间分别为 (3 4± 0 5 )d、(6 8± 0 4 )d、(6 7± 0 7)d及 (3 7± 0 5 )d ,其中B组明显较D组延长(P <0 0 5 ) ,而A组与D组间差异无显著意义 (P >0 0 5 )。伤后各时间点B及C组角膜NV的生长面积均明显较D组减少 (P <0 0 5 ) ,B与C组角膜NV区面积间比较 ,差异无显著意义 (P >0 0 5 )。角膜组织病理学检查 ,D组烧伤区可见大量炎性细胞浸润及角膜NV形成 ,而B及C组角膜炎性反应较轻 ,烧伤区无NV形成。角膜NV区面积与角膜后膜和炎性细胞数均有明显相关性 (P <0 0 5 )。结论重组人K 5蛋白滴眼液可明显抑制碱烧伤引起的角膜NV的生长 ,抑制     

角质细胞生长因子2促进兔角膜碱烧伤上皮愈合机制的研究

目的　探讨角质细胞生长因子2 (KGF- 2 )对实验性兔角膜中央碱烧伤后角膜上皮愈合的作用及其机制。方法　24只新西兰白兔的24只角膜碱烧伤眼按随机数字法分成4组,每组6只眼,其中A、B、C组为治疗组,分别以3种不同浓度: 1μg/ml、50μg/ml、100μg/mlKGF 2滴眼液治疗;D组为对照组,用磷酸盐缓冲液(PBS)滴眼液治疗;观察角膜上皮愈合情况,并做形态学检查及P63、角质蛋白单克隆抗体(AE5)、表皮细胞生长因子单克隆抗体(EGFR)免疫组化研究。结果　1 ~100μg/mlKGF 2能够促进兔角膜上皮愈合。角膜碱烧伤24h后100μg/mlKGF- 2组和对照组角膜上皮愈合率分别为40%和74% (P<0 .05);第4天时4组均出现一定反复;第10天时各治疗组近完全愈合。碱烧伤后第7天即可观察到P63阳性细胞不仅存在于角膜缘区的部分基底细胞中,同时也向角膜内迁移。如角膜碱烧伤后第7天角膜缘区P63阳性细胞数: 100μg/mlKGF 2组为( 53 .8±2. 6)个,对照组为(29. 5±2. 2)个,正常角膜为(17. 0±2. 1)个(P=0. 000);同时非角膜缘区P63阳性细胞数分别为: 100μg/mlKGF 2组为(69. 5±2. 8)个,对照组为(19 5±2 8)个,正常角膜为0个(P=0 .000)。结论　KGF- 2可激活角膜上皮干细胞,使其不断增殖分化,从而促进角膜上皮损伤的愈合。     

Avastin不同给药途径对兔角膜新生血管及超微结构的影响

目的研究阿瓦斯汀不同给药途径对兔角膜新生血管及超微结构的影响。方法健康新西兰大白兔50只,随机选取48只兔左眼制作碱烧伤角膜新生血管动物模型,造模成功后随机分为局部滴眼组(A组)、结膜下注射组(B组)、角膜基质注射组(C组)和模型对照组(D组),每组12只,未造模2只兔双眼为空白对照,于碱烧伤后第1天、第4天、第11天、第18天、第32天观察兔眼结膜充血、角膜混浊、新生血管生长情况,并进行眼前节照相,同时计算各实验兔眼角膜新生血管面积;第11天、第18天、第32天每组各处死4只兔,即刻抽取左眼房水检测血管内皮生长因子(vascular endothelial growth factor,VEGF)含量,取新生血管生长最旺盛的角膜组织分别固定,待做电镜、免疫组织化学等检测。结果角膜新生血管在碱烧伤后11d内生长迅速,第18天时有所消退,第32天时趋于相对稳定,A组、B组、C组角膜新生血管面积与D组在各个时间点之间比较,差异均有统计学意义(均为P<0.05)。碱烧伤后各时间点房水中VEGF浓度均高于正常水平,碱烧伤后11d内房水中VEGF浓度逐渐升高,至第18天时达到高峰,第32天时有所下降并趋于较稳定的水平。CD31在正常兔眼角膜组织中未见表达,A组、B组、C组阳性细胞数明显少于D组,差异均有统计学意义(均为P<0.05)。A组、B组、D组角膜超微结构在第11天、第18天、第32天时除碱烧伤损伤外无明显其他改变,在第18天、第32天时C组角膜超微结构损伤重于A组、B组、D组。结论局部滴眼、结膜下注射、角膜基质注射三种给药途径均对角膜新生血管有较好的抑制作用。局部滴眼与结膜下注射给药途径简单安全、效果稳定,未见对角膜超微结构产生明显影响;角膜基质注射虽短期效果显著,但对角膜超微结构产生了较明显的影响。     

硅胶治疗碱性角膜烧伤的实验研究

目的 探讨硅胶对实验性角膜碱烧伤早期的治疗作用及疗效机制。方法：新西兰兔23只，单眼角膜中度碱烧伤，选择结膜囊内硅胶粉填充法（A组）和眼表局部硅胶粉隔吸法（B组）。C组为对照组，角膜碱烧伤后仅予生理盐水冲洗。第3，5周末摘取角膜行病理检查，烧伤后第7天摘取角膜行扫描电镜检查。结果 A组于第2周角膜溃疡形成，第2周末溃疡穿孔；B组无1例形成溃疡，第7周角膜透明或半透明。对照组多形核白细胞（PMN）大量浸润，角膜细胞显著增多，胶原纤维杂乱排列，新生血管丰富。B组PMN浸润明显减少，胶原排列轻度紊乱，血管少而疏，瘢痕组织少。电镜下见A组角膜烧伤区表面及细胞间明显的硅胶颗粒残留，B组未见硅胶颗粒。结论 在角膜碱烧伤早期应用硅胶治疗可获良效，但应避免硅胶粉直接与眼表接触。     

Treatment of alkali-injured rabbit corneas with a synthetic inhibitor of matrix metalloproteinases.

Healing of corneal alkali injuries remains a severe clinical challenge. The authors evaluated the effect of a new synthetic inhibitor of matrix metalloproteinases (GM6001 or N-[2(R)-2-(hydroxamido carbonylmethyl)-4-methylpentanoyl]-L-tryptophane methylamide) on preventing ulceration of rabbit corneas after alkali injury. Topical treatment of corneas with severe alkali injuries with 400 micrograms/ml or 40 micrograms/ml GM6001 alone prevented ulceration for 28 days, although 8 of 10 corneas treated with vehicle perforated. Corneas treated with 4 micrograms/ml GM6001 had midstromal depth ulcers. Corneas treated with 400 micrograms/ml of GM6001 contained very few inflammatory cells and had significantly reduced vessel ingrowth compared with vehicle-treated corneas. Epithelial regeneration after moderate alkali injuries also was investigated. Persistent epithelial defects developed 4 days after moderate alkali injury in rabbit corneas treated with vehicle and progressively increased to an average of 20% of the original 6 mm diameter wound by 27 days after moderate alkali injury. By contrast, epithelial regeneration was complete and persisted for 21 days for corneas treated with a formulation containing GM6001 (400 micrograms/ml), epidermal growth factor (10 micrograms/ml), fibronectin (500 micrograms/ml), and aprotinin (400 micrograms/ml). Sporadic punctate staining developed in 20% of the corneas treated with the combination of agents between days 21-28 after moderate alkali injury. These results demonstrate that topical application of GM6001 prevented corneal ulceration after severe alkali injury and that a combination containing GM6001, epidermal growth factor, fibronectin, and aprotinin promoted stable regeneration of corneal epithelium after moderate alkali injury.     

Experimental study on the treatment of rabbit corneal melting after alkali burn with Collagen cross-linking

AIM: To evaluate the effect of Collagen cross-linking on the prevention of melting in rabbit corneas after alkali burn. METHODS: Twenty New Zealand white rabbits were randomly divided into model control group and collagen cross-linking treatment group. The second group of rabbits received collagen cross linked treatment. Both groups were applied with antibiotic eye drops to prevent infection. The corneas were evaluated for melting, opacity, pathological and immunohistochemistry, record the changes when 28 days after the animals were killed. RESULTS: In the control group, 6 out of 8 rabbits showed corneal melting after injury (14±4) days, while two corneal perforated. In collagen cross-linking treatment group, one rabbit showed corneal melting after injury 23 days, without corneal perforation; corneal dissolution rate between the two groups was significantly different (P <0.05). Pathological examination suggested that in the treatment group, mild corneal edema, mild damage to collagen fibers, inflammatory cell infiltration was significantly less than the control group. Immunohistochemistry showed that corneal collagen fibers arranged in neat rows in the control group. CONCLUSION: Collagen cross-linking treatment not only can prevent and delay the corneal melting after alkali burn, but also can reduce the destruction of corneal collagen fibers and infiltration of inflammatory cells in the corneal tissue.     

Effect of metalloproteinase inhibitor on corneal cytokine expression after alkali injury.

PURPOSE: Interleukin (IL)-1alpha and IL-6 levels in the cornea are greatly elevated during the early stages after an alkali burn in mice. The authors investigated the effect of synthetic inhibitor of matrix metalloproteinase (SIMP) on the expression of inflammatory cytokines in alkali-burned murine corneas and evaluated the clinical appearance of the eyes. METHODS: After 0.5N NaOH-alkali burns to 400 corneas of ICR mice, 200 received 400 microg/ml of SIMP topically 4 times a day while 200 corneas were similarly treated with vehicle only. At days 4, 7 and 14 after injury, each cornea was assigned a clinical score for corneal opacity, corneal epithelial defect, hyphema and cataract. Extracts of injured corneas in each group were then assayed for cytokine production using ELISA systems for IL-1alpha, IL-1beta, IL-6 and tumor necrosis factor-alpha (TNF-alpha). RESULTS: The levels of IL-1alpha, IL-1beta and IL-6 were significantly lower in the SIMP-treated group than in the vehicle-treated group 7 days after the burn. However, levels of these cytokines were similar in the SIMP and non-SIMP groups at days 4 and 14. Levels of TNF-alpha did not differ between both groups at any postinjury time. In the SIMP-treated corneas, there was less opacification and hyphema formation and epithelial regeneration was faster. CONCLUSIONS: Topical application of SIMP in alkali-burned murine corneas reduced the expression of IL-1alpha, IL-1beta, and IL-6 and lessened the severity of the injury.     

Avastin对大鼠角膜新生血管的抑制及超微结构的影响

目的:探讨Avastin对角膜新生血管形成及角膜内血管内皮生长因子(VEGF)的影响及其超微结构的影响。方法:Wistar大鼠96只随机分3组,采用碱烧伤的方法制备大鼠角膜新生血管模型;正常不烧伤组4只。烧伤后隔日球结膜下注射0.1mL生理盐水组32只,烧伤后隔日球结膜下注射Avastin0.1mL组32只,烧伤后隔日球结膜下注射地塞米松0.1mL组32只。碱烧伤术后在裂隙灯显微镜下观察大鼠角膜混浊度;宏观测量新生血管长度;组织病理切片HE染色作微血管计数;透射电镜观察超微结构的改变;免疫组化检测角膜VEGF的蛋白表达情况;CD34标记新生血管,显微镜下微血管计数方法研究角膜新生血管形成及抑制情况。结果:治疗组在3,7,10,14d较对照组角膜混浊程度轻(P<0.05);14d形成的新生血管数量较对照组少(P<0.05)。实验组新生血管微血管数量减少,VEGF蛋白表达下降,具有统计学差异。VEGF主要表达在角膜受损区的感染细胞胞质内,其出现时间与位置与角膜新生血管一致。Avastin和地塞米松均可有效抑制角膜新生血管,减少角膜内VEGF表达,两者无统计学差异,结膜下注射Avastin和地塞米松后,大鼠角膜超微结构无除烧伤后其它显著改变。结论:Avastin和地塞米松可抑制角膜新生血管,减少角膜内VEGF表达,对角膜的超微结构均无显著毒性。     

Research on mouse model of grade II corneal alkali burn

AIM: To choose appropriate concentration of sodium hydroxide (NaOH) solution to establish a stable and consistent corneal alkali burn mouse model in grade II. METHODS: The mice (n=60) were randomly divided into four groups and 15 mice each group. Corneal alkali burns were induced by placing circle filter paper soaked with NaOH solutions on the right central cornea for 30s. The concentrations of NaOH solutions of groups A, B, C, and D were 0.1 mol/L, 0.15 mol/L , 0.2 mol/L, and 1.0 mol/L respectively. Then these corneas were irrigated with 20 mL physiological saline (0.9% NaCl). On day 7 postburn, slit lamp microscope was used to observe corneal opacity, corneal epithelial sodium fluorescein staining positive rate, incidence of corneal ulcer and corneal neovascularization, meanwhile pictures of the anterior eyes were taken. Cirrus spectral domain optical coherence tomography was used to scan cornea to observe corneal epithelial defect and corneal ulcer. RESULTS: Corneal opacity scores (
) were not significantly different between the group A and group B (P=0.097). Incidence of corneal ulcer in group B was significantly higher than that in group A (P=0.035). Incidence of corneal ulcer and perforation rate in group B was lower than that in group C. Group C and D had corneal neovascularization, and incidence of corneal neovascularization in group D was significantly higher than that in group C (P=0.000). CONCLUSION: Using 0.15 mol/L NaOH can establish grade II mouse model of corneal alkali burns.     

羊膜移植对大鼠角膜碱烧伤后基质金属蛋白酶的影响

目的探讨羊膜移植对大鼠角膜中度碱烧伤后角膜上皮细胞和基质成纤维细胞中基质金属蛋白酶(matrix metalloproteinase，MMP)变化的影响。方法将12只SD大鼠随机分成2组，每组6只，分别作为碱烧伤后1d组和14d组。在2组中，所有大鼠角膜建立中度碱烧伤模型，左眼行羊膜移植，右眼作为对照。应用免疫组化法，分别观察碱烧伤后1d和14d实验组与对照组中MMP-9和MMP-2表达的变化。结果碱烧伤后1d，实验组与对照组中，角膜上皮细胞内的MMP-9和MMP-2的表达与正常角膜上皮细胞内的MMP-9和MMP-2的表达相比明显升高，但两组间的表达差异无显著性；而2组成纤维细胞内的MMP-9和MMP-2的表达与正常成纤维细胞内的MMP-9和MMP-2的表达相比明显升高，两组间的表达差异无显著性。碱烧伤后14d，2组中角膜上皮细胞内的MMP-9和MMP-2的表达与碱烧伤后1d情况相似，两组间的表达差异无显著性；2组成纤维细胞内的MMP-9和MMP-2的表达与碱烧伤后1d组相比明显升高，并且实验组中的MMP-9和MMP-2的表达与对照组相比也有明显升高。结论碱烧伤后大鼠角膜上皮细胞和基质成纤维细胞中的MMP-9和MMP-2的表达都有升高。羊膜移植能增强MMP-9和MMP-2在成纤维细胞中的表达，提示羊膜在加快角膜碱烧伤后的重塑中起一定作用。     

Controlled trial of hyperbaric oxygen treatment for alkali corneal burn in the rabbit

Purpose: To evaluate the efficacy of hyperbaric oxygen therapy in the treatment of alkali‐induced corneal burns in an animal model. Methods: Twenty‐four rabbits were randomized into a control group (n = 12) and hyperbaric oxygen treatment group (n = 12). After induction of anaesthesia, the alkali burn model was established by application of 1 N sodium hydroxide to one eye of each rabbit. The hyperbaric oxygen treatment group was treated each day for 21 days with hyperbaric oxygen at 2.4 Atmospheres Absolute (ATA) for 1 h. The eyes of the animals were examined daily for 2 weeks and then weekly until the end of the trial. The principal endpoint was that of perforation of the cornea at which time the animals were killed with a lethal dose of either intravenous or intraperitoneal barbiturate and the eyes immediately enucleated and fixed in 10% neutral buffered formalin. All animals in which complete healing took placed were also killed, the eyes removed, fixed and examined histologically. Photographs were taken of the rabbit's eyes at weekly intervals and the area of vascularization and epithelial defects in the hyperbaric and control groups were compared. Results: Equal numbers (seven) of the control and hyperbaric oxygen treated groups had perforated corneas and there was no statistical difference in the mean time to perforation (control 30.1 days; treated 30 days). There was also no statistical difference between the two groups with respect to epithelial defect size. Conclusion: Treatment with hyperbaric oxygen for 1 h daily for 21 days had no beneficial effect on alkali‐induced corneal burns.     

Ascorbic acid phosphate ester and wound healing in rabbit corneal alkali burns: Epithelial basement membrane and stroma

We examined the effect of L-ascorbic acid 2-phosphate (P-Asc) on the healing of alkali-burned corneas in rabbits. Round filter paper containing 1 N NaOH was applied to the central cornea for 60 or 120 s to produce the alkali burn. Animals were treated with topical saline, 10% ascorbate, or 6.5% P-Asc applied on the cornea. The corneas were then examined histologically. Burned stroma showed no toluidine blue staining, indicating a loss of glycosaminoglycan. In the 60-s burn group, P-Asc reduced the size of the unstained area as compared with the control. Transmission electron microscopy showed basal lamina under new epithelia in the corneas treated with ascorbate or P-Asc, but not in controls. These observations support the theory that P-Asc may have a therapeutic role in the repair of corneal alkali burns.