实验性角膜新血管的形态观察

目的 观察兔角膜新生血管的形态特点,探讨其发生机制及治疗效果。方法 将16只新西兰兔随机分为实验和对照两组,均以75%硝酸银液烧灼兔角膜,实验组于硝酸银烧灼后行β射线照射,观察两组角膜新生血管的生长规律;选期制做新生血管铸型;扫描电镜下比较两组间新生血管形态差异。结果 角膜新生血管以典型的芽生方式发生和增殖,经β射线照射后的血管芽形成受到明显的抑制和破坏,新生的血管支干发生萎缩、坏死。结论 阻断新生血管的芽生过程可抑制角膜新生血管的形成和发展。     

电离辐射对角膜新生血管形成的抑制作用

背景 角膜新生血管(CNV)可发生在多种跟表疾病中,常可加重病情,但有效的临床治疗方法仍在探索中. 目的 探讨电离辐射对角膜碱烧伤后新生血管的抑制作用.方法 76只清洁级Wistar纯系大鼠中70只用角膜碱烧伤的方法建立大鼠右眼CNV模型,然后按照随机数字表法将造模动物分为β射线10 Gy一次性照射组2只、β射线7 Gy分次照射组17只、β射线10 Gy分次照射组17只、质量分数1％环孢素A(CsA)点眼组17只和角膜碱烧伤模型组17只,6只正常兔6只眼(均取右眼)作为正常对照组.用90 Sr-90Y眼科敷贴器于右眼角膜碱烧伤后第1天开始沿角膜缘进行β射线照射,1％ CsA点眼组用药时间与照射时间相同.实验后每日行裂隙灯检查并计算CNV长度和面积.于角膜碱烧伤后3、5、7d制备角膜组织石蜡切片和匀浆,采用免疫组织化学法检测各组大鼠角膜组织中bcl-2、bax、血管内皮生长因子(VEGF)的表达,分别采用Western blot和逆转录聚合酶链反应(RT-PCR)检测各组大鼠角膜组织中VEGF蛋白及mRNA表达的变化.结果 角膜碱烧伤后7d,裂隙灯下可见β射线10 Gy一次性照射组、β射线10 Gy分次照射组均出现角膜溃疡,角膜碱烧伤模型组可见大量CNV生成,而β射线7 Gy分次照射组和1％CsA点眼组CNV明显较少.角膜碱烧伤后7d,β射线7 Gy分次照射组、1％ CsA点眼组CNV长度和面积均明显小于角膜碱烧伤模型组,差异均有统计学意义(长度:q=14.40、24.20,P＜0.01;面积:q=17.80、14.00,P＜0.01).免疫组织化学检测表明,与角膜碱烧伤模型组比较,β射线7Gy分次照射组、1％CsA点眼组大鼠角膜中bcl-2和VEGF蛋白表达均减弱,而bax蛋白表达均增强.RT-PCR检测表明,β射线7 Gy分次照射组、β射线10 Gy分次照射组、1％CsA点眼组VEGF mRNA表达强度明显低于角膜碱烧伤模型组,Western blot检测发现VEGF蛋白的表达与VEGFmRNA的表达遵循同样的规律.结论 90Sr-90Y跟科敷贴器小剂量分次放射治疗可明显抑制角膜碱烧伤后CNV的生长,并且以β射线7 Gy分次照射作用效果最佳.     

医用几丁糖对角膜碱烧伤后新生血管的抑制作用

目的观察医用几丁糖对角膜碱烧伤后新生血管的抑制作用。方法NaOH烧伤兔角膜制作角膜碱烧伤模型,随机分为碱烧伤组（碱烧伤）和几丁糖组（碱烧伤＋2％医用几丁糖滴眼）。分别于1、4．7、14d观察两组兔角膜新生血管生长情况,HE染色计算多形核粒细胞（PMN）数量,兔疫组化染色测定血管内皮生长因子（VEGF）的活性。结果几丁糖组新生血管较碱烧伤组生长缓慢,PMN计数及VEGF表达较碱烧伤组均明显减少。结论医用几丁糖可抑制碱烧伤后角膜新生血管的形成。     

实验性角膜新生血管形成的形态学研究

采用氢氧化钠灼伤角膜方法，诱导２０只兔眼角膜新生血管形成，并对其发生、发展过程进行裂隙灯显微镜、光镜和透射电镜观察。结果发现，伤后８小时，角膜缘组织已有中性粒细胞浸润等明显急性炎症变化；渗出于血管外的中性粒细胞胞质内吞噬溶酶体异常丰富。在伤后２天，角膜缘才出现新生血管芽，角膜新生血管周围可见中性粒细胞浸润及其崩解产物。提示白细胞，特别是中性粒细胞，参与角膜新生血管形成过程，并可能起介导作用。     

人Kringle1-5蛋白滴眼液抑制兔角膜新生血管的研究

目的:观察人Kringle1-5(K1-5)蛋白滴眼液来观察其抑制角膜新生血管的效果。方法:随机将缝线法诱导单侧角膜新生血管的28只新西兰白兔分为两组。K1-5组给予人K1-5蛋白滴眼液点眼,PBS组给予PBS液点眼。观察两组角膜新生血管形成时间、最长新生血管、新生血管面积并进行统计学分析。随机选择处死实验兔,取下角膜组织进行病理检查。结果:K1-5组最早于3d,平均3.50±0.52d可见新生血管芽进入角膜缘,9～15d新生血管生长最为旺盛;20d时最长新生血管为4.38±0.27mm,新生血管面积27.51±4.19mm2。而对照组最早于2d,平均2.28±0.47d可见新生血管芽进入角膜缘,4～10d时新生血管生长最为旺盛;至20d时新生血管最长为7.33±0.46mm,新生血管面积为38.96±4.11mm2。两组角膜新生血管出现时间、最长新生血管、新生血管面积方面均具有统计学差异(P<0.01)。在不同时段里K1-5组角膜基质层缝线周围新生血管较少,局部有少量浆细胞及成纤维细胞;PBS组新生血管较多,局部有较多浆细胞、淋巴细胞、成纤维细胞。K1-5组在不同时段里角膜组织中VEGF121阳性表达少于PBS组。结论:人K1-5蛋白点眼能够抑制缝线法诱导的角膜新生血管形成和生长。     

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。     

大鼠角膜新生血管生长与其周围基质内相关生物因子表达关系的研究

目的 探讨角膜新生血管周围间质相关生物因子与新生血管生长之间的关系.方法 实验研究.40只Wister大鼠采用NaOH滤纸烧灼法制作碱烧伤角膜新生血管模型.术后1、3及7 d,免疫荧光法检测角膜新生血管周围角膜基质间质相关生物因子包括转化生长因子β1(TGF-β1)、α平滑肌肌动蛋白(α-SMA)、成纤维细胞激活蛋白(FAP),并观察它们与新生血管之间的关系,以血小板内皮细胞黏附因子(CD31)标记血管内皮细胞.采用RT-PCR方法 检测术后3、7 d的FAP在角膜中不同位置的表达.苦味酸天狼猩红-偏振光法检测术后7 d角膜基质中主要胶原Ⅰ型和Ⅲ型胶原的改变.结果 碱烧伤后1、3及7 d角膜冰冻切片免疫荧光单染与双染显示,角膜基质首先出现TGF-β1阳性表达,然后随着新生血管的形成出现α-SMA、FAP同时阳性的细胞,正常角膜组织内无阳性表达.FAP阳性基质细胞位于CD31阳性的血管内皮细胞周围,与血管内皮细胞伴行生长,两者无明显的先后顺序.RT-PCR结果 显示,新生血管生长到达的位置出现FAP阳性表达.角膜新生血管生长后基质中Ⅰ型、Ⅲ型胶原重新排列.结论 角膜新生血管形成时,血管周围基质相关生物因子发生了改变,出现了FAP阳性的基质细胞,此细胞包绕并伴随血管内皮细胞生长;角膜基质中Ⅰ型、Ⅲ型胶原蕈新排列以适应新生血管的生长.(中华眼科杂志,2009,45:158-163)     

地塞米松对兔角膜新生血管组织中IL-1β及TNF-α表达的影响

目的：探讨地塞米松对缝线诱导的兔角膜新生血管组织中IL-1β及TNF-α表达的影响,分析地塞米松治疗角膜新生血管(corneal neovascularization,CNV)可能的分子机制。

方法：成年家兔43只,随机选取40只兔双眼行角膜基质层缝线建立兔角膜新生血管模型,造模成功后右眼(A组)未行特殊处理,左眼(B组)给予地塞米松局部注射,未造模3只兔双眼为正常对照,造模后裂隙灯动态观察新生血管的形态并计算其生长面积,并分别于造模后1,4,7,14,21d各处死8只兔,取角膜新生血管组织行HE染色观察其病理学特点,并检测角膜中IL-1β及TNF-α的表达情况。

结果：缝线后4d可见CNV长入,7～14d生长最为旺盛,HE染色见炎性细胞浸润,浅基质层大量新生血管生长,免疫组化染色提示,随缝线时间延长角膜IL-1β及TNF-α的表达逐渐增加; 而经地塞米松治疗后,CNV较前延迟长入,面积缩小,炎性细胞浸润减轻,且角膜中IL-1β及TNF-α的表达较单纯缝线眼明显降低,结果有统计学意义(P<0.05)。

结论：地塞米松可能通过早期抑制角膜组织中IL-1β及TNF-α表达而抑制新生血管的生长。     

重组色素上皮细胞衍生因子抑制鸡胚绒毛尿囊膜血管及兔角膜新生血管

目的:观察制备的重组色素上皮细胞衍生因子(rPEDF)对鸡胚绒毛尿囊膜(CAM)血管及兔角膜新生血管的抑制作用。方法:制备rPEDF,采用鸡胚绒毛尿囊膜分析,观察rPEDF抑制新生血管生长情况。利用碱烧伤制作兔角膜新生血管模型,观察rPEDF抑制角膜新生血管生长状况。结果:rPEDF能明显抑制鸡胚绒毛尿囊膜血管生长。rPEDF治疗组兔角膜新生血管长度及生长面积明显少于对照组(P<0.05),差异有统计学意义。结论:制备的rPEDF抑制鸡胚绒毛尿囊膜血管生长,抑制兔角膜新生血管的形成。     

光动力学疗法治疗角膜新生血管后角膜的光电镜改变

目的观察应用国产光敏剂行光动力学疗法(PDT)治疗角膜新生血管后角膜的组织学改变。方法碱烧伤有色兔角膜制作角膜新生血管模型。血啉单醚5mg/kg自耳缘静脉注射,不同的能量密度61.2-52.8J/cm2的氲绿激光照射角膜新生血管根部,不注射血啉单醚并单纯行同等能量密度的激光照射组作为对照组,PDT治疗后3h、1周、1个月行角膜光电镜检查。结果PDT后3h可见角膜急性炎症反应,有大量中性粒细胞浸润和少量嗜酸性白细胞浸润,虹膜组织无损伤。PDT后1周角膜炎症反应大部分消失,可见新生血管腔内有无定形物质填塞和许多影子血管。透射电镜显示:PDT组角膜新生血管内皮细胞内线粒体显示出空泡样变,细胞形态不完整。结论血啉单醚作为光敏剂,应用氩绿激光对角膜新生血管行PDT治疗,导致新生血管内皮细胞损伤,能有效封闭角膜新生血管,对周围组织无明显损伤。     

The effect of total-body irradiation on corneal neovascularization in the Fischer 344 rat after chemical cauterization.

Previous investigations of corneal neovascularization after irradiation yielded discordant results. Most studies indicated that new blood vessel formation in the cornea is inhibited by irradiation. However, others reported that angiogenesis after corneal cauterization is similar in both irradiated and nonirradiated animals. To assess the effect of total-body irradiation on neovascularization further, the amount of angiogenesis was determined in irradiated rats after chemically induced corneal injury. Corneal tissue was evaluated quantitatively with computerized image analysis 2, 3, or 4 days postcautery in rats perfused with India ink and gelatin immediately after death. The rats were exposed to a single dose (9 Gy) of total-body irradiation 6 days before corneal cauterization. In both the nonirradiated and irradiated rats, neovascularization increased with the duration of the postcautery interval. The amount of corneal neovascularization was not significantly different in the irradiated and nonirradiated rats at any of the postcautery intervals studied. This investigation suggests that endothelial cell migration plays a more important role than cell replication in the pathogenesis of corneal angiogenesis in the Fischer 344 rat. Moreover, the suppression of corneal angiogenesis by irradiation may be dependent on the experimental conditions and species examined.     

Improved semiautomatic method for morphometry of angiogenesis and lymphangiogenesis in corneal flatmounts

Purpose of the study was to describe a novel semiautomatic, quantitative image analysis method based on threshold analysis for morphometry of corneal (lymph)angiogenesis and to test its validity, reliability and objectivity. Murine corneas were vascularized by using a suture-induced neovascularization assay. For immunohistochemistry, flatmounts of the vascularized corneas were stained with LYVE-1 as a specific lymphatic vascular endothelial marker and with CD31 as panendothelial marker. Morphometry of corneal hem and lymphangiogenesis was performed semi-automatically on digital images using image analysis software. Data were analyzed by a paired t-test, intraclass-correlation and systemic difference analysis compared to a manual method. The semiautomatic method based on threshold analysis was more valid in measuring the area covered by blood or lymphatic vessels. Both methods had a good reproducibility with respect to both vessel types (blood vessels: manual: 0.969, semiautomatic: 0.982; lymphatic vessels: manual: 0.951, semiautomatic: 0.966), whereas the systemic difference was significant for both groups measuring lymphatic vessels (manual: p < 0.003; semiautomatic: p < 0.035) and for the manual method measuring blood vessels (manual: p < 0.0001; semiautomatic: p < 0.419). The new semiautomatic morphometry method based on threshold analysis provides higher accuracy, is more valid than and at least as reproducible and objective as the manual outlining method. Therefore the semiautomatic method can be used to detect even small effects on hem and lymphangiogenesis in murine corneal flatmounts with greater precision.     

高血脂对脉络膜VEGF表达的影响

目的：研究高血脂动物模型脉络膜组织学改变及VEGF的表达,初步探讨高血脂在年龄相关性黄斑变性（AMD）患者脉络膜新生血管（CNV）形成中的作用及其机制。方法：新西兰大白兔36只随机分为正常对照组与实验组,分别喂养普通饲料与高脂饲料。分别于1,2,3mo后应用免疫组织化学法和RT-PCR法对脉络膜VEGF表达进行检测。结果：免疫组织化学结果显示对照组视网膜和脉络膜各层VEGF弱表达;实验组1mo时脉络膜组织中VEGF表达与对照组差异无统计学意义（t=0.442,P=0.668）;2mo时脉络膜组织中VEGF表达较对照组明显增强（t=2.330,P=0.042）;3mo组脉络膜组织中VEGF表达较对照组明显增强（t=3.542,P=0.005）。RT-PCR示对照组脉络膜组织中可以检测到微弱的VEGFmRNA表达;实验组1mo时脉络膜组织中VEGFmRNA的表达与对照组差异无统计学意义（t=1.703,P=0.119）;2mo组脉络膜组织中VEGFmRNA表达较对照组明显增强（t=14.138,P〈0.001）;3mo组脉络膜组织中VEGFmRNA表达较对照组明显增强（t=15.240,P〈0.01）。结论：高血脂通过直接损害脉络膜血管和增强VEGF的表达可能诱导CNV的发生。     

应用血啉单醚光动力疗法治疗角膜新生血管的研究

目的观察应用血啉单醚行光动力疗法(PDT)治疗角膜新生血管的效果。设计前瞻性随机对照实验。研究对象成年有色兔18只。方法制作碱烧伤角膜新生血管模型。血啉单醚5mg/kg静脉注射,不同能量密度(7.6￣152.8J/cm2)的氩绿激光照射角膜新生血管根部,不注射血啉单醚只单纯行同等能量密度的激光照射组作为对照组。主要指标PDT的能量密度,行角膜新生血管荧光素造影观察新生血管封闭情况。结果PDT后3天,角膜新生血管荧光素血管造影显示:应用61.2J/cm2及以上的能量,有67%以上的眼角膜新生血管被完全封闭,33%的眼部分有效。PDT后1周,61.2J/cm2及以上组仍有66.7%(16/24眼)的眼角膜新生血管完全封闭。激光后1个月5/24眼无新生血管出现,其余眼再次出现新生血管。结论采用激光能量密度在(61.2￣152.8)J/cm2照射的PDT治疗能完全或部分封闭兔碱烧伤角膜新生血管模型中的角膜新生血管,但有新生血管再生。(眼科,2006,15:180-183)     

Photodynamic therapy with verteporfin in a rabbit model of corneal neovascularization

PURPOSE: To determine the efficacy of photodynamic therapy (PDT) with verteporfin (Visudyne; Novartis AG, Basel, Switzerland) for treatment of corneal neovascularization in a rabbit eye model. METHODS: Corneal neovascularization was induced in Dutch belted rabbits by placing an intrastromal silk suture near the limbus. Verteporfin was administered by intravenous injection at a dose of 1.5 mg/kg, and the pharmacokinetics of verteporfin distribution in the anterior segment or PDT-induced (laser energy levels 17, 50, and 150 J/cm(2)) regression of corneal blood vessels were then determined. To assess PDT-induced toxicity of the anterior segment, corneal and iris/ciliary body histology, and IOP were evaluated after PDT. RESULTS: Verteporfin accumulation in vascularized regions of the cornea and the iris/ciliary body tissue were time dependent and maximum levels achieved at 60 minutes after injection. In rabbits, PDT of corneal vessels using laser energy of 17 or 50 J/cm(2) resulted in 30% to 50% regression of corneal neovascularization; however, in these animals, a rapid regrowth of new blood vessels occurred between 3 and 5 days. In the rabbits receiving PDT using laser energies of 150 J/cm(2), the mean vessel regression was 56%. During the nine days of the laser therapy follow-up period, no vessel regrowth was observed in these rabbits. Histologic examination of the anterior segment after PDT (150 J/cm(2)) showed localized degeneration of the corneal blood vessels without observable change in other anterior segment structures. CONCLUSIONS: These results provide evidence that PDT can produce significant regression of neovascular corneal vessels with no observable toxicity to the anterior segments. However, the optimal laser energy necessary to induce long-term regression (150 J/cm(2)) was three times that used to treat choroidal neovascularization.     

热灼伤致家兔角膜新生血管形成动物模型研制及皮质激素对其的抑制作用

在热灼伤致家兔角膜新生血管形成动物模型研制中，观察到热灼伤家兔角膜产生类似炎症反应的现象，并从肉眼观察和病理上证实了热灼伤可刺激角膜新生血管的增生。从角膜缘增生的新生血管于第5～7天达到和覆盖灼伤面，20天后基本消退。醋酸可的松可明显地抑制新生血管增生现象。证明此法简单易行。为临床探索抗角膜新生血管药物的研究提供了可靠的实验动物模型。     

Suppression of experimental corneal angiogenesis by focal X-ray irradiation.

PURPOSE: To investigate the effect of focal X-ray irradiation on experimental corneal angiogenesis in the rabbit. METHODS: A gelatin hydrogel sheet impregnated with basic fibroblast growth factor was implanted into the corneal stroma of rabbits; this induced corneal angiogenesis. After the first sign of corneal angiogenesis was noted, the corneal region was irradiated with a dose of 10 Gy or 20 Gy. The control rabbits received no irradiation. The eyes were examined by slitlamp biomicroscopy and photographed, over a period of 28 days. The maximum length and total surface area of corneal angiogenesis were quantified by computerized image analysis. RESULTS: Corneal angiogenesis was noted on day 3 following implantation of the hydrogel sheet. In the rabbits irradiated with 10 Gy, the maximum length and total surface area of corneal angiogenesis were both significantly lower on day 4 and 7 following irradiation, compared to the respective measurement in the controls. In the rabbits irradiated with 20 Gy, the maximum length and total surface area of corneal angiogenesis were significantly lower between days 4 and 21, and between days 4 and 14, respectively, compared to the respective measurement in the controls. CONCLUSIONS: Focal X-ray irradiation to the corneal region suppressed corneal angiogenesis in a dose-dependent manner. Focal X-ray irradiation may be beneficial in treating ocular angiogenesis.     

Pathophysiology of intraocular neovascularization]

The pathology of intraocular neovascularization was studied in human and animal eyes by means of electron microscopy and histochemistry, and also by tissue culture of bovine retinal small vessels. The newly formed vessels in the vitreous obtained at the time of vitrectomy from the eyes with proliferative diabetic retinopathy and retinal vein occlusion lacked tight junction and formed fenestration in the endothelial cells. When 1 microgram of the basic fibroblast growth factor (b-FGF) enveloped in ethylene vinyl acetate copolymer was implanted into the vitreous of monkey eyes, new vessels were formed in the iris in all eyes and in the vitreous in 12 eyes out of 14 experimental eyes. The origins of new vessels were the iris vessels in the iris, and both stromal vessels of the ciliary body and retinal vessels in the vitreous. These vessels showed fenestration in the endothelial cells. The activity of the lysosomal enzyme detected by acid phosphatase increased in the epithelial layer of the ciliary body. The new vessels in the vitreous of rabbits were seen in 9 out of 10 eyes when b-FGF was implanted in the vitreous with an intravitreal injection of amino adipic acid solution (1 mg in 0.2 ml of physical saline), although none of the 8 eyes formed new vessels when sodium iodate was injected intravenously after implantation of b-FGF with aminoadipic acid. Corneal neovascularization was formed by implantation of 250 ng of b-FGF into the corneal micropockets of the guinea pigs, and regressed after the b-FGF was removed. The endothelial budding and protrusion were frequently seen during the course of neovascularization. Immunohistochemical detections showed positive stainings for fibronectin in most front-end lesions, for laminin and type 4 collagen associated with the endothelial cells, and for factor VIII only on the endothelial cells which formed the vascular lumen. The acid phosphatase activity was detected on the leucocytes infiltrating in the corneal stroma. In the course of regression of corneal neovascularization, initial pathological change was thrombus formation followed by disappearance of endothelial cells, although the basement membrane of the endothelial cells remained. Fibronectin reduced its activity in the early stage of regression, laminin and type 4 collagen remained even after the vascular lumen had subsided, and factor VIII was stained in a geographically irregular manner. Migrating activity of the cultured-bovine retinal small vessels was accelerated by fibronectin and fetal bovine serum.     

Effect of irradiation on vascularization of corneas grafted onto chorioallantoic membranes

Several studies have shown that total body irradiation decreases the angiogenic response to corneal cauterization. This inhibition could be due to alterations in angiogenic stimuli within injured corneas and/or to a decreased ability of irradiated animals to respond to such stimuli. To determine whether total body irradiation specifically affects angiogenic stimuli within injured corneal tissue, cauterized corneas from mice exposed to 900 rads of total body irradiation and from non-irradiated controls were grafted onto the chorioallantoic membranes (CAM) of chick embryos and their abilities to stimulate the ingrowth of healthy embryonic blood vessels were compared. Cauterized corneas incorporated into CAM mesenchymal tissue were invaded by blood vessels in 34.6% of the irradiated group and in 75% of the non-irradiated controls. This difference in the two groups was statistically significant (P less than 0.03). Total body irradiation significantly decreased the frequency of vascular invasion of cauterized corneal tissues by healthy CAM blood vessels. This finding suggests that total body irradiation can specifically affect the stimulus for angiogenesis within cauterized corneas.     

Comparison of the inhibitory effect of different doses of subconjunctival bevacizumab application in an experimental model of corneal neovascularization

AIM: To evaluate the inhibitory effect of subconjunctival bevacizumab as single- and multiple-dose application, and compare their effects on corneal neovascularization in a rat model. METHODS: Thirty adult Sprague-Dawley rats were used in this experimental study. The central cornea of the rats was cauterized chemically. The rats were randomly enrolled into three groups. All groups received subconjunctival injections. In Group 1 (control group, n=10), 0.05 mL 0.9% NaCl solution was injected on the first day. In Group 2 (single-dose group, n=10), 0.05 mL bevacizumab (1.25 mg) was injected on the first day. In Group 3 (multiple-dose group, n=10), four doses of 0.05 mL bevacizumab (1.25 mg) were injected on the first, third, fifth and seventh day. Slit-lamp examination of all rats was performed at the third and ninth day. Digital images of the corneas were taken and analyzed using image analysis software to calculate corneal neovascularization area. All rats were sacrificed on the tenth day. In corneal sections, the number of blood vessels, state of inflammation and collagen formation was evaluated histopathologically. RESULTS: In Group 3, corneal edema grades were significantly lower than Group 1 and Group 2 (P=0.02, and P=0.035, respectively). The mean percentage of neovascularized corneal area in Group 3 was significantly lower than Group 2 (P=0.005). On histopathological examination, Group 2 and Group 3 showed significantly less number of blood vessels than Group 1 (P=0.005, and P=0.001, respectively). Additionally, Group 3 showed significantly less number of blood vessels compared to Group 2 (P=0.019). Inflammation and edema grades were significantly lower in Group 3 compared to Group 1 (P=0.001). CONCLUSION: Subconjunctival bevacizumab injection is effective in inhibition of newly formed corneal neovascularization. The multiple-dose bevacizumab treatment seems to be more effective compared to single-dose treatment.