锰离子滴眼液局部应用对眼前节组织的毒性作用

背景 锰离子滴眼液用于活体视觉传导通路的示踪观察方法已有研究,但锰离子局部点眼对眼前节组织的毒性作用尚无深入研究. 目的 研究不同质量浓度锰离子滴眼液对兔眼眼前节组织的毒性作用.方法 选取32只清洁级新西兰白兔,按照随机数字表法随机分为1.00 mol/L MnCl2组、0.50 mol/LMnCl2组、0.25 mol/L MnCl2组以及对照组,每组8只.采用抽签法随机选择动物一侧眼为实验眼,按照分组情况分别用1.00、0.50、0.25 mol/L锰离子滴眼液及生理盐水各1滴点于结膜囊中,分别于点眼后2h及1、3、7、14、21和28 d时在裂隙灯显微镜下观察眼局部刺激反应;用角膜荧光素染色法观察角膜上皮损伤情况并进行评分;采用角膜内皮镜观察角膜内皮细胞密度(ECD)和角膜厚度,并于点眼后3、7、14、28 d行苏木精-伊红染色,检查结膜、角膜、小梁网及睫状体的组织病理学变化.结果 1.00 mol/L MnCl2组和0.50 mol/L MnCl2组兔眼均出现睑结膜充血、水肿及大量分泌物等刺激症状,1.00 mol/L MnCl2组兔眼于点眼后1d刺激反应最强,点眼后7d反应消失;0.50 mol/L MnCl2组兔眼眼表刺激反应程度轻于1.00 mol/L MnCl2组,持续到点眼后3 d;0.25 mol/L MnCl2组兔眼点眼后未见明显的眼表刺激反应.点眼后2h、1d、3d及7d,各组兔眼角膜上皮荧光素染色评分总体比较差异均有统计学意义(x2=17.350、19.200、12.200、10.140,均P＜0.05).各组兔眼点眼后不同时间点ECD总体比较差异无统计学意义(F分组=0.38,P＞0.05;F时间=1.79,P＞0.05).各组兔眼点眼后不同时间点角膜厚度总体比较差异有统计学意义(F分组=18.22,P＜0.05;F时间=116.75,P＜0.05)点眼后2h～3d,1.00 mol/L MnCl2组兔眼角膜厚度值明显增加,但点眼后7～28 d,各组兔眼角膜厚度值接近,点眼后2h～14d角膜厚度值均明显高于点眼后28 d,0.50 mol/L MnCl2组兔点眼后2h～1d角膜厚度值明显高于点眼后28 d,差异均有统计学意义(均P＜0.05).组织病理学检查结果显示,1.00 mol/L MnCl2组兔眼于点眼后3d和7d可见结膜、小梁网和睫状体的炎性细胞浸润及角膜基质水肿,0.50 mol/L MnCl2组于点眼后3d可见结膜炎性细胞浸润,但角膜、小梁网和睫状体组织未见明显异常,而0.25 mol/L MnCl2组兔眼点眼后结膜、角膜、小梁网和睫状体均未见明显异常.结论 1.00 mol/L锰离子滴眼液对兔眼眼前节有明显毒性作用,0.50 mol/L锰离子滴眼液的毒性则明显降低,0.25 mol/L锰离子滴眼液对兔眼眼前节无明显的毒性作用.

Toxic effects of manganese ion eyedrops to ocular anterior segment

Background A preliminary study determined an application of manganese ion eyedrops in tracing observation of visual system in vivo,but whether manganese ion has toxic effects on ocular anterior segment tissues is still unclear.Objective This study was to investigate the toxic effects of different concentrations of manganese ion eyedrops on ocular anterior segment tissues.Methods Thirty-two clean New-Zealand white rabbits were divided into 1.00 mol/L MnCl2 group,0.50 mol/L MnCl2 group,0.25 mol/L MnCl2 group and normal control group according to random number table.The experimental eye was randomly chosen from each rabbit for eyedrops application.The manganese ion eyedrops at concentration of 1.00 mol/L,0.50 mol/L or 0.25 mol/L was topically administered in any lateral eye of each rabbit in the 1.00 mol/L MnCl2 group,0.50 mol/L MnCl2 group,0.25 mol/L MnCl2 group,and normal saline solution was used in the same way in the normal control group.In 2 hours,1 day and 3,7,14,21,28 days after eyedrops application,the irritative response of ocular surface was examined under the slit lamp microscope,and corneal damage was evaluated by corneal fluorescence staining,and corneal endothelial cell density (ECD) and corneal thickness were assessed using corneal specular microscope.The eyeball samples were prepared in 3,7,14 and 28 days after eyedrops application and hematoxylin and eosin staining was performed for histopathological examination of conjunctiva,cornea,trabecular meshwork and ciliary body tissue.The use and care of experimental animals complied with the Statement of ARVO.Results Severe hyperemia and edema in palpebral conjunctiva appeared in the 1.00 mol/L MnCl2 group and 0.50 mol/L MnCl2 group,and the symptoms reached a maximum level 1 day after eyedrop application and disappeared 7 days after eyedrops application in the 1.00 mol/L MnCl2 group.These symptoms were milder in the 0.50 mol/L MnCl2 group in comparison with the 1.00 mol/L MnCl2 group.There were no ocular irritative response in the 0.25 mol/L MnCl2 group.Significant differences were found in the corneal fluorescence scores among the groups 2 hours,1 day,3 and 7 days after eyedrop application (X2 =17.350,19.200,12.200,10.140,all at P＜0.05),with the highest score in the 1.00 mol/L MnCl2 group.The ECD was not significantly different among the groups and different time points (Fgroup =0.38,P＞0.05;Ftime =1.79,P＞0.05).The corneal thickness value was significantly different among the groups and different time points (Fgroup =18.22,P＜0.05;Ftime =116.75,P ＜ 0.05).The corneal thickness value was elevated during 2 hours to 3 days after administration of eyedrops in the 1.00 mol/L MnCl2 group and closed to normal from 7 days to 28 days.The corneal thickness value was higher from 2 hours to 14 days than that in 28 days after administration of eyedrops in the 1.00 moL/L MnCl2 group,and the corneal thickness value was higher in 2 hours to 1 day than that in 28 days after administration of eyedrops in the 0.50 mol/L MnCl2 group (all at P＜0.05).Inflammatory cell infiltration and stromal edema were exhibited in conjunctival,trabecular meshwork and ciliary body tissue in the 1.00 mol/L MnCl2 group 3 days and 7 days after eyedrops application,and only inflammatory cell infiltration in conjunctival tissue in the 0.50 mol/L MnCl2 group 3 days after eyedrops application.No obvious abnormity was seen in the 0.25 mol/L MnCl2 group.Conclusions 1.00 mol/L manganese ion eyedrops has a remarkable toxic effect on ocular anterior segment tissue in rabbit.With the lowing of drug concentrations,the toxic effects were reduced.The manganese-enhanced MRI using 0.25 mol/L manganese ion eyedrops is feasibility bacause of its non-toxicity to ocular tissues.