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目的探究不同强度和时间紫外线照射对大鼠泪膜稳定性和角膜组织的影响。设计实验研究。研究对象50只健康SD大鼠(6周,200~250 g)。方法将大鼠随机分成5组(空白对照组N和实验组A、B、C、D),每组10只,A、C组紫外线照射强度为142μw/cm~2,每次照射时长为8、12分钟;B、D紫外线照射强度为94μw/cm~2,每次照射时长为12、18分钟。共照射42天,每周照射3次,均间隔1天,照射后第14、28、42天,裂隙灯检查、荧光素染色及泪膜破裂时间(BUT)测定、Schirmer I试验(SIt)。49天时注射过量水合氯醛处死大鼠,制作角膜组织切片。主要指标结膜、角膜、泪膜形态结构变化,角膜荧光素染色评分,BUT,SIt值,角膜组织切片观察。结果裂隙灯检查显示B、C组对比,照射强度较高组比较低组睑结膜充血、角膜水肿、角膜混浊出现早且严重,较高强度组照射后出现角膜新生血管,较低强度组以泪液质和量改变为主要特征。A、C组对比,长时间照射组比短时间照射组角膜水肿、混浊和新生血管出现的时间早且严重,且长时间照射组睑裂区出现条状溃疡。荧光素染色显示,正常组染色评价结果为阴性,A组为阳性,B组为弱阳性,C、D组为强阳性。第42天,A、B、C、D组BUT值分别较对照组明显减少(P均<0.01)。第42天,实验组SIt值分别较对照组均明显增加(P均<0.01)。组织学观察显示,较高强度紫外线照射引起角膜新生血管,内皮细胞密度下降,基质层纤维细胞排列紊乱。较低强度短时间照射引起上皮层增厚。较低强度长时间照射引起角膜新生血管,基质层纤维细胞排列紊乱。结论长时间紫外线照射可引起睑结膜充血、角膜上皮损伤、泪液质和量改变等眼表结构变化,这些变化随照射强度增大或照射时间增长而出现更早、程度更重。
Objective To investigate the effects of ultraviolet radiation with different intensity and time on tear film stability and corneal tissue in rats. Design experiment research. Subjects 50 healthy SD rats (6 weeks, 200 ~ 250 g). Methods The rats were randomly divided into 5 groups (blank control group N and experimental group A, B, C, D), each group 10, A, C group UV irradiation intensity of 142μw / cm ~ 2, each irradiation duration of 8 , 12 minutes; B, D UV irradiation intensity of 94μw / cm ~ 2, each irradiation duration of 12,18 minutes. A total of 42 days irradiation, 3 times a week irradiation, 1 day intervals, 14,28,42 days after irradiation, slit lamp examination, fluorescein staining and tear film break time (BUT) determination, Schirmer I test (SIt). On the 49th day, rats were sacrificed by injecting an excess of chloral hydrate, and corneal tissue sections were made. The main indicators of conjunctiva, cornea, tear film morphological changes, corneal fluorescein staining score, BUT, SIt value, corneal tissue section observation. Results Slit lamp examination showed that corneal neovascularization occurred in corneal conjunctival hyperemia, corneal edema, corneal opacity and early severe corneal opacity in groups B and C compared with those in higher intensity groups. Quality and quantity changes as the main features. Compared with group A and group C, corneal edema, turbidity and neovascularization appeared earlier and more severe in long-term irradiation group than in short-time irradiation group, and strip ulcers appeared in the long-term irradiation group. Fluorescein staining showed that the staining results of normal group were negative, group A was positive, group B was weakly positive, group C and D were strongly positive. On the 42nd day, the BUT values in groups A, B, C and D were significantly lower than those in control group (all P <0.01). On the 42nd day, the SIt values in experimental group were significantly higher than those in control group (all P <0.01). Histological observations showed that higher intensity ultraviolet radiation caused corneal neovascularization, endothelial cell density decreased, stromal fibroblasts arranged disorderly. Lower intensity short-term exposure causes thickening of the epithelium. Corneal neovascularization and stromal fibrocytes were disordered when exposed to low intensity for a long time. Conclusion Long-term ultraviolet radiation can cause ocular surface structural changes such as conjunctival hyperemia, corneal epithelial injury, changes in tear fluid and volume. These changes appear earlier and more severe with increasing irradiation intensity or irradiation time.