Effect of 90Sr-90Y ophthalmic applicator on corneal neovascularization after alkali burn

Abstract

Background Corneal neovascularization ( CNV ) is a complication of many ocular surface diseases.It often worsen the pathological course.Effective therapy for CNV is still researching. Objective This study was to investigate the inhibitory effect of irradiation on CNV. Methods CNV models were established in 70 right eyes of 70 clean Wistar rats by corneal alkali burning.The models were randomized into β ray 10 Gy once irradiation group( 2 eyes),β ray 7 Gy multiple irradiation group( 17 eyes),β ray 10 Gy multiple irradiation group( 17 eyes),1％ cyclosporin A ( CsA ) eye drops group ( 17 eyes) and model group ( 17 eyes),and 6 matched normal rats were used as normal controls.All treatments started from the first day of the corneal alkali burning.CNV length and area were measured under the slit lamp every day.Corneal samples and homogenate were prepared 3,5,7 days after corneal alkali burning.The expressions of bcl-2,bax,vascular endothelial growth factor(VEGF) in rat corneas were detected by immunochemistry,VEGF proteins and VEGF mRNA were detected by Western blot and reverse transcription polymerase chain reaction (RT-PCR),respectively. Results Corneal ulceration was found in the βray 10 Gy once irradiation group and β ray 10 Gy multiple irradiation group.CNV length and area were much less in the β ray 7 Gy multiple irradiation group and 1％ CsA eye drops group compared with the model group on the seventh day after experiment( length:q=14.40,24.20,P＜0.01 ;area:q=17.80,14.00,P＜0.01 ).Immunochemistry revealed that compared with the model group,expressions of bcl-2 and VEGF proteins were weaker,but the expression of bax protein was stronger in the β ray 7 Gy multiple irradiation group and 1％ CsA eye drops group.RT-PCR showed that the expression of VEGF mRNA in cornea was lower in the β ray 10 Gy multiple irradiation group,β ray 7 Gy multiple irradiation group and 1％ CsA eye drops group in comparison with that in model group,and the results from Western blot showed the same pattern as RT-PCR. Conclusions Low dose irradiation of 90Sr-90Y ophthalmic applicator inhibits CNV formation after alkali burn.The study provide a new understanding of the irradiation for the treatment of CNV. Key words: Irradiation; Corneal alkali burn; Corneal neovascularization; 90Sr-90Y ophthalmic applicator