Experimental Study Of CO₂ Laser Assisted Filtering Surgery On Rabbits Intraocular Hypertension Model

Purpose:To study the security,feasibility,validity and superiority of performing filtering surgery by using a CO₂ laser device on rabbits intraocular hypertension model.Contents:Part 1:Preparation of rabbits intraocular hypertension model;Part 2: Experimental study of doing CO₂ laser assisted filtering surgery on rabbits intraocular hypertension model.Methods:Part 1:Intraocular hypertension model was induced by posterior chamber injection ofα-chymotrypsin(concentration is 320U/0.25ml)0.15-0.20ml in 8 rabbits' eyes.After injection,the appearance of the rabbits' eyes was obseved,and the intraocular pressure was recorded in 2 months.Part 2:Induce rabbits intraocular hypertension model,then chose 24 rabbits 48 eyes which were successful induced. On the right eye of each rabbit we performed sclerectomy with a scleral flap and iridectomy by pulse CO₂ laser(power 4-5W,pulse duration 0.8ms,frequency 100Hz)which was outputed by the CO₂ laser device,and we called it as laser group,the left eye was treated with conventional trabeculectomy as a comparison,called surgery group.Postoperative anterior chamber reaction,filtering bleb,intraocular pressure and pathology examination were observed and contrasted in 2 months between the two groups.Results:Part 1:Before injection ofα-chymotrypsin,the mean IOP of the 8 eyes was 10.1±1.05mmHg.After injection,all the eyes showed a significant rising IOP,mean IOP of the 3,7,14,30 and 60 days postoperation were 15.98±2.91 mmHg,21.84±5.18mmHg,23.41±5.02mmHg,23.86±3.97 mmHg and 25.37±3.16 mmHg.They were all obviously different from the pre-operation IOP,and the IOP had no difference among the 14,30 and 60 days after injection.Lens dislocation combined staphyloma developed only in one rabbit's eye,and the other eyes had no serious complication occurred.Inflammatory reaction of anterior part had all disapeared within 3-10 days postoperation.Part 2:Anterior chamber reaction of laser group was mild,only 2 eyes had slight hemorrhage around iris hole;surgery group had serious reaction,16 eyes appeared obvious hemorrhage and massive exudation.Both of the two groups had most functional filtering bleb in earlier period postoperation.Until 14 and 21 days postoperation,surgery group appeared a obviously decrease of functional filtering bleb number,the proportions were 62.5%(10/16)and 33.3%(4/12),but laser group still had 93.8%(15/16)and 75%(9/12),there was statistical difference between them.IOP decreased significantly in early period postoperation in both the two groups,and there was no difference between them.Then IOP increased gradually,surgery group happened earlier,IOP of the two groups became differently at 14 and 21 days postoperation.Pathology examination showed both the two groups had unobstructed filtering channel in earlier period,but surgery group appeared serious hemorrhage and exudation.Fiber proliferation reacted later and milder in laser group,until 60 days postoperation there was still some interspace in filtering channel.Conclusion:Part 1:Posterior chamber injection ofα-chymotrypsin(concentration is 320U/0.25ml)0.15-0.20ml in rabbits' eyes could induce successful intraocular hypertension model with stable,lasting higher IOP and little complication.Part 2: Pulse CO₂ laser sclerectomy with a scleral flap and iridectomy in rabbits intraocular hypertension model was safe and feasilbe,it could lower IOP significantly,compared with conventional trabeculactomy it was easier and faster with milder inflammation,hemorrhage,proliferation and stable,lasting lower IOP.