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:strafe laser parameters used sclerotic bed choice.Part 3: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 of a-chymotrypsin (concentration is 250U/0.25ml) 0.15-0.20ml in 10 rabbits'eyes.After injection,the appearance of the rabbits'eyes was obseved,and the intraocular pressure was recorded in 2 months. Part 2:with different laser parameters in the first part of the rabbit already preparation successful steroid-induced ocular hypertension model, eye under the bed strafe scleral flap scleral observed, two eyes in the first week after the first day and the pathological changes of the situation. Used to select the best scleral flap strafing laser parameters. Part 3:preparation rabbit high intraocular pressure model, the preparation of successful choice model 20 rabbit right 40 eyes, super pulse CO2 laser application under the bed for sclera disc strafing (average power scleral 1W, pulse width 0.1 ms, frequency 100Hz) and sclera excision with iridectomy (average power 4-5W, pulse width 0.8 ms, frequency 100Hz, called laser group; Do traditional trabeculectomy left by contrast, called scores. Observe and comparing the two groups of different period after the anterior chamber reaction, filtering bleb, intraocular pressure and histopathological changes.Results:Part 1:Before injection of a-chymotrypsin,the mean IOP of the 10 eyes was 12.10±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 3-7 days postoperation. Part 2:through a microscope and pathological comparative draw strafe the best used the sclerotic bed laser parameters for the average power 1W, pulse width 0.1 ms 100Hz, frequency. Part 3:Anterior chamber reaction of laser group was mild,only 2 eyes had slight hemorrhage around iris hole;surgery group had serious reaction,12eyes appeared obvious hemorrhage and massive exudation. Both of the two groups had most functional filtering bleb in earlier period postoperation.Until 14 days postoperation,surgery group appeared a obviously decrease of functional filtering bleb number,the proportions were 58.3% (7/12) and 12.5%(1/8),but laser group still had 91.7%(11/12) and 62.5%(5/8), 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 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 of a-chymotrypsin (concentration is 250U/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:use CO2 laser parameters can be accommodative can make sclera bed surface solidification and change happened wound of the smooth, without causing too much damage effect, thus reach repair wound and reduce fiber proliferation goal. Part 3: 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.