Discussion On Changes Of Biological Parameters Of Anterior Segment Before And After My Driasis

Objective:To investigate whether mydriasis will affect the biological parameters of the anterior segment of the cataract patients,lead to the deviation of calculation of intraocular lens power,and affect the postoperative uncorrected visual acuity.To dynamically observe the anatomical changes of degree of congestion with anterior segment before and after mydriasis.Methods:This study is a prospective and observational study.Patients who wished to undergo cataract surgery in our hospital were selected for preoperative examination of the whole body and both eyes.The biological parameters of the anterior segment of the eye were measured before and after mydriasis,and the intraocular lens power was calculated.All measurements were performed by the same experienced operator.The patients were dilated using Mydrin-P(compound tropicamide eye drops and Japanese Santen).When the pupil was greater than 6mm,A-scan was used to collect the Axial length(AL),lens thickness(LT)and anterior chamber depth(ACD)before and after mydriasis.Intraocular lens power,anterior chamber crowd rate(CCR,LT/ACD),and lens position(LP,ACD+1/2LT),lens thickness,axial length coefficient,etc were calculated.The differences in the measusanrement results before and after mydriasis were performed as paired t-tests or rank sum tests,respectively.Results:ACD value before mydriasis:2.74±0.50.ACD value after mydriasis:2.92(2.67,3.17).t=59.5,P<0.01.The difference was statistically significant.AL value before mydriasis:23.30±0.90.AL value after mydriasis:23.18±0.87.t=4.59,p<0.001.The difference was statistically significant.LT value before mydriasis:4.74±0.60.LT value after mydriasis:4.33(3.92,4.74).Rank sum test was used to compare LT value differeces.t=91.5,P<0.01.The difference was statistically significant.ACD/AL value before mydriasis:0.12±0.02.ACD/AL value after mydriasis:0.13(0.12,0.14).Rank sum test was used to compare ACD/AL value differeces before and after mydriasis.t=6.5,P<0.01.The difference was statistically significant.LT/AL value before mydriasis:0.20±0.03.LT/AL value after mydriasis:0.18±0.03.t=3,p=0.0049.The difference was statistically significant.LT/ACD value before mydriasis:1.78(1.51,2.05),LT/ACD value after mydriasis:1.46±0.42.t=51,P<0.01.The difference was statistically significant.Target IOL degree value before mydriasis:19.82±2.16,Target IOL degree value after mydriasis:20.42±2.14.t=5.14 and p=0.0000.The difference was statistically significant.Conclusion:1.After being applied cycloplegic,the cataract patients'depth of anterior chamber got deepened,thickness of lens thinned,eye axis shortened,ACD/AL increased,LT/AL decreased and LT/ACD decreased.2.The intraocular lens power calculated after mydriasis in cataract patient increased compared with that before dilation,suggesting that measuring biological parameters and calculating intraocular lens power should be performed without mydriasis.3.Cataract patients can be fully observed of the lens after dilation,suggesting that anterior segment congestion of cataract patients should be observed with dynamic changes in the angle,to exclude possible preoperative incomplete crystal dislocation,suspensory ligament and other diseases,to develop a detailed surgery plan and to avoid unnecessary complications.4.Multiple biological parameters of the anterior segment change after dilation,suggesting that there are still residual accommodations in age-related cataract patients.