Effects Of Changes In Intraocular Pressure On The Calculation Of Intraocular Lens

Aim:To measure the axial eye length(AL)and corneal curvature(K)of age-related cataract patients under different intraocular pressure by IOL master,to evaluate the influence of intraocular pressure(IOP)on the calculation of intraocular lens(IOL).To provide reference for IOL degree selection under high intraocular pressure.Methods:This is a prospective study enrolling 87 cataract patients who have visited the Department of Ophthalmology,Affiliated Hospital of Qingdao University from May to August in 2017.87 cases(87 eyes)age-related cataract patients were divided into 3groups according to the axial eye length,Group A short AL group(AL < 23mm),Group B normal AL group(23mm≤AL≤26mm),Group C long AL group(AL >26mm).Both eyes were examined with slit lamp,ophthalmoscope,non-contact tonometer,ocular ultrasound,OCT and IOL master before the surgery.And the patients’ sex,age and general condition were recorded.The axial eye length and corneal curvature under different intraocular pressure were measured after the phacoemulsification and intraocular lens implantation.The effects of intraocular pressure on the length of axial eye length and corneal curvature were analyzed.Results:As for preoperative data,no significant statistical difference was noted in age,intraocular pressure and corneal curvature among the three group.With the elevation of intraocular pressure between 10 to 50 mm Hg,the axial eye length of the three groups all increased.When the intraocular pressure is increased by 0~10mm Hg,10~20mm Hg,20~30mm Hg,30 ~4mm Hg on the base value,the axial eye length of short AL group was increased by 0.034±0.006μm、0.075±0.007μm、0.093±0.007μm、0.123±0.003μm respectively.The normal AL group was increased by 0.057±0.005μm、0.134±0.017μm、0.140±0.016μm、0.150±0.004μm.The long AL group was increased by 0.201±0.045μm、0.497±0.0980μm、0.598±0.173μm、0.870±0.006μm.The long AL group changed the most,followed by the normal AL group and the short AL group changed the least.When the intraocular pressure is increased by 0~10mm Hg,10~20mm Hg,20~30mm Hg,30~40mm Hg on the base value,the corneal curvature of short AL group was-1.172±0.109 D 、-1.148±0.181 D 、-1.474±0.102 D 、-1.400±0.236 D respectively.The normal AL group was-1.181±0.160D、-1.184±0.113D、-1.096±0.167D、-1.379±0.155 D.The long AL group was-1.750±0.393D、-1.374±0.259D、-1.440±0.198D、-1.693±0.197 D.The corneal curvature in three groups did not follow any obvious regular patterns.Conclusion:The axial eye length became longer,as the intraocular pressure increased.For cataract patients under high intraocular pressure,especially accompanied with high myopia,it would be better to measure the ocular parameter after the intraocular pressure has been kept in normal level.