Influence Of IOP Changes After Phacoemulsification Combined With Iol Implantation And Viscogoniosynechialysis On Post-operative Refraction Among PACG Patients

Purpose : To optimize the IOL calculation by studying the influence of IOP changes before and after phacoemulsification combined with IOL implantation and viscogoniosynechialysis on IOL calculation of PACG patients.Methods: A prospective nonrandom cohort study.Total 50 patients who were diagnosed as primary angle-closure glaucoma at Joint Shantou International Eye Center of Shantou University and the Chinese University of Hong Kong during December 2019 to January 2021 were recruited.All cases received phacoemulsification combined with IOL implantation of a single-piece acrylic IOL and viscogoniosynechialysis.Goldmann tonometer were performed to the patients after preoperative examination(B scan,IOL Master 700 and corneal endothelial endoscopy)instantly in the day before surgery.Pared t test was used to compare the difference between intraocular pressure(IOP)and ocular biometric parameters were measured by IOL Master 700 one month postoperatively and preoperatively.As well,the relationship of intraocular pressure changes before and after surgery(ΔIOP)and refractive prediction error(PE was defined as the actual postoperative spherical equivalent minus predicted target refractive error)was analyzed to know more about the possible factors resulting from IOP fluctuation that might affect the refractive prediction error.Results: Postoperative best corrected visual acuity(Log MAR=0.24±0.19)have significantly improved compared with preoperative one(Log MAR=0.60±0.55)(P< 0.001).The intraocular pressure was 13.0±4.8mm Hg 1 month postoperatively,which was significantly different from the preoperative one(22.0±15.6mm Hg)(P <0.001).The axial length(22.35±0.66mm)and anterior chamber depth(3.96±0.21mm)one month postoperatively were statistically significant compared with those preoperatively(22.47±0.66mm,2.15±0.25mm,respectively).The mean keratometry value(Km=44.49±1.66D)was slightly different from the preoperative one(Km=44.65±1.71D)(P=0.030<0.05).There was no significant difference in flat keratometry value(P=0.210)but the postoperative steep keratometry value(K2=44.95±1.67D)was different from the preoperative one(K2=45.15±1.76D)(P=0.030<0.05).In univariate analysis,the intraocular pressure difference before and after surgery(ΔIOP)was correlated with prediction error(PE)(r=0.503,P<0.05).The correlation equations ofΔIOP and PE were obtained by univariate regression analysis:PE=0.027ΔIOP-0.384(F=16.234,P<0.001).In the multivariate linear regression model(R2=0.438,F=6.855,P<0.001)that prediction error as the dependent variable,Pre-AL(Beta=0.514,P<0.05),Pre-ACD(Beta=-1.035,P<0.05),Pre-K(Beta=0.234,P<0.05),ΔIOP(Beta=0.025,P<0.001)were significantly associated with PE while age was not significant(P=0.997).In the partial correlation analysis,excluding the influence of axial length change(ΔAL),anterior chamber depth change(ΔACD),average keratometric value change(ΔK),ΔIOP was associated with PE(r=0.326,P=0.025<0.05).However,ΔIOP was not associated with PE(r=0.204,P=0.160)while only exclude the influence ofΔAL.Conclusion:Phacoemulsification combined with IOL implantation and viscogoniosynechialysis can effectively lower IOP in PACG patients and improved visual acuity.There was a correlation between ΔIOP and PE which might require us to adjust IOL calculation by different IOP change of PACG patients who underwent phacoemulsification combined with IOL implantation and viscogoniosynechialysis.