Effects of intraocular pressure on the selection of intraocular lens calculation formulas for cataract and glaucoma surgery / 眼科新进展

ABSTRACT

Objective To clarify the effects of intraocular pressure (IOP) on the selection of intraocular lens (IOL) calculation formulas for cataract and glaucoma surgery in order to provide reference for avoiding refractive error (RE) in clinical.Methods The clinical data of 72 patients (80 eyes) with primary angle-closure glaucoma (PACG) and cataract undergoing combined cataract and glaucoma surgery in our department were enrolled from May 2015 to April 2017.The subjects were divided into normal IOP (10-21 mmHg,1 kPa =7.5 mmHg,n =28) and high IOP group (＞ 21 mm-Hg,n =52) based on preoperative mean IOP.Then the differences between the postoperative actual spherical equivalence (PASE) measured 3 months after operation and the predicted preoperative spherical equivalence (PPSE) of 4 kinds of IOL calculation formulas by IOL Master (SRK/T,Holladayl,Hoffer Q,and Haigis) were compared so as to evaluate the effects of IOP on the postoperative absolute refractive error (ARE) and refractive error (RE) of IOL formulas.Results The postoperative IOP for 3 months of all patients was significantly lower than that of preoperative data(t =9.96,P =0.000),and the decrease level was positively correlated with preoperative mean IOP (r =0.974,P =0.000).There were significant differences in the median ARE from SRK/T,Holladayl,Hoffer Q and Haigis formula in the normal and high IOP groups (P =0.008,0.004),while there was no significant difference in RE (RE ＞ 0) from SRK/T,Holladayl,Hoffer Q and Haigis formulas between the two groups (P =0.633,0.422).In the normal IOP group,there was significant difference in RE (RE ＜ 0) from the four formulas (P =0.000),and LSD comparison showed that the SRK/T formula had the smallest RE (all P＜0.01),and Haigis formula had the largest RE than the other formulas (all P ＜ 0.05).In the high IOP group,there was significant difference in RE (RE ＜ 0) from the four formulas (P =0.000),and LSD comparison showed that the Hoffer Q formula had the smallest RE (all P ＜ 0.01),and there was no significant difference in RE from other formulas (all P ＜ 0.05).Conclusions Combination of cataract and glaucoma surgery can improve visual acuity and intraocular pressure in patients,and the decreased level of postoperative IOP is positively correlated with preoperative mean IOP.As for calculation of the degree of IOL,the SRK/T formula shows a good accuracy when preoperative mean IOP is normal,and Hoffer Q formula should be chosen for patients with high preoperative mean IOP.