眼压对青光眼—白内障联合术患者人工晶状体计算公式选择的影响

目的　探讨眼压对青光眼—白内障联合术患者人工晶状体计算公式选择的影响，为临床上避免屈光误差（refractive error，RE）提供参考依据。方法　选取2014年5月至2017年4月在我院行白内障超声乳化吸出并人工晶状体植入联合复合式小梁切除术的原发性闭角型青光眼（primary angle-closure glaucoma，PACG）合并白内障患者72例（80眼），依术前平均眼压将测试眼分为两组:正常眼压组（10～21 mmHg，1 kPa=7.5 mmHg）和高眼压组（＞21 mmHg），分别为28眼和52眼。比较各组内术后3个月验光所得实际等效球镜度与术前人工晶状体 Master中 4种人工晶状体计算公式（SRK/T、Holladay1、Hoffer Q及Haigis）相应预测等效球镜度的差异。定义实际等效球镜度减去预测等效球镜度即为RE，当RE＜0时为屈光近视漂移，而RE＞0则为屈光远视漂移，RE取绝对值为绝对屈光误差（absolute refractive error，ARE），评估眼压对各公式术后ARE及RE的影响。术后随访6个月。结果　全部患者术后3个月眼压较术前下降明显，差异有统计学意义（t=9.96，P=0.000），且眼压降低幅度与术前平均眼压呈正相关（r=0.974，P=0.000）。正常眼压组SRK/T、Holladay1、Hoffer Q、Haigis公式ARE的中位数差异有统计学意义（P=0.008）；高眼压组各公式ARE的中位数差异亦有统计学意义（P=0.004）。正常眼压组和高眼压组远视漂移时SRK/T、Holladay1、Hoffer Q、Haigis公式RE总体差异均无统计学意义（P=0.633、0.422）。正常眼压组近视漂移时各公式RE间总体差异有统计学意义（P=0.000），经LSD两两比较，SRK/T公式较其他公式的RE小（均为P<0.01），Haigis公式较其他公式的RE大（均为P<0.05），其他各公式RE差异均无统计学意义（均为P＞0.05）。而高眼压组近视漂移时各公式RE总体差异亦有统计学意义（F=6.757，P=0.000），经LSD两两比较，Hoffer Q公式RE较其他公式的小（均为P<0.01），其他各公式RE差异均无统计学意义（均为P＞0.05）。结论　青光眼—白内障联合术可提高患者视力并改善眼压，术后眼压降低幅度与术前平均眼压呈明显正相关。计算青光眼—白内障联合术人工晶状体度数时，术前平均眼压正常者应选SRK/T公式较为准确，而术前平均眼压高时Hoffer Q公式更合适。

Effects of intraocular pressure on the selection of intraocular lens calculation formulas for cataract and glaucoma surgery

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 mmHg，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，Holladay1，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，Holladay1，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，Holladay1，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.