| Purpose: We aim to find out the factors that affect the refractive outcomes of combined pars plana vitrectomy(PPV)or silicone oil removal(SOR)with cataract surgery and to investigate the performance of novel intraocular lens(IOL)calculation formulae(Barrett Universal II [BUII],Emmetropia Verifying Optical [EVO],and Kane)and conventional formulae(Haigis,Hoffer Q,Holladay 1,and SRK/T).Methods: The study is a retrospective,case-series study.301 eyes of 301 patients undergoing combined PPV/SOR with cataract surgery were enrolled.Eligible individuals were separated into four groups according to their preoperative diagnoses: silicone oil-filled eyes after PPV(group 1),epiretinal membrane(group 2),macular hole(group 3),and primary retinal detachment(RD)(group 4).The IOLs used in the cohort were Lenstec Softec HD(n =133),Lenstec Softec 1(n = 123),Alcon Acry Sof SN60WF(n = 21),Zeiss CT ASPHINA509M(n = 14),and Zeiss CT ASPHINA 603 P IOL(n = 10).During the combined surgery,27 patients underwent silicone oil tamponade,244 underwent sterilized air tamponade,and 30 underwent C3F8 tamponade.The outcome measurements include the mean refractive prediction error(PE),the median absolute error(Med AE),the mean absolute error(MAE),and the proportions of eyes with a PE within ±0.25 diopter(D),±0.50 D,±0.75 D and±1.00 D.All statistical analyses were performed using IBM SPSS Statistics for Windows(version 26.0,IBM Corp.).The mean and standard deviation(SD)were used to represent the continuous numbers.For all computations and statistical analysis,the visual acuity of each patient was transformed to the logarithm of the minimum angle of resolution(log MAR)value.Results: For all patients,the mean PE was-0.04 ± 1.17 D,and 50.17% of patients had a PE within ±0.50 D.There was a significant difference in refractive outcomes among the four groups(P =0.028),with RD(group 4)showing the least favorable refractive outcome.In multivariate regression analysis,only axial length(AL),vitreoretinal pathology,and anterior chamber depth(ACD)were strongly associated with PE(all P <0.01).In univariate correlation analysis,we found that gender,age,AL,ACD,and vitreoretinal pathology were correlated with postoperative refractive PE(all P < 0.05).It revealed that longer eyes(AL >26mm)and a deeper ACD were correlated with hyperopic PE,and shorter eyes(AL <26 mm)and a shallower ACD were correlated with myopic PE.In total,new-generation formulas displayed statistically significant lower median absolute error(0.39 to 0.41 diopter [D])and higher percentage of eyes within ±1.00 D of prediction error(82.72% to 84.72%)compared with those of traditional formulas,with BUII exhibiting the best overall performance.For long eyes,all traditional formulas showed hyperopic bias(0.35 to 0.58 D,P <0.05)and this bias could be corrected by Wang-Koch(WK)adjustment.In addition,the second liner WK adjustment(WK2)formulas were less aggressive in producing a myopic outcome than the first liner WK adjustment(WK1)formulas.Furthermore,the WK2 adjustment significantly reduced the Med AE of SRK/T and Holladay 1(P = 0.019 and P < 0.001)and exhibited a substantially superior proportion of patients with PE within a certain interval.In addition,we found no statistically significant difference between BUII,EVO,Kane,Holladay 1 formula with WK2 adjustment,and SRK/T formula with WK2 adjustment in terms of prediction accuracy(all P > 0.05),indicating that Holladay 1 and SRK/T formulae with WK2 adjustment performed on par with the new formulae in long eyes.In patients with silicone oil-filled eyes(Group 1),the new formulae showed substantially lower Med AE than Holladay 1,SRK/T,and Hoffer Q(all P < 0.05).Among them,Kane exhibited the smallest MAE(0.62 D),Med AE(0.45 D),and the supreme proportion of patients having a PE within ±0.50 D(55.48%)and ±1.00 D(85.81%).In patients with ERM(Group 2),no substantial difference in prediction accuracy was found between the seven formulae(P = 0.054).Among them,BUII had the minimum MAE(0.49 D)and the supreme proportion of patients having a PE within±0.25 D(45.78%),±0.50 D(69.88%),and ±0.75 D(83.13%).In patients with MH(Group 3),the new formulas showed significantly lower Med AE compared to Holladay 1 and Hoffer Q(all P < 0.05).Among them,BUII showed a comparatively lower Med AE(0.32 D)and the greatest proportion of patients within ±0.50 D(75.61%)of PE.In patients with RD(Group 4),none of the seven formulas showed a statistically significant improvement in prediction accuracy(P = 0.075).When the prediction accuracy of each formula was compared between the different types of vitreoretinal pathology,the RD group exhibited the worst prediction accuracy for all formulas(all P < 0.01).These results indicated that the new formulas displayed favorable accuracy in the silicone oil-filled eyes,ERM,and MH groups;however,in the RD group,the new formulas did not significantly improve the prediction outcomes.Conclusion: Our study showed RD patients have the least favorable refractive outcome after combined PPV or SOR with cataract surgery.Age,gender,preoperative BCVA,keratometry,and different intraocular tamponades filled during the combined surgery are not significantly correlated with PE.However,AL,vitreoretinal pathology,and ACD are strongly associated with PE in the combined surgery.These three factors affect refractive outcomes and thus can be used to predict a better postoperative refractive error in clinical practice.In addition,new formulas performed better than conventional formulas in patients who underwent combined surgery,and the BUII formula offered the best overall performance.In long eyes,Holladay 1 and SRK/T with WK2 adjustment offered satisfactory accuracy,on par with the new formulae.For patients with silicone oil-filled eyes,ERM,and MH,the new formulas showed satisfactory prediction accuracy.However,patients with RD showed the least favorable refractive outcomes,and the new formulas failed to significantly improve the prediction accuracy.Therefore,when planning to perform combined PPV and cataract surgery for patients with RD,surgeons should exercise caution when determining the IOL power.For RD patients with macular-off,a two-step strategy for PPV and cataract surgery may be a better option.In the future,we will focus on how to enhance refractive outcomes after combined surgery in this population. |
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