Optimizing Refractive Accuracy: Evaluating Multifocal Iol Performance In Post-Refractive Surgery Eye

This study aimed to evaluate the clinical outcomes of TECNIS Synergy, AT LISA tri 839MP and Vivinex Geometric multifocal IOLs in post refractive surgery eyes and assess the predictive accuracy of intraocular lens power calculation formulas ( Barrett True-K and Shammas-PL) in such eyes. Given the altered corneal curvature in these patients, achieving accurate IOL power calculation is challenging. By analyzing refractive outcomes and prediction errors, this study seeked to determine the optimal calculation method and IOL choice to enhance the postoperative visual quality and patient satisfaction.

All cataract surgeries were performed by an experienced surgeon under topical anaesthesia. Phacoemulsification was done through a 2.8mm temporal clear corneal incision. Capsulorrhexis of around 5.0 mm diameter was made in each case and phacoemulsification was done using Compact Intuitive device. The IOL was implanted into the capsular bag. After the surgery, antibiotic drops and corticosteroid drops were used for a month in a tapered fashion.

This retrospective study included 80 eyes of 80 patients who underwent cataract surgery with multifocal IOLS from February to April 2024 and had previously undergone corneal refractive surgery for myopia. Exclusion criteria included eyes undergone other refractive surgeries except LASIK, those with corneal diseases, glaucoma, amblyopia, retinal disease.  Preoperatively, unaided near & far vision and manifest refraction were measured. Biometry including anterior keratometry, posterior keratometry, corneal thickness, anterior chamber depth and axial length were noted. IOL power the mIOLs was claculated using Barrett True-k and Shammas- PL formulas. Postoperatively, visual actuity and refractive errors were evaluated at three months.

Synergy IOL was implanted in younger patients with flatter corneas and longer axial lengths (P<0.05). Postoperative UDVA and UNVA improved in all groups (P<0.001). UDVA was better with AT LISA and Vivinex Geometric than Synergy, while UNVA was superior in AT LISA (P<0.05). The Barrett True-K formula showed lower prediction error, absolute error and median absolute error than Shammas-PL (P<0.05). More eyes achieved MR within +/- 0.50 D with Barrett True-K. Higher PE was associated with lower K values and longer axial lenghts. Patients with prior high myopic correction had greater refractive errors postoperatively. 

For patient with prior corneal refractive surgery LASIK undergoing mIOL implantation, the Barrett True-K formula, which accounts for both anterior and posterior corneal curvature, is recommended for improving the refractive outcomes. Furthermore, the degree of prior laser ablation appears to be a key factor influencing prediction error. Hence, personalised IOL selection and precise biometry are crucial for optimal postoperative refractive outcomes in post refractive surgery patients.