Late refractive change after cataract extraction and toric intraocular lens implantation

Purpose: To report rates of change and identify factors associated with late change in refractive outcome after toric intraocular lens (IOL) implantation. Setting: Single-site study at the Minneapolis Veterans Affairs Health Care System, Minneapolis, MN, USA. Design: Retrospective cohort study. Methods: Study inclusion required uncomplicated posterior chamber Alcon SN6ATT toric IOL implantation from 2010 –2017 and refractions 1 month and 5 years after surgery. Exclusion criteria were sulcus IOL placement, subsequent intraocular or refractive surgery in the operative eye, and 5-year Snellen visual acuity of 20/60 or worse. Outcomes of interest were change in spherical equivalent and change in magnitude of the astigmatism vector between the postoperative month 1 and postoperative year 5 refractions. Refractive stability was defined as ≤0.5D change in spherical equivalent and ≤1D change in magnitude of the astigmatism vector. Predictive factors analyzed included age, sex, race, pseudoexfoliation (PXF) syndrome, axial length (AL), pre-operative keratometry measurements (∆K), IOL power, neodymium:yttrium-aluminum-garnet capsulotomy, and intravitreal injections. Results: Of the 320 eyes meeting study criteria, spherical equivalent was stable in 241 (75%) eyes, astigmatism was stable in 266 (83%) eyes, and 205 (64%) eyes met criteria for refractive stability with both measures. Multivariable regression analysis identified shorter AL (p=0.018) and larger ∆K (p=0.002) as significant predictors of change in refractive astigmatism and PXF syndrome (p=0.006) as a predictor of hyperopic shift >0.5D. Conclusions: A minority of eyes exhibit late refractive change after toric IOL implantation. AL, ∆K, and PXF syndrome are independent predictors of late refractive change.