To evaluate the visual and topographic outcomes in patients with keratoconus who have undergone cataract surgery and to analyze different methods of keratometry and formulas for intraocular lens (IOL) calculation in patients with keratoconus.
In a retrospective case series, 12 eyes (nine patients) with keratoconus underwent phacoemulsification with IOL implantation. The IOL power was determined by using standard and corneal topography–derived keratometry in three formulas: SRK, SRKII, and SRKT. Three months after surgery, best-corrected visual acuity (BCVA), visual improvement, simulated keratometry, and contact lens fit were assessed. Retrospectively, the difference between spherical equivalent and desired refraction was evaluated for the ideal IOL power. The difference between the ideal IOL power and the calculated IOL power from the three formulas was determined to evaluate the best formula for these patients.
The mean age was 55 years (range, 38–76 years). All eyes had improved BCVA (mean of four lines). Of the five eyes with mild keratoconus, three were switched from rigid gas-permeable lens wear before surgery to soft toric contact lenses (n = 2) or spectacles (n = 1). Patients with moderate and severe keratoconus (7 of 12) still required rigid gas-permeable lenses after surgery. In mild keratoconus, there was no difference between standard and topography-derived keratometry. The most accurate IOL power was found by using SRKII.
Cataract surgery can improve BCVA in all severities of keratoconus without significant corneal change. IOL calculation is more predictable in mild keratoconus than in moderate and severe disease.