Cataract Surgery in Keratoconus with Irregular Astigmatism

Keratoconus generates highly irregular corneal astigmatism. While age is well known to slow down the progression of keratoconic ectasia and tends to fix the subsequent irregular astigmatism, the natural onset of cataract contributes to further decrease vision in already disabled patients. To offer these patients an optimal strategy for cataract treatment, different options on how to manage irregular astigmatism of a keratoconic patient with surgical cataract have been proposed and are reviewed. The stage of keratoconus and the history of the patient are both critical to orient the strategy. However, combined parameters should be considered for patients with highly irregular astigmatism due to keratoconus, to anticipate refractive results close to those obtained on patients with normal corneas. Contact lens equipment, intracorneal segment rings, lamellar or penetrating keratoplasties and, more generally, therapeutics which are usually applied for keratoconus, can be opportunely combined with the whole range of solutions offered by modern cataract surgery. Different methods of keratometry and formulas for intraocular lens (IOL) calculation have been proposed to improve as much as possible the predictability of the final refractive status, which still remains far from the standards of classical cataract surgery. So far, multifocal IOLs are still not suitable when associated with irregular corneal astigmatism, but toric intraocular lenses (IOL) could be selectively considered as an option in these patients.