Importance of Posterior Corneal Astigmatism in Eyes with Keratoconus

As eye care specialists, we inevitably encounter patients with concomitant keratoconus (KCN) and cataracts. It is known that patients with KCN are more likely to develop cataracts than subjects without KCN and do so at a younger age than the general population.[1] The incidence of KCN is also much higher than what was known in the older literature. A recent review has shown that the incidence of keratoconus is 1:7500 with a prevalence of 1:375. This is 5‑10 fold higher than that previously reported in the literature.[2] In addition, new diagnostic modalities such as Scheimpflug imaging tomography and high resolution optical coherence tomography (OCT) have enhanced our capability to identify eyes with subclinical and early KCN much earlier than before. With the advent of potentially new stabilizing procedures such as collagen cross‑linking and corneal rings, many patients with mild to moderate KCN will eventually require cataract surgery and most likely demand toric intraocular lenses for less dependency on glasses and contact lenses.