Posterior corneal astigmatism calculations contribute to reduced residual astigmatic error
AMSTERDAM — Residual astigmatism is reduced after cataract surgery when posterior corneal measurements are incorporated into total corneal astigmatism estimation, a study author said here.
With the aim of surgery being to correct a patient’s anterior astigmatism after cataract surgery, Yokrat Ton, MD, said the study took into account the contribution of posterior astigmatism to the end result.
“In this study, we wanted to compare the calculated residual astigmatic and residual astigmatism error following cataract surgery using three different methods,” Yokrat Ton, MD, said at the European Society of Cataract and Refractive Surgeons meeting. The first method used anterior astigmatism alone, the second measured posterior astigmatism and the third used the Baylor toric IOL nomogram to estimate residual outcome.
In 54 cases, anterior corneal astigmatism was measured with the Lenstar optical biometer (Haag-Streit), and posterior corneal astigmatism was measured with Pentacam imaging system (Oculus). When calculating residual astigmatism and astigmatic error, there was a larger error when front cornea measurements alone were used for toric IOL calculation than when posterior cornea measurements were incorporated.
When direct measurements of the posterior surface are absent, following published nomograms is recommended, Ton said in the presentation.
Disclosure: Ton has no relevant financial disclosures.