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Posterior corneal curvature may influence IOL power calculations
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CHICAGO — Clinicians should analyze the effects of posterior corneal curvature on corneal power when making IOL power calculations for eyes that have undergone refractive surgery, a speaker said here.
“Measuring posterior corneal power should improve the accuracy of IOL calculations,” Douglas D. Koch, MD, said during the Kelman Lecture presented as part of the Innovator Session at the American Society of Cataract and Refractive Surgery annual meeting. “If we can measure the entire cornea, we ought to be able to nail the corneal element.”
Different formulas and machines employ different assumed ratios of anterior and posterior corneal curvature.
“It’s all been a bit of a guess,” Dr. Koch said. “So, you just pick a ratio and you stick with it.”
Surgeons should address higher-order corneal aberrations that result from refractive surgery because they diminish image quality, Dr. Koch said.
“We can use corneal higher-order aberrations in optimizing the IOL design for our patients,” he said. “Modulating spherical aberration is where this comes into play.”
Dr. Koch and colleagues developed a formula, available on the ASCRS website, for using posterior corneal values to calculate IOL power.
- Disclosure: Dr. Koch has financial relationships with Accutome, Alcon, Calhoun Vision, NuLens, OptiMedica and Ziemer.