Tomographic methods to detect keratoconus can give eye surgeons a strategic advantage, said Michael W. Belin, MD, professor of ophthalmology and vision science, University of Arizona Health Sciences, Tucson.
Dr. Belin contrasted the older use of Placido-based technology and said that many surgeons likely persist in using it because there is comfort in familiarity.
However, “it’s time to abandon that ship,” Dr. Belin said. “No matter what improvements are made, you are still using an outdated technology.”
Dr. Belin said that older imaging devices all have certain disadvantages—for instance, they are limited to the anterior surface, and they do not consider the negative power contributed by the posterior surface.
“If you don’t measure both anterior and posterior, you can’t general a full corneal thickness map,” he said.
Tomographic analysis can assist surgeons for keratoconus detection, post-IOL computations, the need for toric IOLs, and for crosslinking.
Within the realm of refractive screening, tomographic analysis can help identify susceptible individuals who may otherwise be missed. This is especially important for subclinical keratoconus, in which a patient has an abnormal posterior cornea surface and/or pachymetric progression but still has a normal anterior surface.
“Based on Placido alone, these patients look normal, but they do have true disease,” he said.