Correcting corneal coma with an IOL

May 1, 2006

A newly designed IOL corrects corneal coma and is tolerant of largedegrees of ocular misalignment.

A newly designed IOL corrects corneal coma and is tolerant of large degrees of ocular misalignment.

"Corneal coma is compensated for by the eye, but that ability can be disrupted by LASIK and cataract surgery - the latter of which modifies the internal optics of the eye," said Juan Tabernero, MD, of the University of Murcia, Murcia, Spain.

Dr. Tabernero and colleagues designed an IOL using a previously developed computer model to predict the optical performance of individual eyes after IOL implantation from actual data and lens design parameters. The investigators studied the relationship between ocular alignment and aberrations, Dr. Tabernero said. They measured angle kappa, lens tilt, and decentration using a new instrument based on recording of Purkinje images. They compared the optical results predicted by the model using conventional IOLs and the newly designed IOL that corrects coma.

Dr. Tabernero reported that when a conventional IOL was compared with the new IOL in a simulation, the new IOL compensated for the coma generated in the model, but the conventional IOL did not. The new IOL stabilized the visual quality, while the visual quality deteriorated with the conventional IOL.

"In conditions of perfect alignment, the performance of the IOL is quite promising," he stated. "However, IOL misalignments could be a problem and must be considered."

When they measured 21 pseudophakic eyes, the average decentration was about 0.3 mm and the average IOL tilt with respect to the line of sight was about 6 degrees. The conventional IOL still generated coma, but the new IOL nearly suppressed the coma.

"This new IOL, designed to correct coma, provides superior optical quality," Dr. Tabernero said. "The IOL is useful in a full range of conventional physiological powers, but the highest benefit is seen in the lower powers, ranging from 10 to 15 D. The new IOL was tested with real corneas with alignment data and the correction of coma was stable in a range of misalignments."