Toric IOL viable option for keratoconus

April 21, 2012

Emerging experience suggests the boundaries for toric IOL implantation can be expanded to include carefully selected eyes with keratoconus, said Alejandro Navas, MD, MSc.

Chicago-Emerging experience suggests the boundaries for toric IOL implantation can be expanded to include carefully selected eyes with keratoconus, said Alejandro Navas, MD, MSc.

“While there are limited studies that have evaluated toric IOLs for keratoconus, the short term results are promising,” said Dr. Navas, associate professor of ophthalmology, Institute of Ophthalmology, “Conde de Valenciana”, Mexico City. “In our own series of 19 eyes with a mean follow-up of 8 months, patients achieved significant improvement in SE with significant decreases in both sphere and astigmatism.

“However, there are a few important criteria to consider, and patients must be counseled that a risk of progression of keratoconus persists,” he added. “Nevertheless, if the refractive changes are mild or even if refractive surprises occur after the surgery, vision can be corrected with spectacles or contacts.”

Discussing selection criteria, Dr. Navas said toric IOLs should be avoided in patients with central cornea scars, if they have unstable or progressive keratoconus, and if refraction cannot be performed.

In addition, the patient must have a topographically identifiable axis to align the toric IOL properly, and the astigmatism should be “not so irregular.” For the latter reason, Dr. Navas said he initially considered only eyes with mild keratoconus and excludes eyes with advanced disease.

Providing some additional recommendations, Dr. Navas suggested using an age cut-off of <48 years for implanting a phakic IOL and considering refractive lens exchange as a more suitable option in patients older than 55 years. However, he noted these criteria are debatable and that the reversibility of a phakic IOL versus irreversibility of an in-the-bag IOL might also be considered.

For power calculation when implanting a pseudophakic IOL, Dr. Navas recommended the use of keratometry obtained by topography and/or tomography, interferometry for axial length measurement, and the SRK II formula, which, according to the literature, may cover a broader spectrum of cases.

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