Sunday, September 14, 2008

Toric IOL add-on offers new option for reducing pseudophakic astigmatism

Secondary implantation of a toric IOL is an effective method for correcting pseudophakic astigmatism, reported Haiying Jin MD at the XXVI Congress of the ESCRS.

Dr Jin spoke on behalf of his colleagues at the University of Heidelberg where a toric IOL has been used as an add-on implant in selected pseudophakic eyes with astigmatism related to either corneal toricity or rotation of a primarily implanted toric IOL. The implant used is a MicroSil toric IOL designed for piggyback implantation into the ciliary sulcus. Its spherical power, toric power, and alignment axis are determined based on calculation of the optical properties of the pseudophakic eye using a modification of the Holladay-Cravy-Koch vector analysis method.

Dr Jin demonstrated the utility of the piggyback toric IOL implantation in a case of a 72-year-old-man who received a toric IOL at cataract surgery and was found 20 months later to have more than 5 D of refractive astigmatism and almost 4 D of corneal astigmatism associated with a 60-degree off-axis rotation of the primary toric IOL.

“Repositioning of the primary implant would be challenging in this eye because it is 20 months post-surgery, and laser ablation is also not a good option considering the very high astigmatism and because the treatment axis and steep axis of corneal astigmatism are different,” noted Dr Jin.

“It is known that secondary IOL implantation is an effective approach for correcting refractive surprises after cataract surgery. To our knowledge, this is the first report of using a toric IOL as a piggyback implant to correct pseudophakic astigmatism.”

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