Toric Intraocular Lenses for Post-Transplant Astigmatism
Corneal transplants can be very successful at replacing diseased or damaged corneas. However, vision after a corneal transplant is often limited by high amounts of astigmatism. Treating this astigmatism is often difficult. Typically the amount of astigmatism is higher than can be corrected with glasses. Rigid contact lenses are often required. LASIK, PRK and astigmatic incisions in the cornea (astigmatic keratotomy) have all been tried with varying success.
This month, doctors at the Gavin Herbert Eye Institute at the University of California, Irvine, published a paper describing the use of commercially available, FDA approved toric (astigmatism correcting) intraocular lenses (IOL) during cataract surgery in patients with previous corneal transplant surgery.
Good candidates for this procedure are those who have had all transplant sutures removed and had corneal astigmatism that was stable, and for the most part symmetric and regular. (Image 1A shows topography that is both regular and symmetric. Image 1B is regular but not symmetric and image 1C is irregular.)
The study showed improvement in uncorrected vision (post-treatment average 20/40) and vision corrected with glasses only (post-treatment average 20/25). The images below, 1D and 1F, illustrate how toric intraocular lenses are positioned along the axis of corneal astigmatism.
While any intraocular surgery after corneal transplant can decrease the life expectancy of the graft, no complications or graft failures were seen during the course of the study. Not all types of astigmatism can be treated with this procedure.
This study highlights an effective treatment for regular symmetric corneal astigmatism after corneal transplant in patients needing cataract surgery.
Matthew Wade, MD
Assistant Professor of Ophthalmology
Gavin Herbert Eye Institute
University of California, Irvine