In cataract surgery the cloudy natural lens of the eye is removed and replaced with a perfectly clear intra ocular lens (IOL). There are three types of IOL’s used in modern cataract surgery; monofocal, multifocal and toric. The standard lens we have had for decades is a monofocal IOL. This lens can give good vision at a set distance but won’t correct astigmatism and won’t give both reading and distance vision. A multifocal lens will give good vision for reading and distance without glasses. It does not correct astigmatism so that has to be done separately. I am writing about toric IOL’s.
Until recently we have not been able to correct for astigmatism in the eye without performing a second surgery on the cornea. LASIK, for example, can correct astigmatism. Astigmatism is when the cornea is not dome shaped, like half of a basketball, but steeper on one side and flatter on the other, like half of a football. When an eye has astigmatism it can’t see clearly at any distance without glasses or contacts. This left many people dependent on glasses for near and distance vision after cataract surgery.
A few years ago the Food and Drug Administration approved toric lenses to be placed in the eye at the time of cataract surgery. These toric lenses have astigmatism power built into the lens. Cataract surgery can now correct near sightedness, far sightedness, and astigmatism. Correcting astigmatism with glasses is good, correcting it with contact lenses is better, but correcting astigmatism with a toric lens is the best. The distance vision obtained with the toric lenses is excellent but they don’t give both distance and near vision. That is the only problem with toric IOL’s, patients still need glasses for reading. They are not multifocal (yet!).
A toric IOL is right for you if; you need cataract surgery, you have significant astigmatism, and you don’t mind wearing glasses for reading.
David L. McGarey MD