Cataract surgery involves removing a clouded natural lens from inside the eye and replacing it with a plastic one, but while the operation hasn't changed much recently the plastic replacement lenses have.

The report explains that the older types of plastic lenses help people see well at one distance -- close up, far away, or at a medium distance. However, two newer types of lenses -- accommodating and multifocal -- let the eye focus at varying distances, so after surgery fewer patients need glasses for reading or distance vision.

The accommodating intraocular lens has hinges on its sides that permit it to move as the eye's ciliary muscle contracts or relaxes to change focus from near to far. The multifocal intraocular lens uses a new type of refractive technology to provide focus for multiple distances, the report said.

The most common problems with the newer lenses are glare, halos and the continued need for eyeglasses.

The Aging Eye, a 48-page Special Health Report is available for $16 from Harvard Health Publications online at health.harvard.edu/AE or by calling 877–649–9457.