How does Lens Exchange work?

The eye is like a camera.

Inside the eye there is a lens, as there is a lens inside a camera. The natural lens of the eye sits behind the pupil but it cannot be seen without special examination instruments. It is similar in size and shape to a "smartie", i.e. like a little 1cm discus.

The focus of the eye depends on three main factors. These are: the cornea (the window of the eye), the lens inside the eye, and the length of the eye. Ideally the cornea and the lens should work together to create a focused image on the retina at the back of the eye. In short sight (myopia) the clear image falls in front of the retina and in long sight (hyperopia) it would come into focus behind the retina.

To adjust the focus of the eye either the curvature of the cornea may be changed or the optical power of the lens of the eye altered. The length of the eye cannot be changed. The curvature of the cornea is altered during laser refractive surgery. "Lens Exchange" is the procedure that permits the power of the lens to be changed.

Like a cataract operation.

Lens Exchange is technically very similar to modern small incision cataract surgery. A cataract is an opacity or clouding of the natural lens of the eye that reduces and compromises vision. The treatment of a cataract is to remove the cloudy lens and replace it with a clear artificial lens. This restores vision.

With Lens Exchange the same thing is done. The only difference is that the natural lens of the eye is not cloudy it is clear. This is why the procedure is sometimes called Clear Lens Extraction. The operation is not being done to restore vision dimmed by cataract but to alter the focus of the eye.

The phacoemulsification hand piece is about the size and shape of a fountain pen. This is held by the surgeon. At its tip is a needle like probe. This is the bit that is placed into the eye. A conventional phaco tip comprises a metal wide bore needle surrounded by a sheath. It performs three functions simultaneously: disintegration of the natural lens (vibration of the needle); infusion of fluid into the eye (from beneath the sheath); and aspiration of debris (up through the needle).

Because the technology used in Lens Exchange is exactly the same as that used in every day cataract surgery it is well tried and tested. In excess of 300,000 cataract operations are performed in the UK annually.

See Mr. Heaven's Cataractcare website for more details about cataract surgery.