Prof. Brézin, what were the most important innovations in cataract surgery in the last few years?
The most important innovation of the last 25 years was phacoemulsification. With this technique, an incision is made in the cornea and the lens capsule is opened before the lens is broken up (emulsified) into tiny pieces with an ultrasonic probe and then suctioned off. The back of the capsule is preserved and the prosthetic intraocular lens is implanted into it. As eye incisions only have to be a few millimetres in size with this technique, phacoemulsification has improved the safety of this operation and substantially reduced rehabilitation time. It is the standard method used today all over the world, except in some developing countries.
20 years ago, the first foldable intraocular lenses appeared on the market. As long as the prosthetic lenses were rigid, the corneal incision had to be as large as the size of the prosthetic lens, i.e. at least six millimetres. With the advent of new foldable materials such as acrylic and silicone, the incision only had to be as large as necessary for phacoemulsification, i.e. 3 mm or less.
Since then, there has been fierce competition in the industry to minimise the incision size required for phacoemulsification and to produce lenses that can be implanted through smaller and smaller openings. The necessary incision length has thus been reduced to 2.3 to 2.4 mm. Today there are even phaco probes that work through a 1.8 mm opening. At the moment, there is a lot of discussion on whether quality is being sacrificed with these extremely folded lenses. But there is an unmistakable trend towards procedures through mini incisions, also called MICS (MicroIncision Cataract Surgery).
What progress is being made in the development of new lenses?
We used to only have monofocal lenses, with which the patient could either see close up or long-distance and additionally needed glasses to correct his vision. Then, industry developed multifocal lenses, although they cannot really make up for the missing accommodation. They sharply focus both a close-up and a distant image on the retina, and the eye then chooses the right image. However, this may be at the expense of contrast sensitivity, and this type of lens is not suitable for every patient.
A totally new approach is accommodating lenses. New materials and designs are developed to enable the lens in the eye to actively focus . These lenses could take advantage of the fact that the ciliary muscle responsible for accommodation often still functions in very elderly patients. With lenses such as these we could fully restore patients’ eyesight. A great deal of research is being done in this direction, but the products have not achieved sufficiently satisfying results yet.