A cataract is treated by removing the old cloudy, natural lens and replacing it with a new artificial intraocular lens (IOL).
There are several types of intraocular lenses (IOLs):
The first part of the surgery is the creation of small incisions in the cornea (called “clear corneal incisions”), to allow the surgeon to place surgical instruments inside the eye and perform the surgery, removing the old lens, and introducing the new IOL. The old lens is held in place by a structure known as the capsular bag. The surgeon creates circular hole in the bag to (1) enable the removal of the old lens, and (2), hold the new IOL in place, inside the bag. The circular hole can be made manually, with the surgeon grabbing the bag, and tearing the circular shape, or with a femtosecond laser, with the process being called “capsulorrhexis”.
For decades now, conventional cataract surgery has involved the use of ultrasound energy, delivered by the tip of one of the small surgical instruments, to break down the old lens (a process called “phacoemulsification”). The fragments of the old lens are then “aspirated” away – literally, sucked out. This is delicate surgery, and is performed entirely manually – meaning that the surgeon requires a very steady hand. The operation is still very safe and has been ‘tried and tested’ millions of times.
For the last few years, it has also been possible to use a femtosecond laser in a number of parts of cataract surgery. Lasers are even more precise than even the steadiest of hands, as all of their cuts can be planned on the computer in advance and placed exactly where the surgeon wants. The laser can be used to make the initial cuts (the clear corneal incisions), the hole in the capsular bag, and also fragment the old lens, making the phacoemulsification easier and faster to perform. This combination offers the patients the greatest possible gain from the optics of the IOL, and the greatest possible safety. Under certain circumstances, the laser is superior to conventional, ultrasound-only cataract surgery.