Cataract surgery removes the clouded natural lens and replaces it with a clear artificial one, called an intraocular lens or IOL. The surgeon works through a microscope that gives a magnified view of the eye.
The capsule: what stays behind
The natural lens sits inside a thin, clear membrane called the capsule. During surgery the surgeon opens the front of the capsule, removes the cloudy lens from inside it, and leaves the back of the capsule in place.
Keeping the capsule matters. It shields the back of the eye during the operation and gives the new lens a secure place to sit for life.
Phacoemulsification
Most cataracts today are removed by phacoemulsification, or phaco for short.
- The surgeon makes a tiny opening, usually under 3 millimetres, at the edge of the cornea.
- A circular opening is made in the front of the capsule.
- A fine probe, vibrating with ultrasound, breaks the cataract into small pieces and gently suctions them out.
- The soft outer layers of the lens are cleaned away.
- A folded lens implant is passed through the same small opening. It unfolds inside the capsule.
The opening is so small that it usually seals without stitches. Phaco is sometimes called “laser surgery”, but the cataract is broken up with ultrasound, not a laser.
Why the size of the opening matters
The older method, extracapsular extraction (ECCE), needs an opening of 9 to 10 millimetres to take the cataract out whole, and stitches to close it. A smaller opening means less disturbance to the eye, less inflammation, less astigmatism caused by the wound, and a quicker recovery. ECCE is still used in some situations, such as very dense cataracts.
Laser-assisted surgery (FLACS)
In femtosecond laser-assisted cataract surgery, a computer-guided laser performs some steps that are otherwise done by hand: making the openings, the circular cut in the capsule, and softening the cataract. The rest of the operation, including placing the lens, is the same as phaco. Your surgeon can tell you whether it is offered and whether it would make a difference for your eye.
Anaesthesia
Most phaco operations need only numbing drops, sometimes with a mild sedative. You are awake, but you do not feel pain and you will not see the instruments clearly.
Possible complications
Complications are uncommon, but every patient should know about them.
- Infection inside the eye (endophthalmitis). This is the most serious complication of any eye operation. It is rare, and many steps reduce the risk: antiseptic cleaning, sterile instruments and drapes, and antibiotic drops before and after.
- Inflammation. Some is normal and is controlled with drops. It usually settles within a week or two.
- Raised eye pressure. This can happen in the first day or so and is treated with medicine if needed.
- Swelling of the cornea. It usually clears within days, but may take longer in eyes with other conditions.
- A tear in the capsule. This can make the operation more complex and may affect where the lens is placed.
- Swelling of the retina or retinal detachment. These are rare, but need prompt treatment. This is why sudden flashes, floaters or a shadow should be reported straight away.
- Clouding of the capsule later on. This is common months or years afterwards and is easily treated with a laser. See YAG laser capsulotomy.
If you have diabetic eye disease, the retina needs close monitoring before and after surgery, and may need treatment.
This guide explains; it does not diagnose. Your doctor’s advice about your own eyes comes first.