If your cataract is at an advanced stage where it obstructs your vision and significantly impacts on your quality of life, cataract surgery may be the only solution. However, what many doctors don�t tell you is that it is possible to prevent early developing cataracts from getting worse and, if caught early enough, it can even be reversed.

What are cataracts? Cataracts are described according to the site of the opacity. A �nuclear� cataract, commonly associated with ageing, affects the centre of the lens and causes a gradual loss in distance vision. A �cortical� cataract develops from cortex, or outside, of the lens towards the centre. These have little initial effect on vision but, as they grow towards the centre of the lens, light may be seen surrounding objects, especially shiny ones. �Posterior subcapsular� cataracts typically start near the centre of the lens and tend to advance rapidly, causing major vision loss within months.

What doctors tell you Up to some 10 years ago, cataract surgery involved making a small (11-12 mm) cut into the lens to remove the cloudy nucleus. A clear artificial lens - an intraocular lens (IOL) - was then inserted and the incision sutured.

This has now been replaced by phacoemulsification, in which a special probe uses high-frequency ultrasonic waves to break up the lens into fragments, which are simultaneously vacuumed away through the hollow probe. This technique involves a much smaller incision (2-3 mm) and no stitches are required. Healing is also much faster, with patients regaining clear vision after only a day or two.

Given these technological advances, cataract surgery is now thought to have low complication rates and better outcomes. This has led to many patients being operated on earlier than before, as there is no longer any need to wait for the cataract to �ripen� as they would have done in the past.

What doctors don�t tell you Nevertheless, no matter how much the technology moves on, there is still room for error. Although the new-generation phaco systems can improve the outcome of cataract surgery, high levels of skill and concentration are required to use these tools. And surgeons, being only human, can still sometimes make mistakes.

�Phaco surgery is an unforgiving procedure because each step relies on the success of the previous one,� says David Spalton, a consultant ophthalmologist at St Thomas� Hospital in London. One badly performed incision at the start of the operation, for example, can make the whole procedure much more difficult and, indeed, jeopardise the whole operation, he continued (Optometry Today, 2001, Sept 7: 28-33).

Among the various complications that can arise during cataract surgery, one of the most serious is �posterior capsular rupture� (PCR), whereby the bag-like capsule that surrounds the lens is inadvertently torn. Although the incidence of PCR is considered to be a �low� 3-4 per cent, the consequences can be serious. Patients who sustain a capsular tear during surgery are more likely to go on to suffer further complications such as retinal detachment, significant macular oedema, increased pressure within the eye and difficulties in positioning (centring) the artifical lens (Ophthalmic Surg Lasers Imaging, 2004; 35: 219-24).

These problems, in turn, can lead to a marked reduction in eyesight. According to a study by a team of ophthalmologists in London�s Moorfields Eye Hospital, eyes that suffered PCR were nearly four times more likely to be below average in visual acuity (Br J Ophthalmol, 2001; 85: 222-4).

Another complication seen with phacoemulsification - especially when older-generation machines are used - is burns wounds to the cornea. The high-frequency ultrasound beam is concentrated to break up the cataract, but the downside is that the energy generates a lot of heat and, if the surgeon is not careful, this heat can cause thermal injury to the cornea, resulting in visual distortions, or astigmatism.

Another well-known postoperative complication is �posterior capsular opacification� (PCO), also known as a �secondary cataract�. This happens in approximately 20 per cent of patients within the first five years following cataract surgery. PCO is caused by cells accumulating on the backside of the lens capsule, which then becomes increasingly cloudy and begins to interfere with eyesight in the same way as the original cataract did.

To get rid of this secondary cataract requires eye laser surgery, a procedure that, in itself, opens up a gateway to yet another set of problems.