The crystalline lens inside the eye never stops growing throughout life- this growth occurs at the outside of the lens where fibre like cells grow across the surface. This means that the oldest part of the lens is at its centre- called the nucleus.
The cells of the lens contain proteins which are very clear, and this coupled with the regular arrangement of the fibres contributes to the clarity of the lens. Anything which causes a disruption to the proteins or the regularity of the fibres will cause a reduction in clarity.
A cataract is an opacity in, or on the lens of the eye. Cataracts may be congenital or acquired through trauma, disease, medication or just age- most people in their 70’s will have a touch of cataract. Many cataracts never become troublesome enough to require treatment, but others can become troublesome very rapidly.
There is no medical cure for cataract- no tablet will fix it, neither is laser surgery available- the only way to fix one is to remove the cloudy lens, which is usually done under a local anaesthetic. Most times the surgeon will replace the lens with a small plastic one, which for the moment means that you will need to wear a correction at least for near (although most people having cataract will already need a near correction because of their age).
It is possible to reduce the risk of cataract by simple lifestyle changes- smoking is a significant risk factor for example, but with all the other worries smokers have, this is unlikely to be the one to make them quit!
Ultraviolet radiation is known to cause cataract, significant in sunnier climates than ours, perhaps, but people who spend much of their time outdoors, at higher altitudes or in highly reflective places- on water or snow should consider extra protection- most sunglasses now on sale will provide this protection. Interestingly, in very sunny places such as Australia, where people take more care about sun protection- with both their skin and eyes, cataract is not so common. Most spectacle lenses give excellent UV protection- 95% plus of UV hitting the lens is absorbed, but recently it has been discovered that reflected UV- reflections from the back surface of the lens are a significant issue- up to 40% of a spectacle wearers exposure comes from this rear reflection. So although the spectacle wearer is better protected than a non spectacle wearer, even if their lens absorbed 100% of incident UV, they would still have an exposure of perhaps 40% compared to the non spectacle wearer.
New UV absorbing Anti Reflections coatings have been released to entirely defeat the UV reflection problem. Crizal Forte UV and Optifog UV are now available on any Essilor plastic lenses- single vision, bifocals and varifocals.
There is a worrying statistic- we receive 80% of our UV exposure by age 18, which suggests that adults starting to take care of their eyes is too late- it is the children we should be protecting. Children play outside, walk and cycle. Adults work indoors, probably drive, and thus spend significantly more time indoors, or protected in the car.
We should all be trying to prevent cataract by protecting the children NOW.
