How does a cataract develop?

Age-Related

As the lens ages, it increases in weight and thickness. As new layers of fibres are formed, the centre of the lens (nucleus) becomes compressed and hardens. This is called nuclear sclerosis. The lens is made of mostly water and protein. The precise arrangement of the protein ensures the lens is transparent to enable light to pass through. Any structural changes in the protein can therefore alter the transparency of the lens, thus affecting the vision.

Modifications of the lens protein also increases pigmentation, resulting in the yellow to brown discolouration of the lens and decreased opacification over time.

Initially, the cataract may be small and the cloudiness will only affect a small part of the lens.

Age-related cataracts can be classified according to its location:

Nuclear: The cataract is present in the centre of the lens (nucleus). They tend to progress slowly and have a greater impact on distance vision.

Subcapasular: The cataract is present at the back of the lens

Cortical: The cataract forms at the periphery of the lens and moves towards the centre in a spoke-like fashion.