96% of people over 60 have some degree of optical opacification when examined with a slit lamp, an instrument typically used in ophthalmology to measure this condition.

Lens opacity often progresses very slowly without producing significant short-term visual impairment, although sometimes loss of vision makes it necessary to resort to surgery sooner than expected.

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The incidence of blindness due to senile cataract is very high in underdeveloped countries, where they have no efficient health system. However, in Spain, cataract surgery is one of the most common eye surgeries.

People with senile cataract often have a family history of lens opacity, especially in cases where the cataract appears at a relatively early age.

It is not known if cataract development is genetically conditioned or is due to environmental factors, but in cases with a clear inheritance pattern, it is often transmitted from parent to child in an autosomal dominant manner.

The reason why senile cataract occurs is unknown. It seem that, over time, certain factors alter the distribution of proteins within the lens, resulting in an increase in light scattering and subsequent opacification, producing vision problems.

We can classify senile cataract in two ways: by anatomical location within the lens and by the degree of development. The first division is made ​​between the nuclear and cortical senile cataracts, with the subcapsular cataract being a specific subset of cortical cataracts. In turn we can classify them into incipient, immature, mature and hypermature according to their progression in the process.