"Cataract" is the name used to describe a condition where the lens of the eye becomes opacified, blocking some light from reaching the retina and interfering with vision. Cataracts are multi-faceted. The most common cause is age related, other known causes include: diabetes, trauma, certain medications and rare systemic diseases. Typically, cataracts occur in adults ("adult onset"), but may occur as a congenital disorder. Fortunately congenital cataracts are rare, but these need to be diagnosed and managed urgently.

Symptoms
You can be aware of reduced or blurred vision in all situations if the cataract is dense. If the cataract is still relatively early, then you may find that vision in certain conditions is still satisfactory but in other situations (driving at light with oncoming headlights shining towards you for example) it is not good enough. Some people with cataracts feel as if their glasses lenses are dirty and despite cleaning their glasses, see no improvement in their vision.

Treatment