Diabetic cataract

• young insulin dependent diabetics may rapidly develop a cataract over a period of 2 to 3 days, as a result of poorly controlled hyperglycaemia
• cataracts are frequently bilateral and cortical, and predominantly involve the anterior and posterior subcapsular region
  • initially they consist of minute dots of varying size - snow flakes - but soon become completely opaque
  • there may be refractive errors noted first
• the cataract is thought to result from an increase in glucose in the lens which is subsequently reduced to its alcohol, glucose alcohol or L-sorbitol
  • the lens capsule is relatively impermeable to sorbitol and consequently, remains within the lens where it imbibes water, causing an osmotic imbalance
  • the increased sodium, decreased potassium and decreased glutathione levels eventually lead to cataract formation.

Patients with non - insulin dependent diabetes do not develop true diabetic cataracts but on average develop senile cataracts 10 years earlier than non - diabetics.