Aging.
Metabolic disorders such as diabetes mellitus, galactosemia
(inherited disease of infants in which milk cannot be digested).
Congenital- usually obscure. May be caused by drugs such as
corticosteroids in first trimester, sulphonamides,etc.
Inflammation, such as uveitis (inflammation of the parts of the
eyes that make up the iris).
Drugs, especially cortisone.
Exposure to X-rays, microwaves, and infrared radiation.
Intrauterine infections in first trimester (rubella, herpes,
mumps).
Tumors- melanoma, retinoblastoma,
Trauma- concussion, perforating eye injuries, intra-ocular
foreign body, heat, electric shock and radiation