Autopsy is often the only way of obtaining material for histological study from conditions such as age-related macular degeneration or various retinopathies. It is also a valuable source that allows the study of the eye in various systemic or multisystem diseases. If systemic hypertension is uncontrolled this leads to retinal vascular ischaemia usually by way of microinfarcts. Fibrinoid necrosis may be seen in choroidal vessels. Sclerokeratitis may be seen in rheumatoid arthritis, various vasculitides and other autoimmune diseases such as systemic lupus erythematosus. Deposits of leukaemia and lymphoma are usually seen in the choroid and haemorrhages may also occur. Retinitis pigmentosa is frequently only studied at the late stage where there is bone spicule pigmentation with sparing of the macular region. A common feature in syndromic retinal degeneration appears to be abnormalities in the cilia. Metabolic deficiencies may also affect the eye. These include lysosomal storage disorders, peroxisomal storage disorders, lipofuscinosis and aminoacidopathies. Mitochondrial disorders also occur. The effects of demyelinating disease such as multiple sclerosis may also be seen in the eye.