What causes fatty deposits in the eye?

Any disturbance in the lipid metabolism can cause such a case, most commonly manifesting as arcus senilis where the cornea is deposited with fatty material e.g. phospholipids and cholesterol, resulting in corneal opacity. Disturbances in the lipid metabolism can occur in cases such as: hypercholesterolemia, hyperlipoproteinemia and hyperlipidemia

Wow! The above answer is correct to an extent but needs additional information. The MOST COMMON reason for fatty deposits in the eye are age and heredity. Everyone in some way has some natural collection and pooling of fluids around the under eye area, The composition of our eye area makes it naturally prone to accumulation of fluids and fatty tissue deposits which collect under and around the eyes. This often is the cause of dark circles under the eye.