Lattice corneal dystrophy type 3A is rare condition that affects the cornea. It is characterized primarily by protein clumps in the clear, outer covering of the eye which cloud the cornea and impair vision. Affected people also experience recurrent corneal erosion (separation of certain layers of the cornea), which is associated with severe pain and sensitivity to bright light. Lattice corneal dystrophy type 3A is caused by changes (mutations) in the TGFBI gene and is inherited in an autosomal dominant manner. The condition is usually treated surgically.