Lattice corneal dystrophy type I is one of the more common corneal dystrophies and occurs throughout the world.  Randomly oriented linear opacities resembling cotton threads accumulate in the central portions of the stroma.  These usually become apparent in the first decade of life although they are sometimes seen in infancy.  The peripheral cornea is relatively spared and intervening stromal areas are clear.  This is a progressive disorder in which vision during childhood is often normal but by the fifth and sixth decades most patients have severe visual impairment due to increasing accumulations of amyloid.  Corneal erosions may occur in the absence of stromal infiltrates.