Sunday, December 19, 2010

Lattice Corneal Dystrophy

Lattice corneal dystrophy is a type of genetic corneal dystrophy which results in protein fibers deposits in the stroma of the cornea. These abnormal fibrous protein aggregates are called amyloid. Many patients with lattice suffer from visual compromise due to these anterior stromal deposits which form lattice-shaped lines. Lattice dystrophy is usually an autosomal dominant condition and is the most common of stromal dystrophies. Like granular and Avellino dystrophy, the genetic defect of lattice dystrophy has been mapped to the BIGH3 gene on chromosome 5q.

As time go by, the lattice lines grow opaque and involve more of the stroma. They also gradually converge, giving the cornea a cloudiness that may also reduce vision. These abnormal protein fibers can accumulate under the cornea's epithelium, causing it to erode. This condition is known as recurrent epithelial erosion. Although lattice dystrophy can occur at any time in life, the condition usually arises in children between the ages of 2 and 7. By about age 40, some patients have scarring under the corneal epithelium, resulting in a haze on the cornea that can greatly obscure vision. Onset of the corneal changes usually occurs in the first decade of life, although patients may remain asymptomatic for years. Examination of the cornea in the second to third decade of life reveals branching, refractile lattice lines with intervening haze, which are observed best in retroillumination.