Excerpt from Dystrophy, Lattice

Synonyms, Key Words, and Related Terms: lattice dystrophy, corneal dystrophy, stromal dystrophy, stromal dystrophies, corneal erosion, corneal transplant, phototherapeutic keratectomy, PTK

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Background: Lattice dystrophy usually is an autosomal dominant condition, and it is the most common of stromal dystrophies. Like granular and Avellino dystrophy, the genetic defect of lattice dystrophy has been mapped to the BIG H3 gene on chromosome 5q. 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 will reveal branching, refractile lattice lines with intervening haze, which are observed best in retroillumination.

Pathophysiology: The cornea is the clear outer coat of the front of the eye. A dystrophy of the cornea is defined as a bilateral noninflammatory clouding of the cornea. The corneal dystrophies can be placed into 3 categories based on their location within the cornea as follows: (1) the anterior corneal dystrophies affect the corneal epithelium and may involve the Bowman membrane, (2) stromal corneal dystrophies affect the central layer of the cornea (the stroma), and (3) the posterior corneal dystrophies involve the Descemet membrane and the endothelium.

Most corneal dystrophies have an onset prior to age 20 years (exceptions include map-dot-fingerprint dystrophy and Fuchs corneal dystrophy). Most corneal dystrophies are dominantly inherited, exceptions are macular dystrophy, type 3 lattice dystrophy, and the autosomal-recessive form of congenital hereditary endothelial dystrophy.

Frequency:

In the US: Although lattice dystrophy is the most common of the stromal dystrophies, it is relatively rare.

Mortality/Morbidity: Excessive corneal erosions can lead to decreased visual acuity, which may require a corneal transplant or phototherapeutic keratectomy (PTK).

Sex: No sexual predilection exists.

Age: 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, which are observed best in retroillumination. Over time, the lattice lines and other opacities coalesce, forming anterior stromal haze that decreases the visual acuity.