Introduction
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
United States
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.
Clinical
History
Patients may have decreased vision, photosensitivity, and/or eye pain (from recurrent corneal erosions). This dystrophy usually is autosomal dominant, so it is likely that one of the parents will have lattice corneal dystrophy as well.
Physical
Lattice corneal dystrophy is characterized by branching, refractile lattice lines, which are observed best in retroillumination. In the most common form, type 1 lattice dystrophy, the refractile lines are more prominent centrally than peripherally. Later in life, stromal haze can develop. Eventually, significant stromal scarring and subepithelial fibrosis may occur.
Causes
The genetic defect of lattice dystrophy has been mapped to the BIG H3 gene of chromosome 5q. Other corneal dystrophies also have genetic defects of the BIG H3 gene, including granular dystrophy, Avellino dystrophy, and Reis-Bückler dystrophy.
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References
Albert D, Jakobiec F. Principles and Practice of Ophthalmology. Vol 1. 1994: 26-49.
Das S, Langenbucher A, Seitz B. Excimer laser phototherapeutic keratectomy for granular and lattice corneal dystrophy: a comparative study. J Refract Surg. Nov-Dec 2005;21(6):727-31. [Medline].
Das S, Langenbucher A, Seitz B. Delayed healing of corneal epithelium after phototherapeutic keratectomy for lattice dystrophy. Cornea. Apr 2005;24(3):283-7. [Medline].
Kawashima M, Yamada M, Funayama T, et al. Six cases of late-onset lattice corneal dystrophy associated with gene mutations induced by the transforming growth factor-beta. Nippon Ganka Gakkai Zasshi. Feb 2005;109(2):93-100. [Medline].
Krachmer J. Cornea (3 volume set). Vol 2. 1996.
Mashima Y, Yamamoto S, Inoue Y, et al. Association of autosomal dominantly inherited corneal dystrophies with BIGH3 gene mutations in Japan. Am J Ophthalmol. Oct 2000;130(4):516-7. [Medline].
Stone EM, Mathers WD, Rosenwasser GO, et al. Three autosomal dominant corneal dystrophies map to chromosome 5q. Nat Genet. 1994;6(1):47-51. [Medline].
Further Reading
Keywords
lattice dystrophy, corneal dystrophy, stromal dystrophy, stromal dystrophies, corneal erosion, corneal transplant, phototherapeutic keratectomy, PTK
