Lattice Corneal Dystrophy

Updated: Sep 22, 2014
  • Author: Natalie A Afshari, MD, MA, FACS; Chief Editor: Hampton Roy, Sr, MD  more...
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Overview

Background

Lattice corneal dystrophy (LCD), an IC3D category 1 dystrophy, is an autosomal-dominant condition and one of the most common stromal dystrophies. It is a slowly progressive disease that results in significant discomfort and visual impairment.

There are two genetically distinct types: lattice corneal dystrophy type I (classic type), which is isolated to the eye, and the less common lattice corneal dystrophy type II (gelsolin type), which has systemic amyloidosis manifestations. [1] Although lattice corneal dystrophy type II is regarded as a type of familial amyloidosis and not a true corneal dystrophy, it can be easily misdiagnosed as lattice corneal dystrophy type I. [2]

Like granular and Avellino dystrophies, the genetic defect of lattice corneal dystrophy type I has been mapped to the TGFBI (BIGH3) gene on chromosome 5q. [3, 4] Lattice corneal dystrophy type II results from a mutation in the GSN gene. Onset of corneal changes in lattice corneal dystrophy type I 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.

An example of lattice corneal dystrophy is shown in the image below.

Lattice corneal dystrophy. Image courtesy of James Lattice corneal dystrophy. Image courtesy of James J. Reidy, MD, FACS, Associate Professor of Ophthalmology, State University of New York, School of Medicine & Biomedical Sciences, Buffalo, New York.
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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. Corneal dystrophies can be placed into 3 categories based on their location within the cornea: (1) Anterior corneal dystrophies affect the corneal epithelium and may involve the Bowman layer, (2) stromal corneal dystrophies affect the central layer of the cornea (the stroma), and (3) posterior corneal dystrophies involve the Descemet membrane and the endothelium.

Lattice corneal dystrophy is primarily a stromal corneal dystrophy that starts as fine, branching linear central opacities in the Bowman layer and that spread to the periphery. Although the process may involve the deep stroma, it does not reach the Descemet membrane.

The age of onset for most corneal dystrophies is less than 20 years (exceptions include map-dot-fingerprint dystrophy and Fuchs corneal dystrophy). Most corneal dystrophies are inherited in a dominant pattern. Exceptions include macular corneal dystrophy, type 3 lattice corneal dystrophy, and the autosomal-recessive form of congenital hereditary endothelial dystrophy.

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Epidemiology

Frequency

United States

Although lattice corneal dystrophy type I is one of the most common stromal dystrophies in the Western world, it is still relatively rare. [5, 1]

International

Cases of lattice corneal dystrophy type I have been recognized throughout the world. Lattice corneal dystrophy type II is most common in Finland. [6]

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 is noted.

Age

In lattice corneal dystrophy type I, onset of the corneal changes such as recurrent epithelial erosions 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 visual acuity. Onset of corneal changes in lattice corneal dystrophy type II occurs at age 30-40 years, but most patients do not experience symptoms until their seventh decade of life. [2]

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