Granular Corneal Dystrophy (GCD)

Corneal dystrophies are an inherited condition; usually autosomal dominant, as many as 50% of family members may be affected. The frequency is equal among men and women except for Fuchs’ dystrophy, which is more common in females.¹ Genetic mutation occurs on the TGFßI gene located on chromosome 5q31.² A genetic test is now available for testing relatives.

These dystrophies may start in the first decade of life through early adulthood. Because patients may be asymptomatic initially, corneal dystrophies are often detected during a routine eye examination. Lesions tend to start centrally, gradually expanding to the corneal periphery.³

Granular corneal dystrophy type 1 (GCD) is one of the more common conditions of the anterior stroma. Initially categorized as a “stromal” dystrophy, the latest classification is an “epithelial-stromal” dystrophy. Others in this group include Reis-Bucklers dystrophy, Thiel-Behnke dystrophy, lattice corneal dystrophy type 1, and granular corneal dystrophy type 2 (Avellino dystrophy).²

The granular corneal dystrophy name comes from the appearance of small particles that are reminiscent of breadcrumbs. They may be viewed with a thin optic section or sclerotic scatter.⁴ Anterior segment OCT can be helpful in locating and quantifying the lesions. Initially, the corneal surface may be uniform and smooth; however, as the condition progresses, the corneal surface may become more irregular. Although confined to the anterior stroma, epithelial integrity and function may be affected. As the dystrophy progresses, patients may become photophobic. Recurrent corneal erosions (RCEs) may occur, requiring appropriate management.⁵

References:

1. Lusby FW. Fuchs Dystrophy. U.S. National Library of Medicine, Medline Plus. Updated Aug. 18, 2020. Available at https://medlineplus.gov/ency/article/007295.htm . Accessed Sept. 28, 2021.
2. Birkholz EZ, Syed NA, Wagoner MD. Corneal Stromal Dystrophies: A Clinicopathologic Review. Eyerounds.org. 2009 Aug 4. Available at http://www.eyerounds.org/cases/43-corneal-stromal-dystrophies.pdf . Accessed Sept. 23, 2021.
3. National Organization for Rare Disorders. Corneal dystrophies. Rare Disease Database. Updated 2010. Available at https://rarediseases.org/rare-diseases/corneal-dystrophies . Accessed Sept. 23, 2021.
4. Bass S. Digging Deeper into Superficial Corneal Dystrophies. Rev Optom. 2016 Apr 15. Available at https://www.reviewofoptometry.com/article/digging-deeper-into-superficial-corneal-dystrophies . Accessed Sept. 23, 2021.
5. Sorkin S. Corneal Dystrophies 101. Mod Optom. 2021 Apr:19-22. Available at https://modernod.com/articles/2021-apr/corneal-dystrophies-101?c4src=article:infinite-scroll . Accessed Sept. 23, 2021.

Dr. Arnold is the regional vice president – Corporate Development for AEG Vision. He is a Fellow of the Scleral Lens Education Society and has been a consultant for and spoken on behalf of Blanchard Labs, Bausch + Lomb Specialty Vision Products, BostonSight, Eaglet Eye, EyePrint Prosthetics, and AccuLens.