Introduction
Background
Granular dystrophy is an autosomal dominant, bilateral, noninflammatory condition that results in deposition of opacities in the cornea by adulthood. It specifically affects the middle portion of the cornea (stroma) and eventually can cause decreased vision and eye discomfort. Severe cases of granular dystrophy can be treated with either excimer laser ablation or by replacing cornea (corneal transplant). An example is shown in the image below.
Granular 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.
Pathophysiology
The cornea is the clear outer coat of the front of eye. A dystrophy of the cornea is defined as a bilateral noninflammatory clouding of cornea. Corneal dystrophies can be divided into 3 categories based on their location within the cornea, as follows: (1) anterior corneal dystrophies affect the corneal epithelium and may involve the Bowman membrane; (2) stromal corneal dystrophies (which include granular dystrophy) affect the central layer of cornea, the stroma; and (3) posterior corneal dystrophies involve the Descemet membrane and 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 being macular dystrophy, type-3 lattice dystrophy, and the autosomal recessive form of congenital hereditary endothelial dystrophy.
Granular corneal dystrophy types I, II (Avellino dystrophy), have been reported to result from mutations in the BIGH3 gene.1 Depending on the specific mutation in the beta ig-h3 gene, the phenotypes of corneal dystrophy may differ.
Frequency
United States
Granular dystrophy is uncommon in the United States.
International
Granular dystrophy is uncommon worldwide.
Mortality/Morbidity
Corneal changes generally first become visible during the second decade of life, but vision may not be affected until the fourth to fifth decade of life. Eye pain from recurrent corneal erosions also can occur.
Sex
No sexual predilection has been reported.
Age
Corneal changes usually become visible during the second decade of life, but patients may not be affected until the fourth to fifth decade of life.
Clinical
History
- Patients with granular dystrophy may have decreased vision, photosensitivity, and/or eye pain (from recurrent corneal erosions).
- Because granular dystrophy is autosomal dominant, one of the parents likely has granular corneal dystrophy as well.
Physical
- Granular dystrophy is characterized by bilateral formation of discrete, focal, white granular deposits in the anterior stroma of cornea with clear areas between these deposits.
- The granules are primarily located in the central cornea, with an absence of these deposits in the peripheral cornea.
- The deposits can resemble crushed breadcrumbs or snowflakes. As patients advance in age, the deposits become larger and increase in number. Eventually, the intervening clear areas develop a mild-to-severe corneal haze.
- When there are clear spaces between the deposits, the vision generally is not affected severely. However, over time, the clear spaces become involved with opacity. This later onset opacity in the previously clear spaces is usually much more superficial than the longstanding, dense white granules. The vision dramatically declines when the clear spaces opacify.
Causes
- Granular dystrophy is an autosomal dominant condition; its genetic defect has been mapped to chromosome 5q.
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| Treatment & Medication: Dystrophy, Granular |
| Follow-up: Dystrophy, Granular |
| Multimedia: Dystrophy, Granular |
| References |
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References
Grunauer-Kloevekorn C, Brautigam S, Wolter-Roessler M. Molecular genetic analysis of the BIGH3 gene in lattice type I (Biber-Haab-Dimmer) and granular type II (Avellino) corneal dystrophy: is indirect mutation analysis for hot spots recommended?. Klin Monatsbl Augenheilkd. Dec 2005;222(12):1017-23. [Medline].
Mori H, Miura M, Iwasaki T, et al. Three-dimensional optical coherence tomography-guided phototherapeutic keratectomy for granular corneal dystrophy. Cornea. Sep 2009;28(8):944-7. [Medline].
Dalton K, Schneider S, Sorbara L, Jones L. Confocal microscopy and optical coherence tomography imaging of hereditary granular dystrophy. Cont Lens Anterior Eye. Nov 27 2009;[Medline].
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].
Albert D, Jakobiec F. Principles and Practice of Ophthalmology. Vol 1. 1994:26-49.
Klintworth GK. Advances in the molecular genetics of corneal dystrophies. Am J Ophthalmol. Dec 1999;128(6):747-54. [Medline].
Krachmer J. Cornea. Vol 2. 1996.
Yamamoto S, Okada M, Tsujikawa M, et al. The spectrum of beta ig-h3 gene mutations in Japanese patients with corneal dystrophy. Cornea. May 2000;19(3 Suppl):S21-3. [Medline].
Further Reading
Keywords
granular dystrophy, corneal dystrophy, granular corneal dystrophy, corneal transplant, eye problems, Avellino dystrophy, eye pain, corneal changes, diagnosis, treatment, symptoms
