Macular Corneal Dystrophy Clinical Presentation

Updated: May 02, 2018
  • Author: Anna M Edmiston, MD; Chief Editor: Hampton Roy, Sr, MD  more...
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Presentation

History

In many patients, macular corneal dystrophy (MCD) is first visible in the cornea during the first decade of life. Visual acuity decreases over time, and patients develop photosensitivity. They may also experience eye pain from recurrent corneal erosions.

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Causes

Macular corneal dystrophy is autosomal recessive. The gene responsible for macular dystrophy is CHST6 (carbohydrate sulfotransferase 6 gene), located on chromosome 16.

The metabolic defect for this condition appears to be an error in the synthesis of keratan sulfate, which leads to accumulation of glycosaminoglycan in the cornea. Three variants of macular corneal dystrophy exist based on the immunoreactivity of the macular deposits. Macular corneal dystrophy type I has no keratan sulfate reactivity in the cornea or serum. Macular corneal dystrophy type IA has keratan sulfate reactivity in keratocytes but not in serum. Macular corneal dystrophy type II has keratan sulfate reactivity in the cornea, and the serum has normal or low levels of keratan sulfate. [2]

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Physical Examination

Macular dystrophy is characterized by multiple irregular gray-white opacities that are present in the corneal stroma and extend into the peripheral cornea. This is in contrast to granular corneal dystrophy, in which the deposits are located centrally. As the gray-white opacities develop in macular corneal dystrophy, a diffuse haze simultaneously progresses to involve the entire corneal stroma. The lack of clear spaces between stromal opacities differentiates macular corneal dystrophy from granular corneal dystrophy, in which there are usually clear zones between opacities. [1] The corneal epithelium is typically unaffected; however, it can develop corneal erosions. In advanced disease, corneal endothelium and the Descemet membrane may be affected. [2]

Macular corneal dystrophy involves the entire thickness of the corneal stroma and is more superficial centrally and deeper peripherally. The central cornea in this condition may be thinned. Significant cornea guttata may be present in severe disease, although endothelial decompensation is very rare. [1]

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Complications

Complications of macular corneal dystrophy include photophobia, loss of vision, and, less commonly, recurrent corneal erosions.

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