Macular Corneal Dystrophy Clinical Presentation
- Author: Natalie A Afshari, MD, MA, FACS; Chief Editor: Hampton Roy, Sr, MD more...
In many patients, macular corneal dystrophy 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.
Macular dystrophy is characterized by multiple irregular gray-white opacities that are present in the corneal stroma and extend into the peripheral cornea. (In granular corneal dystrophy, the deposits are located centrally.) These stromal opacities are distributed throughout the cornea without clear spaces, whereas granular corneal dystrophy deposits usually have clear zones between them.
Macular corneal dystrophy involves the entire thickness of the cornea 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.
Macular corneal dystrophy is autosomal recessive. The gene responsible for macular dystrophy is CHST6, located on chromosome 16.
The metabolic defect for this condition appears to be an error in the synthesis of keratan sulfate. 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.
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