•Groenouw dystrophy type II.
•Stromal corneal dystrophy caused by the irregular accumulation of glycosaminoglycans in stromal keratocytes due to abnormal carbohydrate sulfotransferase 6
ETIOLOGY:
•Autosomal recessive disorder.
•Mutation in the Carbohydrate sulfotransferase 6 gene (CHST6) on Chromosome 16q22.
•2 types:
•Type I: Presents in childhood, more common. Lacks keratan sulfate in the cornea.
•Type II: Presents in 2nd decade. Keratan sulfate is present in the cornea.
ONSET:
•Early childhood.
•Progressive with fall in vision by 2nd-3rd decade.
SYMPTOMS:
•DOV in 2nd decade of life
•Glare.
•Pain and watering due to recurrent erosions.
SIGNS:
•Ill-defined, central gray-white granular opacities with diffuse haze of the intervening stroma.
•Periphery is involved as it extends upto the limbus.
•Cornea thinner than normal.
•The central focal lesions are superficial whereas the peripheral lesions are deep.
•Associated corneal abnormalities and guttata present.
PATHOLOGY:
•Deposition of Glycosaminoglycan in the corneal stroma that stain blue with Alcian blue and colloidal iron.
INVESTIGATIONS:
•AS-OCT: for visualization of anterior and deeper layers of the cornea for location of deposits.
•Confocal microscopy: hyperreflective material with ill-defined borders and loss of normal keratocytes.
•Corneal Topography: higher density at the corneal apex with central corneal thinning.
TREATMENT:
•Asymptomatic patients: no treatment required.
•Mild ocular irritation: Preservative-free lubricating eye drops.
•Vision is usually affected by 2nd-3rd decade and patients may require a DALK/ Penetrating Keratoplasty.
•Excimer laser PTK – to remove the superficial opacities.
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Image from Rajan Eye Care Hospital
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