The light and electron microscopic studies, gene mutation analysis of a case of macular corneal dystrophy

1. Sung-kun Chung¹
2. Tae-hoon Oh¹

¹Department of Ophthalmology and Visual Science, St. Mary's Hospital, Seoul, South Korea

Purpose: To report light and electron microscopic studies, gene mutation analysis in one case of macular corneal dystrophy after penetrating keratoplasty

Methods: A 59 year-old female presented with progressive loss of vision over a period of 30 years. 15 years ago, She was diagnosed with macular corneal dystrophy of both eyes and underwent penetrating keratoplasty of left eye. She complained of appreciable deterioration in vision of right eye. So, she underwent penetrating keratoplasty of right eye. Light microscopy and transmission electron microscopy were performed on the removed corneal specimens. And, Genomic DNA was obtained from peripheral blood samples.

Results: Light microscopy of the corneas revealed deposits of glycosaminoglycans in keratocytes, endothelial cells and extracellularly within the stroma, all staining positively with Alcian blue, Colloidal iron, and periodic acid-Schiff. Electron microscopy showed keratocytes distended by membrane bound intracytoplasmic vacuoles containing electron dense fibrillogranular material. Some of the vacuoles contained dense osmiophilic whirls. Similar membrane bound, intracytoplasmic vacuoles containing fibrillogranular material were present in endothelial cells, and between stromal lamellae. In addition, We identified gene mutation within the coding region of CHST6. It was homozygous mutation (c.613 C>T (p.Arg205Trp)). This mutation was not previously reported.

Conclusion: We report a rare form of corneal dystrophy, especially in east Asia. We review the histological features associated with this disorder and report new mutation of CHST6 gene.