TREASURES FROM EGYPT – A RARE CASE OF MACULAR CORNEAL DYSTROPHY

Our purpose is to report a case of a patient referred to our Ophthalmology Department with macular corneal dystrophy and describe examination findings performed at our center.

New York Presbyterian Hospital, New York City, USA

A 23-year-old egyptian female was referred to our center due to progressively worsening of vision, nyctalopia and photophobia, bilaterally. Best corrected visual acuity was of 20/250 right eye and 20/150 left eye. Biomicroscopy and Anterior Segment Photography taken at the time of presentation showed diffuse stromal haze with gray white stromal opacities throughout thickness of cornea, sparing the corneal periphery 360º, bilaterally. There was no anterior chamber reaction and intraocular pressure as well as fundoscopic examination were unremarkable. PENTACAM Tomography revealed an irregular astigmatism bilaterally. Anterior segment swept-source optical coherence tomography (AS-OCT) ANTERION depicted hyper-reflective stromal lesions. Presuming Schnyder corneal dystrophy as first diagnosis, a right cornea biopsy for pathological analysis was made, and microscopic findings revealed subepithelial deposits of granular material in the anterior corneal stroma. This material stained positively with Alcian blue, colloidal iron, and PAS stains, which favored to represent the abnormal non-sulfated keratan of macular dystrophy. A genetic testing revealed CHST6 homozygous deletion causative of corneal macular dystrophy. The patient underwent Penetrating Keratoplasty of her right eye and keeps being monitored at our center.

Macular corneal dystrophy has an autosomal recessive inheritance pattern, with locus on chromosome 16q22 with a mutation of the CHST6 gene which codes for carbohydrate sulfotransferase 6, an enzyme responsible for the sulfation of the keratan molecules. This mutation leads to a stromal haze and corneal opacities. The disease rare in the USA and studies have shown that there tends to be increased incidence in families with consanguinity, which happened in our case, in which parents were first degree cousins. Medical treatment is used for symptomatic relief, with artificial tears, lubricants, NSAIDs for pain and antibiotic drops if erosions occur. However Penetrating Keratoplasty remains the definite treatment of choice in this rare set of patients.