Morphological Characteristics of Granular Corneal Dystrophy Type 1 in the Korean Population

Purpose: Granular corneal dystrophy type 1 (GCD1) is a genetic disorder characterized by grayish-white granular deposits in the corneal stroma, typically manifesting before age 10. The specific characteristics of GCD1 in the Korea population remain insufficiently described. This study investigated the morphological features of GCD1 corneas with confirmed genetic mutations in this population.Methods: Medical records of GCD1 patients with the R555W mutation confirmed through transforming growth factor β induced (TGFBI) gene testing on oral epithelium or blood samples from 2005-2022, were analyzed. Corneal photographs obtained using a slit lamp biomicroscope were also examined.Results: The study group included 11 males and 19 females with an average age of 35.7 years, ranging from 3-70 years. All participants were heterozygotes. In 28 individuals (56 eyes, representing 93.3% of the total), there were signs of corneal deposit detachments, known as “drop-off”, observed in patients aged 6 years and above. Surface deposits reemerged at the peripheral margin of previous locations and expanded toward the center. The number and shape of opacities significantly changed with age, showing cycles of deposition and shedding. There were variations in the severity of opacities within the same family, particularly with advancing age, and distinct opacities extending into deeper stromal layers.Conclusions: This study outlines the morphological characteristics of corneas in Korean GCD1 patients, based on corneal photograph analysis. These findings provide a basis for future comparative studies with GCD2 and may aid rapid clinical diagnosis based on clinical findings, prior to genetic testing confirmation.