Background: Granular corneal dystrophy (GCD) is caused by mutations in the transforming growth factor β induced (TGFBI) gene. The International Committee for Classification of Corneal Dystrophies (IC3D) edition 2 classifies a disease that was previously called Avellino corneal dystrophy as GCD type 2 (GCD2). Commonly seen GCD2 corneal opacities caused by heterozygous mutations are treated with phototherapeutic keratectomy (PTK), corneal transplantation, and corneal electrolysis, which is performed only in Japan. However, homozygous GCD2, in which both alleles of TGFBI are mutated, causes more severe corneal opacity than heterozygous GCD2, in which only one allele is mutated, and the treatment of homozygous GCD2 is often difficult. In this study, we report a case of homozygous GCD2 that was treated using combined PTK and corneal electrolysis and maintained good best-corrected visual acuity for a long time.
Case presentation: The subject was a 15-year-old woman. She visited the local doctor due to impaired vision at the age of 7 and was diagnosed with bilateral homozygous GCD2. Because corneal scrape was ineffective, she was referred to the Miyata Eye Hospital. PTK was performed to treat extensive corneal opacity in the right eye, and corneal opacity and corrected visual acuity showed improvement. However, since corneal opacity recurred at the age of 16, corneal electrolysis was performed. At the age of 17, corneal opacity in the left eye exacerbated and PTK was performed. Subsequently, PTK and electrolysis were performed for recurrent corneal opacity. After a total of 25 surgical treatments, she maintained a good visual acuity of 0.4 (1.0×+6.00 D＝cyl-0.50 D Ax 10°) of the right eye and 0.3 (0.6×+6.0 D) of the left eye, although hyperopia progressed at the time of final observation (at age 34). Genetic tests revealed a homozygous R124H mutation in the TGFBI gene.
Conclusion: Multiple combined PTK and corneal electrolysis are effective in maintaining good visual acuity in a patient with corneal opacities due to homozygous GCD2.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 125: 1067-1074,2021.