Does photorefractive keratectomy with mitomycin C application provide reasonable therapeutic and refractive solution for low to moderate myopic patients with type I granular corneal dystrophy and obviate the need for keratoplasty?

To evaluate the use of photorefractive keratectomy (PRK) with mitomycin C (MMC) application as a therapeutic and refractive solution for low to moderate myopic patients with granular corneal dystrophy (GCD) type 1, to study the postoperative complications and the recurrence rate, and to answer this question: Can excimer laser ablation obviate the need for keratoplasty in those patients?. Prospective nonrandomized interventional study was employed. 7 eyes of 5 myopic patients with GCD type 1 were treated with Wavelight EX 500 excimer laser PRK with post ablation intra-operative MMC application. Preoperative and regular postoperative complete ophthalmologic examination, anterior segment colored photographing, and corneal investigations using Wavelight – Allegro Oculyzer pentacam and Optovu corneal ocular coherence tomography (OCT) were performed for all patients. The postoperative follow up period was 18 months. Manifest spherical equivalent (SEq) refraction, best corrected visual acuity (BCVA), and the central 7 mm corneal clarity. The results have shown; statistically significant improvement of mean (M) SEq refraction of the patients from -(3.91±1.4737) preoperatively to -(0.0714±0.4009) 2 weeks postoperatively; (probability value (P) <0.0001), and statistically significant improvement of M BCVA of the patients from (0.314 ± 0.212) to (0.9 ± 0.115) 2 weeks postoperatively; (P<0.0001), and the central cornea became clear after PRK with MMC for all patients. Postoperative follow up revealed that, visually significant corneal haze has occurred in the first post operative few weeks in 2 eyes (28.6 %); and it was resolved by topical steroids, and recurrence of the granular deposits has occurred around 6 months postoperatively in 3 eyes (42.86%), this recurrence significantly caused alteration of the refraction and diminution of vision, with light sensitivity in one eye (14.29 %). PRK redoing was done to treat this eye after complete meticulous corneal examination and investigations. After redoing, all clinically significant opacities have been eliminated with returning of clear vision and stable refraction until the end of follow up period. In the light of suitable topographic and corneal OCT measures, PRK with MMC application can provide good therapeutic and refractive solution for clinically selected low to moderate myopic patients with GCD type 1, and can delay the need for keratoplasty in large numbers of patients in the short term. The recurrence of the GCD may occur but, fortunately; most recurrences don`t significantly affect the visual functions. Visually significant recurrences may be retreated by excimer laser when the clinical, topographic and corneal OCT measures permit.