Superficial Keratectomy Followed By Successive Phototherapeutic Keratectomy For Schnyder Corneal Dystrophy

To restore corneal clarity avoiding keratoplasty in a case with Schnyder Corneal Dystrophy

AKTINA OPHTHALMOLOGY CENTER 

A 63-year-old Caucasian female presented with Schnyder Corneal Dystrophy (SCD) and known amblyopia since childhood. Mature cataract had evolved lately, which, together with the progression of SCD, reduced her visual acuity to Hand Motion in both eyes. Dense central superior stromal calcification and superficial as well as deep corneal neovascularization extending up to the central cornea were evident at slit lamp examination. High resolution Spectral Domain Anterior Segment OCT (Solix, Optovue, Visionix) was used for evaluation and surgical planning. About 350μm of calcified and scarred corneal tissue was removed manually. Multiple superficial corneal vessels were cauterized with a fine needle and 0.2ml of Bevacizumab was administered subconjunctivally. Subsequently, Phototherapeutic Keratectomy (PTK) was performed to smoothen the corneal surface using an Excimer LASER (Wavelight EX500, Alcon, Texas, USA). The ablation zone was set at 6.5mm and the ablation depth at 50μm. Mitomycin-C 0.04% was applied for 30 seconds. Six weeks later, phacoemulsification was feasible given the relative clarity of the cornea. Corneal curvature was estimated using Spectral Domain OCT Topography mapping (Revo FC, Optopol), which was then combined with Swept Source OCT Biometry (Argos, Alcon), taking into consideration the significant flattening of the cornea (mean curvature was 34D). Best corrected visual acuity reached 20/60 and remains stable over a period of 2 years. 

Combined multi-step treatment of Schnyder Corneal Dystrophy (SCD) may consist of superficial keratectomy, subconjunctival anti-VEGF agents, Phototherapeutic Keratectomy (PTK) and Mitomycin-C in order to restore sufficient corneal clarity allowing for the performance of safe phacoemulsification.