The photograph shows the left eye of a 45-year-old patient who has pellucid marginal degeneration (PMD) (Figures 2 and 3). The patient had a history of hydrops in the left eye; he was wearing a corneal GP lens on the right eye and a piggyback system for his left eye. He complained that his left GP lens intermittently popped out.
PMD is an ectatic corneal disorder that is characterized by inferior peripheral thinning in which the maximal thinning can be localized below the corneal apex with 1mm to 2mm of a clear intervening zone leading up to limbus. The above anatomical attributes explain the paralimbal steepening seen with topography and the general fitting challenges with corneal GP lenses.
Corneo-scleral topography (Figures 4 and 5) was performed, and a back-surface-toric scleral contact lens with a diameter of 16.5mm was successfully fit OS (Figure 6). The patient’s best-corrected visual acuity improved to 20/40 with the scleral lens.