Late progressive corneal flattening, haze and visual loss after eccentric crosslinking for Pellucid marginal degeneration

PURPOSE: Pellucid marginal degeneration (PMD) is a rare disease that is often mistaken for keratoconus but can similarly be treated with corneal collagen crosslinking (CXL). We report a case followed though 6 years of progressive irregular corneal flattening and thinning in both eyes (OU) after eccentric CXL for PMD. OBSERVATION: A 46-year-old man with bilateral PMD and corrected distance visual acuity (CDVA) of 20/20 (−2.00x80) in the right eye (OD) and 20/30 (+3.50–5.25x105) in the left eye (OS) underwent conventional 9 mm eccentric CXL in OU and intrastromal corneal ring implantation in the OS. An uneventful first year postoperative follow-up showed stabilization of the ectasia. In subsequent years, progressive inferior flattening was observed with decreased CDVA, corneal thinning and worsening of the haze. At the last follow-up, his CDVA was 20/40 (+5.00–2.00x55) OD and 20/60 (+6.00–1.50x80) OS. CONCLUSION AND IMPORTANCE: The current report highlights the notion that mid- and long-term evaluations of customized crosslinking techniques may reveal progressive flattening and corneal irregularity.