Topographical and functional analysis of different surgical strategies for advanced pellucid marginal degeneration: A long term follow-up.

Purpose: To compare clinical and topographical outcomes of three different surgical strategies for advanced pellucid marginal degeneration (PMD).

Methods: Retrospective, interventional case series of 8 advanced PMDs undergoing three different surgical interventions: Sliding Keratoplasty (SK), Sliding Keratoplasty with Relaxing Incision (SKRI), Sector Lamellar Keratoplasty (SLK). Pre-operatively and at 1, 3, 6, 12-month and final follow-up (50.8 ± 20.6 months) post-operatively, we collected: uncorrected and corrected distance visual acuity (UDVA and CDVA), spherical equivalent (SE), refractive astigmatism (RA), corneal Ks, topographical astigmatism (TA) and calculated against-the-rule (ATR) component.

Results: CDVA significantly improved from 6 months after surgery ( = 0.04), while final CDVA was at least 20/40 in 75% of eyes. As desired, surgery led to an overcorrection toward with-the-rule astigmatism at 1-month, which then decreased at 12-month and at final follow-up ( < 0.05). The ATR-component was significantly decreased at 1-month (1.9 ± 1.1 vs. 17.6 ± 6.3 D pre-operatively,  = 0.0015) and remained quite stable over time (4.2 ± 4.2 D at final follow-up). In subgroup analysis, SK and SKRI offered better CDVA and lower RA, while SLK showed more TA stability. The ATR component, comparing baseline and final follow-ups, decreased from 16.8 ± 8.3 D to 5.9 ± 3.6 after SK; from 18.9 ± 3.6 D to 3.3 ± 3.3 D after SKRI; from 17.0 ± 10.3 D to 1.9 ± 1.5 D after SLK.

Conclusion: The surgical treatment of advanced PMD showed long-term favourable outcomes. SK and SKRI offered better visual outcomes, but were more inclined to astigmatism regression over time. Conversely, SLK had more stable results but offered worse refractive outcomes.