Pellucid Marginal Corneal Degeneration and Keratoconus: Differential Diagnosis and Management of Patients

Abstract

The authors present the problem of differential diagnosis of primary corneal keratectasias: pellucid marginal degeneration (PMD) and keratoconus. Some cases of differential diagnosis can be very challenging and choice of rational treatment for these patients is actual. Despite multiple publications concerning keratoconus and extensive knowledge of this disease, articles about PMD are rare. Results of surgical treatment for PMD are usually worse than for keratoconus. The authors show the value of confocal microscopy, keratotopography, and high-resolution optical tomography of the anterior segment of the eye based on a two-channel Scheimpflug camera and give clinical examples of differential diagnosis that present certain complexity. Recommendations on treatment of patients with PMD are given, including such severe complication of progressive far-advanced corneal ectatic diseases as acute corneal hydrops. The important role of modern scleral gas-permeable contact lenses in visual correction of PMD and keratoconus is summarized. The authors believe that in cases of PMD without critical thinning of the cornea, if patients are satisfied with contact correction, the surgical treatment should be avoided or postponed.