Clinical management of pellucid marginal degeneration (PMD) using scleral rigid contact lenses: A case report

Abstract

A 55-year-old male, KMI, presented to our Optometry clinic for contact lens fitting. The patient complained about blurry distant vision and high astigmatism in both eyes. He denied any remarkable ocular and general health history. After a comprehensive eye examination, the patient was diagnosed to have pellucid marginal degeneration in both eyes, with remarkable inferior corneal steepening and thinning. Multi-curve RGP lenses (Rose K2) with different parameters and piggyback back system were fitted to the patient. However, optimal lens fitting could not be obtained due to his irregular and inferiorly steepened cornea. Scleral RGP contact lenses (ICD 16.5) were then refitted to him. Both visual and fitting performances of the lenses were good during delivery. However, after the patient wore the contact lenses for a month, the lens vaulting thickness reduced significantly due to lens settling, and causing lens bearing in OS. Therefore, lenses with increased lens sag, especially at the limbal and peripheral corneal regions were refitted for the patient. Both visual and fitting performances of the lenses were good. Subjective feeling and corneal health condition were optimal during the subsequent aftercare consultations. In the early stage, PMD can be managed using spectacles or normal soft contact lenses, or at moderate stages, using spherical, bitoric or quadrant specific corneal RGP lenses. However, in advanced stages, as the inferior corneal steepening increases, corneal lenses system may not be able to provide an acceptable fitting, which may result in heavy bearing and excessive inferior edge stand-off. In contrast, With adequate sag, scleral lens can be fitted on eyes with severe corneal distortion without inducing any bearing on the cornea, therefore, lens fitting and visual performance can be significantly improved.