Objective: To report the clinical features and outcome of patients with pellucid marginal corneal degeneration (PMCD).
Design: Retrospective noncomparative case series.
Methods: Retrospective chart review of 116 eyes of 58 patients with PMCD seen between 1990 and 2002 at the Cornea Service at L.V. Prasad Eye Institute, Hyderabad, India. The diagnosis of PMCD was based on the presence of corneal thinning with ectasia of the normal cornea above or below the area of thinning with no evidence of scarring, vascularization, or lipid deposition and typical topographic features whenever topography was performed. A detailed history including the age of presentation, onset of symptoms, systemic diseases, atopy, and relevant family history was reviewed. The visual acuity (VA) at presentation; the location, extent, and degree of thinning; presence of concurrent keratoconus and keratoglobus; and complications, if any, were noted. The mode of visual rehabilitation; surgical procedure, if any; and the final VA achieved were analyzed.
Main outcome measures: Clinical features, associations, complications, and outcome of treatment.
Results: There were 45 males (77.6%) and 13 females (22.4%). All cases were bilateral. In one eye, no clinical features of PMCD were seen, but the diagnosis was made based on topographic features of typical PMCD. The age of the patients ranged from 8 to 66 years, with a mean of 34.0+/-14.8. One patient (1.7%) had associated vernal keratoconjunctivitis (VKC), 1 (1.7%) had Marfan's syndrome, and 1 (1.7%) had ocular hypertension. The degree of astigmatism was <5.0 diopters (D) in 19 eyes (19.2%), 5 to 10 D in 36 (36.4%), 10 to 15 D in 23 (23.2%), 15 to 20 D in 15 (15.2%), and >20 D in 6 (6.1%). Typical inferior PMCD was seen in 99 eyes (85.3%), and superior PMCD was seen in 17 (14.7%). The thinning was commonly seen between the 5-o'clock and 7-o'clock positions. In 12 eyes (10.3%), PMCD was associated with keratoconus, and in 15 eyes (12.9%), keratoglobus was associated. Seven eyes (6.0%) had hydrops. Visual acuity improved in 52 eyes (55.3%) with correction, in 40 eyes (42.6%) it remained the same as that of the initial presentation, and in 2 eyes (2.1%) it worsened relative to the initial presentation. Forty-one eyes (35.3%) received spectacles, and 31 eyes (26.7%) were fitted with rigid gas-permeable contact lenses. Five eyes (4.3%) underwent surgery. Lamellar keratoplasty was performed in 3 eyes, and a crescentic lamellar graft was done in 2 eyes. Visual acuity improved in 4 eyes after surgery with a follow-up of 2 to 37 months. The final astigmatism in the operated eyes at the last follow-up ranged from 4 to 11 D.
Conclusions: Pellucid marginal corneal degeneration was seen predominantly in males in this series, and was not strongly associated with VKC. Keratoconus was seen in approximately 10% of the eyes, and keratoglobus in approximately 13%. Superior PMCD was seen in approximately 15% of the eyes. In our study, patients presented with severe astigmatism, and hydrops was a common complication. The majority of patients were treated with spectacles or contact lens. Surgery for PMCD-lamellar keratoplasty and crescentic lamellar keratoplasty, if indicated-usually results in significant residual astigmatism.