Long-term results of corneal wedge excision for pellucid marginal degeneration

A retrospective study reporting long-term visual and astigmatic results of patients with pellucid marginal degeneration (PMD) treated by corneal wedge excision.

The notes of 9 patients (10 eyes) treated by corneal wedge excision were reviewed. All patients had typical PMD and were treated by excision of an inferior crescent of diseased corneal tissue. The excised area measured approximately 2 mm in width and extended from the 4 o'clock to the 8 o'clock meridian. All thinned corneal tissue was removed. Normal-thickness corneal stroma was then reapposed with 10/0 nylon or 10/0 polypropylene sutures. Post-operative selective suture removal was performed until a satisfactory visual and astigmatic result was achieved. This was guided by refraction, keratometry and photo-keratoscopy results. Pre-operative best corrected visual acuity ranged from 6/12 to 6/60 with an associated mean keratometric astigmatism of +13.8 dioptres (range 8-25 dioptres, axis range 30 degrees-175 degrees). Mean follow-up was 59 months (range 14-138 months).

Post-operatively a stable corrected visual acuity of 6/9 or better was achieved in all cases in a mean time of 5.4 months (range 3-12 months). Mean post-operative keratometric astigmatism was 1.4 dioptres (range 0.5-4 dioptres). Over the course of follow-up long-term astigmatic drift (LTAD) was noted, mean 2.1 dioptres (range 0.5-5.5 dioptres). Three patients developed mild inferior pannus related to peripherally sited sutures. One case developed apparent corneal hydrops within the corneal wound after 9 years of follow-up.

We believe that corneal wedge excision offers an excellent surgical result for patients with PMD, although modification of the technique may be required to improve long-term astigmatic drift.