Surgical Management Options for Advanced Pellucid Marginal Degeneration
Purpose
Surgical management of PMCD is challenging due to the peripheral location of thinning. We report the surgical options and outcomes in patients of advanced PMCD. We also introduce a new technique called C-TILK(Crescentic Tuck in Lamellar Keratoplasty), a combination of crescentic lamellar dissection with peripheral tuck.
Methods
Study included 5 eyes of 3 patients diagnosed with advanced PMCD based on peripheral corneal thinning and corneal topography with keratometric astigmatism 12 to 22D. Mean thinnest pachymetry ranged from 250- 290 microns on scheimpflug imaging (two eyes had maximum thinning superiorly). Two eyes had associated keratoconus. All patients had been on RGP and scleral contact lenses and had become intolerant to them with time. 3 eyes underwent DALK (Deep anterior lamellar keratoplasty), 1 eye compression keratoplasty followed by central penetrating keratoplasty, 1 eye underwent C-TILK. 2 out of 5 eyes developed cataract and underwent cataract surgery with toric IOL.
Results
Follow-up period ranged from 6 to 24 months. The outcome was judged based on reduction in keratometric astigmatism and BCVA(Best Corrected Visual Acuity). Average reduction in keratometric astigmatism was 10.3D. BCVA in 3 eyes ranged between 6/9 - 6/6 post Toric IOL while it was 6/12 in the remaining 2 eyes.
Conclusion
Conventional/modified lamellar surgeries with toric IOLs provide an effective management option for patients with advanced PMCD. C-TILK offers the unique advantage of selectively treating peripheral corneal ectasia by improving thickness and reducing astigmatism.