Main Article Content
PELLUCID MARGINAL DEGENERATION, SCLERAL LENSES, CORNEAL COLLAGEN CROSS-LINKING, RIBOFLAVIN
This case study provides an analysis of an individual affected by pellucid marginal degeneration (PMD). This particular case demonstrates the effectiveness of new scleral lenses over a severe form of PMD that underwent corneal crosslinking (CXL) with riboflavin over intra-stromal corneal ring segments (INTACS). PMD is a rare, progressive, degenerative corneal disease typically characterized as peripheral, bilateral, and inferior ectasia producing a crescent shape. It has been found more commonly in males and appears between the second and fifth decade of life showing no signs of ethnic predilection. Although there is no evidence of the prevalence and etiology of PMD, it may be postulated that PMD is poorly differentiated because this disease is often confused or used interchangeably with keratoconus (KC). KC is a developmental anomaly in which a part of the cornea becomes thinner and bulges forward in a cone-shaped fashion as a result of non-inflammatory stromal thinning. KC is predominantly bilateral (90%) and according to recent studies demonstrates a prevalence of 2.3%. The Collaborative Longitudinal Evaluation of Keratoconus (CLEK) study found the genetic predisposition of KC to be at 13.5%, whereas other studies found it to be between 6–10%. This means most of those found having KC have no known association with the disease. More importantly, the cause of KC is still unknown. Regardless, the Federal Drug Administration (FDA) approval of KC treatment using CXL in April 2016 has shown excellent promise of improving the visual potential for patients with this progressive disease. This case demonstrates the usefulness of utilizing scleral gas permeable (GP) contacts over INTACS post CXL to provide optimal, stable vision, comfort and therapy. In addition, this paper shows an innovative way to utilize corneal topography to ensure proper fitting scleral lenses.
2. Gordon-Shaag A, Millodot M, and Shneor E. The epidemiology and etiology of keratoconus. Epidemiology 2012;70:1.
3. Wagner H., et al. Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study: methods and findings to date. Cont Lens Anter Eye 2007;30(4):223–32.
4. Raiskup-Wolf F, et al. Collagen crosslinking with riboflavin and ultraviolet-A light in keratoconus: long-term results. J Cataract Refract Surg 2008;34(5):796–801.
5. Davidson AE, Hayes S, Hardcastle AJ, Tuft SJ. The pathogenesis of keratoconus. Eye 2014:28:189–95.
6. Schuerch K, Tappeiner C, and Frueh BE. Analysis of pseudoprogression after corneal cross‐linking in children with progressive keratoconus. Acta Ophthalmol 2016;94(7).
7. Shovlin JP. Do I see keratoconus or PMD? How can we differentiate between these two similar ectatic diseases on corneal topography? Rev Optometry 2005;142(4):91–92.
8. Jinabhai A, Radhakrishnan H, O’Donnell C. Pellucid corneal marginal degeneration: A review. Contact Lens Anter Eye 2011;34(2):56–63.
9. Nagy M, Vigvary L: Etiology of the pellucid marginal degeneration of the cornea. Klin Monatsbl Augenheilkd 1972;161:604–611.
10. Khan AO, et al. Pellucid marginal degeneration coexistent with cornea plana in one member of a family exhibiting a novel KERA mutation. Br J Ophthalmol 2005;89(11):1538–40.
11. Barr JT, Wilson BS, Gordon MO, et al Estimation of the incidence and factors predictive of corneal scarring in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study. Cornea 2006;25:16–25.
12. van der Worp ECJ. A Guide to Scleral Lens Fitting, Version 2.0." Forest Grove, IL: 2015.
13. Schornack M, Patel S. Scleral lenses in the management of keratoconus. Eye Contact Lens 2010:1:39-44.
14. Sugar Alan. Factors associated with corneal graft survival in the cornea donor study." JAMA Ophthalmol 2015;133(3):246–54.
15. McCall AS, Kraft S, Edelhauser HF, et al. Mechanisms of corneal tissue cross-linking in response to treatment with topical riboflavin and long-wavelength ultraviolet radiation (UVA) Invest Ophthalmol Vis Sci 2010;51:129–38.
16. Arbelaez MC, et al. Collagen cross-linking with riboflavin and ultraviolet-A light in keratoconus: One-year results. Oman J Ophthalmol 2009;2(1):33.
17. Kanellopoulos AJ, et al. Modified intracorneal ring segment implantations (INTACS) for the management of moderate to advanced keratoconus: efficacy and complications. Cornea 2006;25(1):29–33.
18. Paulus, Y. Pellucid Marginal Corneal Degeneration. 2015; Available at: http://eyewiki.aao.org/pellucid_marginal_corneal_degeneration
19. Harper D. Pellucidity. Online Etymology Dictionary. Available at: Dictionary.com http://www.dictionary.com/browse/pellucidity.
20. Hashemi H, et al. Corneal collagen cross-linking with riboflavin and ultraviolet a irradiation for keratoconus: long-term results. Ophthalmology 2013;120(8):1515–20.
21. Coskunseven E, et al. Complications of intrastromal corneal ring segment implantation using a femtosecond laser for channel creation: a survey of 850 eyes with keratoconus. Acta Ophthalmol 2011:89(1):54–57.
22. Bromley JG and Randleman JB. Treatment strategies for corneal ectasia. Curr Opin Ophthalmol 2010;21(4):255.