Scleral Lenses Reduce the Need for Corneal Transplantation
Keratoconus is the most prevalent primary corneal ectasia, which commonly causes bilateral asymmetric thinning of the paracentral cornea.1 Due to the progressive nature of keratoconus, early diagnosis and management is critical. Corneal collagen cross-linking with prompt intervention can help stop the progression of keratoconus. Visual Rehabilitation with traditional glasses and gas permeable or soft contact lenses may be used in early stages of keratoconus. As the condition advances, specialty contact lenses may be beneficial including custom soft lenses made specifically for keratoconus, gas permeable, piggyback, hybrid and scleral lenses. Surgical options include intrastromal corneal ring segments, conductive keratoplasty, or corneal transplantation. According to the published literature, keratoconus is the single most common indication for scleral lenses fitting.2-6
A recent retrospective published study investigated the success and failure rates of scleral lens correction in severe keratoconus.7 Patients with keratoconus with maximal keratometry values ≥ 70 diopters (determined by Scheimpflug tomography sagittal curvature map) examined in keratoconus clinic between January 1, 2010 and December 31, 2014 were included in the study. Scleral lenses were prescribed in 51 of 75 eyes. In patients with severe keratoconus that would otherwise have undergone corneal transplant surgery, 40 of 51 eyes were successfully treated with long-term scleral lens wear. Thus, the indication for keratoplasty was more than halved in the keratoconus population.
A different study compared scleral lens fitting outcomes to keratoplasty in patients with keratoconus.8 Improvements in vision were achieved more quickly with scleral lens wear than with surgical intervention. Additionally, a statistically significant higher percentage of patients wearing scleral lenses achieved 20/25 visual acuity or better compared to those who underwent keratoplasty. After one year, mean visual acuity was better in the scleral lens group compared to those who had a keratoplasty. Furthermore, more complications were observed in surgical patients compared to scleral lens wearers. According to this study, scleral lenses should be considered for patients with keratoconus prior to surgical intervention for patients who cannot successfully wear other modes of correction.
These studies highlight the importance of specialty contact lens fitting by a skilled practitioner. It is not necessary for every practitioner to fit specialty contact lenses; however, a good referral network is essential to provide optimal care for patients with keratoconus.
1. Krachmer JH, Feder RS, Belin MW. Keratoconus and related noninflammatory corneal thinning disorders. Surv Ophthalmol 1984; 28(4): 293-322.
2. Schein OD, Rosenthal P, Ducharme C. A gas-permeable scleral contact lens for visual rehabilitation. Am J Ophthalmol 1990; 109(3): 318-22.[http://dx.doi.org/10.1016/S0002-9394(14)74558-1] [PMID: 2309865]
3. Tan DT, Pullum KW, Buckley RJ. Medical applications of scleral contact lenses: 1. A retrospective analysis of 343 cases. Cornea 1995; 14(2): 121-9. [http://dx.doi.org/10.1097/00003226-199503000-00001] [PMID: 7743792]
4. Rosenthal P, Croteau A. Fluid-ventilated, gas-permeable scleral contact lens is an effective option for managing severe ocular surface disease and many corneal disorders that would otherwise require penetrating keratoplasty. Eye Contact Lens 2005; 31(3): 130-4. [http://dx.doi.org/10.1097/01.ICL.0000152492.98553.8D] [PMID: 15894881]
5. Pullum KW, Whiting MA, Buckley RJ. Scleral contact lenses: the expanding role. Cornea 2005; 24(3): 269-77. [http://dx.doi.org/10.1097/01.ico.0000148311.94180.6b] [PMID: 15778597]
6. Visser ES, Visser R, van Lier HJ, Otten HM. Modern scleral lenses part I: clinical features. Eye Contact Lens 2007; 33(1): 13- 20.
7. Koppen C, Kreps EO, Anthonissen L, et al. Am J Ophthalmol 2017 Nov 15. pii: S0002-9394(17)30453-1. doi: 10.1016/j.ajo.2017.10.022. [Epub ahead of print]
8. DeLoss KS, Fatteh NH, Hood CT. Prosthetic replacement of the ocular surface ecosystem (PROSE) scleral device compared to keratoplasty for the treatment of corneal ectasia. Am J Ophthalmol 2014; 158(5): 974 82.[http://dx.doi.org/10.1016/j.ajo.2014.07.016]
Dr. Barnett is a principal optometrist at the University of California Davis Eye Center in Sacramento, specializing in anterior segment disease and specialty contact lenses. She is the past president of the Scleral Lens Education Society. She is an advisor to and/or has received honoraria or travel expenses from AccuLens, Alcon, Alden Optical, Allergan, Bausch + Lomb, Contamac, CooperVision, EveryDay Contacts, Johnson & Johnson Vision, Ocusoft, Paragon Bioteck, RaayonNova, ScienceBased Health, Shire, SynergEyes, and Visioneering Technologies.