Eyeworld

JANUARY/FEBRUARY 2020 | SUPPLEMENT TO EYEWORLD | 7 with keratoconus and ectasia Performing the procedure To perform corneal cross- linking, we soak the cornea in viscous riboflavin for ap- proximately 30 minutes and begin checking pachymetry at approximately 20 minutes. If the pachymetry is too thick to crosslink, we switch from the viscous formulation to the non- viscous formula and hydrate the cornea until pachymetry is approximately 400 µm. After 30 minutes, we focus our light over the patient. Two reticules come together as a star, and we switch on the light. We instruct the patient to focus on the light and explain that we will continue to instill eye drops during the 30-minute procedure. Afterward, we place a bandage contact lens on the eye and prescribe antibiotics and anti-inflammatory medica- tions, providing close follow-up. Transepithelial crosslinking One disadvantage of corneal crosslinking is that the epithe- lial defect created during the procedure can cause pain and increase the risk of infection. Therefore, several studies of transepithelial crosslinking have been performed. Early research indicated it is not as effective as epi-off procedures because the cornea does not absorb as much riboflavin, however, others have shown promise. 5,6 Transepithelial crosslinking appears to stop progression to some extent, but we do not see the same amount of regression or flattening as we do with the epithelium-off approach. Corneal inserts are making a resurgence in treating patients with keratoconus. There is ev- idence that combining corneal inserts with crosslinking can be beneficial. 7 In addition, the combina- tion of collagen crosslinking and wavefront-guided PRK has had impressive results. 8 Conclusion Corneal crosslinking is chang- ing some of the paradigms and referral patterns for patients with keratoconus, and it is im- portant to treat our patients as early as possible. The near future will bring additional treatments and pro- tocols. n References 1. Seiler G, et al. Riboflavin/ultravio- let-a–induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol. 2003;135:620–27. 2. Raiskup-Wolf F, et al. Collagen crosslinking with riboflavin and ultraviolet-A light in keratoconus: long-term results. J Cataract Refract Surg. 2008;34:796–801. 3. Hersh PS, et al. United States multi- center clinical trial of corneal collagen crosslinking for keratoconus treatment. Ophthalmology 2017;124:1259–70. 4. Hersh PS, et al. U.S. multicenter clinical trial of corneal collagen cross- linking for treatment of corneal ectasia after refractive surgery. Ophthalmology 2017;124:1475–84. 5. Lesniak SP, et al. Transepithelial corneal collagen crosslinking for kera- Figure 1. Tomographic difference display from left eye showing interval progression of keratoconus Source: Brandon Ayres, MD Corneal crosslinking process Source: Brandon Ayres, MD 1. Riboflavin drops are used to saturate the cornea. 2. Riboflavin is activated by ultraviolet light. 3. Activated riboflavin and reactive oxygen species interact with collagen and glycosaminoglycans in cornea to form crosslinks. toconus: six-month results. J Cataract Refract Surg. 2014;40:1971–9. 6. Stulting RD, et al. Corneal crosslink- ing without epithelial removal. J Cata- ract Refract Surg. 2018;44:1363–70. 7. Hersh PS, et al. Corneal crosslinking and intracorneal ring segments for keratoconus: a randomized study of concurrent versus sequential surgery. J Cataract Refract Surg. 2019;45:830– 9. 8. Tamayo GE, et al. High-resolution wavefront-guided surface ablation with corneal cross-linking in ectatic corneas: a pilot study. Clin Ophthalmol. 2017;11:1777–83. Dr. Ayres practices at the Cornea Service at Wills Eye Hospital in Philadelphia. He can be contacted at brandonayres@me.com. Supported by an unrestricted education grant from Avedro, Avellino Labs, Dompé, and Johnson & Johnson Vision

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