REFRACTIVE EWAP MARCH 2023 33 patients who are borderline. Is it truly keratoconus or not?” he said, explaining that what might look like keratoconus could in fact be epithelial hyperplasia, the latter of which wouldn’t rule out corneal refractive surgery. While epithelial mapping is not critical for a practice in Dr. Trattler’s mind, he said it is quicker than waiting to assess for possible keratoconus progression 6 months to a year later. “This provides a rapid way of understanding what’s going on now versus monitoring patients over time,” he said. Arjan Hura, MD, also does not think that epithelial mapping is standard of care yet, but he took an informal survey of refractive surgeons and found that of 88 respondents, 60% routinely use it. He personally will get an epithelial map for patients with borderline or irregular topography and when planning enhancements. For the latter, it helps him ascertain what degree of the postoperative refractive shift may be due to zonal epithelial hyperplasia. “I keep in mind that ocular surface disease, recent instillation of topical drops, and contact lens wear can impact the appearance of the epithelial maps. I don’t make decisions based solely off epithelial mapping, and the amount of significance I give it varies by case,” Dr. Hura said. “Overall, I view epithelial mapping as a valuable additional data point that has potential to help the surgeon in clinical decision making.” Dr. Hura explained that he finds epithelial mapping most helpful in the context of topography. He offered these examples: (1) An area of topographic steepening with overlying corresponding epithelial thinning would be potentially concerning for keratoconus or ectasia. However, if the epithelium in that area of steepening is thick, it may be that the epithelium is what is causing the steepening and not necessarily some underlying weakness in the cornea. (2) Epithelial hyperplasia in the central area of a previous myopic ablation that appears normal on topography could explain why a patient has experienced a regression in their myopic refractive error. (3) Epithelial maps may suggest subclinical EBMD if there is mild irregular astigmatism on topography and the exam is unremarkable. (4) Unremarkable topography in the postoperative period after refractive surgery in a patient now with unsatisfactory vision who has variable epithelial mapping may suggest that healing is still taking place. Neda Shamie, MD, who said she performs epithelial mapping to detect keratoconus, doesn’t think epithelial mapping is considered the standard of care among refractive surgeons yet either. “I think that tomography and topography are the two critical diagnostic tools with epithelial mapping supplementing the information,” she said. “It’s possible with improvements in technology and further understanding of the results we get that it could potentially move up the ladder of importance. In screening refractive surgical patients, especially as we’re trying to screen for conditions that would not yet be overtly evident, the more information we have, the more confidence we can have in recommending surgery. After all, my job as a refractive surgeon is not just to perform expertly done surgery but to determine safety long term for our patients. To me, risk assessment is the more challenging part of my job as a refractive surgeon.” If a practice is not using this functionality or doesn’t have a device that performs epithelial mapping yet, Dr. Trattler said a refractive surgeon should discern whether they want to incorporate a technology like this that is going to potentially allow more patients to qualify for corneal refractive surgery who might have otherwise been excluded. “Are surgeons willing to acquire epithelial mapping to rule potential patients in for corneal refractive surgery? If surgeons rule patients out because they do not have epithelial mapping available, it’s not the end of the world, but obviously for patients interested in refractive surgery, it would be great to have epithelial thickness mapping available to identify the anatomical cause for inferior corneal steepening on topography,” Dr. Trattler said. EWAP References 1. Reinstein DZ, et al. High-frequency ultrasound measurement of the thickness of the corneal epithelium. Refract Corneal Surg. 1993;9:385–387. 2. Reinstein DZ, et al. Arc-scanning very high-frequency digital ultrasound for 3D pachymetric mapping of the corneal epithelium and stroma in laser in situ keratomileusis. J Refract Surg. 2000;16:414–430. 3. Reinstein DZ, et al. Epithelial thickness in the normal cornea: three-dimensional display with Artemis very high-frequency digital ultrasound. J Refract Surg. 2008;24:571–581. 4. Reinstein DZ, et al. Corneal pachymetric topography. Ophthalmology. 1994;101:432–438. 5. Reinstein DZ, et al. Corneal epithelial thickness profile in the diagnosis of keratoconus. J Refract Surg. 2009;25:604–610. 6. Reinstein DZ, et al. New sizing parameters and model for predicting postoperative vault for the implantable collamer lens posterior chamber phakic intraocular lens. J Refract Surg. 2022;38:272–279. Editors’ note: Dr. Hura practices at the Maloney-Shamie Vision Institute, Los Angeles, California, and has interests with Carl Zeiss Meditec. Dr. Reinstein practices at London Vision Clinic, EuroEyes Group, London, United Kingdom, and has interests with ArcScan, CSO Italia, and Carl Zeiss Meditec. Dr. Shamie practices at the Maloney-Shamie Vision Institute, Los Angeles, California, and declared no relevant financial interests. Dr. Trattler practices at the Center for Excellence in Eye Care, Miami, Florida, and has interests with ArcScan, Carl Zeiss Meditec, and Oculus.
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