Dr. Faktorovich provided the following pearls:
1. If the ETM is normal in patients with one mild topographic or tomographic abnormality, they may be good LASIK candidates. Therefore, the ETM is a useful additional screening tool for patients with topographic or tomographic abnormalities that pose a diagnostic dilemma regarding whether to recommend LASIK, PRK, or any corneal surgery. “I often find this technology helpful as a tie breaker when patients present to me for a third or fourth opinion after receiving different recommendations from different surgeons based on their topographies and tomographies. If the ETM is normal, I recommend LASIK if the residual stromal bed is sufficiently thick. If the ETM is abnormal, I recommend PRK or even no surgery, depending on the severity of the abnormality,” she stated.
2. Patients with several abnormalities on topography and/or tomography, even if very mild, should be approached cautiously. “We found that ETMs are consistent with forme fruste keratoconus in these patients. PRK or no corneal surgery, rather than LASIK, may be best for them,” she advised. She recounted the case of a 39-year-old trauma surgeon with corneal pachymetry of 498 μm and very slight skewing of the astigmatic axis. If the ETM had been normal, LASIK may have been recommended. Instead, the ETM pattern of epithelial thinning overlying the thinnest corneal spot that was displaced slightly inferotemporally led to a recommendation for PRK.
3. Mild inferior corneal steepening and areas of epithelial thickening on ETMs could be signs of epithelial basement membrane dystrophy even when patient’s cornea appears normal on slit lamp exam. PRK is recommended over LASIK to avoid epithelial loosening and sloughing during flap lift often seen in patients with epithelial basement membrane dystrophy.
The technology has proven so valuable that Dr. Faktorovich has incorporated it into the screening protocol of all refractive surgery candidates.