Re: McNabb et al.: Optical coherence tomography accurately measures corneal power change from laser refractive surgery (Ophthalmology 2015;122:677-86)

I read with interest the article by McNabb et al1 regarding the measurement of corneal power in eyes that have undergone refractive surgery. One of the study's limitations was that myopic and hyperopic eyes were analyzed in a single group. It is known that after refractive surgery there is an overestimation of the corneal power in the eyes that had surgery for myopia,2,3 and there is an underestimation of the power of the cornea in eyes that had surgery for hyperopia.4 Evaluating the overall differences in corneal power for both refractive defects may introduce bias in assessing the accuracy of the variations before and after surgery.