Technical note: Comparison of the wavefront aberrations between natural and pharmacological pupil dilations.

Ocular wavefront aberrations were tested with the wavefront-supported corneal ablation (WASCA) aberrometer when the pupil was dilated naturally under scotopic illumination levels, and pharmacologically using tropicamide. Wavefront aberrations were measured across a 5-mm pupil in one eye of each of 58 subjects. There was a significant difference in the pupil diameter between the scotopic and cycloplegic conditions (p < 0.001). For higher order aberrations (HOAs), no significant difference was found in Zernike coefficients between the scotopic and cycloplegic conditions. There was no significant difference in the spherical equivalent refraction. Accommodation can be neglected during the wavefront aberration measurement with the WASCA aberrometer. In view of the shift of the pupil centre caused by pharmacological pupil dilation, obtaining measurements under natural conditions rather than using mydriatics is recommended for customized laser in situ keratomileusis (LASIK) surgery.