Tomography can accurately visualize and quantify higher-order aberrations (HOAs) across the cornea associated with small incision lenticule extraction (SMILE) surgery, findings published in Eye and Vision suggest.

Previous research concluded that total HOAs, coma, and spherical aberration increase significantly for patients after undergoing SMILE procedures. After surgery, improvements in vision can be accompanied by visual effects, such as halos, glare, reduced contrast sensitivity, and poor night vision, according to the researchers. As such, analyzing corneal aberrations can help inform and predict long-term visual outcomes of SMILE surgery.

The tomography examinations employed a technology that is based on Scheimpflug imaging combined with Placido-based reflection. Investigators have previously reported that the system delivers “good to excellent” intrasession repeatability and reproducibility of anterior segment measurements in healthy, post-refractive surgery (PRK/LASIK) and keratoconus patients.


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To examine the precision of corneal morphology measurements in more detail, researchers enrolled 75 eyes of patients who had undergone SMILE surgery. The research team captured 3 consecutive corneal aberrometric measurements with the Scheimpflug-Placido topographer. They report that the repeatability of measurements of anterior and total corneal aberrations in the corneas after SMILE surgery was high, except for trefoil. However, they observed variability in posterior corneal aberrometric measurements. 

The limitations of this study include the possibility of decreased precision, such as misalignment or movement during scanning, short acquisition time, pupil translation, and tear film instability. In addition, the study only included younger patients (18 to 41 years) who experienced a complication-free recovery after SMILE.

Reference

Ning R, Gao R, Piñero DP, et al. Repeatability and reproducibility of corneal higher-order aberrations measurements after small incision lenticule extraction using the Scheimpflug-Placido topographer. Eye and Vis. Published online January 4, 2022. doi:10.1186/s40662-021-00274-y.