Abstract
Purpose :
Small Incision Lenticule Extraction (SMILE) is a corneal refractive procedure designed to treat refractive errors. A femtosecond laser is used to create a corneal lenticule, which is extracted through a small incision. SMILE has been shown to be safe, reliable and precise. However as with any corneal refractive procedure visual disturbances may be present postoperatively.
Corneal light scatter may be estimated with densitometry measurement whereas Zernike polynomials can be used to describe aberrations. The purpose of this study was to evaluate the degree of light scatter and aberrations following SMILE in patients with myopic astigmatism.
Methods :
Prospective controlled study including 101 randomised eyes. Examinations were performed pre- and 3, 6, 9, and 12 months after surgery.
Corrected distance visual acuity (CDVA) and Pentacam HR based densitometry and aberrations measurements were preformed. Densitometry measurements of 0.0-2.0mm and 2.0-6.0mm annular zones were performed in the anterior 120 my of the cornea. Aberration measurements were calculated as root mean square (RMS).
Results :
Densitometry measurements increased significantly from before surgery to 3 months after SMILE (zone 2.0-6.0), but then gradually decreased to a significantly lower level compared. RMS Astigmatism improved significantly at 3 months and remained steady throughout the follow-up period. Coma and higher order aberrations (HOA) increased significantly after surgery and remained steady. No significant change was seen in RMS spherical aberration.
Conclusions :
The improvement in light scatter objectified by densitometry at 12 months post-SMILE compared to pre-SMILE indicates that potential visual disturbances reported by patients are not due to an increase in corneal light scatter, but may be caused by an increase in coma-like higher-order corneal aberrations as seen after other corneal refractive procedures. It is important to note that spherical aberrations did not increase after SMILE, which stands in contrast to most reports on excimer laser based treatments.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.