This study evaluated the visual and refractive outcomes of small incision lenticule extraction (SMILE) for hyperopia in children.
Study design
The authors examined 82 eyes that were treated with hyperopic, vertex-centered SMILE by 3 surgeons over the course of 3 months. All treatments were performed with optical zones ranging from 6.3 to 6.7 mm, a cap thickness of 120 microns and a 2-mm transition zone. Participants had maximum hyperopic meridian of treatment between +1 and +7 D, astigmatism up to 6 D, postoperative corneal curvature of 51 D or less and normal corneal topography. The trial proceeded in 4 phases, during which inclusion criteria of CDVA varied as follows: 20/200 or worse for phase I, 20/100 to 20/200 for phase II, 20/40 to 20/80 for phase III and better than 20/40 for phase IV.
Outcomes
An UDVA of 20/32 was achieved in 58% of eyes, while 64% of eyes had a CDVA of 20/32 or better prior to the procedure. There was minimal loss of visual quality, with a loss of 1 line of CDVA occurring in 17% of eyes and a loss of 3 lines of CDVA in 1 eye. A spherical equivalent manifest refraction (MRx) of ±0.50 D was achieved in 59% of eyes, while a MRx of ±1.00 D was achieved in 76% of eyes. The angle of error evaluation showed that the treatment was centered within 15 degrees of the correct meridian in 86% of eyes.
Limitations
As many of the patients in the study had poor CDVA prior to treatment, especially in the earlier phases, eyes with better CDVA would likely have improved overall visual results beyond what was reported in the study. In addition, 3 months may not have been sufficient to follow a hyperopic treatment, as other forms of laser vision correction show changes 3 to 12 months after treatment. Finally, as no nomogram has been fully developed, refractive accuracy will likely improve after further evaluation.
Clinical significance
Hyperopic LASIK, although much improved with modern lasers, still does not achieve the same visual results as myopic LASIK. Hyperopic SMILE may have the potential to produce larger optical zones and greater long-term stability compared with hyperopic LASIK. It may also leave the anterior sub basal nerve plexus more intact and the cornea stronger. At this time, more study is needed, and the field will wait for future FDA approval.