Dr. Reinstein is participating in a prospective study of hyperopic SMILE at the Tilganga Institute of Ophthalmology, Kathmandu, Nepal. It consists of four phases. The first three phases sequentially enrolled blind eyes, densely amblyopic eyes, and mildly amblyopic eyes with aims of establishing the feasibility of the procedure, optimizing the laser energy settings and lenticule parameters, and evaluating centration.
The study is now in its fourth phase that plans to enroll 200 sighted eyes with best-corrected visual acuity (BCVA) of 20/40 or better, sphere ≤ +7 D, and astigmatism ≤ 6 D.
The hyperopic SMILE lenticule has a doughnut shape, and in the study, is being created with a 6.3- to 6.7-mm optical zone, a 2-mm transition zone, 30-μm minimum thickness, and a 90° side cut.
The cap measures 8.8 mm in diameter and is 120 μm thick, and there is a 0.25-mm clearance between the edge of the lenticule and the periphery. A 2-mm incision is made for removing the lenticule, and an escape incision is created on the opposite side.
“The minimum thickness is set at 30 μm because there is no curvature change in the center of the lenticule, and we wanted to make sure there was no chance of button-holing through the center of the doughnut,” Dr. Reinstein said. “Surgeons performing myopic SMILE will find that the hyperopic procedure is identical and that the lenticule dissection is no more difficult.”
The efficacy and safety of hyperopic SMILE were analyzed in a group of 31 eyes with BCVA of 20/40 or better and compared with outcomes in a cohort of LASIK-treated eyes matched 3:1 for sphere and cylinder (±0.5 D). Mean treated spherical equivalent (SEQ) and cylinder in the SMILE eyes was +5.73 D and 1.15 D, respectively.
The efficacy analysis showed that at 3 months, distance UCVA was the same or better than preoperative BCVA in 47% of SMILE eyes and within 1 line of preoperative BCVA in 93% of SMILE eyes. In the LASIK-treated eyes, distance UCVA was the same or better than preoperative BCVA in 50% of eyes and within 1 line of preoperative BCVA in 81%.
“It is interesting that the vision results are better with SMILE, and we believe this may be explained by the fact that the ocular surface at 3 months is healthier in the SMILE eyes compared with the LASIK eyes,” Dr. Reinstein said.