Accuracy And Precision Of Cap And Lenticule Thickenss In Lenticule Extraction Using Atos

After SMILE surgery using ATOS, we want to measure the difference between the thickness of the cap and lenticule predicted before the procedure and the thickness of the cap and lenticule measured after the procedure.

Epithelial thickness, corneal thickness, and cap thickness were measured preoperatively and one month postoperatively using cirrus HD-OCT in 60 eyes undergoing SMILE.

The difference analysis between postoperative cap thickness and preoperative planned cap thickness was calculated as (planned cap thickness - preoperative cap thickness) - (postoperative cap thickness - preoperative cap thickness) to exclude the effect of postoperative corneal epithelial edema. Lenticule thickness was calculated as (pre-operative corneal thickness - pre-operative corneal epithelial thickness) - (post-operative corneal thickness - pre-operative corneal epithelial thickness) and compared to the lenticule thickness predicted by the pre-operative device software program.

The mean preoperative planned lenticule thickness was 81.59±14.59 μm and the mean measured lenticule thickness at 1 month postoperatively was 71.89±13.84 μm, which was significantly thicker than the preoperative planned lenticule thickness (p<0.001). The preoperative planned cap thickness was 115.63±5.18 μm, and the mean cap thickness measured at 1 month postoperatively was 117.23±1.12 μm, showing no significant difference between the planned and actual cap thickness (p=0.674).

In SMILE surgery using ATOS, the cap thickness error was ±1.6μm, which was accurate, and the lenticule thickness tended to be overpredicted by the laser software platform compared to the actual cut lenticule thickness.