Effect of different laser energy settings on the formation of opaque bubble layer and visual performance in SMILE surgery: a single center clinical study

Abstract

Purpose: To investigate the effect of different laser energy settings, including varying combinations of energy and spot distance setting, on the formation of opaque bubble layers in the first stage of preoperative and postoperative visual quality in patients with myopia and astigmatism. Methods: A total of 72 patients were enrolled in this study. They all had myopia and/or astigmatism and had undergone small incision lenticule extraction (SMILE) in both eyes between April 2021 and February 2022 at Huizhou Municipal Central Hospital, Huizhou, China. They were randomly assigned to four groups of 18 patients each. The energy parameters were set in the four groups, with a pulse energy of 120 or 130 nJ and spot distance of 3.0 μm or 4.5 μm. The indices assessed included formation of opaque bubble layer in the first stage after surgery, uncorrected distance visual acuity (UCVA), higher-order aberrations (HOAs), and visual sensitivity under different light levels at 3 months postoperatively. Results: Total HOAs at 3 months were smaller, and contrast sensitivity at various luminance levels under specific spatial frequencies was better when the laser energy was set to 120 nJ and the spot distance was set to 4.5 μm when compared with the laser energy set at 130 nJ and spot distance set at 3.0 μm, respectively (p < 0.05). Conclusion: Lower energy and larger spot spacing laser settings produce better visual outcomes for patients, and also affect the formation of a first-stage opaque bubble layer, which is a useful laser for clinical ophthalmologists during SMILE surgery. The energy setting provides a reliable basis to achieve better visual outcomes for patients after surgery.