Transient Light Sensitivity Syndrome (TLSS) Incidence Following Femtosecond LASIK for Myopic and Hyperopic Eyes and Femtosecond SMILE for Myopic Eyes.

Purpose: To evaluate and compare the incidence of transient light sensitivity syndrome (TLSS) after myopic laser in situ keratomileusis (LASIK), hyperopic LASIK, and myopic small incision lenticule extraction (SMILE).

Methods: A retrospective analysis was performed of consecutive LASIK and myopic SMILE cases, performed with the VisuMax femtosecond laser and MEL 80 or MEL 90 excimer laser (both Carl Zeiss Meditec AG) between January 2010 and February 2021 at London Vision Clinic, London, United Kingdom. A chart review was performed to find cases of clinically significant TLSS, identified as patients prescribed anti-inflammatory medications between 2 weeks and 6 months after surgery to manage photophobia. The incidence of TLSS was calculated for three groups: myopic SMILE, myopic LASIK, and hyperopic LASIK. The incidence of TLSS was then calculated for three subgroups within each treatment type based on spherical equivalent refraction treated. For myopic SMILE and myopic LASIK, it was 0.00 to -4.00 diopters (D) (low), -4.01 to -8.00 D (moderate), and -8.01 to -14.00 D (high). For hyperopic LASIK, it was 0.00 to +2.00 D (low), +2.01 to +4.00 D (moderate), and +4.01 to +6.50 D (high).

Results: The range of treatment for myopia was similar between the LASIK and SMILE groups. The incidence of TLSS was 1.2% for the myopic SMILE group, 5.3% for the myopic LASIK group, and 9.0% for the hyperopic LASIK group. The difference was statistically significant between all groups ( < .001). For myopic SMILE, the incidence of TLSS was independent of spherical equivalent refraction for low (1.4%), moderate (1.0%), and high (1.1%) myopia ( > .05). Similarly, for hyperopic LASIK, the incidence was similar for low (9.4%), moderate (8.7%), and high (8.7%) hyperopia ( > .05). In contrast, for myopic LASIK, the incidence of TLSS was "dose-dependent" on refractive error treated, with an incidence of 4.7% for low, 5.8% for moderate, and 8.1% for high myopia ( < .001).

Conclusions: The incidence of TLSS was higher after myopic LASIK than after myopic SMILE, higher after hyperopic than myopic LASIK, and "dose-dependent" for myopic LASIK but did not vary by correction in myopic SMILE. This is the first report describing the phenomenon of late TLSS occurring between 8 weeks and 6 months after surgery, .