Changes in Retinal Vasculature and Thickness after Small Incision Lenticule Extraction with Optical Coherence Tomography Angiography

PURPOSE: To evaluate the changes in retinal vessel density and thickness after small incision lenticule extraction (SMILE) with optical coherence tomography angiography (OCTA) in myopic patients. METHODS: In this prospective study, SMILE surgeries were done in 46 eyes of 24 patients with spherical equivalent (SE) more than −6.0 diopters (D). Retinal vessel density and thickness at the macula and optic nerve were recorded with OCTA before and 1 day, 2 weeks, and 1 month after surgery. Intraocular pressure (IOP), uncorrected distance visual acuity (UDVA), and refraction were taken at the same time. RESULTS: The superficial retinal vessel density and deep foveal retinal vessel density 1 day after surgery were less than those before surgery; however, the changes at any timepoints were not statistically significant (p=0.2736 and p=0.1590, respectively). Both the superficial vessel density and deep vessel density at the parafoveal and perifoveal regions decreased significantly 1 day postoperatively (all p < 0.05) and then returned to the preoperative level at 2 weeks and stabilized thereafter. There were no significant changes in any of the 4 vessel densities in the area of peripapillary before and 1 day, 2 weeks, and 1 month after surgery (p=0.3345). No statistically significant differences between preoperative and postoperative retinal thickness were detected for the area of macula and optic nerve (all p > 0.5). CONCLUSIONS: The vessel density at the parafoveal and perifoveal regions decreased at 1 day after SMILE with no effect on the visual acuity and relieved within 2 weeks. Decreased ocular blood flow in response to the spike in IOP may account for such changes.