Short-term changes in the anterior segment and retina after small incision lenticule extraction

Abstract

Background To analyse short-term changes in the anterior segment and retina after small incision lenticule extraction (SMILE). Methods Patients with myopia scheduled for SMILE were recruited from Ruijin Hospital, Shanghai, China. Basic patient information such as age, sex, and refractive errors was recorded. Ocular measurements were taken before surgery, and 1 day and 1 week after surgery; they included axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), white to white (WTW), pupil diameter (PD), macular thickness (MT), ganglion cell layer thickness (GCL), retinal nerve fiber layer thickness (RNFL), choroidal thickness (CT), macular vessel density, and optic disc vessel density. Results Sixty-one eyes of 31 patients were selected for this study. AL, CCT, ACD, and postoperative PD were significantly reduced (p < 0.05), while LT was thickened after surgery (p < 0.05). MT at the fovea decreased 1 day and 1 week after surgery (p < 0.05). GCL showed no significant changes after surgery. RNFL was unchanged 1 day after surgery, but the inferior sector was thickened 1 week after surgery. CT was thicker at the fovea 1 day after surgery and 1.0 mm from the fovea in the nasal sector 1 week after surgery. Macular vessel density was significantly decreased 1 day after surgery and most recovered in 1 week. Optic disc vessel density decreased at the peripapillary part 1 day after surgery and recovered after 1 week. ΔACD and ΔLT showed no significant correlation 1 day after surgery. ΔACD was negatively correlated with ΔLT and sphere 1 week after surgery (r = − 0.847, p < 0.000; r = − 0.398, p = 0.002). ΔLT was positively correlated with the sphere 1 week after surgery (r = 0.256, p = 0.048). Conclusion The anterior segment was the most affected, while the retina also underwent changes with regard to MT, RNFL, CT, macular vessel density, and peripapillary vessel density.

Quantitative changes in iris and retinal blood flow after femtosecond laser-assisted in situ keratomileusis and small-incision lenticule extraction

“…The trends in the postsurgical retinal indices in our study differed from those reported before (10,19). Shen et al divided the macular area into three zones: the foveal avascular zone (FAZ), the parafoveal area, and the perifoveal area.…”

“…However, the exact way of dividing and measuring was not explained. The authors concluded that the vascular density returned to baseline values 1 week after SMILE in all areas except the FAZ zone (10). Using a similar division method, Gong et al reported that 2 weeks after SMILE, the vascular density of the macular area returned to baseline levels, whereas superficial retinal vessel density (VD) in the parafoveal and perifoveal areas remained unchanged (20).…”

“…Usually, the suction duration is longer in SMILE than in FS-LASIK, Zhang et al found macular vessel density decreased after FS-LASIK and recovered 1 month post-operatively (9); however, Shen. et al discovered a decreased macular vessel density recovered 7 days post-operatively (10). Further studies are needed to compare and analyze the retinal vasculature changes and the underlying factors after FS-LASIK and SMILE.…”

Analysis of risk and protective factors associated with retinal nerve fiber layer defect in a Chinese adult population

“…High intraocular pressure changes the ocular blood circulation and perfusion, which can lead to the interruption of the axoplasmic flow of retinal nerve fibers, axonal disintegration, apoptosis of retinal ganglion cells, and or even defect of RNFL. Abnormal blood flow in the eye leads to the reduced blood supply to the eye, leading to chronic ischemia and hypoxia, which in turn can cause RNFL thinning or even defect [40] . In conclusion, these data and findings contribute to the assessment of factors associated with RNFLD, and to predict and evaluate diseases related to RNFLD.…”