This study aimed to evaluate the postoperative vision recovery and corneal morphological changes after corneal stroma pocket irrigation with dexamethasone during Small Incision Lenticule Extraction (SMILE). Methods
This was a prospective case-control study, which included 48 eyes from 24 patients who underwent SMILE. One eye from each case was randomly selected to have corneal pocket irrigation with dexamethasone (experimental group, EG), while the other eye did not undergo irrigation (control group, CG). The morphological changes of the cornea were observed using in vivo confocal microscopy and anterior segment optical coherence tomography (OCT), 1 day and 7 days after surgery. The uncorrected visual acuity (UCVA), spherical equivalent (SE), corneal center thickness (CCT), and non-contact tension (NCT) values between the groups were compared 1 day, 7 days, and 1 month after surgery. Results
No significant differences were observed in the UCVA (EG: 4.99±0.07, 5.06±0.08, 5.05±0.06; CG:5.01±0.07, 5.05±0.08, 5.06±0.09, P>0.05) and SE between the two groups (EG: 0.03±0.49, 0.1±0.37, 0.02±0.4; CG: 0.09±0.54, 0.19±0.48, 0±0.52) the same day as the procedure, and 1 day, 7 days, and 1 month after surgery, p>0.05. The two groups were compared at the same time, 1 day and 7 days before and after SMILE using confocal microscopy and anterior segment OCT. The cell shape, density, cell size and arrangement of the corneal epithelium[pre-operation(4 578.73±268.40, 4 539.57±329.25)cell/mm2, post-1d (4 565.21±247.31, 4 627.23±271.03)cell/mm2, post-7d(4 640.01±246.79, 4 517.71±281.43)cell/mm2] and endothelium [pre-(2541.50±259.59, 2 443.52±305.58)cell/mm2, post-1d(2 387.01±248.55, 2 495.27±238.52) cell/mm2, post-7d (2 484.49±223.71, 2 482.53±323.82)cell/mm2] were not significantly different (P>0.05). There were no significant differences observed in the corneal sub-epithelial nerve fibers. The degree of active corneal stromal cells near the cutting interface was similar between the groups, without any significant differences. Regarding the density of the corneal superficial-stromal cells [pre-(789.51±67.17, 802.03±6 794)cell/mm2, post-1d(889.37±60.62, 912.27±95.87)cell/mm2, post-7d (96.67±75.03, 818.39±59.65)cell/mm2], both groups revealed no significant difference pre- or post-operation. However, a significant difference (P < 0.05)was observed after SMILE in both groups between the day immediately before and after the procedure. Both groups revealed no significant differences regarding the density of the deep stromal cells. Comparisons of the preoperative and postoperative anterior segment OCT show no obvious inter-lamellar space and effusion in the corneal stromal pocket in the two groups. There was no significant difference in the CCT between the groups (P>0.05). Conclusion
Irrigation with dexamethasone in the corneal stromal pocket during SMILE did not have a significant effect on postoperative UCVA, SE, and corneal morphological changes after surgery.