To evaluate ocular fundus biological changes after scleral collagen cross-linking (CXL) with riboflavin/ ultraviolet A (UVA) on rhesus monkeys in vivo by analyzing retina and choroid biological parameters. Six 3-year-old male rhesus monkeys (12 eyes) were observed in this study, with scleral CXL procedures applied on superior temporal equatorial sclera on random eyes of all rhesus. Optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) examination were performed before and 1 week, 1 month, 3 months and 6 months after CXL. The thickness of retina and choroid and the flow density of retinal superficial vascular networks were analyzed respectively in different regions after CXL. As for retina thickness and flow density of retinal superficial vascular networks, no statistical difference was noted between CXL eyes and control eyes at 1 day, 1week, 1 month, 3 months and 6 months (P>0.05). Among choroid parameters, the choroidal thickness in 1500μm temporal to the fovea center of CXL eyes revealed a significant reduction in 1 week postoperatively (P<0.05), but it subsequently increased from 1 month postoperatively, and no statistical difference was found between two groups in the following periods (P>0.05). The choroidal thickness nearby crosslinked region may change temporarily following scleral CXL, and it might recover gradually after 1 month postoperatively. The vascular flow density and thickness of retina were not affected by scleral CXL. Further study should be performed to evaluate the potential adverse effects at the direct vicinity of the application site and the long-term effect of scleral CXL in clinical application.

PURPOSE: To investigate the changes of retinal and choroidal parameters, scleral biomechanical strength, and ocular histopathology after scleral ultraviolet-A (UVA) cross-linking (CXL) in rhesus monkeys eyes, and to evaluate the safety and long-term biomechanical stability of scleral CXL for preventing myopia from progressing further in clinic. METHODS: Six 3-year-old male rhesus monkeys (12 eyes) were randomized to receive UVA-CXL procedures applied on the superotemporal equatorial sclera. Optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) were used for examination before and 1 week and 1, 3, 6, and 12 months after CXL. The stress-strain behaviors of equatorial scleral strips were analyzed 12 months postoperatively by a biomaterial tester. Hematoxylin–eosin and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining were performed 12 months postoperatively. RESULTS: For central retinal thickness, choroidal thickness, and flow density of central retinal superficial vascular networks, no statistical difference was noted between CXL eyes and control eyes at 12 months postoperatively ( P > .05). The biomechanical stability of sclera was increased. The scleral stress and Young modulus at 8% strain corresponded to 184% and 183%, respectively, of the control values at 12 months (each P < .001). No retinal damage was detected on histology in scleral CXL eyes. There was no obvious difference between scleral CXL eyes and control eyes by hematoxylin–eosin and TUNEL staining ( P > .05). CONCLUSIONS: Scleral CXL with riboflavin/UVA in rhesus monkey eyes could strengthen the biomechanical properties of scleral tissues and maintain the stability for 12 months postoperatively. The UVA-CXL on the sclera of rhesus monkey eyes seems to be effective and safe. [ J Refract Surg . 2020;36(10):696–702.]

Objectives To investigate the effect of corneal stromal pocket irrigation after small-incision lenticule extraction (SMILE) on visual acuity, intraocular pressure (IOP), corneal parameters and complications after surgery. Methods A total of 242 eyes of 121 patients undergoing SMILE were enrolled in this prospective controlled study, and it was designed for one eye to randomly undergo SMILE with balanced salt solution irrigation of the corneal stromal pocket, while the other eye was not. The uncorrected distance visual acuity (UDVA) and slit lamp examination were recorded at 1 hour, 1 day, 1 week, and 1 month. Postoperative corneal density, corneal biomechanical, corneal endothelial cell number, and anterior OCT images were compared at 1 day, 1 week, and 1 month. Results Compared with the nonirrigation group, the irrigation group showed significantly higher UDVA at 1 day postoperatively (P < 0.05), but there was no significant difference during the rest of the postoperative period (1 hour, 1 week, and 1 month). In addition, no significant differences were found in IOP, corneal density, corneal biomechanics, corneal endothelial cells, and corneal morphology. No visual decline or severe postoperative complications were found in the patients in this study. Conclusions Interlamellar irrigation did not affect IOP, corneal parameters, morphology, complications, or UDVA at 1 hour, 1 week, and 1 month after the operation, but it may promote UDVA 1 day after the operation.

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