PURPOSE: To investigate the changes of retinal and choroidat parameters, scterat biomechanicat strength, and ocular histopathotogy after scterat ultraviolet-A (UVA) cross-linking (CXL) in rhesus monkeys eyes, and to evaluate the safety and tong-term biomechanicat stability of scterat CXL for preventing myopia from progressing further in clinic. METHODS: Six 3-year-old mate rhesus monkeys (12 eyes) were randomized to receive UVA-CXL procedures applied on the superotemporat 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 scterat strips were analyzed 12 months postoperatively by a biomateriat tester. Hematoxytin-eosin and terminal deoxynucteotidyl transferase dUTP nick-end labeling (TUNEL) staining were performed 12 months postoperatively. RESULTS: For central retinal thickness, choroidat 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 biomechanicat stability of sctera was increased. The scterat 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: Scterat CXL with riboflavin/UVA in rhesus monkey eyes could strengthen the biomechanicat 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.