Observation Of Corneal Structure After Small Incision Lenticule Extraction Procedure In Diabetic Rabbits

Purpose:To observe corneal structure's change after femtosecond laser small incision lenticule extraction?SMILE?in diabetic rabbits with different blood glucose levels,and provide a theoretical basis for the feasibility of SMILE surgery in diabetic patients.Methods:30 New Zealand white rabbits were pre-fed for 1 week.26rabbits were randomly selected to build diabetic models by intravenous injection of alloxan?ALX?,and the rest were Normal group?n=4?.8 models were selected and their blood glucose level was controlled by adjusting insulin's dosage.They were divided into High Glucose group?n=4?and Blood Glucose Control group?n=4?.2 weeks later,3 groups underwent SMILE.Slit lamp microscope,optical coherence tomography?AS-OCT?and in vivo confocal microscope?IVCM?were applied pre-operatively and post-operatively on day 1 and week 1,4,12.SPSS25.0 software was used for statistical analysis,and P<0.05 was considered statistically significant.Results:1. Slit lamp:1^stday after surgery,there was no conjunctival congestion or conjunctival sac secretion in 3 groups,and the corneal incisions were well closed;1^st week after surgery,only 1 eye in High Glucose group had edema on the corneal cap near the incision,and the rest of the cornea was transparent;4^thweek after surgery,the corneas were transparent in 3 groups.2. AS-OCT:There was no statistical difference in central corneal thickness?CCT?among 3 groups preoperatively.The actual CCT was thicker than the theoretical CCT at each time point in 3 groups,but there was no statistical difference between them.The corneal thickness deviation??CT?in Good Blood Glucose Control and Normal group increased with time.3. IVCM:The morphology and arrangement of each layer of cells andnerve fibers in High Glucose group were more irregular than those in Blood Glucose Control and the Normal group,but there was no statistical difference between Blood Glucose Control and Normal group.There was no significant difference in pre-stromal cell density and endothelial cell density?ECD?among 3 groups before surgery.?1?Comparison between groups:the overall density of pre-stromal cells in the High Glucose group was lower than that in other 2 groups significantly,but there was no statistical difference between Blood Glucose Control and the Normal group.There was no significant difference in ECD among 3 groups.?2?Comparison between different time:The density of pre-stromal cells and ECD in High Glucose group decreased significantly with time.There was no difference in the change trend of cell density with time between Blood Glucose Control and Normal group:the pre-stromal cell density in 2 groups decreased on the 1^st week,and then stabilized.There was no statistical difference in ECD between pre and post-operate in 2 groups.Conclusions:1.Hyperglycemia is an adverse factor affecting changes of corneal structure after SMILE.2.SMILE is safe and effective for diabetic rabbits with good blood glucose control.