[Observation and quantification of diabetic keratopathy in type 2 diabetes patients using in vivo laser confocal...

Objective: To study the diabetic keratopathy in type 2 diabetes patients with retinopathy by in vivo laser confocal microscopy. Methods: This was a case-control study. Ninety type 2 diabetes patients were involved in this study from May 2015 to December 2019 in Qingdao Eye Hospital. According to the diabetic retinopathy clinical stage, these patients were divided into the non-proliferative diabetic retinopathy (NPDR) group (30 cases), early stage proliferative diabetic retinopathy (PDR) group (30 cases) and intermediate to late stage PDR group (30 cases). Thirty non-diabetic healthy volunteers were included in the control group. The central cornea was observed with an in vivo laser confocal microscope. The corneal nerve fiber density, nerve fiber length, nerve branch density, and nerve fiber tortuosity were compared between groups. The corneal Langerhans cells, epithelial cells, stromal cells and endothelial cells were also compared. Results: There were more nerve fibers and branches in the control group than the other three diabetic groups. The nerve fiber length in the control group, NPDR group, early stage PDR group and intermediate to late stage PDR group was (21.55±2.57), (14.73±1.56), (11.23±1.40) and (8.02±1.33) mm/mm², respectively, and there were statistically significant differences between the groups (F=316.17, P=0.00). In the nerve fiber density, nerve branch density and curvature, there were statistically significant differences between the groups (F=345.72, 479.46, 167.00, all P=0.00). The basal cell density in the control group, NPDR group, and two PDR groups was (5 761±303), (5 336±367), (4 146±379) and (3 658±365) cells/mm², respectively, and there were statistically significant differences between the groups (F=234.94, P=0.00). The anterior stromal cell density in the four groups was (836±30), (727±57), (544±59) and (360±47) cells/mm², respectively, and there were statistically significant differences between the groups (F=535.08, P=0.00). The hexagonal endothelium cell rate in the four groups was 62.0%±5.5%, 51.1%±3.7%, 40.2%±4.0% and 27.8%±3.9%, respectively, and the Langerhans cell density was (1.5±0.6), (4.2±1.3), (6.8±2.1) and (10.9±2.1) cells/mm², respectively; there were statistically significant differences between the groups (F=342.28, 179.78, all P=0.00). There was no statistically significant difference between the groups in the corneal endothelial cell density (F=1.58, P=0.20). Conclusions: In type 2 diabetes patients with diabetic retinopathy, the corneal nerve fiber and branch density can be significantly reduced, and the density of the hexagonal corneal endothelial cells, epithelial basal cells and anterior stromal cells can also decrease. Langerhans cells may be involved in the development diabetic keratopathy. (Chin J Ophthalmol, 2020, 56: 754-760).