AIM: To analyze the correlation between tear film lipid layer thickness(LLT)and macular microvascular parameters in diabetic retinopathy.

METHODS: Totally 60 eyes of type 2 diabetes patients with non-proliferative stage(NPDR group)and 60 eyes of proliferative stage(PDR group)with diabetic retinopathy diagnosed in our hospital from 2018-01/12 were selected, and 60 eyes of healthy volunteers with appropriate age and gender were selected as the normal control group. The tear film lipid layer thickness(LLT)was examined by Lipiview eye surface interferometer, while the foveal avascular zone(FAZ), superficial capillary layer(SCL)vessel density and deep capillary layer(DCL)vessel density were measured by optical coherence tomography angiography(OCTA)in three groups. The differences and correlations between the parameters were compared.

RESULTS: LLT(69.87±11.401nm)in normal control group was higher than that in NPDR(54.87±7.453nm)and PDR group(42.67±5.246nm), and FAZ(0.312±0.021mm²)was lower than that in NDPR group(0.389±0.037mm²)and PDR group(0.437±0.032mm²). The vascular density of SCL(51.977%±4.164%)was significantly higher than that of NPDR(47.067%±4.757%)and PDR(41.865%±5.512%), and that of DCL(49.578%±2.619%)was higher than that of NPDR(46.032%±2.622%)and PDR(40.598%±2.671%)(all P<0.01). There was no correlation between LLT, FAZ, SCL and DCL in normal subjects. LLT was negatively correlated with FAZ in both NPDR group and PDR group(r=-0.922, r=-0.923, all P<0.01), positively correlated with SCL(r=0.798, r=0.902, all P<0.01), and had no correlation with DCL(r=0.140, r=0.073, P=0.285, P=0.581).

CONCLUSION: In diabetic retinopathy, the lipid layer of tear film is lower and the stability of tear film is decreased, and there is a correlation between diabetic dry eye and macular microvascular changes.