Design and Baseline Data of the Diabetes Registration Study: Guangzhou Diabetic Eye Study.

PURPOSE: The incidence and risk factors for diabetic retinopathy (DR) in southern China remain unclear. This project aims to explore the onset and progression of DR and their determinants through a prospective cohort in South China. METHODS: The Guangzhou Diabetic Eye Study (GDES) recruited patients with type 2 diabetic registered in the community health centers in Guangzhou, China. Comprehensive examinations were performed including visual acuity, refraction, ocular biometry, fundus imaging, blood and urine tests. RESULTS: A total of 2305 eligible patients were included in the final analysis. In total, 14.58% of the participants had any DR and 4.25% had vision-threatening DR (VTDR), among which 76 (3.30%), 197 (8.55%), 45 (1.95%) and 17 (0.74%) were classified as mild NPDR, moderate NPDR, severe NPDR and PDR, respectively. There were 93 (4.03%) patients with diabetic macular edema (DME). The presence of any DR was independently associated with a longer duration of DM, higher degree of HbA1c, insulin treatment, higher average arterial pressure, higher concentration of serum creatinine, presence of urinary microalbumin, older age, and lower body mass index (BMI) (all p < 0.001). For VTDR, seven factors were significant: older age, a longer duration of DM, higher concentration of HbA1c, use of insulin, lower BMI, higher concentration of serum creatinine, and high albuminuria (all p < 0.05). These factors were also independently associated with DME (all p < 0.001). CONCLUSION: The GDES is the first large-scale prospective cohort study of the diabetic population in southern China, which will help to identify novel imaging and genetic biomarkers for DR in this population.

Comparison of Macular Thickness Measurements Using Swept-Source and Spectral-Domain Optical Coherence Tomography in Healthy and Diabetic Subjects.

Purpose: To establish normative data for macular thickness in Chinese aged 30 to 80 years using the swept-source optical coherence tomography (SS-OCT) device.Methods: The study included 290 normal eyes, 430 NDR eyes and 150 DR eyes of community residents aged 30 to 80 years in Guangzhou, China. Mean macular thicknesses in Early Treatment Diabetic Retinopathy Study (ETDRS) subfields, central point thicknesses (CPT), and macular volume was measured by SS-OCT (Triton DRI OCT, Topcon, Tokyo, Japan) and Spectral-Domain OCT (SD-OCT; Heidelberg Engineering, Heidelberg, Germany). We assessed agreement between SS-OCT and SD-OCT measurements by intraclass correlation coefficients (ICC) and Bland-Altman plots. We established a conversion equation relating central subfield (CSF), CPT and macular volume between the two OCT devices.Results: Macular thickness measurements in SS-OCT were significantly thinner than in SD-OCT. The mean CSF thickness in normal eyes measured by SS-OCT and SD-OCT were 227.8 ± 19.4 µm and 260.0 ± 19.7 µm (p < .0001). CSF thickness was a significantly difference between genders (SS-OCT: male 237.2 ± 18.8 µm vs female 222.0 ± 17.5 µm, p < .0001). In all three groups, the agreement between SS-OCT and SD-OCT was excellent (all ICC > 0.9). The conversion equations for CSF, CPT and macular volume from SS-OCT to SD-OCT were derived, with over 95% of the predicted values fell within 10% of the actual measurements in DR and NDR eyes.Conclusion: We propose SS-OCT CSF thicknesses of 275 µm for males and 260 µm for females as the minimum criteria for macular edema in Chinese aged 30 to 80 years based on 2 SDs above the mean CSF. SS-OCT measurements were significantly thinner than SD-OCT. We derived equations from converting SS-OCT measurements to SD-OCT equivalents.