Diabetic retinopathy in China: population-based studies and clinical and experimental investigations

Abstract

BackgroundDiabetic retinopathy is one of the most common causes of irreversible blindness. The aim of this study was to assess the epidemiology of diabetic retinopathy and related factors in China. MethodsWe analysed data from the Beijing Eye Study, the Beijing Eye Public Health Care Project, national studies, the community-based Kailuan study, and experimental investigations to derive prevalence, incidence, and associated factors of diabetic retinopathy in China. FindingsIn the Beijing Eye Public Health Care Project, diabetic retinopathy caused visual impairment in 905 (0·16%) of 562 788 elderly study participants. In the population-based Beijing Eye Study (n=3468) and surveys from 2001, 2006, and 2011, the prevalence of diabetic retinopathy was 2·9% (SD 0·3%, 95% CI 2·3–3·5). Increased prevalence, incidence, and severity of diabetic retinopathy were associated with increased estimated cerebrospinal fluid pressure (p=0·002; odds ratio 1·14; 95% CI 1·05–1·24) after adjusting for blood concentration of glucose and HbA1c, diabetes duration, blood pressure, and level of education. In the community-based Kailuan study (n=101 510), in which patients had biennial follow-up starting in 2006–07, optical coherence tomographic angiography revealed reductions in the retinal capillary system in patients with diabetic retinopathy. Clinical examinations of patients with diabetic retinopathy showed increased intraocular concentrations of many cytokines, including epithelial growth factor, intercellular adhesion molecule 1, monocyte chemoattractant protein 1, placenta growth factor, and vascular endothelial growth factor. The intraocular cytokine concentrations decreased with longer ocular axial length, explaining the protective effect of myopia against diabetic retinopathy, as observed in the epidemiological studies. In experimental studies, glucagon-like peptide 1 released from intraocular cell beads implanted into rabbit eyes and rat eyes had a neuroprotective effect on the retina and optic nerve. Bone-marrow-derived mesenchymal stem cells injected into newborn mice with retinopathy of prematurity, a disorder similar to diabetic retinopathy, reduced the avascular area in the retina. Intravitreal injection of triamcinolone in rat eyes reduced the activity of retinal microglial cells. InterpretationAs the Chinese population ages and the prevalence of risk factors increases, diabetic retinopathy will become one of the most common blinding disorders in China. The marked increase in myopia in young Chinese people might have a protective effect. Increased cerebrospinal fluid pressure in association with elevated blood pressure could help explain retinal vein dilatation and retinal exudation in diabetic retinopathy. Intraocular cell-based production of glucagon-like peptide 1 and related proteins might be of therapeutic use for diabetic retinopathy. Activity of retinal microglial cells involved in diabetic retinopathy might be reduced by steroids injected intravitreally. Bone-marrow derived mesenchymal stem cells injected intravitreally might also be a therapeutic option in diabetic retinopathy. FundingThe National Natural Science Foundation of China (81770890).