This study investigated the influence of nicotine in an experimentally induced diabetic rat model. They used non-invasive high-resolution spectral domain optical coherence tomography (SD-OCT) imaging to provide quantitative information on the temporal alterations of retinal structures at the micrometer resolution level. Cigarette smoking has been associated with progression of diabetic retinopathy and nicotine alone has been shown to promote pathological effects on the retinal pigment epithelium, photoreceptors and cells in the outer nuclear layer in mice. Chronic nicotine toxicity has also been proven to increase the severity of induced choroidal neovascularisation, diabetic nephropathy and cataract development in rat models. The nicotine treatment group in this study demonstrated an average decrease in total retinal thickness of 9.4μm where the loss was mainly in the outer nuclear layer. In the combined nicotine and diabetes group they measured an increase in total retinal thickness, thought to represent a synergistic relationship between hyperglycaemia and nicotine leading to increased fluid retention within the retina, appearing as diabetic macular oedema. One explanation could be that smoking causes a reduction in blood flow due to vasoconstrictive effects of nicotine and hypoxia due to diabetes may perturb auto-regulation leading to oedema. These findings may be important in encouraging patients who smoke or use products containing nicotine to cease to prevent amongst other health risks, the worsening of diabetic retinopathy.