Chronic obstructive pulmonary disease (COPD) is a common complex respiratory condition characterized by chronic inflammation of lung tissues leading to severe lung damage and permanent airflow limitation [1,2]. The systemic clinical findings of COPD are not limited to the lungs; vascular comorbidities are seen in patients with COPD due to increased hypoxia, inflammation, and oxidative stress [3,4]. COPD is triggered by exposure to irritating gases, and one of the most important risk factors is smoking [5].

Smoking is a worldwide health problem that significantly increases the mortality and morbidity rates [6]. Smoking causes endothelial dysfunction and contributes to the formation of vascular system disorders via several mechanisms, including decreased nitric oxide with increased oxidative stress and inflammation [6]. Because smoking was found to be an independent risk factor for the development of new vascular lesions, it is clear that smokers are prone to develop microvascular complications [6].

The eye is the only organ that enables direct and non-invasive investigation of microvascular structures. Therefore, an ocular examination is a convenient way to ensure the early detection of the effects of systemic disorders on retinal microvasculature. Optical coherence tomography angiography (OCTA) is a novel, non-invasive technique that allows for in vivo visualization of the retina and provides quantitative data reflecting ocular blood flow [7]. Several OCTA studies have investigated the effect of systemic diseases on retinal capillaries and have detected the remarkable relationship between ocular impairment and the severity of systemic diseases [8,9].

Using OCTA, previous studies have evaluated retinal vascular impairments in patients with COPD compared to healthy controls [7,10,11]. Although COPD-associated microvascular changes have been reported, the effect of smoking, which is the most common and important risk factor for COPD, on the retinal vascular system has been ignored [12,13]. To address this deficiency and to elucidate the effect of COPD on the retinal microcirculation, this study investigated the retinal vasculature of patients with COPD using OCTA and compared these measurements with those of smokers and healthy non-smokers.