Description

1.1 Introduction

A global increase in the number of people with an eye condition has been registered in the last decades, according to the WHO World Report on Vision 2019. While cataract remains the main cause of visual impairment in developing countries (Shatz et al., 2019), the ageing of population increased the incidence of chronic posterior eye diseases (e.g., age-related macular degeneration (AMD)), glaucoma, and cataract. Increased levels of air pollution, the prolonged use of steroids, and the increased incidence of allergic diseases are associated with disorders of the ocular surface, such as keratoconjunctivitis sicca or dry eye disease (Rathi et al., 2017). Other medical conditions, such as rheumatoid arthritis, multiple sclerosis, and diabetes, also present repercussions in the eye. Systemic microvascular damages that are associated to diabetes, in fact, affect both the anterior and posterior segment of the eye and they can lead to corneal issues, tear film instability, increased intraocular pressure, and a higher incidence of glaucoma, cataract, and uveitis, as well as pathologies of the back of the eye, such as diabetic retinopathy (DR) and diabetic macular edema (DME) (Priyavarshini et al., 2020). Consequently, diabetic patients are 25 times more likely to become blind than the general population (Song et al., 2016).