**Animal Models of Diabetic Retinopathy (Part 1)**

**Animal Models of Diabetic Retinopathy (Part 1)**

DOI: 10.5772/intechopen.70238

Larissa H.C. Tang, Ian Y.H. Wong and Amy C.Y. Lo Amy C.Y. Lo

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.70238

Larissa H.C. Tang, Ian Y.H. Wong and

#### **Abstract**

Diabetic retinopathy (DR) is one of the leading causes of preventable vision impairment and blindness in the working-age population worldwide. Numerous animal models have been developed for therapeutic drug screening and to further our understanding of the molecular and cellular pathological processes involved in DR. In this book chapter, we describe the cellular, molecular and morphological features of mouse models of DR as well as their respective advantages and limitations. To date, no animal model can holistically reproduce the pathological progression of human DR; most only display early or advanced lesions of DR. However, a thorough understanding of genotypic and phenotypic expressions of existing models will facilitate researchers' selection of the appropriate model to simulate their desired clinical scenarios.

**Keywords:** animals, blood glucose, blindness, diabetic complications, diabetes mellitus/ pathology/physiopathology, neovascularization, proliferative, retinal vessels

#### **1. Introduction**

Diabetes mellitus is a growing epidemic and a major contributor to the global burden of disease [1]. Insulin deficiency leading to hyperglycemia occurs in type 1 diabetes (T1D or insulindependent diabetes mellitus) as a result of autoimmune destruction of pancreatic beta islet cells. Type 2 diabetes (T2D or non-insulin-dependent diabetes mellitus) is characterized by insulin resistance, often due to physical inactivity and obesity, and may progress to impaired insulin production. T1D is unpreventable as of current understanding, while T2D, the more common type of the two, is preventable.

Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes and one of the leading causes of preventable vision impairment and blindness in the

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© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

working-age population worldwide. It can be broadly classified as non-proliferative diabetic retinopathy (NPDR) or proliferative diabetic retinopathy (PDR). According to the AAO International Clinic DR Disease Severity Scale, NPDR is further subdivided into mild, moderate or severe NPDR, depending on the extent of microaneurysm, intraretinal hemorrhage, venous beading and intraretinal microvascular abnormality (IRMA) formation [2]. With worsening retinal ischemia and increasing microvascular damage, NPDR may progress to PDR, which is characterized by the presence of neovascularization and/or vitreous or preretinal hemorrhage [2]. Severe cases of PDR may result in retinal edema, tractional retinal detachment and neovascular glaucoma. Diabetic maculopathy or macular edema, the most common cause of vision loss, may also arise at any stage of DR [3].

DR-associated visual impairment results in large socioeconomic costs for both the society and individuals. This calls for effective screening methods and increased efforts to understand the pathophysiological progression and to look for effective treatment strategies using both experimental animal models and clinical trials.
