The conventional imaging diagnostic techniques available for the detection of DR are color fundoscopy and fluorescence angiography and Spectral Domain Optical Coherence Tomography (SD-OCT).
Fundoscopy uses a fundus camera to grab color images of the interior surface of the eye for documenting the presence of disorders and monitor their changes over time (23). A major limitation of fundus photography is that it shows a 2-D representation of the retinal tissue rather than generating a 3-D semi-transparent image of the object. A fluorescein angiography is a widely used medical procedure for DR diagnosis in which a fluorescent dye is injected into the blood stream. The dye highlights the ocular blood vessels in the back of the eye so they can be photographed (24). A recent study has implemented automated classification of retina in ocular tumor induced mouse model using textural features extracted from OCT. However, layer specific textural and intensity attributes may be endorsed for OCT images towards precise diagnostics as ‘Lucidity’ is one of the optical intensity descriptors which tends to vary with different regions of body structures like retina, skin and mucosa in health and pathology (25). OCT was not found to be suitable for quantifying many specific disease components (e.
g. pigment epithelium detachments, sub-retinal fluid) (26). As these imaging technologies have been evolving persistently, their significance in the diagnosis and management of DR has become increasingly evident (27). Further, study of unique biophysical properties of biofluids in terms of their interactive interface with gold-nano particles in different dilutions becoming a promising field for less invasive and low cost precise diagnosis of different chronic disorders (28). Pathobiological metabolomic, proteomic and lipidomic dimensions of eye diseases specially for DR are emerging significantly (29,30).
Reports using animal models are evident on artificially induced DR, since human vitreous and ocular biopsy samples are not easily available for experimental analysis (31).