BeyHealth Quarterly Journal (BHQJ) BHQJ 2018: 001:1 (May 2018) - Page 7

CPD HOT TOPIC These microaneurysmal dilatations are a hallmark of the process described above, the end result of which is haemorrhage from small vessels and leakage of extracellular fluid, often resulting in macula oedema and deposition of lipoproteins (hard exudates) in the retinal layers, visible on close examination of the eye as distinct white or yellowish deposits with sharp margins and varying in size from small specks to much larger patches. On another hand, microvascular occlusion may occur as a consequence of haematological and vascular abnormalities, resulting in retinal ischaemia with cotton wool spots, Intraretinal Microvascular Abnormalities (IRMA) and neovascularization being the features. An ischaemic retina produces vascular endothelial growth factor (VEGF) which stimulates new vessel growth, hence use of the term proliferative diabetic retinopathy (PDR). The consequence of an oedematous or ischaemic retina is the loss of function resulting in vision loss, assuming involvement (or damage) of the central retina or macula. New vessels are prone to bleeding (vitreous haemorrhage) and the accompanying fibrosis leads to tractional retinal detachment. Thus, the sight-threatening manifestations of DR are proliferative retinopathy and diabetic maculopathy, which are both preventable and treatable before vision is lost. The risks of development and progression of retinopathy are related to factors such as glycemic control (or HbA1c), blood pressure and blood lipid levels [3]. Vascular Endothelial Growth Factor (VEGF) VEGF is a 45-KD glycoprotein, which was discovered in 1993. It plays an important role in the pathogenetic cascade promoting vascular growth and permeability. It has been found to promote vascular leakage as well as angiogenesis (formation of new blood vessels originating from pre- existing ones). An elevated level of circulating VEGF is present in conditions with retinal ischaemia. VEGF165 appears to be the dominant isoform in the pathogenetic pathway (in conjunction with other known isoforms and pro-inflammatory mediators). Therefore, the biologic blockage of VEGF in recent times has become a very effective treatment for this condition as will be discussed in the treatment section of this article. Clinical Presentation of Diabetic Retinopathy Diabetic retinopathy may present initially with vision loss due the processes explained above. Several cases can also be detected before vision loss occurs by identification, on fundus examination, of the various exudative, non-proliferative and proliferative features of the disease described earlier in this article. Oftentimes, an eye may manifest a combination of exudative, non-proliferative and proliferative features. In such cases, the various features of diabetic retinopathy as enumerated in the pathogenesis section of this article can nonetheless be observed. Investigations Ocular-specific investigations are usually required aside from tests needed for systemic evaluation of the patient. The value of such ocular investigations includes assessing the current extent of the disease, making a treatment plan and monitoring the outcome of treatment. Necessary investigations are as follows: 1. Fundus Photography 2. Fundus Fluorescein Angiography 3. Ultrasonography and 4. Optical Coherence Tomography Issue 1 | MAY 2018 | “ ...the sight- threatening effects of Diabetic Retinopathy are proliferative retinopathy and diabetic maculopathy, which are both preventable and treatable conditions. 7