c

Fig. 4.5 Young female with poor metabolic control and no adherence to the routinely ophthalmological screening, who complains reduced visual acuity and left eye pain. Complete ophthalmic examination showed a best corrected visual acuity of counting fingers and neovascular glaucoma. (a) Fundus photography of the posterior pole clearly shows few hard exudates (arrowhead) and hemorrhages at the posterior pole, associated to whiteness of the inferior temporal artery (arrow), from non-perfusion and hyalinization. (b) FA reveals massive hypo-fluorescence of the periphery due to confluent areas of retinal non-perfusion and macular ischemia. A mild hyper-fluorescence from breakdown of the blood-retinal barrier is seen in the inter-papillomacular area. (c) OCT horizontal scan shows the presence of subretinal fluid located in the nasal area, juxtafoveal hard exudates (asterisk), reduced retinal thickness temporally to the fovea and epiretinal membrane, with mild vitreomacular traction

4.1.2Classification of PDR

The classification proposed by the Diabetic Retinopathy Study (DRS) in 1981 provided four different levels of severity of PDR, including mild, moderate, high risk, and advanced PDR (Table 4.1) [16]. The DRS defined the concept of high-risk PDR, which is characterized by one or more of the following characteristics: any NVD situated on or within one optic disk area, in association with vitreous or preretinal hemorrhage; moderate to severe NVD (defined as greater than or equal to a size included between 0.24 and 0.33 optic disk areas) in the absence of preretinal or vitreous hemorrhage; and NVE of 0.5 disk area more associated with vitreous or preretinal hemorrhage (Fig. 4.6). Neovascularization of the iris has not been included between the high-risk group defined by the DRS. The identification of the high-risk severity level of PDR revealed a significant role in the prognosis of the treatment with panretinal photocoagulation (PRP).

Fig. 4.6 High-risk PDR associated with complete disorganization of the retinal vasculature: massive NVD (arrow), intraretinal microvascular abnormalities (arrowhead), preretinal hemorrhages, extensive area of capillary non-perfusion, and amputation of the capillary network at the posterior pole

In the later proposed International Clinical Diabetic Retinopathy Disease Severity Scale, proposed by the American Academy of Ophthalmology (AAO) in 2001, the PDR scheme has been widely simplified (Table 4.2) [17]. In this classification, PDR is defined by the presence of one or more of the following clinical findings, including any type of neovascularization and vitreous or preretinal hemorrhage. The authors did not identify a high-risk sublevel of PDR, because significant rates of progression and complications are possibly expected at any stage of PDR.