<unk>  can be classified based on retinal changes into non-proliferative and proliferative subtypes. Non-proliferative<unk>  (NPSCR) Non-proliferative<unk>  (NPSCR) can feature the following retinal manifestations: * Venous tortuousity is commonly observed in patients with homozygous HbSS<unk> <unk>  disease. Numerous diseases that feature blood hyperviscosity similar to<unk> <unk>  disease can manifest as retinal venous tortuousity. Tortuosity is caused by arteriovenous shunting from the retinal periphery. * It can feature small bleeds of the retina known as intra-retinal hemorrhages, due to blockage of blood vessels by the<unk> d blood<unk> s, thus triggering vessel wall necrosis. The resulting hemorrhages are initially bright red and oval shaped. As the hemorrhage ages over a period of days to weeks, the color then changes to a salmon hue known as a salmon patch. They are usually seen adjacent to the retinal arteriole. * Bleeding in the deeper layers of the retina leads to the appearance of dark lesions known as black sunburst spots. These oval or round shaped pigmented spots are formed due to RPE proliferation. * As the haemoglobin within the hemorrhage breaks down over time, yellow spots known as iridescent bodies are formed within the layers of the sensory retina. * Maculopathy occurs in a significant portion of patients affected by<unk> . It is more prevalent in homozygous HbSS type<unk> <unk>  disease. The fovea can be found within the macula and is known as the center of the visual field. Maculopathy in<unk>  is due to long term changes of capillaries that interact at the fovea. Although ischemic changes may be apparent on the retina, maculopathy may be asymptomatic at first leaving visual acuity unchanged. * Central retinal artery occlusion is a known feature of non-proliferative<unk>  that has a low incidence in patients with non proliferative<unk> . * Optic nerve sign is represented by dilated capillaries that can be visualized in the nerve using fluorescein angiography. Visual acuity often remains unchanged with this finding. * Angioid streaks: Angioid streaks may be seen in up to 6% of cases. Proliferative<unk>  (PSCR) Proliferative<unk>  retinopathy is the most severe ocular complication of<unk> <unk>  disease. Even though PSCR begins in the first decade of life, the condition remains asymptomatic and unnoticed until visual symptoms occur due to vitreous hemorrhage or retinal detachment. Goldberg classification Goldberg classified PSR into following 5 different self-explanatory stages: # Stage of peripheral arterial occlusion and ischemia: It is the earliest abnormality that can be visualized by fundus examination. The occluded arterioles can be seen as dark red lines. They eventually turn into white silver-wire vessels. # Stage of peripheral arteriolar-venular anastomoses: Arteriolar-venular anastomoses develop as blood is diverted from blocked arteries to nearby venules. # Stage of neovascularization and fibrous proliferation: Neovascularization starts from the arteriolar-venular anastomoses, and grow into the ischemic retina. Characteristic fan-shaped appearance due to neovasularization is known as sea fan neovascularization. # Stage of vitreous hemorrhage. Peripheral neovascular tufts bleed and cause vitreous hemorrhage. # Stage of vitreoretinal traction bands and tractional retinal detachment: Traction on the sea fan and adjacent retina causes traction retinal detachment.
Sickle cell retinopathy
Autoimmune retinopathy
Diabetic retinopathy
Hypertensive retinopathy
Radiation retinopathy
Chloroquine retinopathy
Photic retinopathy
Autoimmune optic neuropathy