DIABETIC RETINOPATHY

INTRODUCTION:
  • It is retinopathy (damage to the retina) caused by complications of diabetes mellitus, which can eventually lead to blindness. 
  • It is an ocular manifestation of systemic disease which affects up to 80% of all patients who have had diabetes for 10 years or more. 
CLASSIFICATION:
  1. Nonproliferative 
  2. Proliferative 
  3. Background retinopathy 
  4. Microaneurysm 
  5. Dot and blot hemorrhage (deep hemorrhage) 
  6. Hard exudate 
  7. Macular edema 
Preproliferative retinopathy
  1. Cotton-wool spots (soft exudates) 
  2. Venous bleeding 
  3. Extensive hemorrhage 
  4. lntraretinal intravascular abnormalities (IRMA 
  5. Neovasculorization of the disc (NVD) 
  6. Neovasculaization elsewhere in the retina (NVE) 
  7. Viterous hemorrhage 
  8. Fibrovascular proliferation 
  9. Traction retinal detachment 
  10. Iris surface neovascularization (rubeosis iridis or neovascular glacoma) 
SIGNS & SYMPTOMS:
  • Diabetic retinopathy often has no early warning signs. 
  • As new blood vessels form at the back of the eye as a part of proliferative diabetic retinopathy (PDR), they can bleed (ocular hemorrhage) and blur vision. In most cases, it will leave just a few specks of blood, or spots, floating in a person's visual field, though the spots often go away after a few hours. 
  • On funduscopic exam, one see cotton wool spots, flame hemorrhages (similar lesions are also caused by the alpha-toxin of Clostridium novyi), and dot-blot hemorrhages. The screening strategy for prevention of blindness from diabetic retinopathy according to the NPCB involves High Risk Screening 
  • Elevation of blood-glucose levels can also cause edema (swelling) of the crystalline lens (hyperphacosorbitomyopicosis) as a result of sorbitol (sugar alcohol) accumulating in the lens. 
  • This edema often causes temporary myopia (nearsightedness). 
  • A common sign of hyperphacosorbitomyopicosis is blurring of distance vision while near vision remains adequate. 
PATHOGENESIS:
  • Diabetic retinopathy is the result of microvascular retinal changes. 
  • Hyperglycemia-induced intramural pericyte death and thickening of the basement membrane lead to incompetence of the vascular walls. 
  • These damages change the formation of the blood-retinal barrier and also make the retinal blood vessels become more permeable. 
  • During the initial stage, called nonproliferative diabetic retinopathy (NPDR), most people do not notice any change in their vision. 
  • Early changes that are reversible and do not threaten central vision are sometimes termed simplex retinopathy or background retinopathy. 
  • Oxidative stress, VEGF (vascular endothelial growth factor) & Increased protein kinase-C are implicated in the pathogenesis of macular oedema in diabetic retinopathy Some people develop macular edema. 
  • It occurs when the damaged blood vessels leak fluid and lipids onto the macula.The fluid makes the macula swell, which blurs vision. 
Proliferative diabetic retinopathy (PDR) (or PDRP)
  • As the disease progresses, severe nonproliferative diabetic retinopathy enters an advanced, or proliferative, stage when blood vessels proliferate (i.e. grow). The lack of oxygen in the retina causes fragile, new, blood vessels to grow along the retina and in the clear, gel-like vitreous humour that fills the inside of the eye. Without timely treatment, these new blood vessels can bleed, cloud vision, and destroy the retina 
  • Fibrovascular proliferation can also cause tractional retinal detachment. 
  • The new blood vessels can also grow into the angle of the anterior chamber of the eye and cause neovascular glaucoma. 
  • Visual loss in diabetic retinopathy is due to Cataract formation, Ischaemic maculopathy & Vitreous hemorrhage 
  • Treatment of Advanced Proliferative Diabetic Retinopathy with extensive vitreoretinal fibrosis and fractional retinal detachment involves Reattachment of detached or torn retina, Removal of epiretinal membrane & Vitrectomy 
RISK FACTORS:
  • All people with diabetes mellitus are at risk - those with Type I diabetes (juvenile onset) and those with Type II diabetes (adult onset). 
  • The longer a person has diabetes, the higher the risk of developing some ocular problem. 
  • People with Down's syndrome, who have three copies of chromosome 21, almost never acquire diabetic retinopathy. 
  • This protection appears to be due to the elevated levels of endostatin, an anti-angiogenic protein, derived from collagen XVIII. 
  • The collagen XVIII gene is located on chromosome 21. 
MANAGEMENT:
Early treatment for diabetic retinopathy study: 

  • There are three major treatments for diabetic retinopathy, which are very effective in reducing vision loss from this disease. 
  • These three treatments are laser surgery, injection of triamcinolone into the eye, and vitrectomy. 
  • Although these treatments are very successful (in slowing or stopping further vision loss), they do not cure diabetic retinopathy. 
  • Laser photocoagulation 
  • It is widely used for early stages of proliferative retinopathy. 
Panretinal photocoagulation 
  • Panretinal photocoagulation, or PRP (also called scatter laser treatment), is used to treat proliferative diabetic retinopathy (PDR). 
  • The goal is to create 1,600 - 2,000 burns in the retina with the hope of reducing the retina's oxygen demand, and hence the possibility of ischemia. 
Intravitreal triamcinolone acetonide 
  • Triamcinolone is a long acting steroid preparation. 
  • When injected in the vitreous cavity, it decreases the macular edema (thickening of the retina at the macula) caused due to diabetic maculopathy, and results in an increase in visual acuity. 
  • The effect of triamcinolone is transient, lasting up to three months, which necessitates repeated injections for maintaining the beneficial effect. 
  • Complications of intravitreal injection of triamcinolone include cataract, steroid-induced glaucoma and endophthalmitis. 
Vitrectomy 
  • Diabetic macular edema with non progressive diabetic retinopathy treated with Macular grid photocoagulation still showing vitreo macular traction is treated with Pars plana vitrectomy 
  • Instead of laser surgery, some people require a vitrectomy to restore vision. 
  • A vitrectomy is performed when there is a lot of blood in the vitreous. 
  • It involves removing the cloudy vitreous and replacing it with a saline solution 
Exam Question 
  • Earliest feature of Diabetic Retinopathy is Microaneurysms 
  • Diabetic macular edema with non progressive diabetic retinopathy treated with Macular grid photocoagulation still showing vitreo macular traction is treated with Pars plana vitrectomy 
  • HTN and DM with reduced vision showing central bleed on fundoscopy can be diagnosed as Diabetic retinopathy 
  • Diabetic retinopathy is related to Duration of disease 
  • The screening strategy for prevention of blindness from diabetic retinopathy according to the NPCB involves High Risk Screening 
  • Microaneurysms, Retinal hemorrhages & Neovascularisation are feature in diabetic retinopathy on fundus examination 
  • Treatment of Advanced Proliferative Diabetic Retinopathy with extensive vitreoretinal fibrosis and fractional retinal detachment involves Reattachment of detached or torn retina, Removal of epiretinal membrane & Vitrectomy 
  • Oxidative stress, VEGF (vascular endothelial growth factor) & Increased protein kinase-C are implicated in the pathogenesis of macular oedema in diabetic retinopathy In maturity onset diabetes mellitus, screening for diabetic retinopathy should be done Immediately 
  • Cotton wool spots in diabetic retinopathy are due to Retinal edema 
  • ETDRS stands for Early treatment for diabetic retinopathy study 
  • Diabetic retinopathy, most likely present with NIDDM with 2 years duration 
  • Development of Diabetic retinopathy depends on Intensity of disease, Age of onset & Duration of disease 
  • 29 years old man with IDDM for the last 14 years develops sudden vision loss, has non-proliferating diabetic retinopathy, cause is Macular oedema 
  • Diabetic retinopathy is characterized by Hard exudates, dot haemorrhages and microaneurysm & Flame shaped haemorrhages, soft exudates 
  • Diabetic retinopathy is treated by Strict glycemic control, Panphotococagulation & Antihypertensive 
  • Diabetic retinopathy is essentially an angiopathy affecting retinal Precapillary arterioles, Capillaries & Venules 
  • Spontaneous regression of proliferative retinopathy may occur in Diabetic retinopathy 
  • Visual loss in diabetic retinopathy is due to Cataract formation, Ischaemic maculopathy & Vitreous hemorrhage 
  • Commonest cause of loss of vision in non-proliferative diabetic retinopathy is Macular edema 
  • Sudden loss of vision in patient with diabetic retinopathy is due to Vitreous defects 
  • Vitreous haemorrhage in diabetic retinopathy is Prolifertive diabetic retinopathy 
  • Panretinal photocoagulation is indicated in Prolifertive diabetic retinopathy 
  • Capillary microaneurysms is an earliest sign of Non-proliferative diabetic retinopathy 
  • Diabetic retinopathy is the most common cause of ruheosis iridis 
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