Common retinal disorders for medical.pptx

MEDICAL DOCOTRS LEVEL

1. Common retinal disorders Dr. abraham nigussie

2. Applied anatomy The retina is the inner most layer of the eyeball The retina converts focused light images into nerve impulses The retina has two major layers: neurosensory retina and the retinal pigment epithelium ( RPE ) RPE is a single layer of melanin-containing cells. The RPE cells have numerous functions including vitamin A metabolism.

3. Layers of the retina

4. Applied anatomy… Macula is the posterior fundus area lying temporal to the optic disc and between the vascular arcades. The  fundus  is the interior surface of the  eye   There are important anatomic modifications in the macula that subserve the highest level of visual efficiency and color perception. Histologically, the macula is distinct from the rest of the retina. At the center of macula is a specialized area, the fovea , which is for high quality vision. The macula is for central vision. The rest of the retina is for peripheral vision. Ora serrata is the junction of the periphery of the retina & the ciliary body

5. Ophthalmoscopy

6. Applied anatomy… Two types of photoreceptor are present in the retina: cones and rods. Cones , concentrated at the macula, are responsible for fine vision (acuity) and color appreciation. Rods are for vision in low light levels and detection of movement. Rods are distributed throughout the entire retina

7. Photoreceptors

8. Applied anatomy… Blood supply of the retina Outer 1/3 rd of the retina gets oxygen & nutrients by diffusion from the choroid Inner 2/3 rd of the retina is supplied by central retinal artery giving a branch for each of the four quadrants of the retina. Venous drainage from the retina is through central retinal vein draining into the ophthalmic vein The retinal vessels enter and leave the eye through the optic nerve and run in the superficial layer of the retina

9. Applied anatomy… Blood-retinal barrier (BRB) The inner BRB consists of the retinal vascular endothelium, which is nonfenestrated and contains tight junctions. The outer BRB is the retinal pigment epithelium. The BRB isolates the retinal environment from the systemic circulation. Disruption of the barriers, as occurs in diabetic retinopathy, leads to retinal edema and precipitation of lipid and protein, causing loss of retinal transparency and therefore loss of vision.

10. Normal retinal vessels do not leak fluorescein

11. Diabetic retinopathy Diabetic retinopathy (DR) is a common cause of blindness. Many of the complications of DR can be modified by early detection and treatment! The exact mechanism of DR is not known, but it is established that strict control of blood sugar decreases DRP. The clinical manifestations of DRP can be explained by small vessel occlusion and increased permeability (loss of blood-retinal barrier). Proliferation of new vessels ( neovascularization ) occurs in response to vasogenic factors released by ischemic retina

12. Pericyte loss and basement membrane thickening are the earliest histopathologic changes

13. Capillary leakage and occlusion are the basic pathophysiologic features of DR

14. Diabetic retinopathy… Risk factors associated with DR. Duration of diabetes Increasing age since onset of diabetes Blood sugar level Hypertension Hypelipidemia Nephropathy Smoking Pregnancy Anemia

15. Diabetic retinopathy… Classification of DR. Non-proliferative diabetic retinopathy ( NPDR ) Proliferative diabetic retinopathy ( PDR ) Formation of new blood vessels is the hallmark of PDR Macular edema is a frequent cause of visual impairment in DR. It can occur at any stage of DR.

16. microaneurysms dot/blot hages Hard exudates

17. macular edema

18. cotton-wool spots Occluded vessels

19. venous beading venous loops

20. Neovascularization

21. Vitreous hemorrhage

22. Iris neovascularization leading to neovascular glaucoma (NVG)

23. Management Control of blood sugar Control of blood pressure Control of blood lipid Specific treatment of DR Laser therapy In laser therapy tiny retinal burns are made with laser machine. These laser burns are intended to cause abnormal blood vessels to shrink. Pharmacological therapy Anti-VEGF (vascular endothelial growth factor), such as Avastin and Lucentis , are injected inside the eye. VEGF are produced by ischemic tissue causing macular edema and new vessel formation Surgical therapy Vitrectomy is the surgical removal of the vitreous gel. It is performed to remove severe vitreous bleeding and other complications of DR.

24. Screening for DR. Symptoms in DR may not manifest until complications occur! Encourage all diabetic patients to undergo periodic eye evaluation! Treatment of established retinopathy may fail to prevent sight-loss.

25. When to screen? All Type II DM patients must be screened at the time of diagnosis. All Type I patients must be screened after 3 years of diagnosis of DM or at puberty. All diabetic females must be screened before conception.

26. Hypertensive retinopathy The retinal changes mirror the systemic circulation, and their severity correlates well with the development of the systemic complications of hypertension and with survival.

27. Hypertensive retinopathy… Retinal changes in hypertension Grade Features 1 . Generalized arteriolar narrowing 2 . Grade1 PLUS irregular points of focal constriction 3 . Grade 2 PLUS cotton wool spots, retinal hemorrhages, hard exudates 4 . Grade 3 plus optic disk swelling

28. Hypertensive retinopathy… Malignant hypertension is the clinical syndrome of an accelerated rise in blood pressure. It has a high mortality rate. In the retina, it is characterized by Grade 4 hypertensive retinopathy changes.

29. Hypertensive retinopathy Cotton-wool spots and macular star Disc edema Generalied Focal Arteriolar constriction Extravascular signs Flame-shaped retinal haemorrhages

30. Age-related macular degeneration (AMD) AMD is one of the most common causes of blindness AMD causes central vision loss. Peripheral vision, important for navigation, is retained. For this reason, sufferers are generally able to maintain an independent life style.

31. AMD… Classification of AMD ‘Dry’ AMD (non-neovascular AMD) : this is characterized by slowly progressive deterioration in visual function. ‘Wet’ AMD (neovascular AMD) : characterized by sudden loss of vision due to growth of new, abnormally located blood vessels underneath the retina, in the choroid, that leak fluid and blood.

32. Loss of central vision in AMD

33. Macular scar in dry AMD

34. New vessel formation leading to macular degeneration in wet AMD

35. Retinal detachment Retinal detachment (RD) means separation of the neurosensory retina from the RPE. Most cases of RD are rhegmatogenous, caused by a tear in the neurosensory retina, which allows fluid from the vitreous humor to pass through into the retinal space. The subretinal space is the potential space between the neurosensory retina and RPE.

36. Retinal tear leading to retinal detachment

37. RD… The three important predisposing factors to RRD are myopia , cataract surgery and eye trauma . The two important symptoms of RD are flashes and floaters . These symptoms are followed by loss of visual field. Loss of central vision occurs if the macula is detached. On ophthalmoscopy, the fundus appears gray (the red reflex is lost) Refer such pts immediately for surgical management of RD!