Retina 1 Lecture Notes PDF

 2 Retina 1: Retinal Vascular Occlusions What should I know after this 3 By the end of this lecture, you should be able to: Recall the relevant anatomy and physiology with respect to retin...

 2 Retina 1: Retinal Vascular Occlusions What should I know after this 3 By the end of this lecture, you should be able to: Recall the relevant anatomy and physiology with respect to retinal vasculature. Describe the aetiology, pathogenesis, symptoms, signs, management in primary care, management in secondary care, and sequalae of the following conditions: Central Retinal Artery Occlusions Branch Retinal Artery Occlusions Central Retinal Vein Occlusions Branch retinal Vein Occlusions Differentially diagnose the above conditions from a range of other conditions, which will have similar presentation. Design a management plan for a patient presenting with any of the above conditions. Differentiate between a non-ischaemic and ischaemic retinal vein occlusions. Conditions we will cover 4 Retinal Venous Occlusive Disease Central Retinal Vein Occlusions Ischaemic Non-Ischaemic Branch Retinal Vein Occlusions Hemiretinal Vein Occlusions Retinal Arterial Occlusive Disease Central Retinal Artery Occlusions Branch Retinal Artery Occlusions Amaurosis Fugax Ocular Ischaemic Syndrome (Next lecture) Why do I need to know this? 5 Leading Causes of Death Globally (WHO, 2020) Why do I need to know this? Retinal artery occlusion is associated with an increased risk of cardiovascular events. Its aetiology is an embolism from the carotid artery/aortic arch/heart breaking off and traveling to occlude either the central retinal artery or its branches. This is essentially the ocular equivalent of a cerebral infarction. Retinal artery occlusions have a similar aetiology to an ischaemic stroke (85-87% of all strokes). Amaurosis Fugax is both a warning sign of an impending stroke and an opportunity to prevent it. Retinal Vein occlusions are a major cause of sight loss - second most common sight threatening vascular disorder.  7 Recap Structure of 8 Arteries, Veins & capillaries Occlusive lesions vs. Shock 9 Occlusive lesions: These result in partial or complete blockage of a blood vessel which impedes blood flow. Haemodynamic shock: This occurs when the cardiovascular system is unable to deliver sufficient oxygen and nutrients for the body’s metabolic demands. This is a state of circulatory collapse. 10 Pathogenesis of atherosclerosis 11 Recall: Haemodynamic Occlusion 12 Occlusive lesions partially or completely block a blood vessel leading to reduced blood flow. Causes include: Atherosclerosis: Build-up of plaques in arterial walls Thrombosis: Formation of blood clots within vessels Embolism: Movement of a clot or debris to a distant site which then results in a vessel blockage. This ultimately leads to ischaemia and hypoxia Recall: Ischaemia and Hypoxia 13 Ischaemia: Insufficient blood supply/perfusion resulting in the deprivation of vital nutrients (particularly oxygen). Infarction: death (necrosis) of tissue because of ischemia. Hypoxia: Insufficient oxygen to tissues to maintain adequate homeostasis. Angiogenesis: Growth of new vessels Vascular lesions 14 causing Ischaemia  Recall: 15 Retinal Vascular Disease Occlusion of capillaries Leakage from (resulting in capillaries or ischaemia) microaneurysms Intraretinal Cotton wool Irregular microvascular New vessels spots retinal veins Exudates Oedema Haemorrhages anomalies  16 Recap: Ocular Blood Supply  Central 17 Retinal Artery Ophthalmic artery Internal carotid artery Common carotid artery https://www.sciencedirect.com/science/article/pii/S1350946220300203  Common Carotid Artery Recall: Ocular 18 Blood Supply Internal Carotid Artery Ophthalmic Artery Brian Mac Grory. Stroke. Thrombolytic Therapy for Acute Central Retinal Artery Occlusion, Volume: 51, Issue: 2, Pages: 687-695, DOI: (10.1161/STROKEAHA.119.027478) Posterior Ciliary Arteries Retinal Artery Muscular arteries Anterior retinal layers Extraocular muscles Anterior Optic nerve Choroid Posterior retinal layers Anterior Ciliary Arteries Iris Ciliary Body Retinal Blood supply 19 Inner retinal layers (NFL  INL) Supplied by Central retinal artery Drainage: Central retinal vein Outer Retinal Layers (OPL RPE) Supplied by choriocapillaris (via the posterior ciliary arteries) Drainage: Vortex veins Cilioretinal artery 20 15-30% of population has a cilioretinal artery (branch of the short posterior ciliary artery). Supplies blood to part or all of the fovea. Conditions we will cover 21 Retinal Venous Occlusive Disease Central Retinal Vein Occlusions Ischaemic Non-Ischaemic Branch Retinal Vein Occlusions Hemiretinal Vein Occlusions Retinal Arterial Occlusive Disease Central Retinal Artery Occlusions Branch Retinal Artery Occlusions Amaurosis Fugax  22 Retinal Vein Occlusions (RVO) Retinal Vein Occlusions: Introduction 23 A retinal vein occlusion occurs when thrombus (blood clot) formation obstructs the retinal venous system. This is mostly due to atherosclerotic hardening of an overlying artery, which then compresses the vein that sits under it. Retinal Vein Occlusions are the second most common retinal vascular disease after diabetic retinopathy. Affecting 0.77% of population over 30 years old. Retinal Vein Occlusions: Introduction 24 Types of Retinal Vein Occlusions Central retinal vein occlusions (CRVO) Branch retinal vein occlusions (BRVO) Hemi-retinal Vein occlusion (HRVO) Classification of Retinal vein occlusions Ischaemic Non-Ischaemic Risk factors 25 - Age (60- 70 years old) - Diabetes - Hypertension - Hyperlipidaemia - Blood disorders- high plasma viscosity, raised cell counts, and thrombophilic abnormalities. - Systemic inflammatory disorders (ie/ Bechet's disease, systemic lupus, polyarteritis nodosa, sarcoidosis, Wegener’s granulomatosis, and Goodpasture’s syndrome). - Oral contraceptive pill (most common underlying association when this occurs in younger females) - Glaucoma - Short axial length - Retrobulbar compression Aetiology 26 Why does it happen: Thrombus (blood clot) How does the thrombus develop: 1. Arteriosclerosis of the artery which compresses the underlying vein. 2. Inflammation of the blood vessel. 3. High Blood viscosity. 4. Coagulation disorders 5. Others RVO: Aetiology 27 The central retinal vein and central retinal artery share a common adventitial sheath posterior to the lamina cribrosa and at arteriovenous crossings. In a CRVO, the central retinal artery thickens due to atherosclerotic changes. This compresses the underlying central retinal vein, leading to thrombosis in the central retinal vein, as it passes the lamina cribrosa. In a BRVO, the arteriosclerotic thickening of a branch retinal artery (which shares a common adventitial sheath with the branch retinal vein at crossing points) compresses the underlying vein causing venous thrombosis resulting in a BRVO. https://morancore.utah.edu/section-04-ophthalmic- pathology/retina/#central_retinal_vein_occlusion_crvo https://encyclopedia.pub/entry/7594  Pathogenesis 29 Increase in venous and Loss of Atherosclerosis Compression of capillary endothelial cell Leakage of blood Capillaries shut Possible of overlying the underlying Hypoxia pressure + integrity & constituents. down. Ischaemia. artery. vein. stagnation of release of VEGF. blood flow. Complications of RVO's 30 1. Macular Oedema: Thrombosis leads to increased retinal capillary pressure which leads to increased permeability and leakage from capillaries resulting in macular oedema. Furthermore, VEGF that is produced because of ischaemia causes further retinal capillary permeability and leakage. 2. Retinal Ischaemia: Non-perfusion of the capillaries causes retinal ischaemia. The production of VEGF and other cytokines, promote new vessel growth. These new vessels can grow on the iris and angle (resulting in neovascular glaucoma) or in the retina (resulting in vitreous haemorrhages and tractional EyeRounds.org retinal detachments).  31 Central Retinal Vein Occlusion Thrombosis of the Central Retinal Vein when it passes through the lamina cribrosa What does it look like? 32 - Extensive flame haemorrhages - Blot and dot haemorrhages - Disc oedema - Tortuous dilated veins in all 4 quadrants - Other possibilities: o Cotton wool spots o Macular oedema Classification 33 CRVO's can broadly be classified into: 1.Non-Ischaemic Central Retinal Vein Occlusions 2. Ischaemic Central Retinal Vein Occlusions Non-Ischaemic CRVO: Presentation 34 VA ≥6/30 Mild or absent RAPD Rare to have a visual field defect Mild tortuosity and dilation of central retinal vein Haemorrhages (dot/blot and flame) Mild optic disc oedema and hyperaemia Mild retinal and macular oedema Signs present in all 4 quadrants Ischaemic CRVO: Presentation 35 Severe vision loss VA 5DD of non-perfusion). BRVO: Management by Optometrist 48 Optometrists should carry out VA check, fundus photography, OCT, and IOP checks. The patient should be urgently referred to ophthalmology (no more than 2-4 weeks from presentation) and should be referred to the GP urgently for systemic investigation. Investigation by Optometrist 49 History and symptoms: Ask about history of systemic disease (ie/HTN or diabetes) Visual acuity measurement, observe pupil responses, IOP measurements, and gonioscopy (is ischaemia is suspected). Dilated fundus examination- use a 60- or 90- D lens. Ensure that you look for possible neovascularization that may have developed. OCT: for diagnosis, monitoring and determining response to treatment in patients with macular oedema secondary to a retinal vein occlusion. Investigation 50 FFA and OCT-A: These are useful to assess retinal non-perfusion to identify ischaemic RVOs. OCT angiography (OCT-A)- This has largely replaced FFA. FFA- Useful when uncertainty in diagnosis, when VA9-12 months 50% may develop neovascularization within 2-4 months New vessels at disc: Rubeosis Irides (90/100 day glaucoma) New vessels everywhere: Can lead to haemorrhages, secondary traction and Retinal detachments. Conditions we will cover 55  Retinal Venous Occlusive Disease  Central Retinal Vein Occlusions  Ischaemic  Non-Ischaemic  Branch Retinal Vein Occlusions  Hemiretinal Vein Occlusions Retinal Arterial Occlusive Disease Central Retinal Artery Occlusions Branch Retinal Artery Occlusions Amaurosis Fugax  56 Retinal Artery Occlusions Retinal Artery Occlusions: Introduction 57 A retinal artery occlusion occurs because of a blockage to the central retinal artery. This results in retinal hypoperfusion and rapidly progressive cellular damage and thus vision loss. This is an ophthalmic emergency. Prompt diagnosis and treatment is required to dislodge the embolus causing the blockage is necessary. It can be classified largely into: - Central Retinal Artery Occlusion (CRAO) - Branch Retinal Artery Occlusion (BRAO)  Common Carotid Artery Recall: Ocular 58 Blood Supply Internal Carotid Artery Ophthalmic Artery Brian Mac Grory. Stroke. Thrombolytic Therapy for Acute Central Retinal Artery Occlusion, Volume: 51, Issue: 2, Pages: 687-695, DOI: (10.1161/STROKEAHA.119.027478) Posterior Ciliary Arteries Central Retinal Artery Anterior Optic nerve Choroid Anterior retinal layers Posterior retinal layers Aetiology 59 Most retinal artery occlusions are due to atherosclerosis-related embolisms and thrombosis (blood clots). Other less frequent causes: GCA, trauma, collagen vascular disease, hypercoagulable states, vasospasm (i.e./migraines), Behcet’s disease, syphilis, and sickle cell disease. Aetiology 60 Cause: Embolus Types: - Calcium- usually arise from cardiac valves, white single emboli, usually found closer to the optic nerve head - Cholesterol (Hollenhorst plaque)- bright, refractile, yellow/orange plaques seen at bifurcations. Arise from ulcerated atheromas (plaques). - Platelet-fibrin- Usually arise from atheromas (plaques) in the carotid arteries, dull white colour.  61 Central Retinal Artery Occlusion (CRAO)  CRAO: Introduction 62 A central retinal artery occlusion (CRAO) is an occlusion of the central retinal artery at the level of the lamina cribrosa (or just behind). This occlusion results in a retinal hypoperfusion and thus retinal cellular damage and vision loss. This is an ophthalmic emergency Image source: https://www.ahajournals.org/doi/10.1161/SVIN.123.000977 CRAO: Epidemiology 63 Rare Incidence: 1-2 in 100,000 per year Mean age ~ 60-65 years