eyeball anatomy

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  • 1.MOB TCDEyeball Professor Emeritus Moira OBrien FRCPI, FFSEM, FFSEM (UK), FTCD Trinity College Dublin

2. MOB TCDEyeball Surrounded by Tenons fascia Attached to corneoscleral junction Dura on optic nerve Check ligaments Suspensory ligament of Lockwood Cone of muscles Fat 3. MOB TCDEyeball Consists of three coats Outer layer Sclera and cornea Choroid Retina 4. MOB TCDCornea Transparent Avascular Forms anterior 1/6 Smaller sphere than sclera Depression at corneoscleral junction 5. MOB TCDFive Layers of Cornea 1. Corneal epithelium 2. Bowmans or anterior limiting membrane 3. Substantia propria 4. Descements or posterior limiting membrane 5. Endothelium 6. MOB TCDCornea Posterior limiting membrane breaks up at the edges to form pectinate ligament of iris Spaces are called the spaces of the iridiocorneal angle (fontana) 7. MOB TCDIridiocorneal Angle If the iridiocorneal angle is narrowed Reabsorption of aqueous humour into venous sinus of sclera is blocked Causing glaucoma Blindness increased intraocular pressure 8. MOB TCDCornea Cornea is avascular Surface must be moist Rheumatoid dry Not wearing safety goggles Scarring of cornea results in blindness in that portion of the cornea Trachoma, new vessel formation in the cornea Transplants 9. MOB TCDSclera Posterior 5/6 Opaque Insertion muscles Vena vorticosae pierce at equator Optic nerve 2.3 mm medial to axis, the lamina cribrosa Central artery of retina Long and short cilary vessels and nerves 10. MOB TCDSuprachoroid Space Long ciliary nerves Long posterior ciliary arteries going to iris 11. MOB TCDChoroid Choroid proper Ciliary body Iris Vascular layer in posterior part Equator of eyeball Uveal tract or iridocyclitis 12. MOB TCDChoroid Outer limiting membrane Veins Arteries Capillaries Inner limiting membrane of bruch Attached to pigmented layer of retina 13. MOB TCDCiliary Body Triangular Apex posterior Short base anterior Deep surface thrown into folds called the ciliary processes Ciliary body is vascular, pigmented 14. MOB TCDCiliary Zonule Suspensory ligament of lens is attached to the cilary processes The portion of the suspensory ligament closest to the ciliary Processes is called the ciliary zonule 15. MOB TCDCiliary Muscles Smooth muscle Radial is attached to scleral spur Circular within anterior part of radial muscle Parasympathetic oculomotor 3rd nerve Relays in ciliary ganglion 16. MOB TCDAccommodation Reflex Contraction of ciliary muscles Ciliary processes pulled anteriorly Relaxes suspensory ligament of lens Elasticity of lens It becomes more convex Pupils constrict Medial rectus contracts 17. MOB TCDIris 18. MOB TCDIris Cone shaped diaphragm Halfway along anterior of base of choroid Central aperture pupil Vascular pigmented Amount pigment colour Blood vessels long posterior, anterior cilary arteries; two circles 19. MOB TCDIris Circular sphincter pupillae Oculomotor Behind lies radial or dilator pupillae Sympathetic T1 develop from ectoderm 20. MOB TCDAqueous Humour Aqueous humour is secreted by ciliary processes into posterior chamber Through the pupil into anterior chamber Spaces of fontana into venous sinus of sclera or canal of Schlemn 21. MOB TCDPosterior Chamber Bounded posteriorly by suspensory ligament of lens and lens Peripherally by ciliary processes Anteriorly by iris 22. MOB TCDAnterior Chamber Anterior Chamber Bounded posteriorly by iris and pupil Anteriorly by cornea Peripherally by spaces of fontana or iridio-corneal angle 23. MOB TCDRetina Nervous layer Superficial to deep Pigment cells Rods and cones Bipolar cells Ganglion cells Axons of the ganglion cells form optic nerve 24. MOB TCDRods Rods are found at peripheral portion of the retina 70 rods connected to one bipolar cell Peripheral vision Visual purple sees back and white 25. MOB TCDCones Cones see colour Photoreceptors One cone to one bipolar cell Found in fovea or macula lutea Directly behind axis No nerve fibres or vessels in front 26. MOB TCDBlood Supply of Retina Rods and cones supplied by capillaries of choroid by diffusion Bipolar and ganglion cells supplied by central artery of the retina Enters through optic disc, blind spot 27. MOB TCDOptic Disc 28. MOB TCDDiabetic Hypertensive 29. MOB TCDDetached Retina Outer layer of optic cup Pigmented layer Inner layer rods and cones Removed from their blood supply 30. MOB TCDRefractive Media Cornea Aqueous humour of anterior and posterior chamber Lens Vitreous body 31. MOB TCDRefractive Media Greatest refraction of light Takes place at the surface of the cornea Very little refraction after cornea 32. MOB TCDLens Crystalline Translucent Avascular structure Lies in hyloid fossa Posterior surface is highly convex Does not alter its shape 33. MOB TCDLens Suspensory ligament is attached to periphery of the lens Cataract opaque lens Nutrition from aqueous humour 34. MOB TCDLens Supplied by hyloid Artery during development Hyloid artery regresses remains as the hyloid canal May persist, result a form of blindness 35. MOB TCDVitreous Body Semiliquid Translucent Avascular gel Enclosed in hyloid membrane Opacities may develop in elderly 36. MOB TCDSubconjunctival Haemorrhage 37. BMJ Publishing Group Limited (BMJ Group) 2012. All rights reserved.