Eyeball anatomy

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  • Eyeball anatomy

    1. 1. MOB TCD Eyeball Professor Emeritus Moira O’Brien FRCPI, FFSEM, FFSEM (UK), FTCD Trinity College Dublin
    2. 2. MOB TCD Eyeball • Surrounded by Tenon’s fascia • Attached to corneoscleral junction • Dura on optic nerve • Check ligaments • Suspensory ligament of Lockwood • Cone of muscles • Fat
    3. 3. MOB TCD Eyeball • • • • • Consists of three coats Outer layer Sclera and cornea Choroid Retina
    4. 4. MOB TCD Cornea • • • • • Transparent Avascular Forms anterior 1/6 Smaller sphere than sclera Depression at corneoscleral junction
    5. 5. MOB TCD Five Layers of Cornea 1. Corneal epithelium 2. Bowman’s or anterior limiting membrane 3. Substantia propria 4. Descement’s or posterior limiting membrane 5. Endothelium
    6. 6. MOB TCD Cornea • 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. 7. MOB TCD Iridiocorneal 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. 8. MOB TCD Cornea • • • • • 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. 9. MOB TCD Sclera • • • • 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. 10. MOB TCD Suprachoroid Space • Long ciliary nerves • Long posterior ciliary arteries going to iris
    11. 11. MOB TCD Choroid • • • • Choroid proper Ciliary body Iris Vascular layer in posterior part • Equator of eyeball • Uveal tract or iridocyclitis
    12. 12. MOB TCD Choroid • • • • • Outer limiting membrane Veins Arteries Capillaries Inner limiting membrane of bruch • Attached to pigmented layer of retina
    13. 13. MOB TCD Ciliary Body • • • • Triangular Apex posterior Short base anterior Deep surface thrown into folds called the ciliary processes • Ciliary body is vascular, pigmented
    14. 14. MOB TCD Ciliary 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. 15. MOB TCD Ciliary 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. 16. MOB TCD Accommodation 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. 17. MOB TCD Iris
    18. 18. MOB TCD Iris • 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. 19. MOB TCD Iris • Circular sphincter pupillae • Oculomotor • Behind lies radial or dilator pupillae • Sympathetic T1 develop from ectoderm
    20. 20. MOB TCD Aqueous 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. 21. MOB TCD Posterior Chamber • Bounded posteriorly by suspensory ligament of lens and lens • Peripherally by ciliary processes • Anteriorly by iris
    22. 22. MOB TCD Anterior Chamber Anterior Chamber • Bounded posteriorly by iris and pupil • Anteriorly by cornea • Peripherally by spaces of fontana or iridio-corneal angle
    23. 23. MOB TCD Retina • • • • • • • Nervous layer Superficial to deep Pigment cells Rods and cones Bipolar cells Ganglion cells Axons of the ganglion cells form optic nerve
    24. 24. MOB TCD Rods • 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. 25. MOB TCD Cones • • • • 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. 26. MOB TCD Blood 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. 27. MOB TCD Optic Disc
    28. 28. MOB TCD Diabetic Hypertensive
    29. 29. MOB TCD Detached Retina • Outer layer of optic cup • Pigmented layer • Inner layer rods and cones • Removed from their blood supply
    30. 30. MOB TCD Refractive Media • Cornea • Aqueous humour of anterior and posterior chamber • Lens • Vitreous body
    31. 31. MOB TCD Refractive Media • Greatest refraction of light • Takes place at the surface of the cornea • Very little refraction after cornea
    32. 32. MOB TCD Lens • • • • • Crystalline Translucent Avascular structure Lies in hyloid fossa Posterior surface is highly convex • Does not alter its shape
    33. 33. MOB TCD Lens • Suspensory ligament is attached to periphery of the lens • Cataract opaque lens • Nutrition from aqueous humour
    34. 34. MOB TCD Lens • Supplied by hyloid • Artery during development • Hyloid artery regresses remains as the hyloid canal • May persist, result a form of blindness
    35. 35. MOB TCD Vitreous Body • • • • • Semiliquid Translucent Avascular gel Enclosed in hyloid membrane Opacities may develop in elderly
    36. 36. MOB TCD Subconjunctival Haemorrhage
    37. 37. “BMJ Publishing Group Limited (“BMJ Group”) 2012. All rights reserved.”

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