Anatomy for bn


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  • Lubrication, hydration, optical integration and defense mechanism
  • Symmetrical co-ordinated eye movement is governed by six extra ocular muscles
  • Limbal vein to episcleral vessels then drain to anterior ciliary vein.
  • Hyaloid artery system
  • Anatomy for bn

    1. 1. Anatomy of Eye GS Shrestha, M. Optom Teaching Assistant
    2. 2. Learning Objective <ul><li>Describe dimensions and gross anatomical structure of eye </li></ul><ul><li>Describe different coats of eye </li></ul><ul><li>Describe the spaces in eye </li></ul><ul><li>Describe the functions of eye </li></ul>
    3. 3. The Eyeball <ul><li>Eyeball is a cystic structure kept distended by the pressure inside it </li></ul><ul><li>It is not a spherical but consists of two modified spheres fused together. </li></ul><ul><ul><li>The anterior cornea of smaller radius(7.8mm) & </li></ul></ul><ul><ul><li>The posterior sclera (12mm) </li></ul></ul>
    4. 6. EOM
    5. 8. Dimensions of an adult eyeball/new born infant. <ul><ul><ul><ul><ul><li> ADULT INFANT </li></ul></ul></ul></ul></ul><ul><li>Antero-posterior diameter - 24mm 16.4 </li></ul><ul><li>Vertical diameter -23mm 16 </li></ul><ul><li>Lateral diameter -23.5mm 16.4 </li></ul><ul><li>Circumference -75mm </li></ul><ul><li>Volume -6.5ml </li></ul><ul><li>Weight -7gm </li></ul>
    6. 9. Three coat or tunica <ul><li>1 Outer fibrous layer of connective tissue (Cornea and sclera) </li></ul><ul><li>2. Middle vascular layer UVEA ( Iris , Ciliary body and choroid) </li></ul><ul><li>3. Inner neural layer (Retina) </li></ul>
    7. 10. Outer fibrous layer of connective tissue <ul><li>Anterior 1/6 th transparent- Cornea . </li></ul><ul><li>Posterior 5/6 th opaque- Sclera . </li></ul><ul><li>Junction of cornea & sclera – Limbus </li></ul><ul><li>Function </li></ul><ul><ul><li>Protection for structure within </li></ul></ul><ul><ul><li>maintain globe’s shape </li></ul></ul><ul><ul><li>Provide resistance to the pressure of the fluids inside </li></ul></ul><ul><ul><li>Transmittance of light from cornea to retina </li></ul></ul>
    8. 12. Middle vascular layer UVEA <ul><li>Iris , Ciliary body and choroid </li></ul><ul><li>Functions </li></ul><ul><ul><li>acts as diaphragm to regulate the amount of light </li></ul></ul><ul><ul><li>Control shape and diameter of pupil </li></ul></ul><ul><ul><li>Production of aqueous humour </li></ul></ul><ul><ul><li>Control accommodation of crystalline lens </li></ul></ul><ul><ul><li>Supply nutrient to outer layer of retina </li></ul></ul>
    9. 14. Inner neural layer <ul><li>Retina </li></ul><ul><li>Change light energy in to a visual signal for processing in brain via neural pathway </li></ul>
    10. 15. Cornea <ul><li>Cornea </li></ul><ul><ul><li>Corneal epithelium </li></ul></ul><ul><ul><li>Bowman’s layer </li></ul></ul><ul><ul><li>Stroma </li></ul></ul><ul><ul><li>Descemet’s membrane </li></ul></ul><ul><ul><li>Endothelium </li></ul></ul>
    11. 16. Sclera <ul><li>It opaque and porcelain white </li></ul><ul><li>Consists of indistinct 3 layers: outer episclera to inner layer scleral stroma </li></ul><ul><li>Thinnest 0.3mm at insertion of rectus muscles, thickest 1.0mm at post pole, 0.4-0.5mm at equator </li></ul>
    12. 18. Limbus <ul><li>Transition zone between peripheral cornea & anterior sclera </li></ul><ul><li>1.5mm-horizontal & 2mm at vertical meridian </li></ul><ul><li>Structures included </li></ul><ul><ul><li>Conjunctiva </li></ul></ul><ul><ul><li>Tenon’s capsule </li></ul></ul><ul><ul><li>Episclera </li></ul></ul><ul><ul><li>Corneoscleral stroma </li></ul></ul><ul><ul><li>Aqueous outflow apparatus </li></ul></ul>
    13. 19. Globe is covered behind the limbus by tenon’s fascia and above tenon is covered by bulbar conjunctiva
    14. 20. Iris <ul><li>A thin, circular structure located anterior to the lens </li></ul><ul><li>Central aperture is called PUPIL </li></ul><ul><li>Collarette: transition (land mark) to pupillary zone and Ciliary zone </li></ul><ul><li>Divide anterior chamber with posterior chamber </li></ul>
    15. 21. Iris <ul><li>Anterior limiting membrane </li></ul><ul><li>Stroma and spincter muscle </li></ul><ul><li>Anterior non-pigmented epithelium and dilator muscle </li></ul><ul><li>Posterior pigmented epithelium </li></ul>A. Pigment frill
    16. 22. Ciliary body <ul><li>Ring shaped structure </li></ul><ul><ul><li>Width 5.9mm nasal side 6.7mm on temporal side </li></ul></ul><ul><li>Extend from root of iris at scleral spur to ora serrata </li></ul><ul><ul><li>Divided in to two parts </li></ul></ul><ul><ul><ul><li>Pars plicata containing ciliary processes </li></ul></ul></ul><ul><ul><ul><li>Pars plana: a transition b/w pars plicata and ora serrata </li></ul></ul></ul>
    17. 24. Ciliary body <ul><li>1. Supraciliaris (supraciliary lamina) </li></ul><ul><li>2. Stroma of ciliary body </li></ul><ul><ul><li>Ciliary muscles </li></ul></ul><ul><ul><ul><li>Smooth muscle of longitudinal, radial and circular orientation </li></ul></ul></ul><ul><li>3. Outer pigmented ciliary epithelium </li></ul><ul><li>4. Inner non-pigmented ciliary epithelium </li></ul><ul><li>5. Internal limiting membrane </li></ul>
    18. 25. 1 2 3 4 5
    19. 26. Choroid <ul><li>Extend from ora serrata to optic disc </li></ul><ul><li>Primarily made up of blood vessels and covered both side by connective tissue </li></ul><ul><li>Layers </li></ul><ul><ul><li>Suprachoroidal Lamina </li></ul></ul><ul><ul><li>Choroidal stroma </li></ul></ul><ul><ul><li>Choriocapillaries </li></ul></ul><ul><ul><li>Bruch’s membrane </li></ul></ul>
    20. 27. Retina
    21. 28. Retina <ul><li>Inner most and transparent layer </li></ul><ul><li>Extend from optic disc to ora serrata </li></ul><ul><li>Two basic layers: pigment layer and neural layer </li></ul><ul><li>Function </li></ul><ul><ul><li>Transformation of light energy to neural signal by photoreceptor, bipolar cells and ganglion cells </li></ul></ul><ul><li>Its thickness at posterior pole in peripapillary region is approx 0.5mm, at equator 0.18-0.2mm & at ora serrata approx 0.1mm </li></ul>
    22. 30. Retina <ul><li>Retinal pigment epithelium </li></ul><ul><li>Photoreceptor layer </li></ul><ul><li>Outer limiting membrane </li></ul><ul><li>Outer nuclear layer </li></ul><ul><li>Outer plexiform layer </li></ul><ul><li>Inner nuclear layer </li></ul><ul><li>Inner plexiform layer </li></ul><ul><li>Ganglion cell layer </li></ul><ul><li>Nerve fibre layer </li></ul><ul><li>Internal limiting membrane </li></ul><ul><ul><li>Provide blood retinal barrier </li></ul></ul><ul><ul><li>Phagocytosis of dead and shedding photoreceptor </li></ul></ul><ul><ul><li>Metabolize and store vit A </li></ul></ul><ul><ul><li>Absorb light and reduce light scattering </li></ul></ul><ul><ul><li>Provide nutrition to photoreceptor </li></ul></ul>
    23. 32. Anterior chamber <ul><li>Bounded anteriorly by back of cornea & posteriorly by iris, lens in pupillary region & part of ciliary body. </li></ul><ul><li>3.0mm (2.5-4.4)deep in centre. </li></ul><ul><li>Contains 0.25ml of aqueous humour. </li></ul>
    24. 33. Posterior chamber <ul><li>Triangular space. </li></ul><ul><li>Boundary </li></ul><ul><ul><li>anteriorly by posterior surface of iris, part of ciliary body </li></ul></ul><ul><ul><li>posteriorly by anterior vitreous face </li></ul></ul><ul><ul><li>centrally by lens with its zonules </li></ul></ul>
    25. 34. Lens <ul><li>A transparent biconvex, crystalline structure between iris & vitreous in a saucer-shaped depression, the patellar fossa </li></ul><ul><li>It has anterior & posterior surface which meets at equator. </li></ul><ul><li> Birth Adult </li></ul><ul><li>Equatorial diameter 6.5mm 9-10mm </li></ul><ul><li>Thickness 3.5mm 5mm </li></ul><ul><li>Weight 90mg 255mg </li></ul><ul><li>Accommodative power 14-16D 1-2 D(50yrs) </li></ul><ul><li>Refractive index cortex: 1.39 nucleus: 1.41 </li></ul><ul><li>Refractive power 16-20 D </li></ul>
    26. 36. Lens <ul><li>Lens consists of </li></ul><ul><ul><li>-lens capsule </li></ul></ul><ul><ul><li>-anterior lens epithelium </li></ul></ul><ul><ul><li>-lens fibres </li></ul></ul><ul><li>Lens is hold in position by ciliary zonules, which extends from ciliary body to outer layer of lens capsule in equatorial zone. </li></ul>
    27. 38. Vitreous humour <ul><li>It is an inert, transparent, colourless, jellylike structure. </li></ul><ul><li>Vitreous cavity is bounded anteriorly by lens & ciliary body ; posteriorly by retina. </li></ul><ul><li>Space of berger </li></ul><ul><li>Wieger’s ligament </li></ul><ul><li>Weight-4gm </li></ul>
    28. 39. Vitreous humour <ul><li>Vitreous attached firmly to retina at 4 sites: </li></ul><ul><li>At ora serrata </li></ul><ul><li>At peripapillary region </li></ul><ul><li>At fovea </li></ul><ul><li>At retinal vasculatures. </li></ul>
    29. 40. Blood supply to eye <ul><li>Internal carotid artery </li></ul><ul><li>Central retinal artery </li></ul><ul><li>Lacrimal artery </li></ul><ul><li>Posterior ciliary artery </li></ul><ul><li>Long and short </li></ul><ul><li>Ethmoidal artery </li></ul><ul><li>Supraorbital artery </li></ul><ul><li>Muscular artery </li></ul><ul><li>Medial palpebral artery </li></ul><ul><li>Supratrochlear artery </li></ul><ul><li>Dorsonasal artery </li></ul><ul><li>External carotid artery </li></ul><ul><li>Facial artery </li></ul><ul><li>Superficial temporal artery </li></ul><ul><li>Maxillary artery </li></ul>
    30. 41. Blood supply
    31. 42. Blood supply
    32. 44. Vein <ul><li>Superior ophthalmic vein </li></ul><ul><li>Angular vein </li></ul><ul><li>Supraorbital vein </li></ul><ul><li>Ethmoidal vein </li></ul><ul><li>Muscular vein </li></ul><ul><li>Lacrimal vein </li></ul><ul><li>Anterior ciliary vein </li></ul><ul><li>Central retinal vein </li></ul><ul><li>Upper vortex vein </li></ul><ul><li>Inferior ophthalmic vein </li></ul><ul><li>lower eyelids, </li></ul><ul><li>lateral muscles, </li></ul><ul><li>inferior conjunctiva, </li></ul><ul><li>lacrimal sac, </li></ul><ul><li>lower vortex veins </li></ul><ul><li>pterygoid venous plexus </li></ul>
    33. 45. Nerve supply <ul><li>Cranina nerves II, III, IV, V, VI, VII </li></ul><ul><li>Optic nerve-visual signal and afferent fibers </li></ul><ul><li>Oculomotor nerves to extraocular muscles </li></ul><ul><li>Trochlear nerve to superior oblique muscle </li></ul><ul><li>Trigeminal nerves </li></ul><ul><ul><li>Ophthalmic (lacrimal, frontal and nasociliary nerves) </li></ul></ul><ul><ul><li>maxillary division </li></ul></ul><ul><li>Abducent nerve </li></ul><ul><li>Facial nerve (secretomotor fibres) </li></ul>
    34. 46. <ul><li>THANK YOU </li></ul>