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Anatomy of the eyeball An overviews.pptx
- 1. Anatomy of Eye:an overview MUSHAHID RAZA M.OPTOM
- 2. Anatomy ofthe Eye 1. The Eyeball 2. Ocular Adnexa
- 3. THE EYEBALL Theeyeball is a cystic structure situated in the orbit. Eyeball is not a sphere but an OBLATE SPHEROID OBLATE SPHEROID: it is slightly flattened at the poles and wider at the equator. Connected to the brain by the optic nerve. protected by bony orbit and eyelids.
- 4. Dimensions ofan adult eyeball Anteroposterior diameter 24 mm Horizontal diameter 24 mm Vertical diameter 23 mm Circumference 75 mm Volume 6.5 mm Weight 7 gm Corneal diameter ~ 11-12 mm Lens diameter ~ 9-10 mm Vitreous chamber depth ~ 16-17 mm
- 5. Poles andequator of the eyeball – Poles Anterior pole and posterior pole Equator Geometric equator Anatomical Equator
- 6. COATS OF THEEYEBALL 1. Fibrous coat 2. Vascular coat( Uveal tissue) 3. Nervous coat (Retina)
- 8. 1. Fibrous Coat Its dense strong wall which protects the intraocular contents. Anterior 1/6th of the fibrous coat is transparent & its called cornea. Posterior 5/6th opaque part is called Sclera.
- 9. CORNEA Transparent, avascular, watch-glasslike structure covering anterior one sixth part of the outer coat of the eyeball. Anterior surface of the cornea is elliptical and posterior surface of the cornea is circular. Dimensions Horizontal diameter 11.75 mm Vertical diameter 11 mm Thickness 0.52 mm at centre, 0.67 mm periphery Refractive power + 43 to +45 D Refractive index 1.37
- 10. Layers ofthe cornea 1. Epithelium 2. Bowman`s layer 3. Stroma 4. Descemet layer 5. Endothelium layer
- 11. SCLERA Whitish partthat covers posterior 5/6 of the outer surface of the eyeball. Anteriorly ends at the limbus. Limbus- junction between the cornea and sclera. Its outer surface is covered by tenon`s capsule and by bulbar conjunctiva on the anterior part. Posteriorly forms lamina cribrosa for optic nerve. Provides attachment to the extra ocular muscles. Protective coat.
- 12. Vascular Coat( UvealTissue) Its middle layer of the eyeball lying between the fibrous coat(cornea & sclera) and nervous coat(retina). Rich in blood vessels, it supplies nutrients and oxygen to the eye. Parts:- 1. Iris 2. Ciliary body 3. Choroid
- 13. IRIS The irisis the coloured part of the eyeball. Location-Lies between the cornea and the crystalline lens, in front of the ciliary body. Shape – thin circular disc with a central opening is called pupil ( 4mm). Functions- controls the amount of the light entering into the eye by adjusting the pupil size. At periphery attaches to anterior surface of ciliary body.
- 14. Iris consist fourlayer- 1. Anterior limiting layer 2. Iris stroma 3. Anterior epithelial layer 4. Posterior pigmented epithelial layer
- 15. Ciliary body Middlelayer triangular shape of the uvea. Location- between the iris ( anteriorly) and choroid (posteriorly). Forward continuation of the choroid. Aqueous humour formation and drainage. Helps in in accommodation Supports in lens via suspensory ligaments.
- 16. Ciliary body consist5 layers- 1. Supraciliary lamina 2. Stroma of the ciliary body 3. Layer of pigmented epithelium 4. Layer of non-pigmented layer 5. Internal limiting layer
- 17. CHOROID Posterior partof the vascular coat of the eyeball. Provide nutrients and oxygen to the outer layers of the retina. Colour- dark brown (contains melanocytes). Consist of layer of blood vessels. Choroid consist 4 layer- 1. Suprachoroidal lamina 2. Stroma of the choroid 3. Choriocapillaris 4. Basal lamina
- 18. Nervous coat RETINA: Innermostlayer of the eyeball. Thin, delicate and transparent layer is in contact with choroid. Extend from the optic disc to ora serrata. Colour- purplish red due to visual purple of the rods. Surface area- 266 mm2 thickness – at periphery – 0.56 mm at equator - 0.2 mm at the ora serrata 0.1mm
- 19. REGIONS- 1. Opticdisc 2. Macula lutea 3. Peripheral retina
- 20. Segments of theeyeball The eyeball is divided into 2 segments. 1. ANTERIOR SEGMENT Location- in front of the lens Structure anterior to the lens and ciliary body. Anterior segment has two component- A. Anterior chamber- Between the cornea and iris, filled with aqueous humour. About 2.5 mm in depth, and contains 2.5 ml of AH B. Between the iris and lens, also filled with AH.
- 21. Posterior segment Location-behind the lens- posterior to lens include retina, choroid, optic disc. Filled with gel like vitreous humour- largest part of the eyeball.
- 22. Crystalline lens Biconvex Suspended behind iris by zonules Transparent, avascular, no nerves Grows through the life Structure- capsule, epithelium, cortex, nucleus. Thickness- ~ 4 mm Diameter- ~9-10 mm Anterior radius of curvature- 10 mm, posterior curvature- 6 mm Refractive power- 15-17 D Refractive index- 1.39
- 23. Ocular adnexa Theadnexa are the accessory structures surrounding the eyeball, which support and protect it. They do not form part of the eyeball itself but are essential for proper eye function. Included structures that helps in protection, movement, lubricants and overall ocular health. A. The bony orbit B. Eyelids C. Conjunctiva D. Lacrimal apparatus E. Extraocular muscles
- 24. The bonyorbit It is bony cavity in the skull that contains and protects the eyeball. Houses muscles, nerves, vessels and fat ( orbital fat – cushions the eye & allows smooth eye movement).
- 25. The Eyelids Theeyelids mobile structure that protects the eyes, spread tears, and keep the ocular surface moist. Acts like a curtains, protects against injury, excessive light & has tear producing glands. Layers of eyelids 1. Skin 2. Subcutaneous areolar tissue 3. Submuscular areolar tissue 4. Fibrous tissue 5. Non striated muscles 6. Conjunctiva
- 26. Conjunctiva Thin, translucentmucous membrane which lines posterior surface of the eyelids and anterior surface of the sclera except the cornea. Non keratinized squamous epithelium, has goblet cells and highly vascularized. Parts of the conjunctiva 1. Palpebral conjunctiva – firm adherent 2. Bulbar conjunctiva –loosely attached to underlaying sclera allows eye to move inserts at the limbus. 3. Conjunctival fornix – in the forensics
- 27. Lacrimal apparatus Thelacrimal apertures are the small openings on the eyelids through which tears drain from the eye into the lacrimal drainage. Location- there are two lacrimal apertures- puncta Upper lacrimal punctum – on the upper eyelid Lower lacrimal punctum – on the lower eyelid Both are located at the medial canthus(near the nose) specifically on a small elevation called the lacrimal papilla. Appearance & size Tiny pin point holes, diameter is about 0.2-0.3 mm
- 29. Extraocular muscles theextraocular muscles are the six muscles responsible foe eye movements. They are located outside the eyeball and control its precise movements. Classification Rectus Muscles Medial rectus Inferior rectus Lateral rectus Superior rectus Oblique Muscles Superior oblique muscles Inferior oblique muscles