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Eye Introduction and its parts
- 1. EYE BASICS
- 2. EYE • Structure Of Eye • Sclera & cornea • Crystalline lens (eyelens) • Retina • Iris • Pupil • Eyelid • Accessory Structures of the Eye • Eyelids • eyelashes, • Eyebrows • the lacrimal (tear-producing) apparatus • Extrinsic eye muscles.
- 6. Layers Of Eye • Sclera : – The white, opaque cover – Covers 80% of the eye’s outer layer, – Contains thick elastic collagen, – Provides protection. – Blocks extraneous light • cornea : – Transparent, avascular, refracting window] – significant protection to mechanical trauma • Uveal tract – Iris – Ciliary body – Choroid • Retina : contains rod cells and cone cells
- 7. Choroid • The posterior segment of the uvea, between the sclera and the retina. • Reach in blood supply, supplies oxygen and nutrition to the outer two thirds of the retina. • Bruch’s membrane – Internal elastic membrane
- 8. Ciliary body • Pars plana – flat area continuous with the retina • Pars plicata – • contains the ciliary • processes that secretes the aqueous humor • Ciliary muscle runs circularly around the eye and controls accommodation
- 9. Lens • Biconvex, avascular, transparent structure. • Suspends behind the iris by the zonules which are connected to the ciliary body. • Responsible for 1/3rd of the refracting power of the eye.
- 10. The Retina • The innermost layer of the eye, • Composed of nerve tissue which senses the light entering the eye.
- 11. Rods and cones Cones Concentrated in the fovea Most active in daylight Central vision Rods Mostly in the peripheral retina Most active in night vision Peripheral vision
- 12. Optic nerve • Consists of 1 million axons that arise from the retina. • Leaves the eye through the sclera – optic canal – into the cranium.
- 14. Aqueous humor and Vitreous humor • The Aqueous Humor is the clear liquid between the cornea and the lens. It has the benefit of being fairly homogenous and, as a result, the optical properties are easily measured. (Le Grand, 1967) • The space that it inhabits is called the anterior chamber. • The Vitreous Humor is the clear gel between the lens and the retina. • The space that it fills is called the vitreous body.
- 15. Posterior Chamber: Contains Vitreous Humor Anterior Chamber: Contains Aqueous Humor
- 16. Aqueous humor • Produced by the ciliary body. • Serves to nourish ocular structures.
- 17. EYE Disorders And Their Treatments • Glaucoma • Dry Eye • Diabetic Retinopathy • ARMD • Ocular Hypertension
- 18. •“Glaucoma is an optic neuropathy with characteristic structural damage to the optic nerve, associated with progressive retinal ganglion cell death, loss of nerve fibres and visual field loss” Group of eye diseases, which has three common features • Elevated IOP (Intra Ocular Pressure) • Characteristic enlargement of optic cup • Optic nerve damage that produces visual field defects Glaucoma
- 19. • Closing of angle or blockage of Trabecular meshwork. • Aqueous humor accumulation within the eye. • Intra Ocular Pressure (IOP) increases • Impairment of vision results from pressure induced degenerative changes. – In the retina – Optic nerve head – Corneal - edema and opacification Pathology of Glaucoma
- 20. Glaucoma: Optic Nerve Damage Elevated IOP Mechanical back pressure On the junction of optic nerve/retina Reduce the blood supply to the optic nerve Loss of blood supply Ischaemia Retinal Ganglion cell loss
- 21. Glaucoma: Treatment Goal LOWER IOP VASOPROTECTION/ NEUROOPROTECTION PERSISTENCY/COMPLIANCE The goal of glaucoma treatment is to preserve the visual field of patients and prevent the loss of visual function that is associated with the disease.”
- 22. Reduction of formation of Aqueous humour Beta blockers Eg : TIMOLOL Carbonic anhydrase inhibitors Eg: Acetazolamide, brinzolamide , dorzolamide Increases outflow of Aqueous humour Parasympathetics Eg : Pilocarpine Prostaglandin Analogues Eg : Latanoprost /Bimatoprost Dual action Sympathomimetics Eg : Brimonidine Dipivefrine Antiglaucoma Agents
- 23. Eye Dry eye is a disease of the ocular surface attributable to different disturbances of the natural function and protective mechanisms of the external eye, leading to an unstable tear film during the open eye state. Main glands involved in tear formation and in nourishment of eye are: • Lacrimal gland • Meibomian gland
- 24. Lacrimal gland Meibomian gland Function tear production & drainage Responsible for supply of sebum Components and location Lacrimal gland Excretory ducts Lacrimal canaliculi, Sac, and Nasolacrimal duct 50 glands on upper eyelids 25 glands on lower eyelids Function • Nourishing – surface • Eliminating invading debris • Immune functions. •prevents evaporation of eye's tear film •prevents tear spillage onto cheek •Makes closed lids airtight Dry eye occurs due to unstable tear film Meibomian Gland Dysfunction
- 26. Symptoms • Irritation • Redness • Burning/ Stinging • Itchy eyes • Sandy- gritty feeling (foreign body sensation) • Blurred vision • Tearing • Contact lens intolerance. • Increased frequency of blinking • Mucous discharge. • Photophobia (less frequent symptom) • Symptoms worsen in windy or air-conditioned environments. – As day progresses. – After prolonged reading, working on computers Supl P&T Digest 2003, 28(12), 1-45
- 27. Management of Dry Eye Treatment Cyto Protection Eg : Lubricants Tear replacement Eg : Artificial tears Tear Preservation Eg : Punctal Plugs
- 28. ARMD • The macula lutea is the small, yellowish central portion of the retina, and it is the area providing the clearest, most distinct vision • Vision this acute may be due to there being more cones per square millimeter of the macula than in the average eye, enabling that eye to distinguish much greater detail.
- 29. Macular Degeneration • “macular degeneration,” a hereditary ocular disease. • ARMD) is the leading cause of irreversible blindness among 65 and older. • “Dry” macular degeneration generally is caused by a thinning of the macula’s layers, and vision loss typically is gradual. • “Wet” macular degeneration can result when these blood vessels hemorrage, and blood and other fluid further can destroy macular tissue