EYE INTRODUCTION

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

25. Lacrimal gland
Meibomian gland

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