the eye anatomy and physiology. major parts of the eye the outside eyelid eyelashes conjunctiva iris...

THE EYE

ANATOMY AND PHYSIOLOGY

MAJOR PARTS OF THE EYE

The OUTSIDE EYELID EYELASHES CONJUNCTIVA IRIS CORNEA SCLERA EYE MUSCLES

The INSIDE AQUEOUS HUMOUR LENS (PUPIL) CHOROID RETINA – RODS / CONES VITREOUS HUMOUR FOVEA OPTIC NERVE

MUSCLES OF THE EYE

The Lens

Elastic, circular, biconvex, transparent Held in place by suspensory ligaments It is enclosed in transparent capsule Unique ability – vary its refractive power, by

changing its thickness Ciliary muscle contracts, moves forward,

making lens thicker as it releases tension.

HOW THE EYE SEES

Liquid light

Aqueous humour – is in the anterior and posterior chambers – in the Anterior Segment

Divided by Iris Secreted by Ciliary

glands - continous Passes in front of lens Return via Canal of

Schlemm IO pressure -10-20mmHg

Vitreous humour – Posterior segment

99%water, rest salts and mucoprotien

Maintains pressure to support retina

Maintains shape of eye

Constant through life

The Retina

Innermost layer Made of various light sensitive layers Rods (contrast or night vision) – Rhodopsin

(needs Vit A) Cones (colour vision) Fovea – centre – only cones Optic nerve – convergence of all the nerve

fibres

LACHRYMAL GLANDS AND DUCTS

FOODS THAT HELP

Carrots and other orange foods- beta carotene, vit A Leafy greens - lutein and zeaxanthin—antioxidants that,

studies show, lower the risk of developing macular degeneration and cataracts.

Eggs – zinc and antioxidants Berries and citrus fruit – vitamin C Almonds- Vitamin E Fatty Fish - Tuna, salmon, mackerel, anchovies and trout

are rich in DHA, a fatty acid found in your retina—low levels of which have been linked to dry eye syndrome

DISORDERS OF THE EYE

TRAUMA – blunt, scratch, pierce

VASCULAR – ischemia & haemorrhage

INFLAMMATORY – conjunctivitis, scleritis, iritis, keratitis

CATARACT & GLAUCOMA

SYSTEMIC DISORDERS

DIABETES

HYPERTENSION

THYROID DISORDERS