2. THE EYE IS SITUATED IN THE ORBITAL CAVITY OF
THE SKULL
IT IS WELL PROTECTED BY THE BONY WALLS OF THE
ORBIT
ORBIT ALSO CONTAINS MUSCLES OF EYEBALL, THEIR
NERVES, BLOOD VESSELS, AND LACRIMAL GLAND
3. STRUCTURE OF THE EYEBALL
• WALL OF THE EYEBALL
• REFRACTIVE MEDIA
4. WALL OF THE EYEBALL
OUTER LAYER(FIBROUS COAT) : SCLERA AND
CORNEA
MIDDLE LAYER(VASCULAR COAT) : CHOROID,
CILIARY BODY AND IRIS
INNER LAYER(NERVOUS COAT) : RETINA
5.
6.
7.
8.
9. SCLERA AND CORNEA
• SCLERA FORMS THE OUTERMOST LAYER OF THE EYEBALL
• THE ANTERIOR 1/6TH PART OF THE SCLERA IS TRANSPARENT AND
IS KNOWN AS CORNEA
• LIGHT RAYS PASS THROUGH THE CORNEA TO REACH THE RETINA
10. FUNCTIONS OF SCLERA
• IT PROVIDES PROTECTION TO THE DELICATE
STRUCTURES WITHIN THE EYE
• IT RESIST INTRAOCULAR PRESSURE
• IT MAINTAINS THE SHAPE OF THE EYEBALL
• THE SMOOTH EXTERNAL SURFACE ALLOW EASY EYE
MOVEMENT
11. CHOROID
• CHOROID IS A THIN PIGMENTED MEMBRANE, DARK
BROWN IN COLOR WHICH IS SITUATED IN BETWEEN
SCLERA AND RETINA
12. CILIARY BODY
• IT IS THE CONTINUATION OF CHOROID CONSISTING OF SMOOTH MUSCLE FIBRE
I.E. THE CILIARY MUSCLE
• IT CONTAINS SUSPENSORY LIGAMENT FOR ATTACHING THE LENS IN POSITION
• IT HELPS IN ACCOMMODATION BY ADJUSTING THE THICKNESS OF THE LENS
13. IRIS
• IRIS IS THE PIGMENTED MEMBRANE SURROUND THE PUPIL
• IT ARISES FROM THE MARGIN OF CILIARY BODY AND FORMS A DARK
CENTERED OPENING CALLED PUPIL
• THE SPACE BETWEEN CORNEA AND THE LENS IS THE ANTERIOR SEGMENT
• IT IS FURTHER DIVIDED INTO TWO PARTS BY THE IRIS
• THE SPACE BETWEEN THE IRIS AND THE CORNEA IS THE ANTERIOR
CHAMBER
• THE SPACE BETWEEN THE IRIS AND THE LENS IS THE POSTERIOR
CHAMBER
• THEY ARE FILLED WITH AQUEOUS HUMOR
14. RETINA
• IT IS A THIN DELICATE LAYER CONTINUOUS POSTERIORLY WITH OPTIC NERVE
• THE OUTER SURFACE OF THE RETINA, FORMED BY THE PIGMENT CELLS, IS ATTACHED
TO THE CHOROID
• ITS INNER SURFACE IS IN CONTACT WITH HYOID MEMBRANE OF THE VITREOUS
• THE SMALL AREA OF THE RETINA WHERE THE OPTIC NERVE LEAVES THE EYE IS THE
OPTIC DISC OR THE BLIND SPOT
• RETINA HAS THREE PARTS
1) OPTIC
2) CILIARY
3) IRIDIAL
• THE OPTIC PART CONTAINS NERVOUS TISSUE AND IT IS SENSITIVE TO LIGHT
• IT EXTENDS FROM THE OPTIC DISC TO THE CILIARY BODY
• THE THIN NON NERVOUS AND NON SENSITIVE LAYER COVERS THE CILIARY BODY AND
IRIS IS CALLED CILIARY AND IRIDIAL PART OF RETINA
15. • LATERAL TO THE OPTIC DISC A DEPRESSION CALLED
MACULA LUTEA
• THE CENTER OF MACULA IS AGAIN DEPRESSED TO FORM
FOVEA CENTRALIS
• IT CONTAINS CONES ONLY AND IS THE SITE OF MAXIMUM
ACUITY OF VISION
• THE RODS AND CONES ARE THE RECEPTORS OF LIGHT
AND SIGHT
• THESE CELLS CONTAIN PHOTOSENSITIVE PIGMENTS
INVOLVED IN THE CONVERSION OF LIGHT RAYS INTO
NERVE IMPULSES
16.
17.
18.
19. • INTERFERENCE WITH DRAINAGE OF AQUEOUS HUMOR
RESULTS IN AN INCREASE IS INTRAOCULAR PRESSURE
(GLAUCOMA)
(NORMAL IOP : 10-20 MMHG)
• THIS LEADS TO ATROPHY OF RETINA ,LEADING TO BLINDNESS
