It describe the anatomy of eye in detail according to the BD chaurasia textbook. It includes the parts of eye, internal structures, blood and nerve supply.

1. EYEBALL

3. Introduction
◦ Sense of sight perceived through retina of the eyeball is one of the five
speacial senses.
◦ The eyeball is the organ of sight.
◦ It is almost spherical and has a diameter of a out 2.5 cm. Eyeball is
made up of three concentric coats. The outer fibrous coat comprises
the sclera and the cornea.
◦ The middle or vascular coat also called the uveal tract consists of the
choroid , the ciliary body and the iris.
◦ The inner nervous coat is the retina.
◦ Light entering the eyeball passess through several refracting media.

4. Outer coat
◦ Sclera
◦ Cornea

5. Sclera
◦ Opaque and forms the posterior five sixth of the eyeballs.
◦ Composed of dense fibrous tissue which is firm and maintains
the shape of the eyeball.
◦ Thickest behind near the entrance of the optic nerve
◦ Thinneat about 6mm behind sclerocornal junction
◦ Weakest at the entrance of optic nerve

8. Lamina cribrosa
◦ The sclera shows numerous perforations for passage of fibres
of the optic nerve near it’s entrance. Because of its sieve like
appearance , this region is called the lamina cribrosa.

10. Outer surface of sclera
◦ White and smooth
◦ Covered with Tenon’s capsule.
◦ Anterior part covered with conjunctiva .

12. Inner surface
◦ Brown and grooved for the ciliary nerves and vessels.
◦ Sperated from the choroid by the perichoroidal space
containing a delicate tissue called suprachoroidal lamina.

14. Canal of Schlemm
◦ Sclera is continous anteriroly with the cornea at the
sclerocornal junction or limbus. The deep part of the limbus
contains a circular canal known as the sinus venosus sclerae
or the cabal of schlemm
◦ The aqueous humor drains into the anteriro scleral or ciliary
veins through this sinus.

16. Dural sheath of optic nerve
◦ The sclera is fused posteriorly with Dural sheath of the optic
nerve.
◦ It provides insertion to the extrinsic muscles of the eyeball:
◦ 1) the recti in front
◦ 2) the oblique muscle behind

18. Peircings of the sclera
◦ Optic nerve
◦ Ciliary nerves
◦ Anterior ciliary arteries
◦ Four venae vorticosae

20. Episclera
◦ The sclera is almost avascular.
◦ However, the loose connective tissue between the
conjunctiva and sclera called as the elisclera is vascular.

22. Cornea
◦ Transparent
◦ Replaces sclera over anteriro one sixth of the eyeball
◦ Junction with. Sclera is called sclerocornal junction
◦ More convex than sclera
◦ Seperated from the iris by a space called the anterior chamber of the
eye.
◦ Cornea is avascular and is nourished by lymph which is circulated in
numerous corneal spaces and by lacrimal fluid.

24. ◦ It is supplied by branches of the opthalmic nerve and short
ciliary nerves.
◦ Pain is the only sensation aroused from the cornea.

25. Histology/ Microanatomy
◦ Structurally, the cornea consists of these layers, from before
backwards:
◦ 1. Corneal epithelium (stratified squamous non keratinized
type)
◦ 2. Bowman’s membrane
◦ 3. Substantia propria
◦ 4. Descemet’s membrane
◦ 5. Simple squamous mesothelium

27. Middle Coat
◦ 1) Choroid
◦ 2) Ciliary body
◦ 3) Iris

28. Choroid
◦ Choroid is a thin pigmented layer which separates the
posterior part of the sclera from the retina.
◦ Anteriorly- ora serata
◦ Posteriorly perforated by optic nerve

30. Outer surface
◦ Separated from the sclera by the Suprachoroidal lamina
which is traversed by ciliary vessels and nerves .
◦ It’s attachment to the sclera is loose so that it can easily be
stripped

31. Inner surface
◦ The inner surface is firmly United to the retina:
◦ Suprachoroid lamina
◦ Vascular lamina
◦ The choriocapillary lamina
◦ The inner basal lamina prembrane of bruch

33. Ciliary body
◦ It is the thickened part of the uveal tract t just posterior to the
corneal limbus
◦ Continous anteriorly with iris
◦ Posteriorly with choroid
◦ It suspends the lens and helps it in accomodation for near
vision

35. Ciliary body
◦ Triangular in cross section
◦ Thick in front and thin behind
◦ The scleral surface of this body contains the ciliary muscles
◦ Posterior part of viterous humor is smooth and black ( pars plana)
◦ Anteriro part – ridged anteriroly ( pars plicata) to form about 70
ciliary processes.
◦ The central ends of the processes are free and rounded.

37. Ciliary zonule
◦ Thickened viterous membrane
◦ Fitted to the posterior surface of ciliary process

39. Ciliary muscle
◦ Ring of unstriped muscle which are longitudinal or
meridonial, radial and circular.
◦ Longitudinal /meridonial fibres arise from a projection of
sclera or scleral spur near the limbus.
◦ They radiate backwards to the Suprachoroidal lamina.
◦ The radial fibres are obliquely placed and get continous with
the circular fibres.

41. Circular fibres
◦ Lie in the anterior part of the ciliary body and are nearest to
the lens
◦ Contraction of all the parts relaxes the suspensory ligament
so that the lens becomes more convex.
◦ All parts of the muscle are supplied by parasympathetic
nerves.

43. Iris
◦Anterior part of uveal tract
◦Circular curtain with an opening in The centre called
the pupil.
◦By adjusting the size of the pupil it controls the
amount of light entering the eye.

45. ◦ It is placed vertically between the cornea and the lens, thua
divides the anterior and posterior chambers both containing
aqueous humor.
◦ It’s peripheral margin is attached to the middle of the
anterior surface of the ciliary body and is anterior surface of
the ciliary body.
◦ Central margin is free and forms the boundary of the pupil.

47. ◦The anterior surface of the iris is covered by a single
layer of mesothelium
◦Posterior surface by a double layer of deeply
pigmented cells
◦The main bulk of the iris is formed by stroma made
up of blood vessels and loose connective tissue in
which there are pigment cells

48. Arterial circle
◦ The long posterior and anterior ciliary arteries join to form
the major arterial circle .
◦ Form this circle the vessels converge towards the free margin
to form the minor arterial circle of iris.

50. ◦ The colour of iris is determined by the number of pigment
cells in its connective tissue.
◦ If the pigment cells are absent , the iris is blue in colour
◦ The iris contains a well developed ring of muscle called the
sphincter pupillae which lies near the margin of the pupil.

51. Dilator pupillae
◦ An ill define sheet of radial muscle fibres placed near the
posterior surface of the iris.
◦ Supplied by sympathetic nerves.

53. Inner coat (Retina)
◦ Thin, delicate inner layer
◦ Continous posteriorly with optic nerve
◦ Outwr surface attached to choroid, inner surface to hyaloid
membrane of viterous.

55. Optic disc
◦Opposite the entrance of the optic nerve , there is
circular area known as the optic disc.
◦It is 1.5 mm in diameter

57. Parts of retina
◦ Optic
◦ Ciliary
◦ Iridial

58. Ora serrata
◦The anterior margin of optic part of the retina
forms a Wavy line called the ora serrata.

59. Physiological cup
◦Contains no rods or comes
◦Insensitive to light
◦Also called physiological blind spot for the same
reasons.

61. Macula lutea
◦At the posterior pole of eye 3 mm lateral to the optic
disc there is another depression of similar size called
macula lutea.
◦It is avascular ( no blood vessels)
◦Yellow in colour

63. Fovea centralis
◦The centre of macula is further depressed to form the
fovea centralis.
◦This is the thinnest part of retina.
◦It contains cones only and is site of maximum acuity
of vision.

65. Rods
◦Light receptors of the eye
◦Rods contain a pigment called visual purple.
◦They respond to dim light
◦The periphery of retina contains only rods, but the
fovea has none at all.

67. Cones
◦Responds only to bright light
◦Sensitive to colour
◦Fovea centralis have only cones
◦Their number diminishes towards the periphery of the
retina.

68. 10 layers of retina
◦ Outer pigmented layer
◦ Layer of rods and cones
◦ External limiting membrane
◦ Outer nuclear layer
◦ Outer plexiform layer
◦ Inner nuclear layer
◦ Inner plexiform layer
◦ Ganglion cell layer
◦ Nerve fibre layer
◦ Internal limiting membrane

69. Arterial and venous supply
◦Arterial supply- central artery
◦Cones and rods- supplies by diffusion from the
capillaries of the choroid.
◦The retinal veins run with arteries.

70. Aqueous humor
◦ Clear fluid which fills the space between the cornea in front
and lens behind the anterior segment.
◦ The aqueous humor is secreted into the posterior chamber
from capillaries in the cilairay processes.
◦ It passes into the anteriro chamber Through pupil
◦ Fromnanteriro chamber, it is drained into anteriorr ciliary
veins through the spaces of the irido corneal angle and the
canal of Schlemm.

72. ◦ Intraocular pressure is due chiefly to the aqueous humour
which maintains the constancy of the optical dimension of
the eyeball.
◦ The aqueous is rich in ascorbic acid, glucose and amino acids
and nourishes the avascular tissues of the cornea and lens.

74. Lens
◦ Transparent biconvex structure
◦ Lies between the anterior and posterior chamber
◦ Circular in outline
◦ Diameter of 1 cm
◦ Central points of anterior and posterior chambers is called anterior
and posterior poles
◦ Lines connecting the poles constitute axis of lens.
◦ Marginal circumference of the lens is termed equator
◦ It contributes about 15 dioptres to the total 58 dioptric power of the
eye.

75. Dioptres
◦ They determine the optical power of the eye and thus defines
the Vergence of the optical beams helping in forming a clear
picture at particular distance

76. ◦ The posterior surface of lens is more convex than anteriro.
◦ The anterior surface is flat because of the suspensory
ligament.
◦ When the ligament is relaxed by contraction of the Ciliary
muscle , the anteriro surface becomes more convex due to
elasticity of the lens substance.
◦ The lens is enclosed in a transparent, structureless elastic
capsule which is thickest anteriroly.

77. Histology of lens
◦ Covered by capsular epithelium
◦ At the centre the epithelium is made up of cubical cells.
◦ At periphery it is made up of cells that elongate to form the
fibres.
◦ The fibres are concentrically arranged to form the lens
substance.
◦ The centre ( nucleus) of the lens is firm.
◦ The periphery is soft and is made up of more recently formed
fibres

78. Viterous body
◦ Colourless jelly like transparent mass which fills the posterior
4/5th of the eyeball.
◦ Enclosed in a delicate hyaloid membrane.
◦ Posteriorly attached to optic nerve
◦ Anteriroly attached to ora seratta
◦ In between it is free and is attached to the retina

79. THE END