ANATOMY OF EYES REVIEW THIS PROPERLY.pptx

Anatomy of the Eye

Introduction

The human eye is a complex and highly specialized organ that enables vision by capturing light and transmitting signals to the brain. It consists of multiple structures, each with distinct functions that work in harmony to process visual information. This document provides an in-depth analysis of the anatomy of the eye, including its external and internal structures, their functions, and clinical significance.

External Anatomy

The external structures of the eye include the eyelids, conjunctiva, lacrimal apparatus, and extraocular muscles. These structures protect the eye and aid in movement and lubrication.

1. Eyelids (Palpebrae)

The eyelids are thin, mobile folds of skin that protect the anterior surface of the eyeball.

They contain tarsal plates, which provide structural support.

The Meibomian glands within the tarsal plates secrete an oily substance that prevents tear evaporation.

The levator palpebrae superioris muscle elevates the upper eyelid.

The orbicularis oculi muscle closes the eyelids.

The eyelids play a crucial role in protecting the eye from foreign objects and excessive light.

2. Conjunctiva

The conjunctiva is a thin, transparent membrane that covers the inner surface of the eyelids (palpebral conjunctiva) and extends over the sclera (bulbar conjunctiva).

It provides lubrication and immune protection.

Infections such as conjunctivitis (pink eye) affect this structure.

3. Lacrimal Apparatus

The lacrimal apparatus produces and drains tears, which lubricate the eye and remove debris.

It consists of:

Lacrimal gland (produces tears)

Lacrimal puncta (tiny openings that drain tears)

Lacrimal sac and nasolacrimal duct (drain tears into the nasal cavity)

Dysfunction can lead to dry eye syndrome or excessive tearing (epiphora).

4. Extraocular Muscles

The eye is controlled by six extraocular muscles:

Four rectus muscles (superior, inferior, medial, lateral) control primary movements.

Two oblique muscles (superior and inferior) control rotational movements.

Innervated by cranial nerves: Oculomotor (CN III), Trochlear (CN IV), and Abducens (CN VI).

Disorders like strabismus occur when muscle function is impaired.

Internal Anatomy

The internal structures of the eye include three main layers: the fibrous tunic, vascular tunic, and neural tunic, along with supporting structures such as the lens, aqueous humor, and vitreous body.

1. Fibrous Tunic (Outer Layer)

Composed of the sclera and cornea.

Sclera

The white, opaque outer layer provides structural support and protection.

Composed of dense connective tissue and collagen fibers.

The optic nerve (CN II) exits through the lamina cribrosa in the sclera.

Cornea

The transparent anterior surface that allows light to enter.

Composed of five layers:

Epithelium (regenerates rapidly)

Bowman’s layer (collagen structure)

Stroma (thickest layer, maintains transparency)

Descemet’s membrane (supports the endothelium)

Endothelium CORNEA T

1. ANATOMY OF EYES

2. INTRODUCTION

3. STRUCTURE OF THE EYEBALL

4. THANK YOU

5. Lateral rectus muscle

Lens capsule

Posterior 一
chamber ン
we
Susperisory
igament

Medial rectus muscle

Pigment ei

6. WALL OF THE EYEBALL
必 OUTER LAYER (FIBROUS COAT) :

+ MIDDLE LAYER (VASCULAR COAT) :

INNER LAYER (NERVOUS COAT) :

7. MIDDLE LAVER
{TUNICA MEDIA OR.

INNER LAYER

(TUNICA INTERNA OR.
"TUNICA NERVOSA)

RETINA
‘CORNEA Sara ‘CHOROID aan aopy me (AYERS OF RETINA,
OD, CONES, LAYER OF
‘NERVE FIBERS Etc)

TUNICA VASCULOSA)

8. OUTER LAYER (OR) TUNICA EXTERNA (OR)
TUNICA FIBROSA

This gives shape of eyeball and contains sclera
and cornea

Human eye anatomy

| Optic nerve.

Bling spot
(Sptic Gec area)

9. SSS

ee AND CORNEA
-Sclera or the “wi the eye” forms the

outermost layer of the eyeball

- The anterior one sixth part of the sclera is
transparent and is known as cornea.

- The cornea is described as the “window of the
eye”

- Light rays pass through the cornea to reach the
retina.

Cornea

10. It provides protection to the delicate structure
within the eye

It resists intraocular pressure
It maintains shape of the eyeball

The smooth external surface allow easy eye
movement

11. CORNEA

Occupies the centre of the anterior pole of the globe
Size-12mm horizontal meridian

-11mm vertical meridian

-Thickness-1mm
Bordered-anterioly by precorneal tear film

-posterioly by anterior chamber

Transparent
Avascular
Rich nerve supply-unmyelinated nerve

Consists of five layers-epithelium
-Bowman'membrane
-Stroma
-Descemet'smembrane
-Endothelium

Receives most of its nutrient from the aqueous humor and the tear film,

Most important refractive surface-43 Diopters

12. Cornea
a

a

13. LIMBUS

・ Junction between cornea and sclera
・ Surgical landmark-cataract, glaucoma
ㆍ 2mm wide

14. ANTERIOR CHAMBER

Filled with aqueous humor

Lies at the junction of the cornea and iris
About 3mm in depth

Angle of the anterior chamber-Seen using
gonioscopy lens

Aqueous drained through the trabecular
meshwork into canal of schlemn

15. Lig =
デニ ーーー Flow of
q ( aqueous
ie % fluid

16. MIDDLE LAYER (OR) TUNICA MEDIA (OR) TUNICA
VASCULOSA

This layer comprises of three structures:,

*Choroid

eCiliary body nea
elris

Optic Nerve

The choroid, ciliary body and iris
together form the uveal tract.

This layer contains blood vessels

Pupil is the small opening in
front of it

17. Choroid is a thin pigmented membrane, dark
brown in color which is situated in between sclera
(externally) and retina (internally)

Human eye anatomy

„ Choroid

Bind spot
(optic asc oreo)

18. CILIARY BODY

Ciliary body is the continuation of choroid
consisting of smooth muscle fibers, i.e., the ciliary-
muscle

19. ・ Ciliary body contai

‘ligament for
attaching the 18 と

・ The ciliary muscles help in accommodation
by adjusting the thickness of lens

20. IRIS
* Iris is the pigmented membrane surrounds
the pupil

* It arises from the margin of ciliary body and
forms a dark centered opening called pupil \ 3

+ The space between cornea (in front) and the
lens (behind) is the anterior segment | =n=

Uvea: Iris, Ciliary Body and Choroid

pupi —

?

21. : Wy 「
It is again divided à into two a
a
・ The space between the iris "E

anteriolgguageber
between i iris and lens.i Ep

22. INNER LAYER (OR) TUNICA INTERNA (OR)

1,09

is the light sensitive membrane [

TUNICA NERVOSA (OR) RETINA

Choroid
Lens 97

23. RETINA

Retina is the inner most layer of the eyeball

It is a thin delicate layer continuous posteriorly
with optic nerve

The outer surface 0 a, formed by
pigment cells, is attached to,ehoroid

Its inner surface is in a the hyaloid
membrane of the vitreous

The small area of retina where the optic nerve

leaves the eye is the optic disc or the blind spot.
It has no light sensitive cells (Rods or Cones)

24. Contd...

The retina has three parts:

* OPTIC
* CILIARY
* IRIDIAL

Q The optic part c tQ E mue, andit is
sensitive to light

Q It extends from the optic disc to the ciliary body
OThe thin, non nervous, non sensitive layer covers the

ciliary body and iris is called ciliary and iridial part of
retina

25. Contd.......

“ Lateral to the optic disc a depression called macula
lutea (due to its yellow color)

«+ The center of macula is again depressed to form the
fovea centralis

~
nly and is the

党 It contain site af maximum
acuity of vision A

% The rods and cones are the receptors of light and sight
These cells contains photosensitive pigments (Rods-
Rhodopsin, Cones - lodopsin) involved in the conversion
of light rays into nerve impulses

26. = Venous drainage a number of veins including the
central retinal vein

mer -- Rail ot

Long posterior
‘lary anen

= en —
Er. ©;

cross opte
en (OA)

Lor pst la — =) Foor of ot

27. OPTIC NERVE
It is a 2" cranial nerve
Originate in the ganglion layer of the retina

Length varies -35-55mm from the globe to the
chiasma

Consist of about one million axons-fibres within
the retina are transparent

Its organization structure similar to white matter
of the brain

Optic disc —optic nerve head seen with o’cope

Within the orbit -covered with meningeal
sheaths

Blood supply-central retinal artery

28. eAqueous humor

eVitreous humor

eLens

29. A veo IR

+ Aqueous humoris a cle ery

fluid fills the space between
cornea and lens ie

» It is secreted by capillágj
of ciliary process * 내

+ From here the-fluid réaches . aus

to the anterior cl の < S

which finally reachegto theme, 1
2 y ES PUS

canal of schlemm

ENCORE wmr EE

31. FUNCTIONS

¢ It helps to maintain
intraocular pressure and
thus maintains the shape
of eyeball

e It is rich in ascorbic acid,
glucose and amino acids
and nourishes the cornea
and lens

32. VITREOUS HUMOR

> Vitreous humor or
vitreous body is a
colorless, transparent,
jelly-like substance which
fills the posterior segment
of the eye (i.e., behind the
lens).

> Itis enclosed in a viracous
h 上 3 MM
delicate hyaloid membrane

33. FUNCTIONS

It helps to preserve the spherical shape of
the eyeball and to support the retina

34. m

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> The lens of the
> It is situated behind the pupil
> It is biconvex, transparent, (And elastic in structure

> Lens refracts light rays anid helps to focus the image of
the object on retina

> Lens is supported by suspensory ligaments (Zonular
fibers) which are attached with ciliary bodies

36. THANK YOU