Fundamentals of Opthalmology (Anatomy of eye ball and diagnostic tests to evaluate the pathophysiological conditions in eye diseases.

1. Fundamental of
Opthalmology
Faraza Javed
PhD Pharmacology
Diagnostic Tests in Opthalmology

2. What is ophthalmology?
 Opthalmos=eye
 Logos=word, thought, discourse
The science of eyes is opthalmology

3. The branch of medicine concerned with
the eyes
 Anatomy
 Function
 Disease

4. Fundamentals of
Opthalmology

5. The visual system
 A coordinated pair of eyes
 The appropriate protective
mechanisms
 The necessary neural apparatus to
interpret visual information

6.  To produce a clear
image of the external
world and transmit
this to visual cortex of
brain

7. Structure of Eyeball
 Fibrous coat
 Cornea, sclera
 Vascular coat (uveal
tissue)
 Iris, ciliary body, choroid
 Nervous coat
 Retina

8. Sclera
 Collagen
 Variable thickness
 1mm around optic nerve
head,
 0.3mm posterior to
muscle insertions
 Tough, opaque, mainly
avascular
 Outer wall of the eyeball
-protects intraocular
contents, preserve shape
 Attachments for the
extraocular muscles

9. Cornea - anatomy
 500-700 µm thick
 Transparent, avascular
 Forms approximately the
anterior 1/6 of the outer
coat of the eye and is
continuous posteriorly with
the sclera
 5 layers:
 Epithelium
 Bowman’s membrane
 Stroma
 Descemet’s membrane
 Endothelium

10. Iris and pupil (Vascular Coat)
 Attached to ciliary
body
 Forms pupil at center

11. Pupil movements
 Mydriasis (Dilation):
 Dilator pupillae muscles
 Low-intensity light,
excitement, fear
 Sympathetic
 Miosis (Constriction):
 Sphincter pupillae
muscle
 Bright light,
accommodation
 Parasympathetic

12. Ciliary body
 Connects the iris and the
choroid
 Functions:
 Aqueous humor
production
 Suspension of lens,
accommodation

13. Aqueous Humour production
 Active secretion by the
epithelium of the ciliary
processes of the ciliary
body
 Function:
 Carries O2, nutrients to
lens, cornea and waste
products away
 Maintain shape of eye
by intraocular
pressure
 Flushes away blood,
macrophages,
inflammatory cells

14. Lens
 Transparent, biconvex
structure
 Radially arranged zonule
fibers that insert into the
lens around its equator
connect the lens to the
ciliary body
 Can change diopteric
power but amplitude of
accommodation reduces
with age

15. Choroid
 Highly vascularised
structure between the
sclera and the retina
 Vessel layer, capillary
layer
 provides O2 + nutrition
to the outer retinal
layer,
 Temperature
homeostasis
 Conduct blood vessels
 Absorb excess light

16. Vitreous body
 Clear gel-like structure
that fills the posterior eye
 98% water+ 2% collagen,
hyaluronic acid, soluble
proteins
 Transmission of light onto
the retina, cushion to the
eyeball during trauma,
nutritive and supportive
role in retinal metabolism

17. Retina (Neural Layer)
 Converts light into
nerve impulses
 Multilayered
 2 functional layers:
 Neurosensory retina
 Retinal pigment
epithelium (RPE)

18. 1. Retinal pigment epithelium (RPE)
 Single layer
 Microvilli at the apex where
the photoreceptors attach
 Functions:
 Melanin pigments which
absorb light (antireflection)
 Participate in turnover of
photoreceptors
 Recycle vitamin A to form
photosensitive pigments

19. 2. Neurosensory retina
 3 main groups of neuronal cells:
photoreceptors, bipolar cells, ganglion cells
 Photoreceptor cells (rods + cones)
undergo photochemical changes
(phototransduction)
 Bipolar cells relay nerve impulse to
ganglion cells
 Ganglion cell exit at optic disc to become
optic nerve

20. Optic disc
 The location where
ganglion cell axons exit the
eye to form the optic nerve
 Yellowish orange color
 1.5mm diameter (may
vary), vertically oval
 Central retinal vessels
enter and leave the eye
here

21. Retinal blood supply
 Retinal arteries supply O2
+ nutrients to the inner
layers of the retina
 Outer layers (RPE-outer
nuclear) supplied by
choroidal capillaries
 SuperiorSuperior and inferior
branches, which split into
nasal, temporal
branches.
 Capillaries with
nonfenestrated
endothelium, prevent large
molecules and toxins to
permeate; this forms the
inner blood retinal
barrier

22. Optic nerve
 Contains over 1 million
fibres
 Nerve fibres are
myelinated only after
leaving the eye
 Surrounded by
cerebrospinal fluid in the
anterior extension of the
subarachnoid space
 Protected by the same
meningeal layers of the
brain

24. There are many diseases, disorders, and age-
related changes that may affect the eyes and
surrounding structures. The sharpness of vision is
reduced despite use of the best glasses. The
amount of light that reaches the back of the
retina is reduced, and this wear and tear results
in the development of cataract, macular
degeneration or glucoma.

25. Such conditions cause damage to the eye's optic
nerve and gets worse over time. It's often linked
to a buildup of pressure inside the eye. The
increased pressure, called intraocular pressure,
can damage the optic nerve, which transmits
images to your brain. If the damage continues, it
can lead to retinal cell degeneration and
permanent vision loss.

26. Opthamological Method

27. Tonometery
Tonometry measures the
pressure within your eye.
During tonometry, eye drops
are used to numb the eye.
Then a doctor or technician
uses a device called a
tonometer to measure the
inner pressure of the eye. A
small amount of pressure is
applied to the eye by a tiny
device or by a warm puff of
air.

28. The range for normal pressure is 12-22 mm
Hg. Most glaucoma cases are diagnosed
with pressure exceeding 20mm Hg.
However, some people can have glaucoma
at pressures between 12 -22mm Hg. Eye
pressure is unique to each person.

29. Opthalmoscopy
This diagnostic procedure helps the doctor
examine your optic nerve for glaucoma damage.
Eye drops are used to dilate the pupil so that the
doctor can see through your eye to examine the
shape and color of the optic nerve.

30. The doctor will then use a small device with a
light on the end to light and magnify the
optic nerve. If intraocular pressure is not
within the normal range or if the optic nerve
looks unusual, doctor may ask to have one
or two more glaucoma exams: perimetry
and gonioscopy.

31. Perimetry
Perimetry is a visual field test that
produces a map of your complete
field of vision. This test will help a
doctor determine whether your
vision has been affected by
glaucoma. During this test, you
will be asked to look straight
ahead and then indicate when a
moving light passes your
peripheral (or side) vision. This
helps draw a "map" of your
vision.

32.  After glaucoma has been diagnosed, visual field
tests are usually done one to two times a year to
check for any changes in your vision.

33. Gonioscopy
This diagnostic exam helps determine whether
the angle where the iris meets the cornea is open
and wide or narrow and closed. During the exam,
eye drops are used to numb the eye. A hand-held
contact lens is gently placed on the eye.

34. This contact lens has a mirror that shows the
doctor if the angle between the iris and
cornea is closed and blocked (a possible sign
of angle-closure or acute glaucoma) or wide
and open (a possible sign of open-angle,
chronic glaucoma).

35. Pachymetry
Pachymetry is a simple, painless test to measure
the thickness of your cornea. A probe called a
pachymeter is gently placed on the front of the
eye (the cornea) to measure its thickness.
Pachymetry can help your diagnosis, because
corneal thickness has the potential to influence
eye pressure readings.

36. With this measurement,
doctor can better
understand IOP reading
and develop a treatment
plan. The procedure
takes only about a
minute to measure both
eyes.

37. Electroretinography
Electroretinography allows to examine the
function of the light-sensing cells
(photoreceptors) in the retina by measuring
the response of the retina to flashes of light.
Eye drops numb the eye and dilate the pupil. A
recording electrode in the form of a contact
lens is then placed on the cornea, and another
electrode is placed on the skin of the face
nearby.

38. The eyes are then propped open. The room
is darkened, and the person stares at a
flashing light. The electrical activity
generated by the retina in response to the
flashes of light is recorded by the
electrodes.Electroretinography is particularly
useful for evaluating diseases, such as
retinitis pigmentosa, in which the
photoreceptors are affected.

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