Download Conjunctivitis

Common eye diseases and their treatment:
sty
dry eyes
pterygium
Ptosis
retinal tear
Glaucoma
cataracts
diabetic retinopathy
macular degeneration
thyroid eye disease
Watering eyes/
tear duct problems
allergic conjunctivitis
bacterial conjunctivitis
conjunctival hemorrhage
corneal abrasion
central vein occlusion
thyroid eye disease
viral conjunctivitis
eyes
Your eyes are your body's most highly
developed sensory organs. In fact, a far
larger part of your brain is dedicated to the
functions of eyesight than to those of
hearing, taste, touch or smell. We tend to
take eyesight for granted, yet when vision
problems develop, most of us will do
everything in our power to restore our
eyesight to normal.
eye: camera
The eye functions
much like a camera.
Light passes through
the cornea and the
lens of the eye and is
focused on the retina
in much the same way
that an image is
focused on the film of
a camera.
parts
The eye is protected by 3
layers: sclera, choroid, and
the retina.
• The sclera is the white covering
of the eye. It is continuous with
the cornea in the front.
• The middle layer, the choroid, is a
vascular layer lining the posterior
(back) 3/5 of the eyeball. It is
continuous with the ciliary body
and the iris, which is the colored
part of your eye.
• The intermost layer is the retina,
which is light-sensitive and has
rods and cones.
parts you can see…
The pupil is the small black
opening in the iris. The iris
controls the size of the pupil
with 2 muscles: dilator muscle,
which enlarges the pupil and
the sphincter muscle, which
makes the pupil smaller. The
iris is the colored disk which is
right behind the cornea. It's
color comes from melanin. The
more melanin there is and the
closer it is to the surface, the
darker the iris.
sagittal section of the eye
the lens is like a magnifying
The lens is transparent and
glass
helps to focus light rays onto
the retina in the back of the
eye. The macula is the bull'seye center of the retina.
Though the macula makes up
only a small part of the retina,
it is one hundred times more
sensitive to detail than the
peripheral retina and allows us
to see tiny detail, to read fine
print, recognize faces, thread a
needle, read the time, see
street signs, see grains of salt
being poured from a shaker,
etc.
Red Eyes
The "red eye"
effect shown in
this photograph is
due to light
reflection by the
retina
muscles of the eye
There are two different types of muscles in your eye - Intrinsic and Extrinsic! Intrinsic muscles in the eye
are the iris and ciliary muscles. Extrinsic muscles are
the six muscles that control eye movement and make
it possible for the eye to follow a moving object.
functions of extrinsic muscles
• Lateral Rectus -- allows eye to move horizontally
and laterally (sideways)
• Medial Rectus -- allows eye to move horizontally
and medially (middle)
• Superior Rectus -- allows eye to elevate (up)
• Inferior Rectus -- allows eye to depress (down)
• Inferior Oblique -- allows eye to elevate and turn
laterally
• Superior Oblique -- allows eye to depress and turn
laterally
eye movement
The muscles of the eye
are all innervated by the
III cranial nerve
(oculomotor), except for
the superior oblique,
innervated by the IV
cranial nerve (trochlear),
and the lateral rectus,
innervated by the VI
cranial nerve (abducent).
protective structures of
the eye
The exterior structures include:
eyelids, eyelashes, eyebrows, and the
orbit.
The interior structures are the
conjunctiva, lacrimal organs, and the
Meibomian glands.
visual acuity test
Normal vision is measured at 20/20.
This means that you can see clearly at
20 feet what should normally be seen
at that distance. If you have 20/100
vision, that means that you must be
as close as 20 feet to see what a
person with normal vision can see at
100 feet. 20/20 vision is not perfect
vision, it just indicates the visual
acuity. There are many other things
such as peripheral vision, eye
coordination, depth perception,
focusing ability and color vision that
affect overall vision ability.
pupillary response
is another exam used
to survey your visual
system. A light beam
will be directed at
and away from your
eye to observe if
your pupils constrict
and dilate as
expected.
normal focus of image on the retina
If your
visual acuity
is normal
you are
described as
emmetropic
common forms of vision
impairment
The most common forms of vision
impairment are errors of refraction -- the
way light rays are bent inside the eye so
images can be transmitted to the brain.
Nearsightedness, farsightedness and
astigmatism are examples of refraction
disorders. Retinal detachment, color
blindness and night blindness are disorders
of the functional eye and its processing units
that lead to distorted or inaccurate vision.
myopia and hyperopia
• Nearsightedness and
farsightedness have
to do with the way
the eye brings
images into focus on
the back of the
eyeball, where 10
layers of lightsensitive nerve
tissue make up the
retina.
nearsightedness…
Nearsightedness, or myopia, which affects
about 20% of the population, is the result of
images being focused in front of the retina
rather than on it, so distant objects appear
blurred. A nearsighted person holds a book
close to the eyes when reading and has to sit in
the front of the classroom or movie theater to
see clearly. The condition runs in families and
affects men and women equally, usually
appearing in childhood and stabilizing in the
twenties.
farsightedness…
Farsightedness, or hyperopia, is the
opposite of nearsightedness: The lens
of the eye focuses images slightly
behind the retina, making nearby
objects appear blurry. Children often
overcome mild farsightedness as they
grow up and the eye muscles contract.
astigmatism…
occurs when the eye
lacks a single point of
focus. The condition is a
result of an uneven
curvature of the cornea
or, in some cases, an
abnormality in the lens.
People with astigmatism
have a random,
inconsistent vision
pattern, in which some
objects appear clear and
others blurry.
test for astigmatism…
An irregular curvature of the
cornea and/or lens is
determined using this type
of illustration. When using
the test card, a person
would know if he has
astigmatism because
some radial lines would be
blurred.
red-green colorblindness…
is a disorder of the retina's
light-sensitive cone cells,
which respond to colors.
Most people with color
blindness see colors normally
in bright light but have
difficulty distinguishing reds
and greens in dim light. Color
blindness occurs mostly in
men, afflicting 8% of the
male population. It is
extremely rare for someone
to be totally color-blind -able to see only shades of
gray.
Pseudoisochromatic plates
others
• Presbyopia is blurred vision at normal
reading distance. It typically starts at about
age 40 and is the reason many older people
use glasses.
• Retinal detachment occurs when a part of
one of the layers of the retina is pulled out of
place, or when a hole or tear occurs. Although
a detached retina is not painful, it is definitely
a medical emergency. If the retina is not
reattached to its source of nutrients promptly,
the cells die and blindness can result.
more…
• Night blindness difficulty seeing in
dim light -- occurs when the retina's
rod cells, which distinguish light from
dark, begin to deteriorate. The precise
cause is unclear, but it may be linked to
a liver disorder, a vitamin-A deficiency,
or a disease of the retina, such as
retinitis pigmentosa, an inherited
disorder.
…continuing
• Eyestrain does not affect your vision, but it
accompanies some vision disorders and may
bring on a headache. It is often the result of
eye muscles becoming strained from holding
the same focus too long. If you wear
prescriptive lenses, eyestrain may be an
indication that you need new glasses or a
different prescription. Eye exercises or
resting the eyes every 30 minutes helps
relieve eyestrain, especially if you work with
computers.
…
There are other diseases of the eye
that respond in varying degrees to
medical treatment, such as
cataracts, conjunctivitis, glaucoma,
crossed eyes or wall eye
(strabismus) and lazy eye
(amblyopia), and macular
degeneration.
Conjunctivitis
The conjunctiva -- the transparent
membrane that lines your eyeball and your
eyelid -- can become inflamed for various
reasons. Most cases of conjunctivitis run a
predictable course, and the inflammation
usually clears up in a few days. Although
conjunctivitis can be highly contagious, it is
rarely serious and will not damage your
vision if detected and treated promptly.
more on conjunctivitis
• Bacterial conjunctivitis, commonly known as pinkeye, usually
infects both eyes and produces a heavy discharge of mucus. It
is treated with antibiotics, usually as eye drops.
• Viral conjunctivitis is usually limited to one eye, causing
copious tears and a light discharge. This infection will resolve
without treatment.
• Allergic conjunctivitis produces tears, itching and redness in
the eyes, and sometimes an itchy, runny nose. Allergy
medicines in the form of pills or eye drops will relieve these
symptoms.
• Ophthalmia neonatorum is an acute form of conjunctivitis in
newborn babies. It must be treated immediately by a doctor to
prevent permanent eye damage or blindness.
flashes and floaters
The flashes of light are
caused by the tugging of the
vitreous where it is attached
to the retina. As it liquifies
and pulls away from the
retina, the vitreous becomes
somewhat condensed and
stringy and forms strands.
The patient can see these
strands and strings; they
appear as spots, small
circles, or irregular fine
threads in the vision. They
seem to float and are
therefore called "floaters".
vision improvers
Not everyone is blessed with perfect eyes,
but that does not matter because there are
many ways to fix vision defects. Several of
examples are glasses, contacts, or surgery.
Optometrists and ophthalmologists don't
know exactly why people have eye defects,
but they do know that it usually has
something to do with genetics, stress, and
nutrition.
Presbyopia
visual correction with a convex lens
for hyperopia
visual correction with a concave lens
for myopia
references
WebMD Inc. webmd.lycos.com/content/ article/1680.53542
Indiana University School of Optometry
www.opt.indiana.edu/clinics/ educ/iexam/main.htm
Northwest Kansas Eye Clinic
www.nwkec.com/005rd020.htm
Biological Bases, Sensation and Perception
peace.saumag.edu/.../Courses/
GPWeiten/Chapter4SandP.html