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Glaucoma & Cataract
Dr Ibraheem Bashayreh, RN, PhD
Glaucoma
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Glaucoma is optic nerve damage (often, but not
always, associated with increased eye pressure)
that leads to progressive, irreversible loss of
vision.
Glaucoma
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Damage to the optic nerve can occur when
pressure within the eye increases.
The vision loss occurs so slowly that it may not be
noticed for a long time.
People at risk should have a complete eye
examination, including measurement of eye
pressures and testing of side (peripheral) vision.
Eye pressure needs to be controlled throughout
life, usually with eye drops but sometimes with
eye surgery
Epidemiology
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Almost 3 million people in the United States and
14 million people worldwide have glaucoma.
Glaucoma is the third leading cause of blindness
worldwide and the second leading cause of
blindness in the United States, where it is the
leading cause of blindness among blacks and
Hispanics.
In the United States, about one third of glaucoma
occurs with eye pressures within the average
range, a condition called low-tension glaucoma.
Risk Factors
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Age older than 40
Family members who have (or had) the disease
Farsightedness or nearsightedness
Diabetes
Long-term use of corticosteroid drugs
Previous eye injury
Congenital
Mechanism
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Glaucoma occurs when an imbalance in production
and drainage of fluid in the eye (aqueous humor)
increases eye pressure to unhealthy levels.
Normally the aqueous fluid, which nourishes the eye,
is produced by the ciliary body behind the iris (in the
posterior chamber) and flows through the pupil to the
front of the eye (anterior chamber), where it exits into
drainage canals between the iris and cornea (the
“angle”). When functioning properly, the system
works like a faucet (ciliary body) and sink (drainage
canals).
Balance between fluid production and drainage—
between an open faucet and a properly draining sink—
keeps the fluid flowing freely and prevents pressure in
the eye from building up.
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Mechanism
In glaucoma, the drainage canals become clogged,
blocked, or covered. Fluid cannot leave the eye
even though new fluid is being produced in the
posterior chamber.
In other words, the sink “backs up” while the
faucet is still running. Because there is nowhere in
the eye for the fluid to go, pressure in the eye
increases.
When the pressure becomes higher than the optic
nerve can tolerate, damage to the optic nerve
occurs. This damage is called glaucoma.
Sometimes eye pressure increases within the range
of normal but is nonetheless too high for the optic
nerve to tolerate (called low tension glaucoma).
Classification
Open-angle glaucoma
 Closed-angle glaucoma
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Etiology
In most people, the cause of glaucoma is not
known,
 Although both open-angle and closed-angle
glaucomas tend to run in families. In others,
damage to the eye caused by infection,
tumour, inflammation, large cataracts or
surgery for cataracts, or other conditions
keeps the fluid from draining freely and
leads to increased eye pressure and optic
nerve damage (secondary glaucoma).
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Open-angle glaucoma:
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is more common
the drainage canals in the eyes become
clogged gradually over months or years.
Pressure in the eye rises slowly because
fluid is produced at a normal rate but
drains sluggishly.
Symptoms Open-Angle Glaucoma:
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painless and causes no early symptoms.
The most important symptom is the development of
blind spots, or patches of vision loss, over months to
years.
The blind spots slowly grow larger.
Peripheral vision is usually lost first.
Vision loss occurs so gradually that it is often not
noticed until much of it is lost.
Because central vision is generally lost last, many
people develop tunnel vision: they see straight ahead
perfectly but become blind in all other directions.
If glaucoma is left untreated, eventually even tunnel
vision is lost, and a person becomes totally blind.
Closed-angle Glaucoma
is less common than open-angle glaucoma.
 The drainage canals in the eyes become
blocked or covered because the angle
between the iris and cornea is too narrow.
 The blockage can occur suddenly or
slowly. If the blockage occurs suddenly,
pressure in the eye rises rapidly. If the
blockage occurs slowly, the pressure in the
eye rises slowly like in open-angle
glaucoma.
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Symptoms Closed-Angle
Glaucoma
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If eye pressure rises rapidly in closed-angle
glaucoma (acute closed-angle glaucoma), people
typically notice an abrupt onset of severe eye pain
and headache, redness, blurred vision, rainbowcolored halos around lights, and sudden loss of
vision.
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They may also have nausea and vomiting as a response to
the increase in eye pressure.
Acute closed-angle glaucoma is considered a medical
emergency, because people can lose their vision as quickly
as 2 to 3 hours after the appearance of symptoms if the
condition is not treated.
People who have had open-angle or closed-angle glaucoma
in one eye are likely to develop it in the other.
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Screening and Diagnosis
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An early detection of the disease is extremely important.
All people at high risk of glaucoma should have a
comprehensive eye examination every 1 to 2 years
There are four parts to a comprehensive eye examination for
glaucoma
Monitoring eye pressure (20-22 mm Hg)
Ophthalmoscope and a slit lamp to look for changes in the
optic nerve
Visual field (peripheral vision) testing allows a doctor to
detect blind spots
Doctors may also use a special lens to examine the drainage
channels in the eye
Treatment
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The goal of glaucoma treatment is to prevent the
onset of vision loss or stop its progression.
Treatment of glaucoma is lifelong. It involves
decreasing eye pressure by increasing fluid
drainage out of the eyeball or by reducing the
amount of fluid produced inside the eyeball.
Some people with high eye pressure who do not
have signs of optic nerve damage (known as
glaucoma “suspects”) can be monitored closely
without treatment.
Treatment
Eye drops and surgery are the main
treatments for open-angle and closed-angle
glaucomas.
 Eye drops containing beta-blockers,
prostaglandin-like compounds, alphaadrenergic agonists, carbonic anhydrase
inhibitors, or cholinergic drugs are
commonly used to treat glaucoma.
 Laser surgery can be used to increase
drainage
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Cataract
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A cataract is a clouding (opacity) of the lens
of the eye that causes a progressive,
painless loss of vision.
Epidemiology
Cataracts are the leading cause of blindness
worldwide.
 Cataracts are common in the United States, where
they affect mostly older adults.
 Almost one in five people between the ages of 65
and 74 develop cataracts severe enough to reduce
vision, and almost one in two people older than 75
have them.
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Etiology
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Cataracts usually develop without any apparent cause; however,
contributing factors include the following:
Injury to the eye
Prolonged use of certain drugs (such as corticosteroids)
Prolonged exposure to x-rays (such as with radiation therapy to the
eye)
Inflammatory and infectious eye diseases
Diseases such as diabetes
Dark eyes
Prolonged exposure to direct sunlight
Poor nutrition
Smoking
Alcohol use
Heat from infrared exposure
Mechanism
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On the left, a normal lens receives light and focuses it
on the retina. On the right, a cataract blocks some light
from reaching the lens and distorts the light being
focused on the retina.
Types of Cataract
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The lens consists of three
layers
The outer layer is a thin,
clear membrane
It surrounds a soft, clear
material (cortex)
The hard center of the
lens is the nucleus
A cataract can form in
any part of the lens
Nuclear Cataract
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Occurs in the center of the lens
 In its early stages, the patient may become
more nearsighted or even experience a
temporary improvement in reading vision
 This so-called “second sight” disappears as
the lens gradually turns yellow and begins
to cloud the vision
 Seeing in dim light and driving at night may
be especially troublesome
Cortical Cataract
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Begins as whitish, wedge-shaped streaks on
the outer edge of the lens cortex
 As it slowly progresses, the streaks extend
to the center and interfere with light passing
through the nucleus
 Both distance and near vision can be
impaired
 Patients also have problems with glare and
loss of contrast
Subcapsular Cataract
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Starts as a small, opaque area just under the
capsule shell, usually at the back of the lens,
right in the path of light on its way to the
retina
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This type of cataract may occur in both eyes
but tends to be more advanced in one eye
than the other
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Often interferes with reading vision, reduces
your vision in bright light and causes glare
or halos around lights at night
Symptoms
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Blurred vision
 Increasing difficulty with vision at night
 Glare, especially at night
 Halos around lights
 The need for brighter light for reading
 Double vision in a single eye
 Fading or yellowing of colors
The lens appears cloudy
Diagnosis
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A doctor can usually detect a cataract while
examining the eye with an ophthalmoscope.
A doctor can identify the exact location of
the cataract and the extent to which it blocks
light by using an instrument called a slit
lamp, which allows examination of the lens
and other parts of the eye in more detail.
Prevention
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Consistent use of sunglasses with a coating to filter ultraviolet
(UV) light
Not smoking is useful and has other health advantages.
People with diabetes should work with their doctor to be sure the
level of sugar in their blood is well controlled.
A diet high in vitamin C, vitamin A , and substances known as
carotenoids (contained in vegetables such as spinach and kale)
may protect against cataracts.
Estrogen use by women after menopause may also be protective,
but estrogen should not be used solely for this purpose.
Finally, people who are taking corticosteroids for extended
periods might discuss with their doctor the possibility of using a
different drug.
Treatment
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Until vision is significantly impaired, eyeglasses
and contact lenses may improve a person's vision.
Wearing sunglasses in bright light and using lamps
that provide over-the-shoulder lighting may
decrease glare and aid vision.
Occasionally, drugs that keep the pupil dilated
may be used to help vision if the cataract is small
and located in the center of the lens.
The only treatment that provides a cure for
cataracts is surgery.
MACULAR
DEGENERATION
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MECHANISM
– (The area next to optic disc that defines fine
details at the center of visual field = macula)
* not enough blood supply to area
(disappearance of central vision due to
deterioration of pigment layer of retina)
ETIOLOGY
– * age
– * atherosclerosis
* hemorrhage
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SYMPTOMS AND SIGNS
– * Fine detailed vision is impaired
* Sharp vision deterioration (reading)
* peripheral vision is not affected
* loss of central vision
DIAGNOSIS
– * Ophthalmoscopy
* fluorescein angiography
* patient history
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TREATMENT
– * no known cure
* laser photocoagulation
* increase zinc in diet
* strong magnifying glasses
DIABETIC RETINOPATHY
MECHANISM
– * constriction of ocular blood vessels &
leakage of blood into retina
(microaneurysms, neovascularization =
new blood vessels)
* leakage of blood into vitreous humor
* scar tissue
 ETIOLOGY
– diabetics with uncontrolled glucose
levels
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SYMPTOMS AND SIGNS
– * impaired sharp vision
* blurred vision
* could lead to permanent blindness
DIAGNOSIS
– * Ophthalmoscopy
TREATMENT
– * Laser photocoagulation
* vitrectomy
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