Transcript שקופית 1

Glaucoma
What is Glaucoma?
• Glaucoma is an eye disease where the
eye’s optic nerve is damaged
• It is one of the leading causes of blindness
in Canada
Eye Anatomy
• The optic nerve is a
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bundle of nerve
fibers
It carries visual
information from
the retina to the
brain
Fluid Circulation
• The eye has an
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internal fluid
circulation system
Fluid is produced at
the base of the iris
Fluid Circulation
• The fluid flows
through the pupil
to the front of the
iris
Normal Visual Field Healthy Optic Nerve
Damaged Visual Field
Sick Optic nerve
Elevated
IOP
There are several different forms of
glaucoma
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Primary Open Angle Glaucoma
Low Tension Glaucoma
Secondary Glaucoma
Angle Closure Glaucoma
Primary Open Angle
Glaucoma (POAG)
• POAG is the most common form of glaucoma
• It occurs when the fluid drainage is poor and
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fluid builds up in the eye and the internal eye
pressure goes up
This increased pressure can cause damage to
the optic nerve and vision loss
The exact mechanism of damage is still
unknown
Symptoms of Primary Open
Angle Glaucoma
• POAG develops gradually and painlessly and
has no initial symptoms
Vision is normal in
the early stages
Symptoms of Primary Open
Angle Glaucoma
• If untreated, peripheral or side vision is
slowly lost
Tunnel vision
Symptoms of Primary Open
Angle Glaucoma
• Eventually, all vision may be lost
Risk Factors for Primary
Open Angle Glaucoma
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High Intraocular (Eye) Pressure
Over the age of 40
Family history of glaucoma
African or Caribbean descent
Thin cornea
High myopia (Nearsightedness)
Diabetes
High blood pressure
Ocular Hypertension
• Some people can have high eye pressure but
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the optic nerve does not get damaged
This condition is called ocular hypertension
These patients must be closely followed
because of the risk of developing glaucoma
Low Tension Glaucoma
• Low Tension (or Normal Tension) Glaucoma is
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not as common
In these cases, the eye pressure is in the
normal range but the optic nerve still gets
damaged
The exact mechanism of damage is still
unknown
Secondary Glaucoma
• Glaucoma can develop as a complication from
other conditions including:
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Eye injuries
Uveitis (internal eye inflammation)
Pigment dispersion
Diabetes (Neovascular glaucoma)
Steroid use
Angle Closure Glaucoma
• This type of glaucoma is an emergency
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situation
It occurs when the iris itself blocks the
drainage angle and results in a sudden
increase in pressure
Symptoms include severe eye pain, nausea,
eye redness and very blurred vision
Immediate treatment is required
How is glaucoma detected?
• Regular eye examinations by an optometrist
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or ophthalmologist are vital to detecting
glaucoma
A number of tests are performed
Glaucoma Tests:
Case History
• A patient’s medical history, family history and
background are important to determine the
presence of risk factors
Glaucoma Tests:
Visual Acuity
• A refraction is done to determine best corrected
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vision
This shows central vision function
Glaucoma Tests:
Slit Lamp & Gonioscopy
• A special microscope called a slit lamp is used to
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examine the structures of the eye
A gonioscopy lens may be used to view the
drainage angle
Glaucoma Tests:
Tonometry
• Eye pressure is measured with an instrument
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called a tonometer
Three types that are commonly used are:
– Goldmann (Perkins)
– Non-contact (air puff)
Glaucoma Tests:
Ophthalmoscopy
• Eye drops may be placed in the eyes to dilate the
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pupils
Special magnifying lenses are used to examine the
retina and optic nerve for damage
Normal Optic Nerve
Suspicious Optic Nerve
Glaucoma Tests:
Ophthalmoscopy
• Advances are being made in digital imaging of the
retina
Glaucoma Tests:
Visual Field Test
• Peripheral (side) vision is tested with a
perimeter
The patient responds to flashes of
light in different locations
Recent Developments
• Recent studies have found that patients with
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thin corneas have a greater risk of developing
glaucoma
Measurement of corneal thickness using an
instrument called a pachymeter will become
increasingly important
Recent Developments
• New tools for measuring peripheral vision
(visual field) have been developed such as
the FDT
Recent Developments
• Laser technology can now be used to image
the retina and optic nerve and measure nerve
fiber layer thickness
Recent Developments
Recent Developments OCT
Recent Developments HRT
Glaucoma Treatment
• The goal is to decrease the eye pressure
• The three main categories of treatment are:
– Medication
– Laser trabeculoplasty
– Conventional surgery
• Unfortunately, these treatments will not
reverse any existing damage but they can
slow the progression of the disease
Glaucoma Medications
• Medications are usually
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the first type of
treatment used
Eyedrops or pills are
used to either decrease
the fluid production or to
increase the fluid
drainage
Glaucoma Medications
• There are several different types of
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medication available
The right choice will depend on what other
medications are being taken, other medical
conditions and the effectiveness in
decreasing the eye pressure
Often, combinations of eyedrops are used •
Glaucoma Medications
Non Specific Beta Blockers
• Levobunolol 0.25%, 0.5%Betagan Timolol0.25%,
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0.5%, 0.1%Gell
Nonselective beta-adrenergic blocking agents
lower IOP by reducing aqueous humor
production
Contraindications;
Lung : bronchial asthma; COPD
Heart :sinus bradycardia; second- and third-degree AV
block; overt cardiac failure; cardiogenic shock
May cause bradycardia and asystole when used in
combination with systemic beta-blockers (may cause
additive effects).
Precautions May potentiate muscle weakness with
myasthenic symptoms (e.g., diplopia, ptosis,)
Glaucoma Medications Beta2 Spesific
• -Betaxolol
• (Betoptic-S)– Beta1-selective adre’
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antagonist,
Possibly less pulmonary effects
• IOP-lowering effect is slightly less than
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nonselective beta-blockers.
Contraindications: bronchial asthma; severe
COPD.
Heart Same as nonselective beta-blockers
Adrenergic Drugs:
• Brimonidine (Alphagan) –
• lower IOP by reducing aqueous humor
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production
Coadministration:
Tricyclic antidepressants may decrease effects .
CNS depressants (eg, barbiturates, opiates,
sedatives) may potentiate effect.
Caution in CVS disease, depression, cerebral or
coronary insufficiency, orthostatic hypotension,
and Raynaud syndrome;
Apraclonidine 0.5%, 1% (Iopidine)
Selective alpha-adrenergic agonist
Monitor pulse and BP with CVS drugs;
Not for use concurrently with MAOIs
Carbonic Anhydrase Inhibitors
• TOPICAL
– Dorzolamide (Trusopt) 2%; Brinzolamide (Azopt)
1%;
– Reversibly inhibits CA, reducing H+ secretion at
renal tubule, increases renal excretion of Na / K- CO2,
and H2O to decrease production of aqueous humor.
– Azopt may cause less ocular discomfort
• Systemic
– Acetazolamide- Methazolamide
– CI :Hx metabolic or ketoacidosis, hepatic
insufficiency, severe COPD, kidney stones, sulfa
allergy, or blood dyscrasias (eg, sickle cell anemia);
– contraindicated in first trimester of pregnancy
because of possibility of teratogenicity
Prostaglandines- Prostamides
Xalatan – Travatan – Lumigan
• Decreases IOP by increasing outflow of
aqueous humor through Uveoscleral
pathways
• Long-term use can cause darkening of iris
and thickening of lashes; use with care in
monocular therapy for cosmetic reasons;
do not administer while wearing contact
lenses
Pilocarpine – The oldest drug
• Pilocarpine 1%, 2%, 4% - A naturally occurring
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alkaloid, pilocarpine
Mimics the muscarinic effects of acetylcholine at
postganglionic parasympathetic nerves.
Directly stimulates cholinergic receptors in the
eye, decreasing resistance to aqueous humor
outflow
Facilitates Convetional outflow ( TM)
Laser Trabeculoplasty
• This laser treatment helps to increase the
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fluid drainage
The surgeon uses a laser to burn the spongy
meshwork that is located in the drainage
angle
Conventional Surgery
• With this treatment, the surgeon creates a
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new opening in the eye for the fluid to drain
out from
If the new opening becomes plugged or
narrowed, further surgery may be required
Coping with Vision Loss
• Many patients with sight loss due to
glaucoma can benefit from low vision aids
• Optometrists can perform low vision
assessments and prescribe magnifying
devices to enhance both distance and
reading vision
These aids will not restore sight to normal •
levels but they allow people to maximize
the amount of vision remaining
Early Detection and
Treatment
• Regular eye health examinations are
important to detect glaucoma early so that
treatment can be started and vision loss
can be prevented