Glaucoma
Open Angle Glaucoma
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Open Angle Glaucoma
, Primary Open-Angle Glaucoma, POAG
See Also
Glaucoma
Narrow Angle Glaucoma
Epidemiology
Most common type of
Glaucoma
(89%)
Lifetime
Prevalence
: 10% of U.S. population (50% are unaware of diagnosis)
More common in older patients
Rare under age 40 years
Prevalence
among those over 80 years old: 14%
However most undiagnosed
Glaucoma
is at age <60 years old
Risk Factors
Increasing age
Odds Ratio
increases 1.6 to 2.2 per decade of life
Prevalence
at age 40-49 years old
Black: 1.3 to 1.4%
Hispanic: 0.5 to 1.3%
Caucasian: 0.2 to 0.5%
Prevalence
at age >80 years old
Black: 11.3 to 23.2%
Hispanic: 12.6 to 21.8%
Caucasian: 1.9 to 11.4%
Ethnicity or Race
See age related
Prevalence
above
Black patients
Relative Risk
: 3.5 to 4 fold increase in
Glaucoma
risk over caucasian patients
Hispanic Patients
Relative Risk
: 2 fold increase in
Glaucoma
risk over caucasian patients
First Degree Relative with
Glaucoma
(4-16% Risk)
Sibling
Relative Risk
: 3.7 to 16
Child or parent
Relative Risk
: 1.1 to 2.2
Specific
Glaucoma
related genetic mutation accounts for <5% of cases
Diabetes Mellitus
Relative Risk
: 1.4 to 1.5
Severe
Myopia
(
Nearsighted
ness)
Eye Injury
Eye Trauma
Uveitis
Corticosteroid
s (especially intra- and periocular)
Pathophysiology
Increased
Aqueous Humor
production
Aqueous outflow obstruction by microscopic blockages
Normal chamber angles
Symptoms
Bilateral eyes affected but asymmetrically
Colored halos around lights
Asymptomatic until severe
Visual Field
or central loss
Visual Field
loss irreversible unless caught early
Compensation from opposite eye masks earlier visual changes
Insidious painless
Vision Loss
Peripheral
Vision Loss
progresses to blindness
Loss not symptomatic until 40% of nerve fibers lost
Signs
Pupil
dilatation
Increased Intraocular Pressure
(by
Tonometer
)
IOP < 22 mmHg: Normal if optic disks normal
IOP 22-30 mmHg: Borderline
IOP >31 mmHg: Abnormal
Progressive peripheral
Vision Loss
Stages of
Vision Loss
Stage 1: Loss of nasal and superior
Visual Field
Stage 2: Loss of peripheral
Visual Field
Stage 3: Total blindness
Screen
Visual Field
s by confrontation
Perimetry offers computerized
Visual Field
evaluation
Glaucoma
tous changes in the optic disc
Gene
ral
Focal thinning of neural rim
Nerves at edge of cup and edge of disc
Thinning seen at temporal (lateral) disc margin
Superficial
Hemorrhage
overlying disc edge
Diagnostic changes
Symmetrically enlarged cup-to-disc ratio >0.5 or
Cup-to-disc ratio difference between eyes >0.2 or
Significantly asymmetric cup in one eye
Diagnosis
Formal Open Angle Glaucoma diagnosis requires a combination of findings
IOP measurement
Stereoscopic
Optic Nerve
exam
Visual Field
testing
Intraocular Pressure
alone is not sufficient for diagnosis
Normal
Intraocular Pressure
in 50% of POAG
Most patients with
Intraocular Pressure
>22 mm Hg do not develop
Glaucoma
(with
Optic Nerve
injury)
Screening is not recommended to be performed in primary care (USPTF)
Combination of factors needed for diagnosis (see signs above)
Typically performed by eye specialists
Differential Diagnosis
Acute Angle Closure
Glaucoma
Presents as a painful
Red Eye
Requires immediate evaluation and management
Management
Gene
ral
Regular aerobic
Exercise
reduces
Intraocular Pressure
Emphasize
Medication Compliance
(<50% continue medications >1 year)
Simplify regimens as much as possible
Approach treatment in similar fashion to systemic
Hypertension Management
Start with initial first-line agents
Advance first-line agents
Add additional medications as needed for persistent elevated pressures
First Line Agents
Prostaglandin
Analogues (
Latanoprost
,
Travoprost
,
Bimatoprost
,
Tafluprost
,
Unoprostone
)
Once daily, effective agent with low side effects
Latanoprost
(
Xalatan
) 0.005% one drop daily
Intraocular Beta Blocker
s (
Betaxolol
,
Carteolol
,
Levobunolol
,
Metipranolol
,
Timolol
)
Less expensive than other
Glaucoma
medications
Consider other medications if higher risk for adverse effects
Systemic
Beta Blocker
use
Beta Blocker
s otherwise contraindicated (e.g.
COPD
,
Asthma
)
More adverse effects
Due to
Beta Blocker
systemic absorption with
Hypotension
and bronchoconstriction risk
See
Don't Open Eyes Technique for Eye Drop Instillation
(to reduce systemic absorption)
Second Line Agents
Intraocular Cholinergic
s (
Pilocarpine
,
Carbachol
)
Adjunctive Agents
Intraocular Sympathomimetic
(
Dipivefrin
,
Propine
)
Topical Carbonic Anhydrase Inhibitor (
Brinzolamide
,
Dorzolamide
)
Intraocular Alpha-Adrenergic
(
Apraclonidine
,
Brimonidine
)
Acute exacerbations of refractory chronic
Glaucoma
Systemic Carbonic Anhydrase Inhibitor
Combination agents to consider
Dorzolamide
and
Timolol
Maleate (Cosopt, generic)
Brinzolamide
and
Brimonidine
(Simbrinza, expensive)
Brimonidine
and
Timolol
(Combigen, expensive)
Surgery for refractory cases
Laser trabeculoplasty
May be used as first line therapy (esp. for patients non-compliant with topical drops)
Surgical trabeculectomy
Higher risk procedure used as last available option
Prevention
See
Preventive Eye Examination
for
Glaucoma
screening intervals
References
Alward (1998) N Engl J Med 339:1298-307 [PubMed]
Distelhorst (2003) Am Fam Physician 67(9):1937-50 [PubMed]
Gupta (2016) Am Fam Physician 93(8):668-74 [PubMed]
Infeld (1998) Postgrad Med 74:709-15 [PubMed]
Pelletier (2016) Am Fam Physician 94(3):219-26 [PubMed]
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