Increased Intraocular Pressure:

Definition/Etiology:

Increased intraocular pressure is just what it sounds like, an increase in the pressure of the eye. For our purposes, we are going to talk about 2 conditions which can cause that increase: 

• Central Retinal Artery Occlusion (CRAO)
• Acute Angle Closure Glaucoma (AACG)

Central retinal artery occlusion is a condition which causes sudden, painless, unilateral blindness. Failure to restore circulation to the retina can cause permanent loss of vision within 60-90 minutes. It can be caused by:

• Emboli (maybe a-fib)
• Thrombosis
• Hypertension
• Giant Cell arteritis
• Angiospasm

Acute Angle Closure Glaucoma occurs when aqueous humor cannot escape the anterior chamber. For those who don’t know, aqueous humor is the clear fluid filling the space in the front of the eyeball between the lens and the cornea. I know, it always makes me think of good humor which makes me think of ice cream, but I digress.

The resulting pressure eventually compresses the optic nerve. Just like the retinal occlusion, this is an emergency that requires prompt treatment. 

Pathophysiology:

In CRAO occlusion of the central retinal artery from one of the earlier mentioned conditions, results in retinal ischemia, vision loss, and eventual necrosis.

An acute attack of angle-closure glaucoma is precipitated by pupillary dilatation, leading to increasing iris and lens contact increasing the pupillary block.[7] The increasing pupillary block leads to bulging of the iris, acutely closing the angle between the iris and cornea, thus obstructing the aqueous humor outflow tract. The intraocular pressure rises acutely, leading to symptomology.

Clinical Presentation:

CRAO
Sudden, painless, unilateral blindness
Patients have stated this feels like “a curtain shade coming down over the eye”
Elevated intraocular pressure. Normal is 10-21 mm Hg as measured by a tonometer.

AACG

• Acute Eye pain
• Decreased peripheral vision
• Halo around lights – this one is important. When it comes to eye problems, if the patient sees a halo around lights, the most probable diagnosis is this one
• Severe headache
• Eye redness
• Fixed or slightly dilated pupil
• Cornea with a foggy appearance

Collaborative Management:

With both of these conditions we want to get a visual acuity test. It should be part of your initial assessment. 

Both will need an intraocular pressure measurement with a tonopen.

With CRAO, we should get an EKG (a-fib?) and some blood work (coagulopathies?)

Management:

CRAO

• Place supine to optimize circulation
• Breathe into a paper bak which may increase arterial pCO2 and cause vasodilation
• Diamox IV and a topical beta blocker like timoptic may decrease pressure
• Sublingual Nitro – you tell me why! Thats right, vasodilation.
• Fibrinolytics may be considered. Yes, you heard me right, you might give TPA or TNK for an eye problem. 

AACG

• Focus is on draining aqueous humor and decreasing pressure
• Topical miotic (pupil contracting) eye drops like pilocarpine to help the outflow of the humor
• Topical beta-blockers like Timoptic and carbonic anhydrase inhibitors like Diamox to decrease production of aqueous humor.
• Antiemetic
• Narcotics

Evaluation | Patient Monitoring | Education:

CRAO 

Does their vision return?

Did the occlusion resolve?

AACG

Decrease in pain

Increase in visual acuity

Pt education for AACG will include ways to not increase the pressure:

Do not have your head lower than your waist

Avoid coughing and straining

Do not lift more than 5 pounds

Linchpins: (Key Points)

• Early identification
• Early intervention
• Emergency