In the first part of the fifth installment of Clinical Conversations in Retina, Daniel Epshtein, OD, FAAO, discusses retinal emergencies with Alison Bozung, OD, FAAO, who works in the ophthalmic emergency department at the Bascom Palmer Eye Institute.
Defining acute retinal artery occlusions
Retinal artery occlusions occur when the retinal arterial blood supply is cut off or blocked, leading to retinal ischemia. Occlusions are often considered acute within hours of onset, but Dr. Bozung acknowledges that it can be difficult to clearly define this time period.
Cases of ischemia in a limb are considered acute when it has been less than 2 weeks—an example of the variability of defining “acute.” For a number of reasons, patients may not present to their eyecare provider immediately. Unfortunately, this means that, for many, retinal damage could lead to irreversible vision loss.
Of note, 4.5 hours is considered the cutoff for the administration of tissue plasminogen activator (TPA) at many stroke centers. When it comes to retinal artery occlusions, 24 hours has become a fairly common standard, as it is an important window of time that may allow for some vision recovery.
Managing patients with acute retinal artery occlusions
Dr. Bozung emphasizes the importance of first searching the eye for a visible embolic source, which could assist in determining the etiology of the occlusion and deciding the next steps.
If no embolic source is visible, then other sources for the occlusion must be considered, such as giant cell arteritis (GCA). Usually, GCA does not present with emboli but does come with retinal whitening.
By definition, a retinal artery occlusion is classified as a stroke, and it is important to send patients to a stroke center or at least an emergency room. Patients may be tempted to believe their vision loss to simply be an eye problem, but these occlusions are indicative of central nervous system ischemia.
Roughly 25% of patients will present with evidence of silent stroke on magnetic resonance imaging (MRI), and patients with retinal artery occlusions are at risk for further stroke in the future.
Key symptoms of GCA to consider
Although GCA is typically handled in the neuro-ophthalmology space, 5% of central retinal artery occlusions are caused by GCAs. It is important for doctors to monitor for symptoms of GCA as it is an emergency that needs to be treated immediately.
Some symptoms to look out for include:
- Jaw claudication
- Headache
- Weight or appetite loss
- Lethargy for the past few months
Testing for giant cell arteritis
Dr. Bozung makes sure to leave a note about any lab work that needs to be done, such as testing for the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP).
Patients under 50 have a rare chance of developing GCA, but it is important to ask patients over 50 about GCA symptoms. Testing older patients, even if they are not showing any symptoms, could be an important preventative step.
Dr. Bozung describes a recent incident with a patient who clearly had GCA in one eye but was either not tested or treated for it during her stay at the hospital. When Dr. Bozung took a look at her eyes a week later, the patient’s other eye had unfortunately become involved.
She emphasizes the importance of testing to prevent circumstances such as this one. It might be easy to overlook the details of ocular examinations in general hospitals, but GCA should be treated as a top emergency among optometrists and ophthalmologists.
Treatments for patients with acute retinal artery occlusions
It is unclear whether ocular massages lead to a great visual benefit, though it is worth a try. Paracentesis also has unclear visual benefits, though it should be used with caution due to the possibly harmful side effects. Additionally, hyperbaric oxygen therapy seems to have one of the best outcomes, though it can be difficult to find.
In an ongoing study at Mount Sinai hospitals, emergency rooms now have optical coherence tomography (OCT) on hand. If a neurologist suspects a central retinal artery occlusion (CRAO) or a central branch retinal artery occlusion (BRAO), they can perform an OCT and send it to an on-call retina specialist to confirm the diagnosis.
Then, with the patient’s approval, doctors can go ahead with the TPA protocol. Interestingly, TPA originally started as a treatment for ischemia with an onset within 4.5 hours—and appears to work well.
Factoring in the window for TPA treatments
A study used TPA for CRAO, but ended the trials early due to cerebral hemorrhaging. The researcher believes a major issue in this study was the relatively lengthy time from the onset of symptoms to the initiation of TPA treatment.
Many patients were coming in 15 to 20 hours after onset, which is far beyond the 4.5-hour window within which TPA is used in ischemic stroke patients.
Conclusion
Acute arterial occlusions should be taken seriously and treated urgently to prevent further vision loss. As they may be indicative of other strokes or diseases, it is important for doctors to thoroughly assess patients’ symptoms.
In part II, Dr. Epshtein and Dr. Bozung will discuss treatment for patients who have had onset for a week and retinal detachments.
Don't miss In Case of Retina Emergency: Part II for further insights on managing retinal detachments!
