A 60 year old woman presents to the emergency department with painless right sided vision loss that began 16 hours ago. She initially experienced a right sided headache that spontaneously resolved. Since that time, she has had progressively worsening vision deficits. On arrival, patient reported right upper quadrantanopsia.
Vital signs: Blood pressure of 149/75mmHg, heart rate 92 BPM, SpO2 98%, and temperature of 36.8C.
What bedside imaging can be done to help differentiate causes of vision loss?
Bedside ocular POCUS can be performed with the linear probe to help visualize if there is a pathologic cause within the eye.
3 clips of the right eye are shown below. What are the findings that are noted within the images?
The first clip is performed in B mode and demonstrates the retrobulbar spot sign, thought to be caused by a calcified embolic plaque that has obstructed flow within the central retinal artery.
The second and third clips displays flow disturbance that has been detected color flow doppler. As you can see, there is difference in flow between the left and right eyes.
The fourth image shows resistive index measured within the right eye.
RI = (PSV – EDV)/PSV
- RI = Resistive Index
- PSV = Peak Systolic Velocity
- EDV = End Diastolic Velocity
This is a measure of vascular resistance against blood flow. When elevated, this suggests a process that is associated with decreased ocular blood flow.
Case Conclusion:
A CT head was performed in the EC and the patient was evaluated by ophthalmology. She was subsequently given the diagnosis of central retinal artery occlusion. She was admitted to the hospital for further workup. Her workup within the hospital was significant for a patent foramen ovale, and she was recommended outpatient heart monitor and TEE. She was started on steroids, brimonidine, and aspirin. She was also recommended for ocular massage.
Learning Points
In-patient workup for CRAO is similar to that of a CVA. Patient’s should receive:
- TTE
- Carotid Duplex
- MRI/MRA of the brain
- Lower extremity duplex
There is no one definitive treatment for CRAO, however, current management guidelines do include recommendations such as:
- Hyperbaric oxygen
- Ocular massage
- Thrombectomy
- IV thrombolytics
If thrombolytics are to be given, they should be administered within 4.5 hours of symptom onset to further facilitate function recovery and improved visual outcomes.