Case Presentation by Dr. Sean Teshima McCormick, MD
The patient is a 74 year old male with a history of HTN, HLD who reports to the emergency department complaining of vision loss in his right eye 2 hours prior to presentation. The patient reports that he was sitting on his couch watching TV when it looked like someone was “turning down a dimmer switch” on the vision in his right eye. After a few seconds, it went completely black. He denies any pain at the time or currently. He denies any trauma. He denies seeing flashing lights, floating specs or cobwebs in his vision. He denies seeing anything that looked like a curtain coming over his vision. He reports no changes in his left eye. He denies any headaches, dizziness, focal numbness or weakness.
Reports changes in his vision as described above
Denies fever, headache, chest pain, shortness of breath, N/V, diarrhea, constipation, dysuria, bleeding problems, new rashes
PMH: HTN, HLD
PSH: Left knee
Medications: HCTZ, simvastatin
FH: HTN, DM
SH: reports 1 pack per day tobacco use, reports occ alcohol use, denies any illegal drugs
BP: 170/ 110 HR: 64 RR: 18 T: 37.0 Spo2: 99%
General: well-appearing thin man in no acute distress
Eyes: right pupil is round, shows afferent pupillary defect, left pupil is round and reactive, EOM intact bilaterally, painless, visual acuity is hand motion only right side, 20/40 on left, loss of confrontation fields on right eye, no conjuctival hemorrhage bilaterally, no signs of trauma
Cardiovascular: RRR, normal s1, s2
Respiratory: CTAB, no wheezes, crackles
Gastrointestinal: abdomen soft, non-tender, non-distended, no organomegaly
Neurological: APD noted on right pupil, other CN intact, strength 5/5 bilaterally in upper and lower extremities, no sensory deficits
Musculoskeletal: no lower extremity edema
Skin: no rashes seen
1) Based on the history and physical examination, what is the most likely diagnosis?
a) Retinal Detachment
b) Vitreous Hemorrhage
c) Amaurosis Fugax
d) Central Retinal Artery Occlusion
e) Pituitary tumor
2) What would you expect to see on fundoscopic exam?
3) Which diagnostic test should be ordered immediately?
a) Ocular Ultrasound
b) MRI Head and Brain
c) Carotid Duplex
d) Fluorescein Stain
e) Optical Coherence Tomography
Answers and Discussion:
1) D. Central Retinal Artery Occlusion.
CRAO causes sudden painless monocular vision loss. Patients often describe the vison loss as someone slowly dimming their vision until it is completely black. These patients will only be able to see hand motions out of the affected eye and will have an afferent pupillary defect. The most common risk factors for CRAO are HTN, HLD and smoking. Patients with a retinal detachment can also experience a sudden painless monocular vision loss. However, these patients will often describe flashing lights and floating specs, thought to be caused by nonspecific stimulation of the retina as it detatches. They will describe their visual field as obscured by a moving curtain. They should still have parts of their visual field intact. Patients with vitreous hemorrhage will decribe their vison as seeing “cobwebs.” This is usually a progression of diabetic disease or the result of trauma. Amaurosis fugax is by definition a transient phenomenon and often is resolved by the time the patient presents to a healthcare professional. Pituitary tumor will cause a bitemporal hemianopsia, not a monocular vision loss.
CRAO is caused by the occulsion of the central retinal artery, which supplies the portion of the retina responsible for central vision. In this image, since the artery is occluded, the central retina is pale. A “cherry red spot” is seen at the macula. This occurs because the retina is thinner at the macula and the retinal pigment and choroid vessels can be seen. Additionaly, some people have addional blood supply to the macula that may result in a small area of preserved vision known as macular sparing. Image A is a branch retinal artery occlusion. Here you can see the area of pallor is confined to smaller distribution in the inferior portion of the retina instead of the entire central vision. Image C is a retinal detachment. Image D is a vitreous hemorhage. Image E is a normal retina. In contrast to image B, here you can see good blood supply to the central retina.
3) C. Carotid Duplex
The most common cause of CRAO is ipsilateral carotid artery athlerosclerosis. Since these patients are at risk of stroke, carotid duplex must be ordered emergently. Cardiogenic embolism is the second most common cause so an EKG should also be ordered. An echocardiogram should be considered if there are significant risk factrors. Risk factors for cardiogenic source include atrial fibrillation, endocarditis, valvular disease, MI, IVDA. An ocular ultrasound would aid in the diagnosis of retinal detachment. An MRI would aid in the diagnosis of intracranial mass. A fluorescein stain would aid in the diagnosis of corneal abrasion. OCT would aid in the diagnosis of macular degneration, macular edema and epiretinal membrane.
CRAO will present as sudden painless monocular vision loss that patients describe as “dimming” of their vision. This is an emergency due to the risk of stroke. Patients with HTN, HLD and smoking are at greater risk. On physical exam, patients will have an APD in the affected eye and will often only be able to make out hand movements. Diagnosis is made by fundoscopic examination which reveals a pale central retina often with macular sparing which appears as a “cherry red spot.” Since carotid artery atherosclerosis and cardiogenic emboli are the most common etiologies, there is concern for cerebral vascular accident. A work up should include carodtid duplex and EKG, and possibly an echocardiogram. 10-15% of CRAO are associated with giant cell arteritits so a CRP and ESR should also be ordered. Vasculitis, sickle cell disease and hypercoagulable states are less common causes. Therefore, hematologic and coagulation studies should also be considered. Currently there is no standard treatment, however several therapies have been associated with better outcomes. Ocular massage and anti-platelet therapy may be initiated to help restore blood flow. Hyperbaric oxygen therapy has also been shown to improve outcomes in CRAO and Detroit Receiving Hospital is a hyperbaric referral center. Other experimental therapies include thrombolytics, mannitol to decrease intraocular pressure and nitroglycerin to increase bloodflow.