Question of the Week

It is 9PM on St. Patrick’s Day, and you are the resident on-call. You are paged regarding a 57-year-old man in the emergency room who says he has been “seeing rainbows” for about 2 hours. During your interview, he tells you he was walking out of a well-lit bar at night when all the sudden he had a horrible pain in his left eye. Now, he reports blurry vision with a headache and sees little rainbows when looking at lights. He also reports nausea, but assures you that he has not had anything to drink tonight. He has no ocular or surgical history aside from glasses for many years.

Which of the following is most useful to confirm the leading diagnosis?

A. Order a blood alcohol level.

B. Order an immediate CT with IV contrast.
C. Perform gonioscopy.

D. Perform indirect biomicroscopy with scleral depression.

E. Recommend OTC pain control and proceed with his St. Patrick’s Day plans.

Answer

Correct Answer: C

Explanation:

The correct answer is C. This patient is having an angle-closure attack, which would be seen on gonioscopy. Acute angle-closure (AAC) is an ophthalmic emergency caused by blocked outflow of aqueous through the trabecular meshwork, leading to a rapid and severe rise in intraocular pressure (often 50–80 mmHg). Risk factors include hyperopia (hinted at here by his long-time use of reading glasses), shallow anterior chamber, narrow angles, cataracts, female sex, and Southeast Asian, Chinese, or Inuit ancestry. Smaller, hyperopic eyes are more anatomically predisposed to AAC. The mechanism usually involves a “pupillary block,” where fluid builds up behind the iris, pushing it forward until it occludes the trabecular meshwork. Aqueous humor keeps being produced, with no outflow tract, leading to a spike in IOP and symptoms such as intense pain, headache, blurred vision, nausea, and vomiting. The rainbow-colored halos this patient sees around lights are a classic AAC finding—not just a St. Patrick’s Day coincidence—caused by corneal edema and abnormal light refraction. Other possible exam findings (not included in the stem) are a fixed mid-dilated pupil, conjunctival injection, mild anterior chamber inflammation, and optic nerve swelling. Immediate treatment includes medications to lower IOP (acetazolamide, mannitol, topical beta-blockers, alpha-2 agonists) and pilocarpine to constrict the pupil. IOP should be monitored every 30–60 minutes. Definitive treatment is laser peripheral iridotomy or cataract extraction with surgical iridotomy, and it’s essential to examine the fellow eye since it may have similar anatomy. Although it’s St. Patrick’s Day, we should believe the patient when he says he hasn’t been drinking, so checking a BAC (A) isn’t needed. A CT scan (B) isn’t indicated at this stage with no concerning neurologic symptoms. Indirect ophthalmoscopy with scleral depression (D) would be for retinal tear/detachment suspicion, and you definitely shouldn’t discharge him (E) until his IOP is under control.

Source:

Khazaeni B, Zeppieri M, Khazaeni L. Acute Angle-Closure Glaucoma. In: StatPearls. StatPearls Publishing; 2025. Accessed March 14, 2025. http://www.ncbi.nlm.nih.gov/books/NBK430857/

Image credit: AAO