A patient presents with sudden decreased vision, a pupil about 4 mm and fixed, and a red eye. Which diagnosis is most likely?

A patient presents with sudden decreased vision, a pupil about 4 mm and fixed, and a red eye. Which diagnosis is most likely?

• A. Stroke
• B. Cataract
• C. Brain Tumor
• D. Glaucoma

Answer: (D)

When the eye presents with sudden vision loss, a red eye, and a pupil that is mid-dilated and fixed, the scenario points most strongly to acute angle-closure glaucoma. This is an emergency caused by a rapid rise in intraocular pressure when the drainage angle of the eye becomes blocked. The high pressure affects the optic nerve and the iris, making the pupil appear mid-dilated and poorly responsive to light, while the eye looks red and painful. This combination—acute red eye with sudden vision change and a fixed, mid-sized pupil—is classic for glaucoma. Other causes listed don’t fit this picture. A stroke or brain tumor can affect vision but would not produce a red, inflamed eye with a fixed pupil. A cataract causes progressive, not sudden, vision decline and typically doesn’t produce a red eye or a fixed pupil.

When the eye presents with sudden vision loss, a red eye, and a pupil that is mid-dilated and fixed, the scenario points most strongly to acute angle-closure glaucoma. This is an emergency caused by a rapid rise in intraocular pressure when the drainage angle of the eye becomes blocked. The high pressure affects the optic nerve and the iris, making the pupil appear mid-dilated and poorly responsive to light, while the eye looks red and painful. This combination—acute red eye with sudden vision change and a fixed, mid-sized pupil—is classic for glaucoma.

Other causes listed don’t fit this picture. A stroke or brain tumor can affect vision but would not produce a red, inflamed eye with a fixed pupil. A cataract causes progressive, not sudden, vision decline and typically doesn’t produce a red eye or a fixed pupil.