This 2-year-old boy is found to have poor vision with his left eye when his mother covers his right eye casually. His health has been completely normal. Your exam confirms that he is nearly blind in the left eye but sees normally with the right eye. You also find that the red reflex is absent in the left eye. What is the most worrisome and urgent diagnosis?
Incorrect. You are looking at loss of the red reflection (called a “reflex”) in the pupil of the left eye. You see the normal red reflex in the normal right eye. The abnormal pupil appears white—so-called “leukocoria,” also called the “cat’s eye reflex.” Cataract is an important—but not the most worrisome--cause. For most congenital cataracts, there is no apparent precipitating cause. The infant might have had an occult intrauterine infection. Try for the most important cause!
Correct. You are looking at loss of the red reflection (called a “reflex”) in the pupil of the left eye. You see the normal red reflection in the right eye. The abnormal pupil is white—so-called “leukocoria,” also called the “cat’s eye reflex.” Retinoblastoma is the most worrisome cause. The most common intraocular tumor of childhood, it starts in the retina, often growing into the vitreous to obliterate the red reflex. Untreated patients have a 100% mortality rate. Prompt and skilled treatment can be life-saving, so urgent referral is needed. Examination of the pupillary light reflections is a standard maneuver in newborn nurseries.
Incorrect. Not a bad guess, but this is not the most worrisome cause of loss of the pupillary red reflex, as you see here in the left eye. Toxocariasis is a rare retinal infection acquired by ingestion of dirt-based round worms. It is very difficult to treat but not life-threatening. Try again!
Incorrect. Coats’ disease is a congenital retinal disorder characterized by massive serous leakage from incompetent retinal vessels. The leakage turns the normal pupillary reflection from red to white (“leukocoria,” also called “cat’s eye reflex”). Typically monocular, Coats’ disease impairs vision and is difficult to treat, but is not life-threatening. Try again!