Red reflex examination. (A) Normal, symmetric red reflex. (B) Normal red reflex in the patient’s right eye, and abnormal, diminished red reflex in the patient’s left eye, which is most commonly caused by refractive error between the eyes, but can also be caused by a more serious pathology (e.g., retinoblastoma). (C) Normal red reflex in the patient’s right eye and no reflex in the patient’s left eye, which occurs when the reflection is blocked by an opacity such as a cataract.
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