A 23-year-old woman is noticed to have irregular pupils on routine examination. She has one large pupil, which has minimal response to light stimulation, but it does respond to accommodation. The eye movements are normal and she experiences no double vision.For the above patient with a pupillary abnormality, select the most likely diagnosis
**Core Concept:** Pupillary reflexes are essential components of the light reflex (ocular reflex) and are mediated by the parasympathetic and sympathetic autonomic nervous systems. The pupillary light reflex includes constriction and dilation in response to light, while accommodation is a response to the distance of objects. The size and responsiveness of pupils can provide valuable information about neurological and ocular health.
**Why the Correct Answer is Right:** The patient in this scenario has a combination of pupillary abnormalities, including a large pupil, minimal light response, and accommodation response. This suggests a lesion affecting the parasympathetic part of the pupillary reflex. The presence of accommodation response indicates that the lesion is located above the optic chiasm, excluding conditions like optic neuritis, optic pit, and Leber's hereditary optic neuropathy.
**Why Each Wrong Option is Inaccurate:**
A. This option is incorrect because the patient's accommodation response rules out optic neuritis and optic pit, which would typically present with a loss of accommodation response.
B. While the patient's accommodation response is preserved, the lesion is located above the optic chiasm, not in the optic nerve head. Optic nerve head edema is not the correct diagnosis.
C. The preservation of accommodation response in this patient makes this diagnosis less likely compared to other options.
D. This option is inaccurate due to the preservation of accommodation response, which is not seen in amaurosis fugax.
**Clinical Pearl:** Recognizing the preserved accommodation response and the lesion location helps narrow down potential differential diagnoses for the patient's pupillary abnormalities. A clinical examination with attention to pupillary reflexes and accommodation can provide valuable information in diagnosing neurological and ocular disorders.
**Correct Answer:** C. Amaurosis fugax (brief loss of vision due to transient cerebral ischemia) is a possible diagnosis for this patient, considering the preserved accommodation response and the lesion location. Amaurosis fugax can cause transient focal neurologic deficits, including visual loss, when a blood vessel is occluded. This condition should be considered alongside other possibilities like migraine, migraine-related visual disturbances, or other transient ischemic attacks.