Professional and Linguistic Assessments Board (PLAB) Practice Exam

Which condition may cause pupils to be unreactive to light?

1. Congenital glaucoma

2. Argyll Robertson pupil

3. Acute glaucoma

4. Traumatic iritis

The correct answer is: Argyll Robertson pupil

The Argyll Robertson pupil is characterized by the pupils being small and unequal, and importantly, they do not react to light but do constrict during accommodation. This phenomenon is often associated with neurosyphilis, a condition that can affect the central nervous system. The unreactive pupils to light are a direct result of the loss of the reflex pathways that mediate the pupillary light response, while the accommodation reflex remains intact. Understanding this pupil reaction is crucial in clinical settings as it can serve as an indicator of underlying neurological issues, particularly those related to syphilis, which can lead to significant morbidity if left untreated. In contrast, other conditions listed, like congenital glaucoma, acute glaucoma, and traumatic iritis, typically do not specifically present with pupils that are unreactive to light in the manner seen in Argyll Robertson pupils. Instead, these conditions often affect the overall health of the eye or lead to changes in intraocular pressure rather than purely affecting the pupillary light reflex.