National Physical Therapy Examination (NPTE) Practice Exam

What does a lack of pupillary constriction in the right eye indicate when light is shone in that eye?

1. L optic nerve is affected

2. R oculomotor nerve is affected

3. R optic nerve is affected

4. L oculomotor nerve is affected

The correct answer is: R optic nerve is affected

When light is shone in one eye, the normal physiological response includes pupillary constriction in both the illuminated eye and the opposite eye, commonly referred to as the consensual reflex. If there is a lack of pupillary constriction in the right eye upon illumination, it suggests that there is a potential issue with the afferent pathway (the optic nerve) that transmits visual information from the eye to the brain. In this case, the correct interpretation points to an issue with the right optic nerve. A lack of pupillary constriction indicates that the input from the right eye is not being properly relayed to the brain to elicit the pupillary response, demonstrating that the right optic nerve is compromised. The other options focus on nerve pathways associated with the motor response or the other eye, which would not account for the specific lack of constriction observed in the right eye when light is shone directly into it.