A pupil responds to accomodation but light reflex is absent. It is known as: March 2005

Ans. C: Argyll Robeson pupil Argyll Robeson pupil is miotic, irregular pupil that does not react to light but responds to accommodation, which indicates a lesion in the rostral midbrain and is seen in 70% of tabetic (Tabes dorsalis is syphilitic demyelination of the posterior columns, dorsal roots and the dorsal root ganglion leading to ataxic gait, paraesthesiae, loss of deep pain, temperature and joint position sensation, areflexia, bladder disturbance and impotence). Elicitation: To check for pupillary reflex, lights should be switched off in the examination room. A flashlight is shown in one eye at a time and both the direct and consensual reflexes (i.e., reflex in other pupil) are observed. The light is then switched on, and after a few minutes pass for the patient to adjust to the ambient light, the patient is asked to look straight at a distant object. Either the examiner's finger or the tip of a pen is placed about 4 to 6 inches in front of the eyes at the level of the bridge of the nose and patient is asked to switch gaze from the distant object to the object in front of the patient. Pupillary response to this near focus is noted. Normal response: Pupils are regular and constrict promptly and equally to accommodation and to direct and indirect light. Positive response: Brisk pupillary constriction occurs after accommodation. Pupils do not respond to light In diphtheria, the reverse of Argyll Robeson pupil may be seen.