Congenital tonic pupil - what's behind?

Objective Tonic pupils are characterized by 1) a poor response to light, 2) a slightly better response to near stimuli, and 3) a slow redilation phase. This phenomenon most commonly occurs in adults between the ages of 20 and 40. It is associated with dysfunction of the ipsilateral ciliary ganglion. Tonic pupils in infants are extremely rare, only a few case reports associated with central hypoventilation syndrome, neuroblastoma, and Hirschsprung disease exist. Also two cases of orbital mass as the cause of unilateral tonic pupil in infants are documented in literature. In both cases biopsy was consistent with a benign, glial neural hamartoma with favorable outcome. Case report A two week-old female infant presented with anisocoria to the eye clinic. The diagnosis of a congenital tonic pupil on the left side was made after a diluted 0,1% pilocarpine test. Results of ocular motility, alignment, external and neurological examination were normal. Magnetic resonance imaging (MRI) demonstrated a soft-tissue mass in the inferolateral portion of the left orbit, interposed between the lateral and inferior rectus muscles. Results Repeated ultrasound examinations of the orbit, MRI scans, ophthalmological and neurological follow-up examinations have shown no changes over two years. Conclusion Follow-up of the lesion without biopsy might be appropriate in infants with congenital unilateral tonic pupil and typical imaging findings. In addition to clinical controls, ultrasound is particularly suitable as a non-invasive examination method.
Keywords: tonic pupil, glial neural hamartoma, orbit