Dynamics and static pupillometry in congenital Brown syndrome

Brown syndrome is conventionally regarded as a mechanical restriction of elevation in adduction, yet congenital cases have been presented that overlap with congenital cranial dysinnervation disorders (CCDDs), raising the possibility of subtle autonomic or neurogenic involvement.

In this cross-sectional comparative study, 12 patients with unilateral congenital Brown syndrome (mean age: 10.00 ± 4.73 years) and 20 age-matched healthy controls (11.3 ± 3.65 years) underwent comprehensive ophthalmic examination and quantitative static/dynamic pupillometry using the MonPack One Vision Monitor System. Static pupil diameter was measured under scotopic (0.1 cd/m²), mesopic (1 cd/m²), low photopic (10 cd/m²), and high photopic (100 cd/m²) conditions. Dynamic recordings included initial diameter; contraction amplitude, latency, duration, and velocity; and dilation latency, duration, and velocity.

There were no statistically significant differences between the groups in age, gender, best-corrected visual acuity, or any static or dynamic pupillometric parameter (all p > .05).

Static and dynamic pupillary functions appear preserved in unilateral congenital Brown syndrome, with no measurable involvement of pupillary autonomic pathways in the studied sample. Larger, multicenter studies are warranted to detect any subtle effects and to further clarify Brown syndrome pathophysiology within the proposed CCDD spectrum.