If significant orbital edema prevents visual assessment of the pupillary light reflex, ocular ultrasound can be a useful alternative. 

1. Set up for a standard ocular POCUS exam. 
2. Place the linear probe transversely over the lower portion of the eye and tilt it upward to visualize the iris and pupil. 
3. Shine a light over the affected eye to observe the direct light reflex. 
4. For consensual reflex, shine the light over the opposite eye.

References

Ocular Ultrasound Made Easy: Step-By-Step Guide - POCUS 101

Ramamoorthy T, Manu Ayyan S, Deb AK. Diagnostic Value of Point-of-Care Ultrasound-Guided Assessment of Relative Afferent Pupillary Defect in Adult Ocular Trauma Patients Presenting to the Emergency Department: A Prospective Cohort Study. J Ultrasound Med. 2024 Jul;43(7):1343-1351. doi: 10.1002/jum.16458.