The oculosympathetic pathway is a three-neuron chain that carries sympathetic nervous system signals from the brain to the eye and face. It controls things like pupil dilation, eyelid elevation, and sweating on the face. ⸻ 🧠 Breakdown of the Pathway: 1st Order Neuron (Central) • Starts in the hypothalamus • Travels down the brainstem and spinal cord to the T1–T2 level (ciliospinal center of Budge) 2nd Order Neuron (Preganglionic) • Leaves the spinal cord and travels over the apex of the lung to

Your PD, or pupillary distance, is the measurement between the centre of your pupils. It’s measured in mm and very important if you have a strong prescription or are ordering varifocal lenses, so that the optical centre of the lenses can match the wearer's PD for best vision.⁣ In this episode of our "Ask the Optician" series, David Hutchfield, Head of Professional Services and Qualified Optician, explains how we obtain your PD from selfies and what's the best way for you to send them. bit.ly/3q4