Certified Ophthalmic Medical Technologist (COMT) Practice Exam

What percent of the nerve fibers in the optic tract are responsible for pupillary function?

1. 10 percent

2. 20 percent

3. 30 percent

4. 50 percent

The correct answer is: 20 percent

The correct answer indicates that 20 percent of the nerve fibers in the optic tract are responsible for pupillary function. This is significant because the optic tract conveys visual information from the retina to the lateral geniculate nucleus, and a subset of those fibers leads to the Edinger-Westphal nucleus, which controls the pupillary light reflex and accommodation. The pupillary reflex involves the response of the pupils to light, allowing them to constrict when exposed to bright light, which helps prevent excessive light from damaging the retina and allows for better visual acuity in varying lighting conditions. It's essential for maintaining the proper function of the visual system. While the majority of the optic tract fibers are involved in transmitting visual stimuli for processing within the visual cortex, the fibers dedicated to the pupillary function, although smaller in percentage, play a crucial role in the autonomic response of the pupils. This understanding emphasizes how only a portion of the optic nerve fibers is implicated in controlling non-image-forming tasks, highlighting the specialized functions within the visual pathway.