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Special senses: vision – eye movement

Published on June 30, 2025   16 min

A selection of talks on Neurology

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0:00
Hello. My name is Helena Lee. I'm an associate professor and consultant neuro-ophthalmologist at the University of Southampton. Today, we are going to explore supranuclear eye movements in this lecture.
0:14
First, let's start with some definitions. Supranuclear eye movements address the following visual demands. Saccades place a visual target onto the fovea. Smooth pursuits (SPs) track a moving visual target without moving the head. Vergence movements allow binocular coordinated eye movements to achieve and maintain binocular foveation. The vestibular-ocular reflex or VOR compensates for large head movements. The optokinetic reflex (OKR) uses visual information to fine-tune the VOR and to return the eyes to the central position after full excursion. Gaze holding maintains eccentric eye position.
0:55
Starting with saccades.
0:59
A saccade is a quick, simultaneous movement of both eyes between two or more phases of fixation in the same direction. This arose early in fish evolution and acted to re-center the eye as the fish turned. So, think of this as saccade and fixate. This helps to keep the gaze stationary relative to their surroundings.
1:21
In primates & other foveate vertebrates, saccades direct a visual target onto the fovea and this evolved as a result of the development of the fovea or a retinal area of higher visual acuity. Think of this as a way of hunting down an animal or something that you needed to eat.

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