Diagnostics Cervical Spine Maddox glass

Instruct the person to sit comfortably, with feet on the floor and hands relaxed on the lap. This test illuminates how an eye positions itself when it cannot focus on an object and is at rest. An eye is considered at rest when the eyelids are closed, or an obstruction prevents it from seeing an object, preventing it from focusing. The eye tends to turn either inward or outward, depending on its preferred position.

Have the person look at a candle or any small light source from a distance of approximately 2 meters with both eyes. Using a Maddox glass, which is a transparent piece with parallel prismatic indentations (usually red in colour), to cover one eye to hinder its focus on the light source.

The covered eye will either rotate inward (esophoria) or outward (exophoria). The light passing through the Maddox glass displays a vertical line.

When the eye rotates inward, the light hits the retina on the medial side of the central line, interpreted as if the light source is coming from the lateral side of the original light source, indicating endophoria. Conversely, when the eye rotates outward, the light hits the retina on the lateral side of the central line, suggesting that the red light from the Maddox glass is medial to the original light source, indicating esophoria.

Understanding the rotational resting position of the eyes is crucial as it predicts the preferred position of C0 in the sagittal plane. If the test reveals endophoria, C0 prefers a position and movement into flexion. On the other hand, if the test shows esophoria, C0 prefers a position and movement into extension.