Subjective and Motor Adaptation to Monocular Torsion

Abstract

Subjective adaptation to image tilt in the sagittal axis is a physiological phenomenon and can be observed during head tilt to the shoulder. Oculomotor adaptation has been found to have a minor influence. Nevertheless, contours are perceived as vertically and horizontally aligned even though they do not fall on the vertical and horizontal anatomic-geometric retinal meridians. Unilateral macular translocation with surgical rotation of the macula around the optic nerve head on to a healthier retinal pigment epithelium leads to similar torsional misalignment of the retinal meridians. To analyse the mechanisms of adaptation to image tilt without superimposition of binocular problems, we followed two monocular patients after macular translocation with upward rotation of the fovea in their left eyes (incyclorotation). In both cases, in spite of subjective adaptation of the visual system, a pronounced head and body tilt to the side of the operated eye (here to the left) developed. This is the first report on a medical procedure demonstrating an impressive ability to coordinate head and eye position during retinal image tilt.

KEYWORDS::

• Adaptation
• Head tilt
• Macular translocation
• Monocular torsion
• Retinal image

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.