Clinical measurement of compensatory torsional eye movement during head tilt.

Abstract

To measure the degree of compensatory torsional eye movement during head tilt using a fundus photography method. We enrolled 55 healthy subjects who were 20-66years of age. Fundus photographs were obtained in the presumed baseline position and in stepwise head tilt positions to evaluate ocular torsion using a non-mydriatic fundus camera. Horizontal marks on the nose were photographed simultaneously to evaluate head tilt. Images were analysed using Photoshop to measure the degree of ocular torsion and head tilt. A consistent compensatory torsional eye movement was observed in all subjects during head tilt. The degree of compensatory torsional eye movement showed a positive correlation with the angle of head tilt. Ocular torsional disconjugacy was observed during head tilt, with larger excycloductional eye movement than incycloductional eye movement (4.88±2.91° versus 4.50±2.76°, p<0.001). In multiple linear regression analysis, the degree of compensatory torsional eye movement was significantly associated with the degree of head tilt (β=0.191, p<0.001), and the direction of cycloduction (β=-0.548, p<0.001). The fundus photography method is a non-invasive, accurate and objective tool for measuring compensatory torsional eye movement. Considering the availability of fundus photography in clinical ophthalmology practice, the proposed method can be used as a clinical tool to measure compensatory torsional eye movement.