Digital measurement of torsional eye movement due to postural change and its effect on reading performance

Abstract

The results presented here demonstrate that we have developed an objective and instantaneous method with good precision, which could be applied in other studies that require the measurement of torsional eye movements. The induced cycloduction did not affect the reading performance.

Influence of corneal astigmatism, corneal curvature and meridional differences on corneal hysteresis and corneal resistance factor

“…No study has investigated the effect of cyclo‐rotation on IOP. Although the attempted gaze was at an angle of 22° in the study by Nardi and co‐workers, 41 while the greatest compensatory eye rotation was within 10°, 37 there is a possibility that changes in the extraocular muscle tension from torsional eye movements might have influenced the ORA measurements.…”

“…Although the calculated corneal power represented the curvature of that particular meridian, the measured ORA parameters were not exactly along these meridians due to compensatory torsional eye movement from the head tilt. Lam and colleagues reported an average of 6.5° compensatory eye rotation during a 90° head tilt 37 . Therefore, the measured ORA parameters with a 30° head tilt might represent only the corneal biomechanical properties along 24° superior temporal, not exactly 30° superior temporal.…”

Reading tilted: Does the use of tablets impact performance? An oculometric study

“…This finding is interesting considering the literature about reading and torsional eye movement is extremely sparse. Lam, Chung, Kho, and Wong (2000) studied the effect of this movement on capital letter identification performance; they measured the torsion of the eye due to a 90°left or right head tilt. As the measurement was not processed during the task, we cannot be sure that the torsion was the same when just lying or sitting and when the subjects were actually reading.…”

Effect of instrument rotation on handheld keratometry

“…Previous studies show that the eyes are capable of compensating for a small amount of head tilt through incycloduction or excycloduction. 13,14 We completed the measurements with handheld keratometers within 5 minutes in each subject. Therefore, errors from subjects' head tilting should be very small.…”