title: Measurement of ocular aberrations in downward gaze using a modified clinical aberrometer.
abstract: Changes in corneal optics have been measured after downward gaze. However, ocular aberrations during downward gaze have not been previously measured. A commercial Shack-Hartmann aberrometer (COAS-HD) was modified by adding a relay lens system and a rotatable beam splitter to allow on-axis aberration measurements in primary gaze and downward gaze with binocular fixation. Measurements with the modified aberrometer (COAS-HD relay system) in primary and downward gaze were validated against a conventional aberrometer. In human eyes, there were significant changes (p<0.05) in defocus C(2,0), primary astigmatism C(2,2) and vertical coma C(3,-1) in downward gaze (25 degrees) compared to primary gaze, indicating the potential influence of biomechanical forces on the optics of the eye in downward gaze. To demonstrate a further clinical application of this modified aberrometer, we measured ocular aberrations when wearing a progressive addition lens (PAL) in primary gaze (0 degree), 15 degrees downward gaze and 25 degrees downward gaze.
authors.forename: Atanu
authors.initials: A
authors.lastname: Ghosh
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Collins
authors.forename: Scott A
authors.initials: SA
authors.lastname: Read
authors.forename: Brett A
authors.initials: BA
authors.lastname: Davis
authors.forename: D Robert
authors.initials: DR
authors.lastname: Iskander