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Changes in the Objective Amplitude of Accommodation with Pupil Size

Lara, Francisco*; Bernal-Molina, Paula*; Fernández-Sánchez, Vicente; López-Gil, Norberto

doi: 10.1097/OPX.0000000000000383
ORIGINAL ARTICLES
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Purpose We evaluate the effect of pupil size on objectively measured amplitude of accommodation (AA).

Methods Pupil diameter and wavefront aberrometry were obtained in 15 eyes when stimulus swept across the range of clear vision in steps of 0.5 diopters. Wavefront refraction techniques were used to compute objective AA as the maximum refractive change. Measurements were obtained monocularly under low and high ambient room lighting conditions with a fixed luminance of the fixation target. Amplitude of accommodation computations were performed taking into account just paraxial rays (paraxial AA) or including the effects of the change of spherical aberration during accommodation (minRMS AA).

Results Mean pupil size values at low light level were 6.26 mm (relaxed) and 4.15 mm (maximum accommodation), whereas at the high light level, those values became 4.74 and 3.04 mm, respectively. The effects of both light level on accommodation were significant (p < 0.001), and accommodative miosis was slightly larger at low light levels. Mean minRMS and paraxial AA were always greater by more than 1 diopter in high than in low ambient lighting conditions (p < 0.01), indicating a significant impact of pupil size on AA.

Conclusions The influence of the ambient lighting on the objective AA is not only attributed to the increased effects of spherical aberration as the pupil dilates but mostly attributed to a decrease in the paraxial accommodation as pupil dilates.

*MSc

PhD

Grupo de Ciencias de la Visión, Universidad de Murcia, Murcia, Spain (all authors); and Grupo de Investigación en Optometría, Universidad de Valencia, Valencia, Spain (PB-M).

Norberto López-Gil Facultad de Óptica y Optometría Universidad de Murcia Campus de Espinardo 30100 Murcia Spain e-mail: norberto@um.es

© 2014 American Academy of Optometry