PURPOSE To compare the objective accommodative amplitude and dynamics of eyes implanted with the one-compartment-unit (1CU; HumanOptics AG, Erlangen, Germany) accommodative intraocular lenses (IOLs) with that measured subjectively. METHODS Twenty eyes with a 1CU accommodative IOL implanted were refracted and distance and near acuity measured with a logMAR (logarithm of the minimum angle of re...

Poor visual ergonomics is associated with visual and neck/shoulder discomfort, but the relation between visual demands and neck/shoulder muscle activity is unclear. The aims of this study were to investigate whether trapezius muscle activity was affected by: (i) eye-lens accommodation; (ii) incongruence between accommodation and convergence; and (iii) presence of neck/shoulder discomfort. Sixty...

PURPOSE To investigate the relationship between photopic open-loop accommodation and vergence and the effect of mental effort on these positions. METHODS Twenty subjects (11 men and 9 women) viewed monocularly a photopic (25 cdm-2), high-contrast (90%) Maltese cross-target for 3 minutes, through a 0.5-mm pinhole drilled into an infrared filter. Accommodation was measured objectively at 1-seco...

PURPOSE Some debate surrounds the accommodative mechanism in primates, particularly whether the lens equatorial diameter increases or decreases during accommodation. This study has been undertaken to measure the relationship between changes in lens diameter and refraction during accommodation in rhesus monkeys. METHODS Photorefraction was used to measure accommodation, and goniovideography wa...

The objective was to measure the change in shape of the aging human crystalline eye lens in vivo during accommodation. Scheimpflug images were made of 65 subjects between 16 and 51 years of age, who were able to accommodate at least 1D. The Scheimpflug images were corrected for distortion due to the geometry of the camera and the refraction of the cornea and anterior lens surface, which is nece...

In young individuals, the C-values of tonograms obtained during accommodation were shown to be significantly greater than those obtained on the same eye when accommodation was completely relaxed. In the same group, the Schiotz pressure reading was found to be lower following 4 minutes of accommodation. Thus, the increase in C-values could not be interpreted to reflect exclusively the change in ...

Voluntary effort can be used to elicit changes in accommodation and vergence. We investigated the potential cross-coupling interactions of accommodative vergence/accommodation (AC/A) and vergence accommodation/vergence (CA/C) in response to voluntary effort. The responses of accommodation and vergence were measured simultaneously with a dual Purkinje image eye tracker and infrared optometer whi...

We determined the foveal Stiles-Crawford Effect as a function of up to 8 D accommodation stimulus in 6 young emmetropes and 6 young myopes using a psychophysical two-channel Maxwellian system in which the threshold luminance increment of a 1mm spot entering through variable positions in the pupil was determined against a background formed by a 4 mm spot entering the pupil centrally. The SCE bec...

Spatiotopic cues, such as perceived distance, have little effect on accommodation unless blur has been reduced or eliminated. We investigated the effect of perceived distance on accommodation under binocular steady-state conditions, about which little is known. Blur was reduced but not eliminated by using a stimulus with a moderately low luminance. Accommodation was measured under two condition...