Kenneth J. Ciuffreda

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Although the depth-of-focus in the foveal region has been well investigated, knowledge regarding the effect of retinal eccentricity on blur detection and sensitivity is limited. In the present study, the depth-of-focus at the fovea and in the near retinal periphery (0 degrees -8 degrees ) was assessed psychophysically in 7 human subjects using a 5 mm(More)
There has been no comprehensive study involving each of the primary dynamic components of accommodation in the same cohort as related to age and presbyopic onset; furthermore, the current findings are equivocal. Dynamic monocular components of accommodation (latency, time constant, peak velocity/amplitude relationship, and microfluctuations) were assessed(More)
Earlier evidence suggests qualitatively that at least two control modes may mediate a single vergence response. Thus, in a vergence response to step disparity, the transient component drives the initial fast dynamic portion of the response, while the sustained component maintains the latter slower portion of the response. The authors extended this(More)
The dynamic characteristics of horizontal convergence and divergence eye movement responses to symmetric stimuli were examined. Binocular eye movements were recorded in five, visually normal adult subjects using the infrared reflection technique for symmetric convergent and divergent blur-free, disparity-only, step stimuli of 2, 4, 8, 12, and 16 deg. The(More)
Horizontal eye position was monitored using a photoelectric method during monocular and binocular fixation in four patients having amblyopia without strabismus, thirteen patients having constant strabismus with amblyopia, and five patients having intermittent strabismus. Four abnormalities of fixation were found: increased drift, saccadic intrusions,(More)
PURPOSE To determine whether there are any fundamental differences in vergence dynamics under different viewing conditions, both in instrument space and free space. METHODS Symmetric vergence responses were measured for a variety of conditions under the traditional instrument space as well as the more natural free space viewing environment. Vergence eye(More)
Voluntary and reflex accommodation were measured monocularly in five normal subjects using a dynamic infrared optometer. Comparison of the peak velocity/amplitude relation (i.e., "main sequence") showed complete overlapping of the response distributions, suggesting similarity of motoneuronal controller signals for voluntary and reflex accommodation.(More)
The human accommodation system was investigated using a dynamic infra-red optometer to determine whether its feedback control process exhibited dual-mode behaviour. Ramp changes of target accommodative demand presented monocularly at various velocities (0.5-0.6 D s-1) with a fixed 2 D amplitude elicited two modes of behaviour. Smooth ramp movements were(More)
PURPOSE Some aspects of accommodation may be slightly abnormal (or different) in myopes, compared with accommodation in emmetropes and hyperopes. For example, the initial magnitude of accommodative adaptation in the dark after nearwork is greatest in myopes. However, the critical test is to assess this initial accommodative aftereffect and its subsequent(More)