Dynamic aspects of accommodation: age and presbyopia
نویسندگان
چکیده
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 objectively using an infrared optometer within the linear region of accommodation in 30 visually-normal human subjects aged 21-50 years. The time constant and the peak velocity/amplitude relationship did not change with age. However, latency progressively increased, and microfluctuation amplitude and frequency progressively decreased, with increasing age. The invariance in time constant suggests that the gross biomechanical aspects of the lens and related structures in the remaining linear region are relatively unaffected by age. In contrast, the decrease in microfluctuation activity with age suggests more subtle alterations in the biomechanical aspects of the lens to these very small perturbations, such as a response amplitude non-linearity. With respect to neurologic control, the progressive latency increase suggests a processing delay of the blur input, and this is consistent with age-related changes in reaction time measures. The lack of any age-related changes in the peak velocity/amplitude relationship implies normalcy of central and peripheral neuromotor control, as well as grossly normal first-order lens biomechanics, in this linear response region. The results are consistent with the Hess-Gullstrand theory of presbyopia.
منابع مشابه
Dynamic aspects of accommodation: age and presbyopia
Dear Editor Mordi and Ciuffreda (2004) have used an objective infrared optometer to measure the dynamic aspects of accommodation with aging in a large well-designed study. Their study demonstrates no change in the time constant and peak velocity/amplitude of accommodation with age. Based upon this observation, the authors correctly conclude that their findings imply that presbyopia cannot be du...
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ورودعنوان ژورنال:
- Vision Research
دوره 44 شماره
صفحات -
تاریخ انتشار 2004