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Published on: May 3, 2016
Age-related changes in static accommodation and accommodative miosis
Hema Radhakrishnan1, W Neil Charman
1Optometry and Neuroscience, Faculty of Life Sciences, University of Manchester, Manchester M60 1QD, UK. hema.radhakrishnan@manchester.ac.uk
Summary
Investigating presbyopia models, this study found accommodative miosis varies widely and doesn't reliably indicate ciliary muscle effort. Therefore, pupil size changes cannot validate or refute theories on age-related vision changes.
Area of Science:
- Ophthalmology
- Physiological Optics
- Vision Science
Background:
- Presbyopia, the age-related loss of accommodation, is modeled by Hess-Gullstrand and Duane-Fincham theories.
- Accommodative miosis (pupil constriction during focusing) has been proposed as an indicator of ciliary muscle effort.
Purpose of the Study:
- To evaluate the validity of the Hess-Gullstrand and Duane-Fincham models of presbyopia.
- To determine if accommodative miosis can serve as a reliable indicator of ciliary muscle effort in presbyopia development.
Main Methods:
- Measured monocular accommodation response and pupil size in 48 normal subjects (ages 17-56).
- Assessed responses across a 0-4 Diopter accommodation demand range.
- Analyzed the relationship between age, accommodation response, and accommodative miosis.
Main Results:
- Accommodation response/stimulus slope decreased slowly with age until ~35 years, then declined faster.
- Accommodative miosis per diopter of accommodation response showed no systematic age-related change up to ~35 years.
- Significant inter-individual variation in accommodative miosis was observed, even in young subjects.
Conclusions:
- Accommodative miosis does not consistently accompany accommodation.
- Pupil size changes are not simply related to ciliary muscle contraction.
- Accommodative miosis cannot be used to support or refute current theories of presbyopia.
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