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Age-related changes in human ciliary muscle
1School of Optometry, University of Waterloo, Canada. pardue@research.hines.med.va.gov
Summary
The ciliary muscle contracts throughout life, but age-related changes, including increased connective tissue, affect its function. These changes may contribute to presbyopia due to interactions with the aging lens and zonules.
Area of Science:
- Ophthalmology
- Human Anatomy
- Ageing Research
Background:
- Accommodation is crucial for clear vision.
- Presbyopia, age-related loss of accommodation, affects nearly all adults.
- The ciliary muscle's role in accommodation and its changes with age are not fully understood.
Purpose of the Study:
- To investigate the ciliary muscle's function in accommodation across different age groups.
- To identify age-related structural changes in the ciliary muscle.
- To explore the contribution of ciliary muscle changes to presbyopia.
Main Methods:
- Light microscopy was used on human eye donors aged 1 to 107 years.
- Eyes were treated with atropine or pilocarpine to assess muscle response.
- Morphometric analysis included muscle dimensions, fiber area, and connective tissue percentage.
Main Results:
- The ciliary muscle demonstrated contraction in response to drug treatment at all ages.
- Older subjects' ciliary muscles had increased connective tissue.
- Age-related changes included a shorter, wider ciliary muscle with forward internal apical edge displacement.
Conclusions:
- The human ciliary muscle maintains contractile ability throughout life.
- Age-related alterations in the ciliary muscle occur.
- These changes, influenced by the aging lens and zonules, may contribute to presbyopia.