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Influence of Gravity on Ocular Lens Position
Lucas J Lister1, Marwan Suheimat1, Pavan K Verkicharla1
1Institute of Health and Biomedical Innovation & School of Optometry and Vision Science Queensland University of Technology, Kelvin Grove, Australia.
Investigative Ophthalmology & Visual Science
|April 16, 2016
Summary
Gravity slightly affects human eye lens position, particularly the anterior chamber depth, especially during maximum accommodation with a downward head posture. This suggests the eye
Area of Science:
- Ophthalmology
- Human Physiology
- Biomechanics
Background:
- The human crystalline lens position is crucial for maintaining visual acuity.
- Understanding factors influencing lens position, such as gravity, is important for ophthalmic research.
Purpose of the Study:
- To investigate the influence of gravity on human ocular lens position.
- To determine if head posture affects anterior chamber depth (ACD) and lens thickness (LT).
Main Methods:
- Measurements of ACD and LT were taken using a Haag-Streit Lenstar LS900.
- Participants were divided into young (18-21 years) and older (50-63 years) age groups.
- Sessions involved upright and downward head positions, with and without accommodation and pilocarpine stimulation.
Main Results:
- Gravity, altered by head posture, had a small but significant effect on ACD in both age groups (0.04-0.12 mm).
- A weakly significant effect of gravity on LT was observed in the young group without accommodation or pilocarpine (0.04 ± 0.06 mm).
- The effect on ACD in older adults often required accommodation-stimulating drugs.
Conclusions:
- Gravity exerts a small but measurable influence on ocular lens position.
- A downward head position with maximal accommodation leads to reduced ACD.
- This finding provides evidence for the zonules' ability to slacken during accommodation.
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