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Does the presbyopic visual system adapt to contact lenses?
J E Sheedy1, M G Harris, C M Gan
1Morton D. Sarver Laboratory for Contact Lens and Corneal Research, University of California School of Optometry, Berkeley.
Summary
Task performance with presbyopic contact lenses showed adaptation in some cases. Concentric bifocal lenses improved task performance, unlike monovision or diffractive lenses, suggesting learned adaptation to visual changes.
Area of Science:
- Ophthalmology
- Vision Science
- Optometry
Background:
- Presbyopia management often involves contact lenses, but adaptation to these corrections can impact task performance.
- Previous studies indicated performance decreases with initial wear of monovision, concentric bifocal, and diffractive presbyopic contact lenses.
- A control condition using distance contact lenses with reading spectacles was employed in prior investigations.
Purpose of the Study:
- To retrospectively analyze data to determine if task performance decreases with presbyopic contact lenses adapt over an initial wearing period.
- To investigate whether task performance shows adaptation relative to control conditions after lens wear.
- To compare adaptation between monovision, concentric bifocal, and diffractive presbyopic contact lens corrections.
Main Methods:
- Retrospective analysis of data from previous studies involving presbyopic contact lens wear.
- Statistical analysis using the Wilcoxon matched pair signed rank test to compare performance at dispensing versus the end of the wearing period.
- Evaluation of task performance, visual acuity, and stereoacuity changes relative to a control group.
Main Results:
- No significant improvement in task performance was observed with monovision or diffractive bifocal lenses.
- Significant improvements in task performance were found with concentric bifocal lenses (p < 0.05).
- Measures of visual acuity and stereoacuity did not improve, indicating these basic visual skills did not adapt.
Conclusions:
- Task performance can adapt during the initial wearing period of certain presbyopic contact lenses, specifically concentric bifocal lenses.
- Adaptation in task performance may be due to patients learning to utilize reduced visual acuity for complex tasks.
- Basic visual skills like acuity and stereoacuity do not appear to adapt with these lens types during the initial wear period.