Clinical Report: Spherical-equivalent contacts may shift binocular function
Overview
Switching from spectacles to spherical-equivalent soft contact lenses may lead to changes in binocular vision measures among patients with low myopic astigmatism. However, these changes are characterized as subtle adaptations.
Background
Understanding the impact of different optical corrections on binocular vision is essential, particularly for patients with low myopic astigmatism. This population may experience varying degrees of visual performance when transitioning from spectacles to contact lenses.
Data Highlights
Parameter
Spectacles
Contact Lenses
Accommodative Lag (Diopters)
0.70
0.81
Near Point of Convergence (cm)
6.67
7.02
PRA (Diopters)
-2.81
-3.17
Key Findings
Changes in accommodative lag, near point of convergence, and positive relative accommodation were observed when switching from spectacles to contact lenses.
Despite statistical significance, the absolute changes in binocular measures remained within normative clinical ranges.
Four patients developed exophoria after switching to contact lenses, while the number of patients with exophoria increased from 9 with spectacles to 13 with contact lenses.
Accommodative amplitude and facility showed positive correlations between spectacle and contact lens wear.
The study noted limitations including non-randomized testing order and short adaptation period to contact lenses.
Clinical Implications
Clinicians should be aware that while switching to spherical-equivalent soft contact lenses may result in measurable changes in binocular function, these changes are often subtle and may not indicate significant clinical issues.
Conclusion
The transition from spectacles to spherical-equivalent soft contact lenses can induce minor changes in binocular vision parameters, but these changes are not clinically significant. Further research is needed to explore the effects of toric lenses in this context.
Nearly 10 years of observational follow-up suggested sustained axial-length slowing, although refractive findings were less consistent and comparisons relied on statistical modeling.
