Marginal aberrations of different bifocal-lens designs

Area of Science:

• Optics
• Ophthalmology
• Vision Science

Background:

• Bifocal lenses are commonly prescribed to correct presbyopia.
• Optical aberrations can affect visual acuity and image quality in corrective lenses.
• Understanding lens design parameters is crucial for optimal visual correction.

Purpose of the Study:

• To measure marginal astigmatism and longitudinal chromatic aberration in +2-D bifocal lenses.
• To investigate the impact of different bifocal lens designs, base curves, and major-lens powers on optical performance.
• To identify factors contributing to optical image deterioration at reading levels.

Main Methods:

• Utilized a modified Vertometer for precise measurement of optical aberrations.
• Evaluated bifocal lenses with varying designs, base curves, and major-lens powers.
• Assessed image quality at a specific reading angle (20 degrees below the major lens pole).

Main Results:

• Deterioration of optical image quality was observed at the reading level.
• This image degradation resulted from the combined effects of marginal astigmatism (tangential error) and lateral chromatic aberration (prismatic dispersion).
• Specific lens designs and parameters influenced the magnitude of these aberrations.

Conclusions:

• Marginal astigmatism and lateral chromatic aberration interact to degrade image quality in bifocal lenses at reading distances.
• Lens design, base curve, and major-lens power are critical factors influencing bifocal lens performance.
• Recommendations are provided for selecting optimal bifocal lens designs based on refractive error.