Progressive-toric IOL design reduces residual astigmatism with increasing pupil size: a ray-tracing simulation based on corneal topography data

Area of Science:

• Ophthalmology
• Optical Engineering
• Biomedical Engineering

Background:

• Astigmatism correction using intraocular lenses (IOLs) is challenged by the natural decrease in corneal astigmatism from the center to the periphery.
• Standard toric IOLs with constant cylinder power provide uniform correction, which is suboptimal for the non-uniform astigmatism gradient in the eye.

Purpose of the Study:

• To evaluate the efficacy of a novel progressive-toric IOL in correcting peripheral corneal astigmatism.
• To compare the optical performance and residual astigmatism of a progressive-toric IOL against a standard toric IOL.

Main Methods:

• An advanced astigmatic eye model was developed using corneal topography data.
• A progressive-toric IOL with gradually decreasing cylinder power was designed and compared to a standard toric IOL with conventional correction.
• Residual astigmatism and Strehl ratio were measured at 3 mm and 5 mm optical zones.

Main Results:

• At a 3 mm optical zone, both IOLs showed comparable optical performance with no significant difference in residual astigmatism (P=0.06).
• At a 5 mm optical zone, the progressive-toric IOL demonstrated significantly lower residual astigmatism (0.10 D reduction, P<0.001) compared to the standard toric IOL.
• The Strehl ratio was similar at 3 mm but showed a statistically significant difference at 5 mm (P<0.001), favoring the progressive IOL.

Conclusions:

• The progressive-toric IOL is more effective in correcting peripheral astigmatism than standard toric IOLs.
• This lens design offers potential for improved visual quality in patients with naturally occurring astigmatism gradients.
• The study highlights the benefit of accommodating correction for non-uniform astigmatism in the visual axis.