IOL with square-edged optic and reduced dysphotopsia.

Purpose: To demonstrate a new optic edge design that preserves advantages of the square-edged optic and substantially reduces intensity of the light pattern formed at the retina by internal reflection off the optic edge.

Methods: Non-sequential ray tracing (Zemax optical design software) was used to model light intensity and distribution of the light pattern at the retina formed by internal light reflection off different optic edges in intraocular lens of otherwise equivalent configurations.

Results: A maximum intensity of the light pattern formed by internal reflection off the optic edge occurs within 35 to 42.5° of the field angle. An undulated square-edged optic reduces the maximum light intensity of the light pattern formed at the retina by a factor of 5, when compared with a conventional double square-edged optic.

Conclusions: Edge undulation of the square-edged optic is an effective addition to intraocular lens designs that reduces the potential for dysphotopsia caused by the optic edge internal reflection of light.