Abstract
Purpose: :
To compare the optical performance of +3D-Add aspheric apodized diffractive multifocal IOL, a +4D-Add aspheric full-aperture diffractive IOL and a sector-based bifocal IOL lens designs.
Methods: :
A ReSTOR +3D add apodized diffractive (Alcon Laboratories), a Tecnis diffractive multifocal with +4D add (Abbott Laboratories) and two Lentis Mplus (Oculentis) IOLs were tested. Instead of a diffractive element, the latter lens uses a wedge-shaped refractive zone in its inferior portion to achieve multifocality. The ReSTOR and Tecnis lenses each had a base power of 21D. The Mplus lenses had base powers of 25 and 30D, with add powers in the spectacle plane of 3.00 and 1.50 D, respectively. Each was mounted in a wet cell and inserted into a custom eye model. The eye model has an artificial corneal element with 0.27 µm of spherical aberration, which is consistent with clinically measured values of corneal spherical aberration. Through-focus MTF measurements at 50 lp/mm, which corresponds to Snellen visual acuity of 20/40, was evaluated for each of the lenses. Data was collected with 5 mm apertures to simulate mesopic pupil sizes. Finally, through-focus images of an ETDRS chart were obtained.
Results: :
The apodized diffractive multifocal lens had MTF values at 50 cyc/mm of 0.24 and 0.11 for distance and near vision, respectively. The full aperture diffractive had an MTF performance of 0.16 and 0.14 for distance and near respectively. The sector-based bifocal lenses had distance and near MTF values of 0.16 and 0.08 for the 25D/+3.00D lens and MTF values of 0.18 and 0.16 for the 30D/+1.50D lens. Peaks for near vision were seen at the approximate locations of the specified add powers, with the caveat that the diffractive lenses label their add power with respect to the IOL plane, while the sector-based lens labels add power with respect to the spectacle plane.
Conclusions: :
MTF testing and direct imaging of an eye chart show that the apodized diffractive lens tends to suppress extraneous light for large pupil sizes suggest a benefit of this lens under dim lighting conditions.
Keywords: intraocular lens • optical properties • presbyopia