Extending Depth Of Focus With An Intraocular Lens Based On Controlled Increase Of Chromatic Aberration (Chromiol)

Clinical evaluation of monofocal and multifocal patients demonstrated the advantages of chromatic aberration in expanding the range of vision while maintaining good distance visual quality. Stemming from those studies, a new concept of a chromatic intraocular lens (ChromIOL) that utilizes chromatic aberration is now being proposed, implemented in a monofocal lens with enhanced intermediate distance for presbyopia correction.

David J. Apple International Laboratory for Ocular Pathology - Dept. of Ophthalmology, University of Heidelberg

A prototype ChromIOL was manufactured from hydrophilic acrylic material that utilizes three diffractive rings to increase chromatic aberration. The amount of chromatic aberration induced through this feature effectively doubles the amount of chromatic focus separation of a pseudophakic eye. Three samples of the ChromIOL were evaluated, each having a nominal power of 18.5 D. The lenses were measured using an optical metrology setup under industry-standard monochromatic conditions and with spherical- and chromatic-aberration conditions to mimic clinical scenarios. The modulation transfer function (MTF) was measured, from which simulated visual acuity (simVA) was derived.

The optical quality of the new lens under monochromatic conditions demonstrated good performance. The monochromatic MTF at 100 lp/mm (corresponding to 20/20 visual acuity) was on average 0.46, thus meeting the industry standard for monofocal IOLs. Under white light, in a model eye with a natural level of spherical aberration, the ChromIOL yielded a simVA of -0.06 logMAR at distance and provided good simulated vision of 0.2 logMAR or better down to -1.75 D (57 cm). The lens also demonstrated a small impact of residual uncorrected refractive error, with simVA of -0.02 and -0.03 logMAR at +0.50 D and -0.50 D defocus, respectively.

For the first time, the concept of an IOL that takes advantage of chromatic aberration has been implemented, showing promising results. The ChromIOL demonstrated a clear advantage in extending intermediate vision from far to approximately 57 cm, while the low sensitivity to uncorrected refractive error offers a broad landing zone and makes the concept suitable for a mini-monovision approach. Nevertheless, the concept requires further development to expand the range of vision while maintaining good distance vision.