An Intraocular Lens to Improve Field Curvature and Off-axis Astigmatism in Pseudophakic patients

Investigative Ophthalmology and Visual Science
Pablo Artal, Harilaos Ginis, Dimitrios Christaras, Eloy A. Villegas, Pedro Prieto
Purpose: Current intraocular lenses (IOLs) are designed to optimize focus at the eye’s central retina overlooking their off-axis performance. This may be the reason for the worse optical quality in the periphery of the retina in pseudophakic patients compared to the normal phakic eye (Jaeken et al., IOVS, 2013). There are specific visual tasks where a degraded peripheral optics can have a significant impact in patient’s orientation in space and therefore in their safety. In this context, we have designed a new type of IOL to provide better peripheral optical quality.
Methods: We applied personalized eye models using anatomical data from normal older eyes to design optimized IOLs in the peripheral retina. A ray-tracing analysis was used to determine the IOL’s shapes and asphericities that control field curvature and peripheral astigmatism. Retinal eccentricities of 30, 40 and 50 degrees were used in the optimization process. The lenses were manufactured and evaluated in a custom-built realistic artificial eye. The images of a point source and extended targets were directly recorded at various field angles with standard and the new IOLs.
Results: We designed a new type of IOLs with an inverted meniscus shape to improve the optical quality in the periphery of the visual field while remaining of similar quality to standard IOLs on axis. This new has aspheric surfaces with concave-convex shape. The curvature radius of the posterior surface is smaller than that of the anterior surface by a factor ranging between 2 and 6. The accompanying figures show images recorded at 40 degrees in the artificial eye using a standard monofocal lens (left) and the new meniscus lens (right). As noted, a significant improvement in image quality was achieved.
Conclusions: An IOL designed to control field curvature and to reduce peripheral astigmatism in the pseudophakic eye was developed. It has an inverted meniscus shape and showed, in an artificial eye, superior image quality in the whole visual field. Further research will be required to establish how this improvement in optical image quality translates to a measurable increases in patient`s quality of life.