Extended Depth of Focus Contact Lens Design

Presbyopia is an ophthalmic condition where the eye loses the ability to focus clearly due to lens aging. It can significantly affect the quality of life. Since eventually every person is undergoing this condition, it’s important to find a solution to it. Spectacle-free treatment can be achieved by contact lenses and intraocular lenses. A lens with multi-focus or extended depth of focus (EDoF) allows clear vision of objects from far to near. A monofocal EDoF lens can hardly reach 2D of depth of focus (DoF). Bifocal lenses suffer from degraded intermediate distance image quality and pupil-size dependency. Trifocal diffractive lenses provide improved intermediate image quality, but with degraded image quality between the focal points. The goal of this invention was to propose a new approach to designing refractive presbyopia-correcting ophthalmic lenses with a large continuous DoF and pupil size independency.

 

A design example was found and used to evaluate the performance through focus. The area MTF was well balanced through 2.5D of DoF for a range of pupil sizes (from 3mm to 5mm). The orientation of the 20/20 letter ‘E’ on a visual acuity chart was clearly recognized subjectively over defocus ranging from 0 to 2.5D.

 

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URV Reference Number: 6-20054
Patent Information:
Category(s):
Optics
For Information, Contact:
Joynita Sur (URV)
Licensing Manager
University of Rochester
Joynita_Sur@urmc.rochester.edu
Inventors:
Geunyoung Yoon
Jiakai Lyu
Keywords: