Purchase this article with an account.
Karen Lahav-Yacouel, Arthur Ho, Ravi Chandra Bakaraju; Optical performance of phase-step contact lenses in the Arizona model eye. Invest. Ophthalmol. Vis. Sci. 2019;60(9):592.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Increasing global prevalence of presbyopia is poorly served by contact lens (CL) options, due to limitations such as loss of contrast, ghosting and haloes. Phase-step (PS) optics is a novel technology which has potential to deliver extended depth of focus (EDOF); allowing for a continuously clear range of vision. We evaluated the effects of different pupil sizes, inherent spherical aberration (SA) levels and lens decentration positions on the optical performance of PS rigid CL.
A presbyopic emmetropic eye was modelled in OpticStudio (Zemax LLC, USA). The designs evaluated included single vision (SV), bifocal (BF) and EDOF CL. The PS CL parameters were optimised to achieve a +2.00 add BF and EDOF in green light (550 nm). The modulation transfer function (MTF) was used as the image quality metric to assess the effect of pupils (3 mm to 6 mm, in 0.5 mm steps), SAs (5th, 25th, 50th, 75th and 95th percentile of population distribution) and lens decentration (0 mm to 1 mm, in 0.2 mm steps, vertical direction), computed over various object vergences from -3.00 D to +3.00 D.
The optical performance of SV lenses across all pupils and SAs was comparable to published results: a 7% difference across pupils, 18% between the 5th and 95th SA percentiles and 34% between well centred and decentred positions were observed.For BF CL, a pupil above 4.5 mm favoured distance performance, which was about 70% less than the performance obtained at 6 mm pupil. With a full decentration of 1 mm, BF CL performance at distance improved (by 25%) at the cost of reduction of performance at near (by 40%). Distance and near performance showed a difference of 25% and 18%, respectively between all SA levels.Similar to BF CL, the EDOF design showed better distance performance with increased pupil by about 30%. Distance performance varied by about 56% across all SA, while the near performance varied by about 23%. Lens decentration mainly affected distance performance. With 1 mm decentration, the distance performance dropped 50% from the peak performance, while the near and intermediate performance only demonstrated a reduction of 11% and 20% from the peak performance, respectively.
PS technology is in an early stage of research. Further lens designs and analyses will aid in understanding this technology and its performance in relation to ocular parameters.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
This PDF is available to Subscribers Only