Abstract
Purpose :
At present, simultaneous vision multifocal contact lenses (MFCLs) are being used not only for presbyopia correction, but for other purposes such as myopia control. We investigate the influence of two different designs of multifocal contact lenses on the accommodative response (AR) function and higher order aberrations (HOAs).
Methods :
Measurements of the ocular aberrations and AR were taken for 21 eyes of young healthy subjects aged between 18 and 41 years with astigmatism less than 1.25 D (mean spherical equivalent was: -1.58 D). We used a Hartman-Shack aberrometer (IRX3, Imagine Eyes) which incorporates a Badal system that was programmed to present fixed stimuli from 0 D to 4 D of accommodation in 0.50 D steps. Accommodation measurements were recorded for distance vision correction of the spherical equivalent with the Badal system and with two MFCLs. Participants were randomly fitted with two different MFCLs: PureVision 2 For Presbyopia (centre-near design) and Proclear Multifocal (centre-distance design). The later has been previously used in myopia control studies. Aberrations data was extracted for a 4mm fixed pupil diameter, so the effects of the contact lenses could be assumed to be the same for every subject.
Results :
The slope of the best linear trend fit for the AR function and the change of equivalent spherical aberration (ESA) with accommodation was calculated. No statistically significant differences were found either for the AR (F = 0.415, p = 0.663) or for the ESA (F = 1.862, p = 0.169) between the three conditions tested. However, the high standard deviation values show that the effective AR as well as the ESA during accommodation differs across subjects.
Conclusions :
Young subjects fitted with the MFCLs used in this study preserved their accommodative function. Therefore, good visual performance and tolerance of these lenses can be expected by early-presbyopes and young patients undergoing myopia control treatments. Presbyopes may still be benefited by the use of these MFCLs since our results are highly subject dependent and they might develop different neural strategies to discriminate the two foci generated by these lenses.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.