Abstract
Purpose :
The use of multifocal contact lenses (MFCL) to retard myopia progression has been reported previously. The purpose of this study is to quantify the accuracy of accommodation responses in emmetropic and myopic subjects wearing MFCL.
Methods :
Ten emmetropic (EMM) and 10 myopic (MYO) subjects (mean±SD age: 25.2±4.9 years) were fitted with a centre-distance MFCL (Biofinity, CooperVision, UK) with a near add of +2.50D, and also with single vision contact lenses (Biofinity, CooperVision, UK) with the same distance prescription. The accommodation response was measured continuously with a specially modified infrared, open field autorefractor (SRW-5000, Shin-Nippon, Japan) in the occluded eye, while subjects viewed monocularly a high-contrast Maltese cross target presented randomly at stimulus vergence levels of 0D, 2D and 4D. Two experimental sessions were carried out with subjects wearing either the MFCL or the single vision contact lenses, assiged randomly, after the lenses were allowed to settle for 20 minutes.
Results :
Mean accommodation response levels with the MFCL were found to show significant (p<0.001) inaccuracies of up to 2.00D in the EMM group and up to 2.50D in the MYO group when viewing the 0D and 4D stimulus levels. The magnitude of the accommodation microfluctuations was significantly (p<0.001) greater with the MFCL at the 0D stimulus level in both subject groups. Frequency spectrum analysis revealed this was due to a significant (p<0.001) increase in low frequency variation (frequency range 0.12Hz to 0.59Hz) in the accommodation response.
Conclusions :
The use of MFCL produces substantial variability in the steady-state accommodation response in both EMM and MYO subjects. Further work is needed to establish whether these inaccuracies in accommodation response are replicated in children, and whether the inaccuracies persist with longer term lens wear. These accommodation response inaccuracies will create varying levels of blur in both the central and peripheral retina, which may have consequences for the myopia control effect of these MFCL designs.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.