Short-term adaptation of accommodative lag, facility and phoria in myopes fitted with multifocal contact lenses

Abstract

Purpose: Multifocals have been proposed as a method of controlling myopia progression. Adaptation time to multifocal contact lenses, in terms of accommodative response, has not been explored in depth. A study was conducted to investigate if accommodative response adaptation is dependent on the type of multifocal contact lens.

Methods: Prospective, subject-masked clinical trial in which 40 participants were randomised to two of four lenses of different multifocal designs (Proclear Multifocal [Distance and Near], Air Optix Aqua Multifocal, PureVision Multifocal) and a single vision control lens (Air Optix Aqua) on a bilateral, daily wear basis with a 1-week washout period between lenses. Subjects wore each allocated lens for a minimum of 8 days (maximum 14) over 4 scheduled visits (baseline and 3 follow-up visits) with a 1-week washout between lens types. Accommodative lag was assessed at all visits with the EyeMapper at +1D, -2D, -3D, -4D and -5D demand settings. Accommodative facility was assessed by the number of flips of ±2D per minute and horizontal phoria was assessed with a Howell phoria card at 33 cm and 300 cm.

Results: A significant difference was found with Proclear Multifocal Distance lenses between baseline (V1) and the first follow-up visit (V2) for measurements performed at an accommodative demand of +2D (-1.66 ± 0.68D vs -2.24 ± 1.02D, p= 0.019, V1 vs V2 respectively). Linear mixed model test showed an increase in accommodative facility over the 4 visits with the Air Optix Aqua Multifocal and PureVision Multifocal lenses (p= 0.003). There was no significant change in distance and near horizontal phoria state over the 4 visits (p= 0.973).

Conclusions: Adaptation differences were not consistently found in the static accommodative measures (lag and phoria) but were found in dynamic measures (facility), the latter may be related to learning effects. We speculate that accommodative adaptation is unlikely to occur with long-term multifocal wear.

Keywords: 605 myopia • 404 accommodation • 477 contact lens