Multifocal contact lenses may be at the top of the list when it comes to the amount of time and research devoted to their development. Whether it is a soft, GP, orthokeratology, or scleral lens, there’s a multifocal option for it.

Despite significant progress in multifocal designs, one aspect of practice that hasn’t changed is the need to allow and to encourage our patients to adapt neurologically to this new way of using their vision. To be successful multifocal contact lens prescribers, we must understand how multifocal lenses work and how the visual system adapts to the new optical platform. Let’s take a look at how two of these optical platforms work.

Aspheric and Extended Depth of Focus Key Features

Most contact lenses for presbyopia use optics described as simultaneous images; distance, intermediate, and near image foci are placed on the retina at the same time, and the brain learns to use the clearest image to achieve an extended range of usable vision (Benjamin, 1993). These lenses generate vision with aspheric power changes across the lens surface (Madrid-Costa et al, 2015). This gradual change in power works well with most average pupils, but because aberrations increase exponentially with pupil size (Fuller, 2019), patients who have larger pupils may struggle with this design. While larger pupils in the presbyopic population are less common, note that a pupil size greater than 5.0mm is associated with increased glare and halos (Bennett, 2008).

Lenses with extended depth of focus (EDOF) optics use higher-order aberrations rather than multiple images to create a range of clear vision (Fuller, 2019). This results in less degradation of distance vision and fewer shadows compared with aspheric designs (Bakaraju, 2018). Research data on contact lens and intraocular lens EDOF designs also show superior visual performance at intermediate ranges (Bennett, 2008; Savini et al, 2018). Currently, only a few EDOF contact lens designs are available, but we can look forward to their continuing development.

Choosing a Design

With the expansion of multifocal options, deciding which design to use for a patient can be overwhelming and difficult. In my experience, patients who have good retina health and limited cataract development adapt well to aspheric multifocals. We can choose from many aspheric designs, such as center-distance or center-near, to best meet patients’ needs depending on their lifestyle.

I typically select EDOF lenses for patients who have mild cataracts or mild macular findings, as they may already experience some light scatter. These ocular findings, in addition to the multiple images generated by an aspheric design, may degrade their vision quality.

Adaptation Tips

The first step toward successful adaptation to simultaneous images is educating patients about how their vision quality might look when they first start wearing multifocal contact lenses. When patients are seeing some shadows or double images, I explain that those are signs that the lens is creating the desired extended vision range. I also remind them that this is their first experience with simultaneous vision, and adaptation may take up to two weeks (Gispets et al, 2011). During this time, vision quality and contrast sensitivity improve (Montés-Micó and Alió, 2003).

If a patient continues to struggle with vision quality for more than a month, I may decrease the add power in the lens or add some minus power to the sphere. While this reduces near acuity, it negates some of the shadowing, which encourages acceptance and allows for further adaptation. This should enable the patient to continue to wear the lenses so that add power can be increased in the future.

From Cautious to Confident

The expansion of multifocal designs during my career has taken me from being a cautious prescriber to a confident one. Delivering the freedom from eyeglasses that my patients desire has become one of my favorite moments of everyday patient care. CLS

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