Making the most of multifocal contact lenses in your practice.
The versatility of multifocal contact lenses is sometimes lost with the addition of new contact lenses every year. There is a place for these lenses in every phase of life. Traditionally, multifocal contact lenses were introduced to the market to address the needs of presbyopes by containing multiple prescriptions (distance and near) in 1 lens. But these lenses truly can be used for any age.
Perhaps the most common use for multifocal lenses outside presbyopia is for myopia management. With the continued rise in myopia prevalence, practitioners are looking for therapies to delay the onset of myopia and slow its progression. Among these therapies are multifocal soft contact lenses most used off label with designs to increase the amount of peripheral myopic defocus that falls on the retina.
This increase in myopic defocus is the primary theory as to how multifocal lenses can slow myopia progression. Several designs have gone through longitudinal studies to demonstrate their efficacy in slowing axial length elongation and refractive error change; however, no research has been done comparing different types of multifocal designs to each other. One study looked at the peripheral profile of different lenses, including aspheric center distance, aspheric center near, and extended depth of focus center distance designs, and found that the center distance designs induced myopic defocus, while the center near design induced hyperopic defocus across the entire retina.1 Therefore, center distance designs are most commonly used for myopia management.
The Bifocal Lenses In Nearsighted Kids (BLINK) study evaluated single vision, low add, and high add aspheric center distance multifocal contact lenses. In the initial prescribing, they found that children needed a –0.50 to –0.75 D overrefraction with the multifocal lens design to achieve best-corrected visual acuity.2 After 3 years of wear, they found that the highest add power (+2.50) was most effective in slowing axial elongation and refractive error.3 The study also pointed out that a low add (+1.50) was no different in terms of efficacy compared with a single vision lens. Therefore, practitioners should prescribe a high add power if using these lenses off label for myopia management. The caveat to prescribing any higher than a +2.50 add is that there is a reduction in low-contrast visual acuity.4
The aspheric center distance design used in the BLINK study was a monthly replacement modality. While the risk of infection in young children is still relatively low, a daily disposable option is likely better at mitigating this risk. There is currently 1 FDA-approved lens with the indication for slowing myopia progression in children aged 8 to 12 years. This lens is a dual-focus concentric ring daily disposable design. A 7-year, longitudinal study has shown the efficacy of this lens in slowing axial elongation and myopia progression.5,6
When prescribing multifocal lens designs for children, we do not follow fitting guides, but rather prescribe the full distance prescription to ensure adequate distance visual acuity, center distance design to induce myopic defocus, and a high add power.
In today’s digital age, teens and young adults frequently use computers, tablets, phones, and other digital devices. This long-term use has brought about issues of eyestrain and dry eye due to reduced blink rates. One study found the average screen time for university students to be almost 5 hours daily.7 High levels of screen time have also been associated with migraines in young adults.8 To address these issues, prescribers can think about trialing a low add multifocal to provide a boost at near. While not true multifocal lenses, the aspheric, single-vision Biofinity Energys and MyDay Energys offer a DigitalBoost of a +0.30 D near power.
There is also the idea of blue light, as it has been shown that smartphone screens emit short wavelengths of light (380-495 nm) that suppress the production of melatonin, which is needed to regulate the sleep-wake cycle.7 Contact lenses with the ability to filter high-energy visible light have been shown to reduce the size of halos and starbursts as well as decrease light scatter.9 The Acuvue Oasys Max contact lens is available in both a single-vision and a multifocal design and offers OptiBlue Light Filter, the highest-level blue violet light filtering available.
Young adult dependency on digital devices should lead practitioners to consider designs with a low add power to reduce eye strain at near and lenses that offer high-energy visible light filtering to diminish optical distortions.
In a 2018 meta-analysis, researchers found that only 37% of presbyopes 45 years and older were offered contact lenses, and fewer were offered a multifocal contact lens.10 Perhaps this percentage is low because practitioners may struggle with the fitting of these contact lenses and therefore may see it as extra chair time required to achieve success and patient satisfaction. Though patient motivation is likely not lacking, it is important to keep open lines of communication and set realistic expectations. With the simultaneous viewing of these lenses, there is a slight compromise in acuity and quality of vision to maintain the balance between distance and near.
As our 40-something patients start to experience the signs of presbyopia, we often discuss different contact lens options for visual correction, including monovision, multifocals, or single vision with overlay spectacles. Though monovision may seem like an enticing option for the emerging presbyope with a low add power, the lack of depth perception and increasing disparity between the 2 eyes as the add increases should be discussed upfront with the patient. Clinically, monovision may be most useful in emmetropic patients who are accustomed to sharp distance vision. These patients are rather challenging to fit in multifocal lenses because they dislike the slight blur at distance they experience.
Though there are several ways to determine ocular dominance, there is poor intra-individual agreement between sighting and sensory methods.11 In research, it appears the sensory method of measuring ocular dominance is preferred.
When fitting multifocal contact lenses on your presbyopic patients, it is important to follow the manufacturer’s recommended fitting guide, determine ocular dominance with the sensory method, and set realistic expectations about the quality of vision with these lens designs. The No. 1 reason for lens dropout among presbyopes is poor vision.12 Factors contributing to poor vision include lack of astigmatic correction (for those in daily disposable lenses), subjective vision at distance or near, and lower subjective visual contrast.
Successful wearers cited convenience as a top priority to continue in contact lenses.12 Therefore, as practitioners, we should continue to offer contact lenses to our presbyopic patients and troubleshoot as best we can so they are able to remain in lenses for as long as desired. When it comes to highly astigmatic patients, there are several toric multifocal lenses in our arsenal. Though they are all monthly replacement modalities, there are both center distance and center near options.
We also often forget about lens types outside of our disposable soft lenses. Corneal gas permeable (GP) lenses often provide sharper visual acuity than soft lenses. There are aspheric gas permeable lenses that operate in the same way as their soft lens counterparts, but a design specific to GP lenses is the translating design. The translating multifocal is similar to a spectacle bifocal or trifocal where there are distinct zones separated by a line or junction. Translating lenses offer the benefit of clear vision at each distance, like monovision, with the added benefit of maintaining depth perception. The one caveat to the translating design is the need for proper lid anatomy to push the lens up when the patient looks in downgaze or allow the lens to properly “translate.”
Another consideration for this absolute presbyopic group is a scleral multifocal lens. The prevalence of dry eye increases with age, and scleral lenses are an option for dry eye therapy. The customization that is available with scleral lenses allows for decentered optics to account for lens decentration, varying zone widths to address different pupil sizes, and customized lens powers to achieve maximum visual acuity.
Overall, practitioners should consider multifocal lens designs for all stages of life. Though the specific designs and fitting processes may vary depending on the intended use, these multifocal lenses continue to be a treatment we can offer every patient. Considerations beyond the typical disposable soft lens should also be made. Patients prefer the convenience of contact lenses, and we as practitioners should continue to offer these products to our patients.