Article

Cutting Edge Contact Lenses for Presbyopia

IT IS ESTIMATED THAT MORE than 140 million people worldwide wear contact lenses.1 The global market size was valued at $7.84 billion in 2020 and is projected to grow from $8.58 billion in 2021 to $12.56 billion in 2028, a compound annual growth rate of 5.6%.2 One of the reasons for growth of the contact lens market is the correction of presbyopia.3

The prevalence of unmanaged presbyopia is up to 50% of those older than 50 in developing nations, due to a lack of awareness and accessibility to affordable treatment, and it is even as high as 34% in developed countries. Currently, there are an estimated 1.8 billion people worldwide with presbyopia.4 In fact, the number of presbyopes is expected to increase as the millennial generation (born 1980 to 1994) enters its 40s. Millennials are now the largest adult cohort worldwide at 72.1 million, surpassing the size of the baby boomer population (ages 58 to 76) of 71.6 million.5 As these aging millennials are added to the 65.2 million people who make up Generation X (ages 42 to 57), the total number of presbyopes needing vision correction will increase substantially.5,6 It is not surprising that presbyopia is considered a growing revenue stream, as doctors and patients alike are looking for treatment options.

All methods of presbyopic correction have advantages and disadvantages. Over-the-counter (OTC) reading glasses are the most common solution to presbyopia, worn by 33 million Americans.7 However, many people want to be spectacle independent. There are different types of contact lens materials (soft, rigid, hybrid) and a variety of lens options depending on the individual and his or her visual goals. This article focuses on innovative contact lens options.

Soft Multifocal Contact Lenses

Both commercially available and custom-made soft multifocal contact lens designs are available. With commercially available lenses, the lenses are replaced daily, biweekly, or monthly and are available in a range of multifocal designs. With custom designed lenses, the base curve, diameter, and powers can be specified. For some lenses, custom optic zones can be manufactured.

Custom monthly replacement soft multifocal lenses—including toric and options in both standard hydrogel and silicone hydrogel materials—are vast, with combinations of sphere (+30.00D to -30.00D), cylinder (-0.75D to -10.00D), axis (any degree), and add power (up to +4.00D). Multiple custom designs are made to order, including near-center, distance-center and aspheric near-center and distance-center. CooperVision, Concise Custom Soft, and SpecialEyes are examples of custom soft contact lens producers.

Revive (Bausch + Lomb) is a novel soft lens option that is available as a multifocal and multifocal toric (sphere and toric powers are also available). This custom soft multifocal comes in standard and custom parameters with adaptive trizone technology, which is beneficial for presbyopes with flat or steep corneas or small or large pupils. A customizable near add zone (from 1.8 mm to 3.0 mm) for multifocal alignment is available with adaptive trizone technology. Sphere powers range from +/-30.00D in 0.25D steps. Add powers options range from +0.50D to +3.00D in 0.25D steps. The multifocal toric offers dual elliptical stabilization for a thin ballast. Toric cylinder powers range from -0.50D to -10.00D in 0.25D steps in 1º increments. Custom diameters are offered from 10.0 mm to 16.0 mm.

Lentechs is developing a new generation of suspended soft contact lenses for presbyopia, for presbyopia with astigmatism, and for single vision with and without astigmatism.8 Lentechs has a novel technology called Apioc, which is a suspended soft contact lens with optics designed to provide crisp vision correction at distance, intermediate, and near. The lens is designed to be suspended from the inside of the upper lid and float above the cornea on the tear film. Unlike traditional contact lenses, in which the lens moves with the eye, the Apioc lens is suspended behind the upper eyelid, allowing for free, translational eye movement, behind the rotationally stable, centered contact lens. With the eye freely moving behind the contact lens, wearers can access the actual prescription needed for each visual distance correction.

Hybrid Multifocal Lenses

Hybrid lenses have a gas permeable center bonded with a peripheral soft hydrogel or silicone hydrogel skirt. Hybrid lenses provide the optics of a corneal gas permeable lens and comfort and centration similar to those with a soft lens. Ideal candidates for hybrid lenses are individuals with high visual demands, those who experience blur due to soft toric lens rotation, or those who want more sharp vision similar to corneal lenses but with the comfort of a soft lens. Hybrid lenses may be designed by diagnostic or empirical fitting with either raw topographical data or specific values, such as axial keratometry readings and eccentricity. Established hybrid multifocal lenses are center-near or center-distance designs with multiple near zone diameters. Modern hybrid multifocal lenses have an extended depth of focus design.9 The SynergEyes iD Multifocal EDOF lens is available with multiple base curves and skirt curves. Sphere powrs range from +5.50D to -8.00D in 0.25D steps and -8.50D to -10.00D in 0.50D steps. Add powers are available in low, medium, and high. Hybrid contact lenses are available from SynergEyes in the United States.

Scleral Multifocal Designs

Scleral lenses (SLs) provide many optical and therapeutic indications, the major ones being visual rehabilitation in irregular corneas, therapeutic treatment of ocular surface disease, and correction of refractive error in normal or healthy eyes.10 Scleral lenses are among the best options for visual correction in eyes that have been unsuccessful with conventional contact lens modalities. Modern scleral lenses are used to correct simple refractive errors, including presbyopia, especially when other modalities fail due to vision or comfort issues.10 Advancements in the manufacturing process, lens materials and lens designs, and increased knowledge of scleral anatomy have enhanced SL fitting.

Scleral lenses tend to typically decenter in the inferotemporal direction due to the effects of gravity, eyelid morphology, and scleral shape.10 Inferior decentration can generate a small base-down prismatic effect due to an asymmetric fluid reservoir, which can create residual higher-order aberrations11 and problems for those who wear a single SL. These optical effects can be reduced by decreasing the amount of decentration, by fitting a toric or customized landing zone.10

Many SL manufacturers offer the option to include multifocal optics with their own proprietary design for multifocal lenses.12 Scleral multifocal designs may include near centered, distance centered, aspheric, and periscopic.12 Although most SL multifocal fittings are based on fitting a monofocal SL first, a few manufacturers offer specific diagnostic fitting sets for multifocal SLs. Since lens designs are unique and require different approaches for troubleshooting, it is essential to follow the manufacturer’s recommendations for enhanced success and laboratory consultant recommendations and, if available, to follow the fitting guide.

Mojo Vision

The Silicon Valley company Mojo Vision is developing a consumer-oriented augmented reality smart SL that includes the world’s smallest LED display, a microprocessor, eye-tracking sensors, wireless data, and rechargeable batteries.13 Mojo Vision is applying its smart lens technology to provide such a lens, recognizing that there is no perfect contact lens that provides sustained clear vision at all distances for presbyopic patients without compromised vision or spectacles. Rather than addressing presbyopia with multifocal optics, the company has set out to essentially restore accommodation to patients digitally.

The Mojo Autofocusing Lens for Presbyopia begins with a monofocal SL (also helpful for treating dry eye, which affects presbyopes) that is prescribed for the patient’s distance vision (Figure 1). Placed directly on top of the lens is another lens capable of adding up to 3D, which is continuously adjustable by varying electrical input. This setup essentially provides an on-demand monofocal lens with the precise add required to enable a patient to see clearly at a given distance, not unlike the behavior of a healthy crystalline lens.

Figure 1. Mojo smart autofocus contact lens. Provided by Mojo Vision.

Mojo then uses its in-lens eye-tracking sensors to determine the exact position and orientation of both eyes, enabling the lenses to precisely ascertain an individual’s vergence. The vergence data enables the smart lens microprocessor algorithms to compute the distance of the object that the patient is attempting to focus on, signaling the variable focus lens to change the add power needed for that distance.

The practitioner plays a critical role in calibrating and dispensing the lens. Using an app to “train” the lens while the individual is in the exam chair, the practitioner sets the lens to the correct power for near and intermediate vision. This calibration is expected to drastically reduce the amount of chair time a practitioner spends trying to fit an individual with multifocal, or even monovision, lenses. Once the lens is configured, and the patient leaves the office, the lens then provides automatic accommodation without any patient involvement, enabling the patient to see clearly at all distances without spectacles or any of the complications and compromises of multifocal optics. If adjustments are needed due to presbyopic changes, the practitioner can readjust the lens without needing to dispense a new lens.

With multiple presbyopia treatment options, including contact lens options, we have the ability to personalize the management strategy for each individual patient and customize options to fit patients’ needs. It is critical to educate patients that there are many options to correct presbyopia, including progressive lenses, contact lenses, pharmaceuticals, and surgical options.

Eyecare practitioners have the opportunity to provide presbyopes excellent vision and freedom from spectacles with contact lens options. ■

References

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  13. Mojo Vision. Personal Communication. August 1, 2022.