MONOVISION AS AN OPTION FOR PRESBYOPIA MANAGEMENT has been conventionally successful in patients who are motivated to decrease their need for bifocals or reading glasses. It is a tool that optometrists certainly utilize by combining a monofocal contact lens with different myopic offset powers in the reading eye, leaving patients with anywhere from -1.25D to -2.50D myopia. A greater disparity between the two eyes leads to greater potential issues, including monovision intolerance with headaches, feelings of imbalance, and loss of stereopsis when the myopia is beyond -1.25D. Patients can also have difficulty with night driving and increasing problems with positive dysphotopsias with their night vision in the myopic eye.

For surgeons, monovision is commonly utilized as a way to manage presbyopia in our patients. Based on MarketScope data and ASCRS clinical surveys, upwards of 50% of cataract surgeons utilize monovision, and monovision may be used 3 times as frequently as the presbyopia-correcting technologies that are available to date. Notably, presbyopia-correcting lenses have undergone an increasing trend in market penetrance over the last handful of years due to the introduction of both diffractive and refractive extended depth of focus (EDOF) lenses, as well as trifocal lenses and the high-performance hybrid EDOF/bifocal lens implants that have been introduced.

This being said, monovision is a nice option to utilize for different reasons, including the lower costs and fewer side effects that are seen when utilizing monofocal intraocular lens (IOL) implants. Surgical monovision is most successful in those patients who were successful monovision patients in their contact lens wear or through soft contact lens trials. Importantly, pseudophakic monovision with a standard monofocal IOL implant has not been the same as phakic monovision because there is no accommodative reserve left when a patient is pseudophakic.

Customizing Options

I believe there is a paradigm shift that will happen with modernizing monovision, allowing this to be even a more viable option as we become able to customize options for our patients today. This is a result of the EDOF lenses, as well as enhanced monofocal lens implants, which provide a greater pseudophakic accommodative amplitude due to their optic design (the Tecnis Eyhance, the Rayner RayOne EMV, and zero asphericity lens implants, like the Bausch + Lomb Envista and BVI iPURE monofocal IOLs). In addition, presbyopia topical therapies are entering the market, and the likely commercialization of the AcuFocus small aperture IC-8 IOL implant should occur later in 2022.

Monovision has the inherent benefit of allowing for presbyopia correction while mitigating night vision symptoms, particularly in the distance eye. This is an exciting benefit of presbyopia correction utilizing monovision. Customizing this process with a modern approach with increasing technologies for the reading eye will allow surgeons to provide the same levels or greater amounts of near vision, with less disruption to stereopsis, as well as providing a more complete range of vision. In pseudophakic monovision, with standard lens implants, the near eye generally has a “sweet spot” that is either for the near range or the intermediate range but not necessarily both. Customizing monovision will certainly broaden our opportunities, and it has already done so very successfully in my surgical practice.

EDOF Lenses

For several years I have utilized EDOF lenses with great success. In the nondominant eye, I have used both the Tecnis Symfony EDOF IOL, as well as the Alcon Vivity IOL, with offset at upwards of -0.75D to -1.25D. This is specifically done in those patients who have already been successful in their monovision contact lenses. Patients are extremely happy that their depth perception is better than what they experienced with their prior contact lenses (especially when the near eye was a goal ≥1.50D) and that they have a more complete range of vision, particularly those who are 60 years old or older and have lost most of their natural accommodative reserve.

Patients have a very full range from far, intermediate, through near vision, and by virtue of lens designs I do notice that patients have greater range of vision with the Tecnis Symfony/Symfony OptiBlue IOL. By design, the Tecnis Symfony has approximately 1D over the monofocal in near defocus vision, while the Alcon Vivity has approximately 0.5D of greater near vision and defocus over the monofocal IOL.

Enhanced Monofocal IOLs

The enhanced monofocal IOLs alone have also been very helpful for me. I specifically have more experience with the Tecnis Eyhance lens family. But the availability of this lens has provided me the freedom to provide some greater range of vision to patients who have been successful monovision soft contact lens wearers, offsetting the patients to only a -1.50D in the near eye without necessitating a conversation about having only intermediate vision. Thus, the enhanced monofocal IOL makes pseudophakic monovision more similar to phakic monovision because the Tecnis Eyhance lens provides an extra 1-2 lines of near vision routinely due to the greater negative spherical aberration that is built into the optic itself. This also further allows me to provide an option for presbyopia correction to patients who have other ocular comorbidities, such as corneal or macular pathologies. For myself, the enhanced monofocal IOLs can be used in any patient who could receive a standard monofocal lens implant. In my hands, this has provided an incredible freedom to be able to provide a little extra range of vision for those with ocular comorbidities without sacrificing contrast sensitivity.

For any monovision approach, in the dominant eye I will place either a monofocal lens implant, or now, I have been utilizing an enhanced monofocal IOL counterpart. I’ve been very happy with using the Tecnis Eyhance implant in this way. Patients experience a very sharp distance vision, which I target to land first plano, or first plus, without sacrificing or compromising their night vision. I always comment, and let patients know, that they will experience 85%-95% freedom from their spectacles, but there will always be circumstances where they may want their distance eye to have some aid if reading for a long time, particularly under dimly lit situations, and there may be certain driving conditions that would warrant the near eye brought out to the distance with some driving glasses to aid the distance eye. Driving in the rain at dusk might be a great example of an environmental condition that might warrant using some prescription driving glasses to maintain the best binocular distance vision possible for certain scenarios.

Blended Monovision for Multifocal IOLs

Similarly, I have also utilized a blended, or customized, presbyopia-correcting lens approach, which some may consider to be in the monovision realm, using a trifocal lens implant in the nondominant eye. The trifocal or the high-performance hybrid EDOF/bifocal IOL (Alcon PanOptix and Tecnis Synergy, respectively) are excellent additions to our presbyopia-correcting lens options. However there are patients who desire the fullest range of vision, and they are willing to move forward with surgery, but trepidation exists concerning their nighttime driving with the glare and halo profile.

For patients who are experiencing a more significant amount of positive dysphotopsia with nighttime driving after the diffractive presbyopia-correcting IOL implant has been placed, I give them a choice. Either they can have the first lens implant in the first eye exchanged for one that has much fewer night vision symptoms at the sacrifice of their new near vision, or they can allow me to proceed in the second eye with an enhanced monofocal lens implant. This provides a “social” reading ability. There is no disruption to the distance vision, and patients will still be able to enjoy the ability to see their cell phone texts, as well as look at a restaurant menu or review text on computers for short periods of time. They would need to supplement with reading glasses for any extended period of near or computer work.

Doing so has allowed for significant satisfaction in my patients who were concerned about and unhappy with their night vision profiles after the first eye surgery, preventing me from having to perform IOL exchanges. Simply stated, patients appreciate that it provides the best of both worlds and that we started with the technology that provided the fullest range of vision for them.

The Near Future: Small Aperture Lens

Along the same lines, a likely new player in the presbyopia-correcting lens implant space, the AcuFocus IC-8 lens implant, will be a tremendous asset to cataracts surgeons. This will be the first time that we will have a small aperture lens implant, allowing for higher quality of vision while providing an extended depth of focus.

I was fortunate to be an investigator in the FDA clinical trials, and 1.5 years out, my patients who had the IC-8 lens implant in 1 eye do not use reading glasses to date. The eye with the IC-8 lens implant experiences the benefit of having both extended distance acuity due to the pinhole effect and an additional 1D of accommodative amplitude at near. Thus, a patient who is offset for a -0.75D often experiences an uncorrected distance visual acuity of 20/25, and can read through J2 with ease.

There is no break or required “sweet spot” for their near vision either. The second eye has the monofocal lens implant placed, allowing for the best of all worlds, with the highest quality of vision while mitigating positive dysphotopsias. This obviates any stereopsis issues at a lower price point than having to implant 2 presbyopia-correcting lenses, with a lower night vision symptom profile and without the need to align the IOL for toricity correction of up to 1.50D. The binocular contrast sensitivity is unaffected bilaterally compared to monofocal lens implants.

Finally, we now have a lens that can be implanted to provide a better quality of vision for those patients with irregular astigmatism or a greater landing zone for potential vision issues from refractive misses in those eyes that are status postcorneal refractive surgery and laser vision correction or radiokeratotomy surgeries. This will be an exciting prospect to be able to offer to patients, hopefully later in 2022.

The Role of Topical Therapies

I believe the presbyopia-correcting topical therapies provide an additional source of presbyopia correction for our pseudophakes as an off label use. It is surprising how pupil size and corneal higher order aberrations plus pseudophakic optic designs actually provide a decent amount of intermediate range of vision, with a slight, minus offset.

Giving patients a miotic drop to use in the more myopic eye is a likely brilliant idea to provide an extra few lines of vision. I have done so with a modicum of success in patients since it does provide some additional freedom from the use of reading glasses in my more emmetropic postoperative patients.

Conclusion

As presbyopia-correcting technologies continue to improve, we will find increasingly effective combinations for our patients. This individual customization is the future of monovision, or blended vision, as our management of presbyopia evolves. ■

Dr. Yeu joined Virginia Eye Consultants in 2013, has been a partner since 2014, and continues her commitment to residency training in ophthalmology as an assistant professor of ophthalmology at the Eastern Virginia Medical School. She is medical director of the CVP Mid-Atlantic Surgery Center and sits on the board of directors for the Virginia Eye Foundation.