It is normal to experience a loss of close vision after age 40. This process, called “presbyopia” (Greek for “aging of the eye”) affects everyone who sees well in the distance.

Presbyopia is therefore an age-related need for reading glasses (“cheaters”) or bifocals in glasses. It occurs as the natural lens of the eye becomes progressively stiffer with age.

STEREO VISION

If both eyes are perfectly focused at distance, either by birth, by contacts or glasses, or by LASIK, it is normal to start needing reading glasses (“cheaters”) after your early 40s. The need for reading glasses gets stronger every year, typically until your early 60s, at which time the lens has become completely stiff. A good rule of thumb is that with stereo vision, everything from a fully extended arm’s reach and beyond will be clear, but within the fully extended arm, you will eventually need reading glasses as you age and your presbyopia worsens.

MONOVISION

One option for presbyopic people who wish to avoid reading glasses is to create “monovision” in which the dominant eye is corrected for distance and the non-dominant eye is corrected for close vision. With both eyes functioning as a team, the presbyopic patient can see near and far, all without glasses. Monovision can be an excellent option for presbyopic patients, but there is a downside: the quality of the distance vision is often not as good as if both eyes were corrected for distance. This is particularly noticeable at night or under dim lights. A night-time pair of driving glasses can fill this gap and allow patients to enjoy the other benefits of monovision.

BLENDED VISION

Blended vision, or “mid-monovision,” is a less severe variation of monovision. With monovision, the dominant eye is set for distance and the non-dominant eye is corrected for close vision. By contrast, with blended vision, the non-dominant eye is set for mid-range vision, rather than close range, creating less of a disparity between the eyes. Blended vision is often more comfortable for patients and tends to minimize the distance impact of monovision. Unlike monovision, the goal of blended vision is not to eliminate reading glasses altogether, but rather to dramatically reduce their need. With blended vision, presbyopic patients typically can still read a cell phone or write a check without “cheaters,” but will often wear a light pair of reading glasses to read a phone book. Blended vision offers patients a different balance of priorities than monovision does — the emphasis is more on the mid range (where computer screens are) rather than the close — and also provides better and more comfortable distance vision than monovision does. As with monovision, a night-time pair of driving glasses can help fine tune low light distance vision.

WHO BENEFITS FROM MONOVISION OR BLENDED VISION?

To some people, the idea of having one eye for distance and one eye for closer up sounds strange and imbalanced. In fact, not all patients are good candidates for monovision or blended vision. However, many people are surprised by how much they do enjoy monovision with little or no sacrifice in vision or balance. In fact, the data shows that 80% of people are very pleased with either monovision or blended vision, whereas 20% have trouble adapting to it. We can help determine if you will benefit from either monovision or blended vision before surgery by simulating these two options for you in the office. Ultimately, you will best know how you react to monovision or blended vision by this simulation, giving you a chance to “try on” the surgery before any surgery is done!

Similarly, people who have otherwise never worn glasses in their lives, but now need reading glasses, can be offered monovision or blended vision. For these patients, LASIK is performed only in the non-dominant eye to allow it to see closer and the dominant eye is left untouched for distance, allowing the team of both eyes to see well near and far without glasses.

CORNEAL INLAYS

Corneal inlays are a new technological approach to addressing presbyopia. As with monovision or blended vision, some degree of compromise is involved. Corneal inlays involve placing a piece of plastic permanently within the cornea to help with near focus. The only corneal inlay currently approved by the FDA is the Kamra (by AccuFocus) Corneal Inlay. It utilizes “small aperature optics” to achieve its near vision improvement much in the same way looking through a pinhole lens increases the range of focus. The inlay — which looks like a tiny washer — is inserted in the non-dominant eye in the cornea. The FDA approved the Kamra in 2015, but while the FDA Ophthalmic Devices Committee voted to recommend its efficacy, it did not endorse its safety. While the inlay typically is well tolerated, atypical healing responses over time have been reported. The Kamra inlay is removable. Other corneal inlays are expected to also soon be approved by the FDA, including the Raindrop Near Vision Inlay and the Presbia Flexivue Microlens.

LENS IMPLANTS

During cataract surgery, the human lens — located inside the eye behind the pupil — is removed and a plastic lens implant is permanently put in its place. New generation “premium” implants can be used to correct presbyopia. There are two types of presbyopia correcting implants: flexible implants and multi-focal implants. Both types of lenses have both pros and cons to them. Cataract surgery can be performed on your eyes even if you do not have a cataract in a process called “refractive lens exchange.” At the time of refractive lens exchange, a presbyopia correcting implants can be used. In general, Dr. Shapiro’s preference is not to recommend cataract surgery or refractive lens exchange as a treatment for presbyopia until you actually have a visually significant cataract.