About LASIK Treatment

Will I Lose My Near Vision After LASIK?  LASIK Surgeon Matthew Sharpe, M.D. Addresses Common Concerns

The need for reading glasses is one of the most difficult concepts for patients to understand and for doctors (speaking for myself anyway) to explain. I have used many different ways to convey this concept to my patients over the years, and no single way works for everyone. I have found showing you, as my patient is the best, but we must also be able to put it in words. I will do my best to explain it here:

First, I've often heard a few misconceptions regarding the need for reading glasses:

“My parents still don’t need reading glasses in their 60’s, so I probably won’t”
“I see just fine up close without my glasses, so it won’t affect me.”
“Doesn't Lasik or PRK speed up the need for reading glasses?”

Presbyopia, or the need for reading glasses, affects everyone at some point in their lives. That is, there is a “moving part” in your eyes that doesn’t move as well when you are 50 as it does when you are 30. The moving part of the eye to which I am referring is the crystalline lens, which sits behind the iris- the colored part of your eye. The crystalline lens is about the size and shape of an M&M candy, and is normally a clear flexible structure. When it gets significantly cloudy, which it will in almost everyone if you live long enough, we call it a cataract, and may remove it. Important for our patients though, is the loss of flexibility in this lens that occurs throughout life.

Decreasing flexibility – The lens has an amazing amount of flexibility when we are born, which allows children to focus on very near objects; even 2 inches from our face, while still able to see distant objects clearly. The gradual loss of flexibility in the lens usually becomes apparent in our mid 40’s. That is, we can only see clearly either up close or far away, but not both. If you are nearsighted, your eyes are focused up close, but you can’t see far away. If you can see well far away, you will start to need readers in your 40’s. If you are farsighted, usually the need for readers begins a little bit earlier, and may progress to needing glasses even to drive when you are closer to 50. Some people with astigmatism can see “okay” up close and far away at age 50, but not perfectly at either distance.

The “take-home” message here is that the misconceptions stated above stem from the different prescription types that affect different people, but the loss in flexibility of the lens affects virtually 100% of people.

I would like to describe the way the eye bends light, as I find it miraculous, and hope you will find this easy to understand. The important parts in the bending of the light as it enters your eye are the cornea, and the crystalline lens. The cornea does most of the bending of the light, but the lens does the fine tuning.

For a 25 year old who doesn’t need glasses, the system is perfect-the amount of bending of the light by the cornea and lens focuses pictures perfectly on the back of the eye like a slide projector on the screen. When they want to read something, the lens moves automatically to “add” bending power and focuses the light without the person even knowing this is happening. However, when they hit a certain age, the lens won’t be able to add bending power, and they’ll have to add the bending power with store bought “cheaters” or reading glasses

For a nearsighted person, the light has “too much” bending power. Things that are up close are in focus, and the bending power of the cornea and lens must be reduced (i.e. Light is focused in front of the retina - the back of the eye. It’s like you moved the well focused slide projector and screen farther apart.). This can be done with glasses or contacts that are thicker at the edges, or by flattening the cornea with laser vision correction to reduce the bending power of the eye.

For a farsighted person, the eye doesn’t have enough bending power. Young farsighted people can flex the lens of their eyes and increase the bending power of the eye and often go without wearing glasses for a large part of their lives. Eventually as they lose the flexibility in the lens, they have to add glasses to read, and then when they lose more of the flexibility, they have to wear glasses even to see road signs (i.e. It's like when a slide projector and screen are too close together.). This can also be helped with laser vision correction to increase the curvature of the eye to add bending power to the eye.

What Are My Options?

There are several technologies available to help our patients see up close better. No current technology is perfect at solving the problem of the loss of flexibility in the lens of the eye. Laser vision correction does not affect the flexibility in the lens of the eye. It won’t “speed up” your need for reading glasses, but it can change your eye’s focus from seeing well up close to seeing well far away. If you’re well into your 40’s, you may be able to see well either up close or far away well, but not both out of both eyes.

Monovision: Monovision is when we design a treatment for you to allow one of your eyes to be focused well for near objects, those within arm’s reach. The other eye is intended to focus perfectly on distant objects. I also hear concerns from my patients about monovision like: Will it make me dizzy, give me headaches, throw off my depth perception, etc. There are certainly many considerations regarding whether or not monovision will work for you, and there is no substitute for a discussion with the doctor at the center. My own biases on this are developed after hearing feedback from hundreds, if not thousands of patients on this subject over the years. I’d like to list them as Pros and Cons.

Pros of monovision: Convenience! My patients generally are pleased with monovision. They are nearly all glad they did it that way, as they generally don’t experience the problems they initially were concerned about. They don’t have to hunt down reading glasses to look at their watches, phones or food. I can’t recall any patients saying they were dizzy or who had headaches that they felt were caused by the monovision. As for depth perception, I can only recall one patient who noticed it, and it was when she was threading a needle. “It’s a little harder” she said. True depth perception becomes less important as things get farther away from us. Reversible! For most patients, we could do additional laser to correct the vision in the near eye to see well at distant objects, which would then make near objects harder to see. I require at least a three month wait to let your eyes heal, and you adapt to monovision prior to performing a reversal. Most of our patients who initially didn’t care for the monovision end up deciding that they want to stick with it after all. I would guess that somewhere around one out of every fifty monovision patients we have desires a reversal after three months. Importantly, it’s not just reading that is blurry without the monovision in our patients over 45, it’s your watch, your phone and even your food can be blurry. So it’s a desirable choice for many of our patients.

Cons of Monovision: Some of our patients do have more difficulty driving at night due to the blur coming from the near eye. There fortunately is a product called “Spare-specs” http://www.spare-specs.com/ that solves the problem of night driving without giving up the ability to go without readers at home and office. If you have a commercial driver’s license (CDL) or are a pilot, the visual requirements prohibit monovision.

Please come in and let us show you monovision, and know that there is no “best” option for everyone, it just has to be right for your needs. We need to demonstrate monovision to you for you to be able to decide. The one addition I’d have to that is that if you really cannot decide, I would lean toward doing monovision as patient feedback has been very positive. For those who don’t care for it, it can generally be reversed. Our patients who want to reverse the monovision also know what their near vision will be like, as it should be the same as the distant eye’s near vision.