Want lasik? Want to also avoid reading glasses? Well, then you want to look into monovision lasik.
Monovision with lasik can be a very successful way to correct vision and get out of glasses for everything or almost everything.
Already used to monovision with contact lenses? Well, then good news, it shouldn't be difficult for you to transition over to lasik as well.
But for everyone else, the concept of monovision can be a little confusing. So let's review what it is actually doing and what you can expect with monovision.
Vision Changes In Our Forties
If it weren't for one thing that happens in the lives of everyone, monovision wouldn't be necessary.
Within our eye is a natural lens. You can't really see this lens, you just have to trust me that it's there.
But we actually unconsciously control this natural lens and make it change shape. When you are young and look up close, we change the shape of this lens to focus and seamlessly look up close (assuming your are wearing your glasses or contact lenses if needed).
How the eye focuses up close, image by MikeRun, CC BY-SA 4.0, via Wikimedia Commons
But unfortunately this doesn't last forever.
Through something called presbyopia, this lens and the muscles that control this lens become weak. This means this lens can't change shape enough and our ability to see up close becomes weaker and weaker.
Eventually we need progressive glasses or reading glasses to replace the focusing this lens was doing in order to see things up close.
But there is another way…
Monovision
Typically the prescription in a pair of prescription glasses or contact lenses corrects your vision to see far away in the distance. But changing the prescription of the glasses can actually change where vision focuses. In fact, reading glasses already do this. Reading glasses focus our vision up close instead.
Imagine if you only put the reading glasses over one eye. Just that eye would be focused up close. The other would still see off in the distance. What you've done is you've created monovision.
That’s all there is to monovision. One eye is corrected for far away distance vision while the other is corrected for up close vision.
But that sounds weird!
It does, but our brain is actually capable of adjusting to that difference.
When we see, vision passes from our eyes to our brain. The brain then interprets the image and tells us what we see. Imagine that our eyes are the lens and photocells of the digital camera and our brain is the computer chip that spits that image back out to us.
Normally, vision from both eyes are combined together to provide even better vision.
However, if one eye is a little more blurred than the other (which it is in monovision), the brain suppresses or turns off the image from that eye. We may be none the wiser that an eye is even blurry (until we cover and compare the eyes).
Most people are capable of adjusting to monovision. Learn more about it at Is My Brain Adjusting To Monovision?
So because monovision works very well, it has a long long track-record of being successfully used with contact lenses. But how does it do with lasik?
Monovision Success With Lasik
In fact, monovision with lasik can have a higher success rate than monovision with contact lenses.
Lasik eliminates one key variable - contact lenses. Try as many people may, sometimes contact lenses can just be too irritable to the eye. Contact lenses can cause your eyes to dry out more.
So many people get lasik for this exact reason, to get out of contact lenses.
When you boil monovision down to just pure correction of vision, it becomes very successful with lasik. Between 90-95% of individuals are able to adjust to monovision after lasik.
Monovision is a great way to get out of reading glasses with lasik.
Limitations And Drawbacks Of Monovision
Of course, there is a catch. Monovision isn't perfect.
There is a fine balance between how strong the monovision is and the ability to adjust to the monovision.
- The stronger the monovision, the stronger the up close vision, but the more challenging it can become to adjust to the monovision.
- Conversely, the weaker the monovision, the better the ability to adjust to the monovision, but the weaker the reading vision.
It turns out that most people adjust well with just a little bit less strength than traditional full monovision. This has led to the development of the terms mini-monovision and blended vision to differentiate this from full monovision.
To get into numbers, this equates to a reading vision power of +1.50 or less. This reading focus is actually quite close to the distance you would read a computer from (about arms length).
This focus for the reading eye actually works quite well for most people. Because, remember that weak lens that prompted you to get monovision lasik in the first place? Well, it still works some, and can boost the reading vision a little bit more. This lens is able to extend the focus a little bit closer than that arms length distance; providing a good focus range to your vision with monovision.
But even with all that, you can have some trouble if you like to hold things real close or when trying to read tiny print after monovision lasik.
And, as you get older and as your lens gets even weaker, your reading vision can decline just a little bit more necessitating reading glasses more frequently.
If you desire to have a weaker monovision, expect stronger distance vision from both eyes working together more, but expect weaker reading vision. It's all a trade-off.
Trialing the monovision with glasses or contact lenses prior to the lasik can help fine-tune the optimal focus for your eyes.
Reduced binocular vision
Because our two eyes are spaced apart, they each see things in our 3D world slightly different. The brain then pieces these together to give us our 3D perception of vision.
When we have monovision, we reduce this 3D perception.
It's not typically enough to have you stumbling over curves when walking. But it can be something noticed when more sophisticated levels of 3D perception are required (playing tennis is one such activity).
More issues at nighttime
Driving at night can be more challenging with monovision than without.
The suppression that our brain naturally does on its own works a little less at nighttime. Bright lights from oncoming headlights will be sharp and in focus in your distance eye but will be blurry in your up close eye. This will add additional blur and glare around lights at night.
For some, its enough to make them wear glasses when driving at night to balance out the two eyes and sharpen things back up again.
What If You Don't Adjust?
It can happen. Not everyone is capable of adjusting to monovision, try as they may.
There can be a few "roadblocks" to preventing you from adjusting. Getting those roadblocks out of the way can set you on the pathway to recovery.
Anything that causes your vision to be blurry can prevent you doing well with monovision. The biggest cause after lasik is dry eye.
Dry eye
After lasik, your eye will dry out more. When the eye dries out, your vision can fluctuate and become blurry.
This becomes MORE significant with monovision. When both eyes are focused together and one eye becomes blurry, the other eye compensates and we may not even notice the fluctuation and blurry vision as much. But with monovision, each eye is on its own. ANY blurring or fluctuation of vision prevents you from seeing well.
Dry eye must be treated aggressively. The best initial first step is by using frequent preservative-free artificial tears. Check out Visit These Are The Best Eye Drops After Lasik to learn all about the different types.
Lasik Touch Up or Reverse Monovision
If your vision and eye all look good, perhaps you just fall into the 5-10% that can't adjust.
For some, tweaking the monovision and making it weaker can help. Having a weaker monovision may help get you to adjust.
But for others, monovision after lasik can be completely reversed if needed.
This can be done through a lasik touch up enhancement procedure. During this, your surgeon lifts up the lasik flap, corrects the prescription of the eye and then repositions the lasik flap back in place.
Fortunately, if you can't adjust to monovision, you don't have to live with it. You may just have to live with needing reading glasses instead.
Summary
Monovision lasik is very successful. However, reading glasses may still be required to see small print or details and there are some limitations on vision after the correction. However, despite all that, many people are able to adjust and significantly get out of glasses.
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