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News & Blog

Does Laser Eye Surgery Affect Night Vision?

6th August, 2014  

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This week The Eye Blog seeks to address a myth that has long plagued procedures such as LASIK; does laser eye surgery affect night vision?

Complications Occur in Less than 5% of Patients

Despite the fact that laser eye surgery has helped over 20 million people worldwide back to 20/20 vision, it is continually plagued by myths of side effects.

The reality though, is that often patients don’t feel any side effects. According to the NHS, less than 5% of laser eye surgery patients experience any kind of complications. These complications most commonly include; dry eyes in the month after surgery, or seeing a glare/halo effect when driving at night. We know we’ve said this before, but severe loss of eye-sight is a very rare side effect of laser eye surgery. It almost never happens.

In Most Cases, Laser Eye Surgery Does Not Affect Night Vision

The fact that it is possible for patients to experience a glare/halo effect when driving at night after having had laser eye surgery, even if it’s rare, does raise questions. Primarily, it makes people wonder does laser eye surgery affect night vision. If it does; is it temporary or permanent? How severe is it?

It’s important to remember what we’ve just said; complications only occur in less than 5% of laser eye surgery patients. This means that for the vast majority of people, they will not experience any problems with their night time vision. But in some cases, they just might.

What is Night Vision?

To understand the whys and hows, we first have to start by explaining what night vision is. Night vision is the ability to see light in dim conditions. So how does it work?

Well, the pupil is the part of the eye that controls the amount of light that enters the retina. That is why your pupils are bigger in the dark. They expand to let more light in, because there is less light to work with. Therefore, night vision is the ability of your pupil to expand to provide more light to the retina at night.

So How Would Laser Eye Surgery Affect Night Vision?

This leads us to ask, how laser eye surgery, in some cases, could affect the ability of the pupil to provide extra light to the retina.

Basically, one of the causes of glares/halos at night is the size of your pupil. If your pupil expands beyond the area of the cornea that has received laser treatment, that can cause halos and glares in low light conditions.

Is This the Only Way Laser Eye Surgery Can Affect Night Vision?

So now we know one way laser eye surgery can affect night vision. But are there any others? Yes in fact, there are two.

One way is if the laser couldn’t quite change the shape of your eye enough during surgery. This is usually because you have a fairly strong prescription to begin with, thus are still slightly long or short-sighted after surgery, or because you have a minor astigmatism. The other is that sometimes the treatment can cause the halo/glare affect to night vision when the area of the cornea being treated is to the side. This is known as off-centre ablation.

Are These Side Effects Treatable?

This leads us to ask, are these side effects treatable? In some cases yes. In the case of glares caused by the pupil, for example.The surgeon themselves can act to prevent the effect on the pupils. All they have to do, is measure the size of your pupil when dilated before the procedure. This would allow them to ascertain whether they can treat a large enough area of the cornea. Be warned though, that if they can’t, it could prevent you from receiving laser eye surgery.

What about the other two side effects? In the case of the former, this can be corrected either by a follow up procedure or by wearing glasses at night. In the case of the latter, however, the best way to prevent this is simply to pick a skilled surgeon. It is less treatable, although can again be compensated for with wearing glasses at night.

Every Patient Will Experience Some Night Glare

In these cases, the side effects are permanent until treated (if they can be). Even if they are rare. But it is important to remember that every patient will experience some night glare after laser eye surgery.

This is because after the treatment itself, you will experience some swelling. In this case, it is the swelling that produces the glare/halo effect with night vision. Even then though, most patients won’t experience the problem with any severity. And after three months, the swelling will settle.  For the vast majority of patients, that means the problem will go away. If it doesn’t, go to your ophthalmologist.  They can conduct tests to better determine the cause of the night vision glare.

Who Can Experience Side Effects to Their Night Time Vision?

This leads us to ask who could be effected. Temporary night vision glare effects everyone. In the case of pupil-based glares, as long as you have a good surgeon, you won’t be affect. Again, in the case of off-centre glares, as long as you have a good surgeon, you’ll be fine.

Only people with really strong prescriptions should worry about the side effect. As we’ve previously explained, this is because in the case of strong prescriptions, surgery can’t completely correct the problem. However, this, and thus the glare, will be minimal, as your vision will be very near 20/20.

Why Should You Even Care?

In most cases, we’d suggest that you don’t really need to think about it. Complications effect less than 5%of patients, and in most cases are minor anyway. So unless you do a lot of driving at night, it doesn’t matter too much.

However there are cases where you need to factor the chance of the night time glare affect into whether you have laser eye surgery. If you do a lot of driving at night, for example, or if you depend on night vision for your occupation. In these cases, you depend on night vision, so laser eye surgery could affect your ability to earn a living.

So to Answer the Question…

So to answer the question, does laser eye surgery affect night time vision, the answer is yes. It can produce glare/halo affect which make is harder to see clearly at night. However, in most people this disappears after three months. In those that it doesn’t, you might want to factor in any potential night time vision effect into whether you invest in laser eye surgery

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