Joel Hunter, MD Refractive Surgeon, Hunter Vision Updated 10/31/18 11:33 AM
I discovered a while back it’s important to be clear about the definition of night vision with this question. How did I learn this? In a sitcom-like moment with a post-operative LASIK patient, he was telling me about his only problem with his vision. “When I’m in my car at night, I can’t see.” So I started to tell him about how occasionally headlights can have starbursts at first and it gets better over a few months. No worries though, because based on his treatment, it was still likely that he’d end up with better night vision than he had with contacts.
Then he told me that’s not what he meant. “No. I mean, I have really dark tinted windows, and at night I can’t see stuff in the dark when I’m my car. Like if there isn’t light, I can’t see it.” And I think I accidentally made him feel more nervous about it. Because when he looked at me, I had a face of pained confusion as if he’d just asked me if why he doesn’t have hands on his legs instead of feet. At some point, I had conveyed the message that excellent night vision would mean the ability to see in the dark like the alien trophy-hunter, Predator. Once I figured it out, his disappointment made a lot of sense.
What exactly is night vision?
With night vision after RLE, we’re talking about clarity of vision at night and low-light situations. The most famous version of this is nighttime driving. It’s important to have the right expectation—or more accurately the right timeline of expectations—when walking through the process of RLE. The reason being, the night vision experience one week after the surgery is not the same as it will be further down the road. And it’s the “down the road” that matters because it represents the permanent, lasting version of your final vision.
When the old lens is taken away and a new, perfectly clear lens is put in its place, there is a big increase in clarity. This is true of RLE just like it is of cataracts. Sure, cataracts are extra cloudy lenses, but your natural lens at the time of RLE—before full-on cataracts have set in—still isn’t remotely close in clarity to a new artificial lens. So that should mean the clarity of night vision gets an automatic boost, right? Well, sometimes it does. But oftentimes that boost takes time.
Neuro-adaptation takes time
When you gain both distance and near vision without glasses, it means the light entering your eye must be shared with some of it focused at distance and some at near. Luckily, your brain is amazing at doing this, and it only takes somewhere between a day and a few months for you to register only the clear distance light and neurologically delete the blurry stuff. It’s during the period of neuro-adaptation—your brain “learning” your new eyes—that you can still see the blurry stuff along with the clear stuff. It leads to a situation where you can read a road sign just fine, but it also doesn’t feel clear.
A week or two after surgery, I tell almost every patient going through LASIK or RLE, they don’t ever need to ask the question, “Am I going to be able to get used to this?” Because whatever the vision looks like at that point, it isn’t the same vision they are going to have further down the road. It’s not that it’ll look weird or blurry, but they’ll learn to be bothered less by it. The vision actually clarifies and tests better on an eye exam. Everything we see is a result of our brain creating the picture. Once you’ve had RLE to correct the focusing power, the only step required your brain learning to create the picture perfectly with new and better optics.
For good candidates for RLE, the final result should be night vision that’s easy in a way that you never have to think about it. But to get there, sometimes some conscious and subconscious thinking and learning pave the way. And yes, it’s true that boring, clear vision at night isn’t nearly as exciting as permanent special-ops night vision goggles. If we had a way to do the latter, I definitely wouldn’t keep it a secret. Until then, the version of night vision most of us are looking for can definitely be made clearer.