The best place to start with the question “Can LASIK fix a lazy eye?” is to figure out what we’re really asking. A lazy eye is one of those diagnoses so firmly rooted into our common vernacular that the specifics of the condition get lost. It’s similar to wondering if there’s a surgery that can fix a “bum knee.” It’s gonna take getting down to the nuts and bolts (or specific anatomy and pathology) to determine whether that can be an easy fix, or impossible.
In this case, a lazy eye is usually thought of as an eye that looks in the wrong direction or can’t see well. But why does it look in the wrong direction, or for that matter, why can’t it see well? The answer to both of these questions usually isn’t found in what’s happening in the eye, but instead lies further back in what’s misfiring in the brain.
Where good vision comes from
Quality of vision is determined by (1) how well the eye works and (2) how well the brain is processing information from the eye. Both components have to be there. It’s impossible to say which one is more important. It’s like asking whether the right or left blade of a pair of scissors matters more. A person with perfectly functioning eyes and a brain with no visual cortex is exactly as blind as a person with a flawless brain and no eyes. It’s an important point to make because eyes get all the credit. They’re right there on the front of your face. We see people every day with poor vision that is cured by glasses. Inevitably, we tend to assume that good eyes equal good vision. It’s reasonable because bad vision almost always means bad eyes. Almost.
A lazy eye, clinically known as amblyopia, would be an exception to this rule. Amblyopia is present from a very young age and persists into adulthood. Why point that out? Well, it’s incredibly rare to develop vision problems because of a brain problem later in life. As a result, vision problems are further cemented into our consciousness as eye problems. It’s very easy to get poked in the eye, but (thankfully) very difficult to get poked in the brain. When you take all of that into account, it makes sense for people to ask the question, “Can LASIK fix a lazy eye?” It makes sense because we are asking about the only condition most people will ever encounter where bad vision is caused by the brain.
By this point, I feel like we’ve drawn a slightly clearer picture of the details behind the question. Maybe you read a lot of mystery novels and have jumped ahead in solving this. But before you say, “No! LASIK can’t fix a lazy eye because the brain did it in the visual cortex with a developmental error!” you should know, there is one more chapter in the story. No good detective story can finish without a twist. In this case, it’s that LASIK sometimes can help with a lazy eye. As for why and when, we must turn to a motive.
Three reasons for lazy eye
We now know that amblyopia is a brain visual problem, not an eye visual problem, but we never uncovered why that problem shows up in some kids and not others. There are three reasons:
- One eye looks in a different direction. The brain hates double vision, so it turns off for that eye.
- One eye has an obstacle blocking the vision. The brain isn’t getting any information from the eye so it can’t develop vision for that eye.
- One eye is just too blurry. The picture simply isn’t clear enough to develop vision for that eye.
It’s in this last case, where someone has a much higher prescription in one eye, that LASIK can sometimes help. There are some prerequisites to be met—the vision must be correctable to 20/40 and the vision must be poor because of a prescription that LASIK can fix—but in those cases, there is hope.
Your brain on LASIK
When someone is a candidate for LASIK in spite of some level of amblyopia, we find that something magical can happen. Despite a half-century of common wisdom saying (and I’m summarizing here) “the visual cortex you’ve got when you’re nine determines how good your vision can be,” we now know we can get better vision from our brains even through adulthood. When a prescription gets fixed for an eye that hasn’t been doing much for all those years, it turns out the brain can go through a bit of an awakening too. When the vision is improved in the eye, it can start to improve vision at the brain level. It means that the ceiling for “this is the best I can see with glasses” can be raised higher, allowing even better vision after LASIK.
So in answer to the question “Can LASIK fix a lazy eye?”, I can confidently give you a resounding “sometimes!” The chances of having the right level of amblyopia and the right reason for it make the odds of LASIK candidacy lower, but it is a wide and important gulf between low odds and no odds at all.
It may be that the story of your eyes has a plot twist of its own. And if it doesn’t, that’s okay too. It just means you’re more like the Rocky movies where everyone still likes you even though what happens is exactly what you expected.
Editor’s note: This post was originally published in March 2014. It has since been updated and expanded.