"I had LASIK four years ago and my eyes are blurry. Is this from my surgery or is something new?"
In this specific question in the title, the cause of blurry vision after LASIK can’t be determined from the data given. What if this guy asking the question just got pepper sprayed yesterday? Right? What if this guy, with rivulets of tears clearing lines down his orange-tinted, pepper-sprayed face, decided to ask us if his LASIK caused the new blurry vision? What a chowderhead that guy would be! It’s obvious that resisting arrest caused that blur.
It’s super annoying to ask a question and get the noncommittal answer, “It depends.” I just wanted to make it clear that I’m on your side when I give the answer to this question. Sometimes the annoying answer happens to be the correct one. For the cause of LASIK Halos, it depends.
The difficulty in answering your question well is that it’s not always that obvious. Most cases can be split into two groups: vision blurriness caused by surgery or not caused by surgery. There are times that blurry vision after LASIK can happen because the treatment has “worn off.”
Blurry Vision Caused by LASIK Surgery
There are times that blurry vision a few years after LASIK is absolutely because the treatment has “worn off.” In those cases, the epithelium (that covers the surface of the eye) increases in thickness where the laser treated the cornea. This effectively reduces the treatment. The laser treats the permanent layer of the cornea — called the stroma — but that doesn’t matter much if another layer increases in thickness.
The chances from the surgery being effectively erased by your healing are directly affected by the level of the laser technology (Bladed vs Bladeless). It was much, much more common back in the late ‘90s and early 2000s. Wavelight excimer lasers debuted about 10 years ago, and now we don’t see nearly the level of vision regression after LASIK that we did back then. There have been three new generations of Wavelight, and they just keep getting better.
Blurriness Not Caused by Eye Surgery
And now we turn to the other cause of blurry vision, or blurry contacts. Namely, those not caused by surgery. The list of these causes is longer than a CVS receipt. But, also like a CVS receipt, it could be shortened to a few relevant points. 9 times out of 10 the cause is an unpolished surface of the eye. This can be due to allergies, not enough tears, tears that are too salty, tears that evaporate too quickly, makeup, lotions, humidity changes... the point here is there are lots of reasons to have an unpolished cornea. And they’re usually relatively easy to fix.
To get more comprehensive than that — and have an answer better than “it depends” — would require you to see someone like me who specializes in refractive surgery. There are pretty definitive imaging and other diagnostic tests able to determine the cause. The good news in all of this is, you can usually get better! There’s nothing more annoying than having eagle vision and then wondering the reason for losing it. Except for hearing the answer, “It depends.”