Everything You Need To Know About Flap Dislocation After Lasik
Arguably the biggest fear with lasik today is the fear of something happening to the lasik flap. During lasik, a laser creates a flap just below the surface of the cornea. This flap is folded back to perform the lasik treatment and then replaced at the end of the case. But in rare cases, this flap can become dislocated. But don't let this fear paralyze you after lasik: Flap dislocations after lasik are much rarer than you think.
When is the risk the greatest?
Immediately after lasik, there is a a small scratch between the lasik flap and the rest of the cornea (this scratch allows the lasik flap to be folded back). Really quickly within the first few hours after lasik, this scratch heals up. But until this scratch heals up, the edges of the lasik flap can be lifted up easily and the flap can slip out of position. It is within the first few hours after lasik that the risk of moving the lasik flap is the greatest.
Don't you worry, however, the lasik flap isn't going to dislocate on it's own. Picture a large rug laying down on the floor. You can walk all along the rug all day without causing the rug to move around. But, if you apply a sideways force at the edge of the rug, you will cause it to fold up on itself. The lasik flap is the same way. Sideways movement on the lasik flap (such as rubbing the eye) is what actually can cause it to move around.
Beyond the first few hours, the risk of a flap dislocation drops pretty significantly. To heal up this scratch, a thin layer of cells called epithelium grow over the lasik flap to secure it down. The recently healed up epithelium acts like tape to prevent just any movement from dislodging the lasik flap. But this epithelium isn't at full strength. As you get beyond the first day and first week the lasik flap gets stronger and stronger as the epithelium is restored to full function. It becomes like duct tape locking the lasik flap in place.
How do you know if your lasik flap is dislocated?
If the flap dislocates, a much larger "scratch" is created. The sensitive part of the cornea is exposed and no longer protected by the lasik flap. Unless it's a very small dislocation, this will be painful. This pain will eventually go away. The epithelium will grow over that exposed area similar to how it heals up the original scratch after lasik. Depending on how much cornea became exposed, this can take a day or two to heal over.
But in addition to pain, you will most likely have some degree of blurred vision. When a lasik flap dislodges, typically only one side of the lasik flap gets moved. The lasik flap has some flex, but it can't squeeze together well enough to fit in a smaller area. If you try to fit a too large rug into a too small room, you develop folds in the rug. Same thing with the lasik flap; a fold will develop in the lasik flap if one edge gets pushed and dislocated. There is a good chance that this fold can affect your vision and cause more blurring. This blurry vision is persistent until the flap dislocation is fixed.
Flap dislocations can be fixed
If you do develop a flap dislocation after lasik, there is treatment. But you do have to go through another procedure. This additional procedure is called a "re-float" (named that way due to the fact that sterile water is used to position the lasik flap in place). During a "re-float", your surgeon will fold back the lasik flap completely, clean the lasik flap bed of any epithelium and reposition your lasik flap in place. The recovery is similar to your first lasik procedure. You can just have a little bit more scratchiness as the healing epithelium surrounding the lasik flap will be more irregular.
However, if the fold in the flap was large or has been there for a while, the surgeon may also have to remove the epithelium on top of the fold (the epithelium can prevent a fold from unfolding). If this is needed, then the recovery will be longer as you wait for that epithelium to grow back. You will have discomfort and blurred vision for anywhere from 2 to 5 days depending on how much epithelium needed to be removed.
Once repaired, the risks after a re-float aren't all too different from the original lasik procedure. The one exception is that there is a slightly greater chance that the epithelium can grow under the lasik flap (called epithelial-ingrowth). Still rare, but if this occurs, this again would require another procedure to remove and fix. But overall the results and long-term prognosis after a flap dislocation are quite good.
But flap dislocations don't happen very frequently in today's modern laser-based lasik era
Laser created lasik flaps are stronger than microkeratome created lasik flaps (those created with blades). There are a few features that can only be created with lasers that allow for these stronger lasik flaps.
- The laser creates a lasik flap in a 3D shape. This is more than just marketing hype. Having a three dimensional shape to the lasik flap matters. When you create a lasik flap with a blade, you only have a single plane 2D structure. When you reposition a 2D lasik flap, it simply rests back onto the surface of the cornea. In comparison, a 3D flap is created at depth with walls below the surface of the cornea. Once created, there is a perfect lasik flap shaped depression on the the surface of the cornea. The lasik flap fits back into that depression like a custom glove. This helps prevent the lasik flap from going anywhere.
- The edges or walls of the lasik flap can also be created in an inverted fashion. Instead of a perfectly vertical wall, the wall slopes toward the lasik flap and the lasik flap must slide underneath the lip of this wall. This allows the lasik flap to lock in like a puzzle piece. The lip of the wall helps provide additional resistance to the edge of the lasik flap from moving anywhere.
As you get further and further from lasik, the chance of a flap dislocation drops dramatically. Beyond the first week, you really need to be poked in the eye in just the right way in order to actually cause the lasik flap to shift. Can it happen? Well yeah, anything can happen. But given those low odds, unless you are a boxer and expect to be hit in the eye frequently, a flap dislocation isn't any reason to fear lasik.
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