PRK is a great way to correct vision. But it does come with some additional recovery. During this recovery you will have some blurry vision as well as some scratchiness, discomfort or pain to the eye. But you also can develop some swelling of the eyelids after PRK. Why is this?
While the eye is recovering after PRK, the surface of the eye is “injured". This generates an immune response from the body. This immune response causes fluid to leak out of blood vessels and can create extra edema or swelling of the eyelids.
This swelling will slowly resolve as things continue to heal up from the PRK. But there are ways to treat it and resolve it quicker. But to first understand what causes a swollen eyelid after PRK and how to treat it, we have to rewind back to the procedure itself.
How Is PRK Different From Lasik
Both of these laser eye surgeries correct vision. Both in fact, use the exact same laser which does the actual prescription treatment. But these two procedures have a key difference.
In order for the laser to work properly and correct vision, it must be applied to the rigid structural framework layer of the cornea called the stroma. This layer exists beneath the surface of the cornea (and makes up 90% of the whole thickness of the cornea).
Layers of the cornea; Image by StemBook (CC BY 3.0) / modified from original
The key difference between lasik and PRK is how that stroma is exposed.
Lasik creates a lasik flap within the stroma. This lasik flap is folded back to expose the stroma for treatment. After the treatment, the lasik flap is repositioned.
With PRK, the very surface layer on top of the stroma, called epithelium, is removed in order to expose the stroma. This layer is like the “skin" on our eye. Following the treatment, this layer regrows.
While lasik has a quick one day recovery; the recovery after PRK is longer. Because that “skin" layer on the eye is removed, the eye has a large scratch on the eye until it grows back.
What Does An Eye Scratch Do?
The main things that this eye scratch (also known as an epithelial defect or epithelial abrasion) does is that it gives you blurry vision and pain.
- The cornea is one of the most sensitive parts of the body. Typically, the epithelium covers the cornea and you don't notice this (unless you go and touch your eye with your finger). But when the epithelium is missing and the stroma exposed, you have pain and discomfort. Following PRK, surgeons will often place a soft contact lens on the eye to help cover the cornea and prevent a lot of the pain and discomfort.
- In addition, the epithelium contributes to the smooth surface of the cornea. When removed, you are looking through a more irregular surface and will have some blurry vision until it fully heals over and everything becomes smooth again.
But this surgically created eye scratch is detected by the body as an injury. When our body detects an injury, it mounts a protective immune system defense.
How Are The Eyelids Related?
Our immune response comes from white blood cells. These white blood cells travel around in blood vessels. Once these white blood cells reach their target (where the injury is detected), they leak out of the blood vessels. With the white blood cells comes extra fluid. This leads to swelling or edema around an area of injury.
Injury leading to swelling; image by Nason vassiliev, CC BY-SA 4.0, via Wikimedia Commons
The cornea doesn't actually have any blood vessels. But the “injury" after PRK is actually large enough to affect surrounding blood vessels. This includes blood vessels in the conjunctiva or the white part of our eye.
The inflammation signals from the cornea wash over the conjunctiva and trigger the blood vessels in our cornea. This gives the conjunctiva a red and slightly swollen appearance after PRK.
But the conjunctiva is actually connected to the eyelids. In fact, the underside of the eyelids IS conjunctiva. Thus, blood vessels in the eyelids can also mount an immune response as a result to inflammation that washes onto the conjunctiva underneath the eyelids. This can cause your eyelids to become swollen after PRK.
Treating Swollen Eyelids After PRK
Now that we know what is causing the swollen eyelids, we know what to target to get rid of the swelling: inflammation.
Unfortunately, you can't instantly heal up the epithelial scratch after PRK. But you can take steps to control the inflammation and encourage the healing.
- Make sure you are using your prescription drops (such as the steroid eye drop) as prescribed. This steroid eye drop will treat and reduce that inflammation.
- Use artificial tears. The primary function of artificial tears is to prevent the eyes from drying out. Keeping the cornea hydrated keeps the cornea as healthy as possible to optimize how well new epithelial cells are regenerated. In addition, artificial tears will also help wash away any excess inflammation on the surface of the eye.
- Using an NSAID medication such as ibuprofen can help. These also work to prevent inflammation from developing.
But you can also treat the swollen eyelid directly.
- To reduce the amount of fluid leaking out of the blood vessels, we can cause the blood vessels to constrict. What causes blood vessels to constrict? Cold. So by using some cold such as ice, cold washcloth or cold eye mask, you can reduce the amount of swelling.
With these treatments and with time, the swelling on the eyelids will gradually go away.
Summary
It will take some time to recover from PRK. Following the treatment, the surface layer of your cornea has to regrow. While this is occurring, you can develop more inflammation on the surface of the eye. This inflammation can cause swelling in the eyelids. By taking your prescription eye drops, using artificial tears and perhaps using something cool or cold on the eyelids, you can reduce this swelling. And as your eyes recover, everything returns back to normal.
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