What Causes a Headache After ICL Surgery?

What Causes a Headache After ICL Surgery?

So you just had ICL surgery and now you have a headache. That's a bummer. But typically not anything to really worry about. Headaches after ICL surgery don't typically last beyond the first day and there are ready available treatments to control the discomfort. The causes of headaches after ICL are actually quite limited. The vast majority even fall into one single category.

The most common reason a bad headache can happen after ICL surgery is that the eye pressure is too high. Milder headaches after ICL surgery are often caused by irritation on the surface of the cornea.

Let's see how high eye pressure and eye irritation can occur after ICL surgery to cause headaches and what can be done to resolve it.

High Eye Pressure after ICL surgery

High eye pressure causes a severe pounding headache and sometimes nausea and / or vomiting. It can also cause blurry & hazy vision by causing swelling of the cornea.

Flow of Aqueous Humor within the eye

Flow of Aqueous Humor within the eye;, Public domain, via Wikimedia Commons

The pressure in the eye is regulated by the production and drainage of a fluid in the eye called aqueous. This aqueous flow is produced behind the iris, flows through the pupil and out at the angle where the cornea meets the iris (see diagram above). There aren't really any situations in which too much is produced, but there are many things which can prevent this aqueous from draining out of the eye. If the aqueous can't drain out, it builds up pressure inside of the eye.

High eye pressure can occur for a variety of reasons after surgery. High eye pressure can even occur even despite a very normal ICL surgery. For this reason, it is very common to have an additional appointment a few hours after surgery just to check the pressure within the eye.

During ICL surgery, a thick gel-like substance called viscoelastic is used to protect all the delicate structures within the eye. At the end of the procedure, this viscoelastic is washed out of the eye. It's no problem if a small amount of it remains, it will just dissolve over time. But, if a larger amount of it is left over, this thick substance can also clog up the angle and provide a barrier to the normal flow of aqueous in the eye. The aqueous can't drain out so the pressure builds up within the eye. Gradually as this viscoelastic dissolves, the pressure normalizes but that doesn't really help you feel comfortable quickly.

Tylenol and ibuprofen can help with the headache, but the main goal to treat the headache is to lower the pressure inside the eye. This can be done by prescription eye drops and / or acetazolamide pills. These types of medications all work to slow down the production of aqueous to drop the pressure of the eye. Less produced = less that has to drain out = less pressure. As the pressure goes down, you will commonly notice very quick resolution of the severe headache.

There are also some other rare ways that the pressure can be high after ICL surgery. In rare cases, the ICL can actually push the iris into the "drain" and prevent the aqueous from draining out (see also What Can Be Some Big Problems After ICL Surgery?). In these cases, eye drops and acetazolamide pills are often used but these cases typically require other steps such as additional procedures.

But even with a normal eye pressure, you can still have a headache after ICL surgery

This is a different type of headache than that caused by high pressure. This headache isn't quite as painful. It's more of just general eye ache and irritation. Unlike the headache caused by high eye pressure, this type of ache will affect most people having ICL surgery (in some degree).

Lots of drops are used before and after ICL surgery. Dilating drops, antibiotic drops, betadine antiseptic, etc. All of these drops are all important but they all cause a small amount of irritation to the surface of the cornea (especially the betadine). However, the benefit of the eye drop outweighs this excess irritation they can cause. This irritation builds up cumulatively to give the eye a scratchy irritable feeling right after surgery. This achiness from the eye can refer to the rest of the head causing a more generalized headache.

Not much really NEEDS to be done about this headache. Over the first day, the surface of the cornea improves considerably. The eye just needs some time to heal up on its own. Whatever doesn't heal up during that first day is typically restored as the cornea lies covered while sleeping. Again, tylenol and ibuprofen can help, but using preservative-free artificial tears throughout the day is what can speed this recovery.

Beyond the first day, it is still normal to have some mild irritation during the first week while you are on eye drops. But as you get further and further from the ICL surgery, this irritation continues to get better until the eyes just feel like normal (except having clear vision without glasses or contact lenses).


Severe headaches after ICL surgery are caused by an increased pressure within the eye. Milder headaches are due to extra irritation on the surface of the cornea. But whatever causes your headache after ICL surgery, know that you can typically get great relief with medications and / or time. Headaches are just a speed bump on your journey to great clear vision with ICL.

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