swollen cornea due to fluid build up

You may have heard (or even been diagnosed with) of corneal edema, but you haven’t the slightest clue as to what it is.

Well, this is the article meant to address this condition, help you learn more about the anatomy of your eye and, of course, help you understand corneal edema, its symptoms, causes, and treatment process.


The cornea is at the very front of your eye, it covers the iris, and its primary function is allowing you to see clearly (if it is healthy you vision should not be blurred). Though it may not seem or feel this way, our cornea is very thick – 0.5mm. Of course, when we’re speaking of its thickness, we are talking about the anatomy of the eye.

It has five distinct layers, these are:

  1. Anterior corneal epithelium
  2. Bowman’s layer
  3. Corneal stroma
  4. Descemet’s membrane and
  5. Endothelium

You might have noticed these layers are in alphabetical order; this is just a technique commonly used to remember them.

From our today’s point of view, the most important layer is the last one – Endothelium. The endothelium is an epithelial layer, and its principal role is fluid filtration. Disturbed fluid filtration is what’s responsible for corneal edema!

The cornea is very sensitive as a whole; it has a lot of nerve endings so you must be extra careful with it, not only when it comes to mechanical injury, you should also pay attention to proper hydration and nutrition. Otherwise, you might find yourself seeing rainbows even on a bright sunny day.

How Is Corneal Edema Formed?

We already learned that the most important factor for our vision is a clear, transparent cornea. The healthy cornea is the reason we see the light and focus objects correctly. If something is wrong with our cornea, objects and our surrounding may appear blurry.

Usually, water is being filtrated through the endothelium, keeping the cornea clean and healthy, but if the water flow is disrupted for some reason, the patient might experience swelling of the cornea. This is one of the leading causes of corneal edema.

The problem with endothelium cells is that they do not regenerate in the case of a more severe injury. If the damage is small, the destroyed cells will easily get replaced by healthy ones, and your eye will function normally; but if the damage is more severe and a lot of cells are affected, there will simply not be enough healthy cells to take their place.

Too many damaged cells will disrupt the fluid filtration function we talked about earlier, causing it to build up and damage a person’s vision. There are also some cases where a patient will have several edemas present, forming bullae on the surface of the eye. In addition to affecting your eyesight, this can cause irritation and intense pain.


The list of causes of coronal edema is quite long, but we will try to cover as many as we can. We will start with the more benign ones and work our way down:

  • Dehydration – we already covered this, dehydration will negatively affect the condition of your eye and can cause damage in the long turn
  • Interocular pressure – normal ocular pressure is 12-22 mm HG, and any value over 22 is considered high. Individuals with diagnosed high ocular pressure should get regular examinations as it can also lead to glaucoma
  • Endothelial disorder – also known as endothelial dysfunction, is a vascular disease negatively affecting the inner lining of your blood vessels
  • Endothelial Fuchs dystrophy – this is one of the most common causes of this type of edema. This is a condition where the layers of cornea begin to degenerate(deteriorate). These degenerations will, of course, affect the proper functioning of your eye and cause problems. This is a genetic disorder, and it mostly hits women population.
  • Eye surgery – every surgery comes with its risks. Eye surgery may lead to corneal edema, though these cases are rare. One of the biggest problems here is linking eye operation to the edema since it can go up to two years before it forms. You might even forget you had a surgery by the time you start experiencing the first signs of corneal edema
  • Corneal transplantation
  • Poorly constructed lens
  • Strong medication or an invasive eye exam
  • Infections and other inflammatory processes in our body

As for the risk factors, eye edema is more prevalent in older individuals, 55 years or older.


As we already mentioned, the most common symptom of this condition is blurred vision. The interesting thing to point out here is that the vision will get worse as the day progresses. So, by the end of the day, your eyesight will be very poor.

In the early stages of this condition, you will only feel a slight discomfort and might see halos around a light source. As the time goes by, the light sensitivity will increase and it may develop into a full blown photophobia.

This progression may even go further and damage the nerves to such extent, you start experiencing intense pain that does not go away.


When it comes to eye problems in general, the most important starting point is a good diagnosis. Some conditions may present with similar symptoms (such as corneal edema and cataract), so your doctor might use as many tests as needed (from optical pachymetry to ultrasound) before he uncovers the true cause of your problem.

The therapy will largely depend on the cause of your edema. Something you can do yourself at home to reduce the swelling is using a hypertonic saline or sodium chloride drops to draw water out of a swollen cornea. Of course, it is advised to consult with your doctor first, rather than trying something on your own.

This is especially true if you’ve had this condition for a long time (years). The fluid build up might be so severe that it requires a puncture around Bowman layer.

If the cause is inflammation or a bacteria, your doctor will prescribe anti-inflammatory medication or antibiotics; you might even get corticosteroids.

To reduce the ocular pressure ( if it is the cause of edema) the drugs used are prostaglandin and alpha 2-adrenergic agonists. If all medication fails, a corneal transplantation might be your only choice.

And as for the incorrect contact lenses, you just need to consult your doctor and get those sorted out and fitted properly.