What is Corneal Edema?

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  • Written By: Mary McMahon
  • Edited By: Kristen Osborne
  • Last Modified Date: 30 September 2019
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Corneal edema is a swelling of the cornea, the thin transparent covering over the iris of the eye, caused by fluid retention. A number of things can lead to the development of corneal edema and the condition can be treated with medication and surgery in some cases. Treatment of this condition requires evaluation by an ophthalmologist and follow-ups may be needed with other medical professionals to address the underlying cause.

The cornea is key to clear, crisp vision. In healthy individuals, it is continuously lubricated with fresh tears, and old fluid is drained away to keep the shape of the cornea consistent and even. In people with corneal edema, it starts to swell and vision distortions like halos around lights and blurred vision can develop. Left untreated, pain can emerge in the eye and small blisters may form in and around the cornea.

Common causes of corneal edema include eye surgery, particularly on the cornea itself, trauma to the eye, inflammation, infections, increased pressure in the eye, improper contact use, and chronic eye diseases. Glaucoma, for example, can cause edema by increasing pressure inside the eye. Most commonly, this condition is seen in people over age 50, although younger patients can develop corneal edema as well, especially if they have chronic eye problems or experience eye trauma.


In an examination, a doctor can confirm that swelling in the cornea is the problem and look for signs of damage to the eye. The longer this condition is allowed to persist, the greater the risk of damaging the structures in the eye. The doctor will usually prescribe a rest from contacts, if the patient uses them, and provide some medications to treat the edema by flushing out the excess fluid. Pain medication may also be offered to alleviate any discomfort. If the edema was caused by contacts, the patient may need a new contact fitting, as well as a review on proper eye care with contacts.

If these treatments do not resolve the problem, surgery may be considered as an option. This depends on the cause of the corneal edema and the patient's general level of fitness. After surgery, patients will be provided with detailed instructions to reduce recurrence of edema, since surgery is a known risk factor and issues like inflammation and infection can also develop after surgery, putting the patient at risk of corneal swelling. It is advisable to get postoperative care instructions before surgery, so patients can prepare and know what to expect when the surgery is over.


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Post 3

@clintflint - It's possible that they called it something else, or described the symptoms rather than using the medical name for the sake of clarity.

Although I know there are a lot of different kinds of laser surgery, and maybe some of them aren't very traumatic in the way that, say, a corneal transplant would be.

Besides, from my own research on laser surgery, it seems like complications are extremely rare and usually only happen when the person who had the surgery isn't cleaning the wound properly. Most of the time the damage is healed within a few days and at most there's only a little bit of pain.

Post 2

@irontoenail - That's the point. The contact lens shifts light in the same way that the cornea does, when the cornea, or at least the parts that manipulate the cornea, aren't doing the job properly.

I'm actually surprised that corneal edema wasn't listed as one of the side effects in the laser surgery that I'm thinking about getting. It seems like the kind of thing that could be a possible risk.

Post 1

If you want to know what it might look like if you were developing a corneal edema, try opening your eyes underwater without goggles.

The reason it gets blurry underwater is because the light passes through the water more slowly and when it hits your eye the cornea (being roughly the same density as the water) can't bend it as strongly as it would if the light was passing through air.

Whereas, if you've got fluid building up behind your cornea, you basically have the same problem, with the fluid interrupting the passage of light so it doesn't hit the back of your eye properly.

It's interesting that contact lenses don't do this though, you'd think they would since the light has to pass through them as well.

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