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How to Treat a Scratched Cornea

Melissa Flagg, COA, OSC, has worked in the medical field for over two decades as an ophthalmic technician and is certified by JCAHPO.

how-to-treat-a-scratched-cornea

One of the most common injuries seen in an ophthalmologist’s office is a scratched cornea, also known as a corneal abrasion.

In my 26 years in ophthalmology, my main specialty was the cornea. I have seen thousands of scratched and lacerated corneas, and almost as many causes of those injuries.

The treatment of these injuries is typically the same. But the number one way to allow the cornea to heal much more quickly is to keep it moist. Let's take a look at why that's the key.

The Cornea

The cornea is the clear tissue in front of the iris (the color part) and gives the eye about 70 percent of it's focusing power. It's made up of five layers of cells that all work together to make a clear window-like dome.

The cornea becomes “dirty” when it is dry, injured or edematous (swollen). Corneal scratches, among other things, can cause both edema (swelling) and dryness which exacerbates the injury and clouds the window.

In order to better understand corneal abrasions, we need to know a little about the structure of the cornea. Here’s a crash course in corneal anatomy:

An image showing how dryness affects the eye. The first arrow points to the smooth tear film, coating the cornea properly. The second arrow shows what happens when the tear film is allowed to evaporate.

An image showing how dryness affects the eye. The first arrow points to the smooth tear film, coating the cornea properly. The second arrow shows what happens when the tear film is allowed to evaporate.

Corneal Anatomy

The cornea is an amazing cellular matrix. It is protected from the environment by the tear film, eyelid and eyelashes. It is densely packed with nerve endings and has no blood vessels. Despite this, it is the fastest healing part of the body, healing superficial abrasions within 24 hours.

Corneal Layers

The five layers of the cornea.

The five layers of the cornea.

The cornea is comprised of five layers:

  • The Epithelium – the first layer of the cornea is very thin and heals very quickly. It does not scar because it is the only part of the body that can actually regenerate.
  • Bowman’s Membrane – the function of this second layer of the cornea is unclear. It is acellular (meaning it is not made of actual cells), instead it is made up of primarily collagen fibrils. These fibrils create a layer that allows cells to attach to it, so it is assumed that this membrane exists for the epithelium and stroma to attach to it.
  • The Stroma – the third layer of the cornea and the thickest layer. The stroma gives the cornea its shape and stability. It is usually injured by deep lacerations, although this is rare. The stroma does not regenerate and when injured typically leaves a scar, which results in loss of vision if the scarring is in the visual axis (in front of the pupil).
  • Descemet’s Membrane – this fourth layer is made up of type IV and VIII collagen and has no regenerative properties. It is the basement layer of the endothelium, meaning this layer connects the endothelium to the rest of the cornea. It is made up of two layers, the anterior banded layer which is created during gestation, and the posterior non-banded layer which is created by the endothelium throughout a person's lifespan.
  • The Endothelium – the last layer of the cornea maintains corneal deturgescence (relative dehydration that maintain