A damaged cornea can look very different depending on the type and severity of the injury. Minor scratches may be invisible to the naked eye, while more serious damage can cause visible cloudiness, white spots, redness, or even a change in the shape of the eye’s surface. Here’s what each type of corneal damage actually looks like, from minor abrasions to severe scarring.
Scratches and Abrasions
A corneal abrasion, the most common type of corneal damage, is often impossible to see just by looking in the mirror. The scratch itself is too small and the cornea too transparent for most surface injuries to show up without magnification. What you will notice is redness, tearing, and a gritty sensation like something is stuck in your eye.
Eye doctors detect abrasions by applying a yellow-orange dye called fluorescein to the eye’s surface. Under normal light, the scratched area absorbs the dye and appears yellow. Under a blue light (which most eye clinics use), the damaged area glows bright green, making even tiny scratches easy to spot. Traumatic scratches from a fingernail or tree branch typically show up as linear or irregular geographic shapes. Contact lens injuries look different: they often appear as clusters of tiny dots that merge into a round defect near the center of the cornea.
White Spots and Corneal Ulcers
A corneal ulcer, which is essentially an open sore on the cornea caused by infection, creates a visible white or grayish spot on the eye’s surface. This spot sits over the clear part of your eye, in front of the colored iris. Depending on the size and location, you or someone looking at your eye may be able to see it without any special equipment, though smaller ulcers can be hard to detect without a microscope.
In severe infections, a condition called hypopyon can develop. This looks like a layer of white liquid pooling at the bottom of the colored part of your eye, almost as if milk is settling behind the cornea. This white fluid is actually a collection of inflammatory cells, and it signals a serious infection that needs immediate treatment.
Cloudiness and Swelling
When the cornea swells from injury, surgery, or disease, it loses its crystal-clear transparency. The result is a hazy, cloudy appearance over part or all of the eye’s surface. Think of it like fog on a window. The cloudiness can range from a faint haze that slightly blurs your vision to dense opacification that makes the cornea look almost milky white.
Corneal edema (swelling) often develops gradually. You might notice that your vision seems worse in the morning and improves slightly throughout the day, because fluid accumulates overnight when your eyes are closed. To someone looking at your eye, the normally glossy, clear surface appears dull and washed out.
Blood Vessels Growing Into the Cornea
A healthy cornea has no blood vessels at all. That’s part of what makes it transparent. When the cornea is damaged by chronic contact lens overwear, infections, chemical burns, or herpes eye disease, tiny red blood vessels can begin creeping inward from the white of the eye onto the clear corneal surface. This is called corneal neovascularization.
In mild cases, you might see fine red lines extending just past the border between the white of the eye and the cornea. In more advanced cases, a network of vessels fans across the cornea, and fatty deposits can accumulate along those vessels, creating yellowish patches. The vessels themselves block and scatter light, which is why this type of damage progressively worsens vision. There are three levels of severity: superficial vessel growth on the surface, a vascular sheet called a pannus, and deep vessel growth within the cornea’s inner layers.
Chemical Burns
Chemical injuries to the cornea create some of the most dramatic visible changes. After exposure to a strong acid or alkali, the cornea can develop a hazy, ground-glass appearance as the surface cells are destroyed. The white of the eye around the cornea may also turn pale or blanched as blood vessels in the surrounding tissue are damaged and lose circulation.
The severity of a chemical burn is judged partly by how cloudy the cornea becomes and how much of the surrounding tissue loses its blood supply. A cornea that stays relatively clear after a chemical splash has a better chance of healing. One that turns opaque with widespread blanching of the surrounding vessels carries a much worse prognosis.
Corneal Scarring
After the acute phase of any corneal injury passes, the healing process can leave behind a permanent scar. Corneal scars appear as white, gray, or opaque patches on what should be a perfectly clear surface. Unlike the temporary cloudiness of swelling, a scar is fixed. It doesn’t fluctuate with time of day or improve with drops.
Small scars at the edge of the cornea may not affect vision at all. A scar that sits over the pupil, however, blocks light from entering the eye and can significantly reduce vision. The density matters too: a faint haze (sometimes called a nebula) may only slightly blur things, while a dense white scar (called a leukoma) can make the cornea look almost like porcelain in that area.
Changes in Corneal Shape
Keratoconus is a condition where the cornea progressively thins and bulges outward into a cone shape instead of maintaining its normal gentle dome. In early stages, there’s nothing visually obvious. The cornea looks normal, and the only sign is increasingly distorted vision that glasses can’t fully correct.
In advanced keratoconus, the shape change becomes visible. The most recognizable sign is called Munson’s sign: when the person looks down, the lower eyelid bulges outward in a V-shape, pushed by the cone of the cornea. The cone can be small and centered (5 mm or less, near the middle of the cornea) or large and displaced downward, covering 75% or more of the corneal diameter. Through a slit lamp microscope, doctors can also see thin stress lines in the cornea, a brownish ring of iron deposits around the base of the cone, and localized thinning of the tissue.
What Only a Doctor Can See
Many forms of corneal damage are invisible without specialized equipment. A slit lamp biomicroscope, the standard tool in every eye exam room, lets doctors examine each layer of the cornea individually by shining a thin beam of light at different angles. By reflecting light off the back of the eye to illuminate the cornea from behind (a technique called retroillumination), they can detect subtle swelling, microcysts, early blood vessel growth, and inherited corneal conditions that would be completely invisible in a mirror or even in a well-lit photograph.
Another technique called sclerotic scatter sends a beam of light through the edge of the cornea, which lights up the entire corneal tissue like a fiber optic cable. Any scarring, swelling, foreign bodies, or white inflammatory spots glow against the dark background, making them easy to identify even when they’re too small to see with direct lighting.
Signs That Need Urgent Attention
Some visual changes to the cornea signal an emergency. A rapidly expanding white spot, increasing cloudiness, or a visible fluid level in the front of the eye all suggest infection or severe inflammation that can permanently damage vision within hours. The National Eye Institute recommends going to an eye doctor or emergency room if you have intense eye pain, a sudden change in vision, very red and watery eyes, something stuck in your eye, or a serious blow or trauma to the eye. Even if the cornea looks normal to you, these symptoms can indicate damage that only shows up under magnification.