Eye Health · Patient Series
A scratch smaller
than a grain of rice.
Pain out of all proportion.
A fingernail, a twig, a makeup brush, a contact lens taken out the wrong way — and suddenly the eye streams, burns and will not stay open. That is usually a corneal abrasion: a scrape of the cornea’s outer skin. How a drop of orange dye turns it bright green, why most heal in a few days, why the eye patch has gone, and the injuries that are not “just a scratch”.
a small abrasion
with fluorescein
abrasions today
Section 01 — What Has Happened
The outer skin
of the cornea,
scraped away.
The cornea is the clear dome over the iris and pupil. Its surface is a layer of epithelium only five or so cells thick, sitting on a basement membrane. A corneal abrasion is a patch where that epithelium has been rubbed or torn off, leaving the nerve endings beneath it exposed to every blink.
That is why the pain feels so out of scale. The cornea is among the most densely innervated tissues in the body, and the eyelid sweeps across the raw area thousands of times a day. Watering, a gritty “something is still in there” feeling, light sensitivity and a reflex urge to keep the eye shut are all part of the typical picture — even when nothing is left in the eye at all.
A corneal abrasion is a scratch that removes part of the cornea’s surface epithelium. It causes sharp pain, watering, light sensitivity and a foreign-body feeling, sometimes with blurred vision. It is diagnosed with fluorescein dye under blue light, which makes the defect glow green, and by checking under the eyelids for a trapped particle. Most small abrasions heal within one to three days because the epithelium regrows quickly from its edges. Patching is no longer routine. Contact lens wearers have a higher infection risk and need specific treatment. High-speed injuries, chemicals, worsening pain or vision, or a white spot on the cornea need urgent care.
Section 02 — Interactive
How the surface
closes over.
Corneal epithelium heals unusually fast. Cells at the edge of the defect flatten and slide across the bare area, then divide to rebuild full thickness. Move the slider to see how a moderate abrasion, stained with fluorescein, typically shrinks over the first three days.
The dye trick is simple and old. Fluorescein is an orange dye that fluoresces yellow-green under cobalt blue light. Intact epithelium, with its tight cell junctions, keeps it out; where the epithelium is missing, the dye pools in the bare stroma and glows. The clinician sees the exact outline of the injury — and the pattern itself is a clue. Several fine vertical lines suggest a particle trapped under the upper lid scratching with each blink, which is why the lid is turned over and checked.
Section 03 — Red Flags
When it is
not just
a scratch.
The reassuring course above applies to a simple surface abrasion from a low-energy injury. Some histories and findings change the plan completely.
| Feature | Why it matters | What to do |
|---|---|---|
| Hammering metal, grinding, drilling, strimmers | High-velocity fragments can penetrate the eye and leave an intraocular foreign body with only a tiny entry wound | Same-day eye examination; imaging may be needed |
| Chemical splash — especially alkali such as cement or cleaners | A chemical burn, not an abrasion; damage continues until the chemical is washed out | Irrigate immediately with plenty of clean water, then emergency care |
| Misshapen pupil, dark tissue at the wound, leaking fluid | Signs of an open globe injury | Emergency; shield the eye, do not press on it or apply drops |
| White or grey spot on the cornea, discharge, worsening pain | Possible infection (keratitis), which can scar the cornea | Urgent review, the same day |
| Contact lens wearer | Higher risk of aggressive bacterial infection, notably Pseudomonas | Prompt examination; lens-specific treatment; no patch |
| Injury from plant matter — a branch, a thorn, crop material | Raises concern for fungal infection | Examination and follow-up; report any new spot or worsening |
| Vision clearly reduced, or no improvement after 24 hours | Larger or deeper injury, retained foreign body or early infection | Re-examination |
Section 04 — Treatment
Comfort, protection,
and letting the cells
do the work.
Treatment of an uncomplicated abrasion is about pain control and preventing infection while the epithelium heals itself. Exact choices are made by the examining clinician.
simple abrasion to heal
large or lens-related
routine eye patching
The patching story is a good example of evidence changing practice. For decades a pressure patch was standard, on the logic that a closed lid would protect the healing surface. When randomised trials were pooled in a Cochrane review, patching did not improve healing or pain in simple abrasions — and it costs the patient depth perception for a day or two. Topical anaesthetics are a live debate: the long-standing concern is corneal toxicity from repeated, unsupervised use, while a few small emergency-department trials of short, dilute courses have reported no clear harm. Most guidance still does not send patients home with them.
A parent is caught in the eye by a toddler’s fingernail and spends the evening with a streaming, light-sensitive eye they cannot keep open. At the clinic, fluorescein shows a curved green defect a few millimetres long off the centre of the cornea; nothing is under the lids. They go home with antibiotic ointment and oral pain relief, no patch. By the next evening the pain has mostly settled, and by day three the surface has closed. Six weeks later a sharp pain on waking turns out to be a small recurrent erosion at the same spot — managed with night-time lubricating ointment.
Section 05 — Weeks Later
Morning pain
after it healed:
recurrent corneal erosion.
New epithelium covers the defect quickly but takes longer to anchor firmly to the layer beneath. Until it does, the surface can stick to the inside of the eyelid overnight and tear away on waking.
The classic story is sharp pain, watering and light sensitivity on first opening the eyes in the morning, sometimes weeks or months after the original scratch, settling over hours. It is more common after sharp, shearing injuries — fingernails, paper edges, plant matter — and in people with an underlying basement membrane dystrophy. Lubricating ointment at bedtime is the usual first step; persistent cases can be treated with options such as a bandage contact lens, anterior stromal puncture or phototherapeutic keratectomy, chosen by an eye specialist.
Section 06 — FAQ
Frequently asked questions
about corneal abrasions.
A corneal abrasion is a scratch or scrape that removes part of the epithelium, the thin outer cell layer of the cornea, the clear window at the front of the eye. Because the cornea is one of the most densely innervated tissues in the body, even a small abrasion can be very painful, with watering, light sensitivity and a feeling that something is still in the eye.
Most small, uncomplicated abrasions heal within about one to three days, because the corneal epithelium regenerates quickly by sliding and dividing in from the edges. Larger abrasions can take longer. If pain is not clearly improving after a day, or vision is getting worse, the eye should be re-examined.
After numbing drops, the doctor touches a fluorescein strip to the tear film and looks at the cornea under cobalt blue light, usually with a slit lamp. Healthy epithelium resists the dye, but an area where it is missing takes it up and glows bright green, showing the size and shape of the scratch. The eyelids are also checked for a trapped foreign body.
Routine patching is no longer recommended for most abrasions. A Cochrane review of randomised trials found that patching did not speed healing or reduce pain, and it removes depth perception. Abrasions in contact lens wearers should never be patched because of the infection risk.
Anaesthetic drops are used in the clinic to allow examination, but they are not routinely given for home use. Repeated use has been linked to toxic damage to the cornea and slower healing, and a numb eye hides warning signs. A few small trials of short, supervised courses exist, but practice varies and this is a decision for the treating doctor, not self-treatment.
It carries a higher risk of infection, particularly with Pseudomonas, which can turn a simple scratch into a sight-threatening corneal ulcer. Lens wearers are usually given an antibiotic drop with activity against Pseudomonas, told not to wear lenses until the eye has healed, and should never have the eye patched. Worsening pain, a white spot or discharge needs urgent review.
This can be recurrent corneal erosion. The new epithelium may not anchor firmly at first, and overnight it can stick to the inside of the eyelid and tear away on waking, causing sudden pain. It is more likely after scratches from fingernails, paper or plant matter. Lubricating ointment at night is the usual first step; persistent cases have specific treatments.
References & Evidence Base
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