A corneal dellen is a small dry patch at the edge of the cornea, the clear front window of the eye. It forms when tears stop spreading evenly over one small spot.1PubMed Central. Successful treatment of conjunctival lymphangiectasia accompanied by corneal dellen using a high-frequency radiowave electrosurgical device Treatment is mostly about getting that spot wet again, and most dellen heal quickly. The cause is usually a raised bump next to the cornea rather than a problem with the cornea itself, which is why a dellen so often follows eye surgery.
What a Dellen Is and Why It Forms
Doctors use the word “dellen,” German for dimples, for shallow saucer-shaped dips at the edge of the cornea.2EyeWiki. Corneal Dellen One is usually about 2 to 3 millimetres across, roughly the size of a peppercorn.3EyeWiki. Corneal Dellen It most often sits on the side of the eye toward the ear, shaped like a small oval running along the cornea’s edge.4EyeWiki. Corneal Dellen
Dellen form most often next to something that rises above the eye’s surface beside the cornea.5JAMA Ophthalmology. On the Nature of Dellen The bump breaks the thin oily layer of the tear film just downstream of it, so tears fail to cover that patch with each blink.6JAMA Ophthalmology. On the Nature of Dellen That patch of cornea dries out locally.7PubMed Central. Successful treatment of conjunctival lymphangiectasia accompanied by corneal dellen using a high-frequency radiowave electrosurgical device
The dip sits in the gap between the bump and the cornea, not on top of the bump. In a mirror you may be able to see the raised spot, but the dip itself is too small and clear to notice without magnification.
As the patch dries, the cornea’s collagen fibres pack closer together, so the spot looks thinner.8PubMed. Development of an Ex Vivo Model of Focal Corneal Desiccation to Investigate the Pathophysiology of Corneal Dellen and Ulcers No tissue is actually lost; the fibres are compacted, not destroyed.9PubMed. Development of an Ex Vivo Model of Focal Corneal Desiccation to Investigate the Pathophysiology of Corneal Dellen and Ulcers Once the area is rehydrated, the cornea can plump back up to normal thickness, which is why recovery is often fast. The surface layer of cells over the dip is usually still intact.10EyeWiki. Corneal Dellen
Common Causes, From Surgery to Swelling
Several things can raise the surface next to the cornea:
- Inflammation: swelling of the white of the eye (episcleritis or scleritis) can puff up the tissue beside the cornea.11EyeWiki. Corneal Dellen
- Growths: a thick pinguecula or pterygium, a fleshy growth onto the cornea’s edge, can create the bump.12EyeWiki. Corneal Dellen
- Bleeding: a bleed under the clear surface layer, the bright red patch called subconjunctival hemorrhage, can do it.13EyeWiki. Corneal Dellen
- Chemosis: severe swelling of the eye’s surface layer.14EyeWiki. Corneal Dellen
- Surgical or injection sites: injections under the eye’s surface, filtering blebs from glaucoma surgery, stitch lumps and small growths near the edge can all do it.15EyeWiki. Corneal Dellen
Surgery is the most common setting. Dellen can follow cataract, eye muscle and glaucoma surgery.16EyeWiki. Corneal Dellen After removal of a pterygium (a tissue growth onto the cornea), swelling of the patch of tissue grafted into place can raise the edge and block tear spread.17PubMed Central. Resolution of Corneal Dellen After an Uneventful Pterygium Surgery with Punctal Cautery The tissue glue sometimes used to hold that graft commonly causes graft swelling.18PubMed Central. Resolution of Corneal Dellen After an Uneventful Pterygium Surgery with Punctal Cautery Even so, a dellen after this operation is rarely reported.19PubMed Central. Resolution of Corneal Dellen After an Uneventful Pterygium Surgery with Punctal Cautery
Eye muscle surgery carries a clearer risk in some operations. After repeat surgery on the inner eye muscle, about 1 in 6 eyes developed a dellen.20PubMed. Corneal ‘dellen’ as a complication of strabismus surgery After muscle transposition procedures the rate was about 1 in 5.21PubMed. Corneal ‘dellen’ as a complication of strabismus surgery Across nearly 1,000 eyes having other kinds of eye muscle surgery, none did.22PubMed. Corneal ‘dellen’ as a complication of strabismus surgery In children, though, a dellen is probably often missed because it may cause no symptoms and young children are hard to examine.23PubMed Central. Complications of Strabismus Surgery Watch for rubbing, redness near the cornea’s edge, or squinting in light, and mention them at the next visit.
Some dellen have no bump behind them. Long-term contact lens wear can lead to one.24EyeWiki. Corneal Dellen So can an eye that can’t close fully, as after facial nerve paralysis.25EyeWiki. Corneal Dellen Eye injury can cause one, and some appear in older people with no clear cause.26EyeWiki. Corneal Dellen
Symptoms and How a Doctor Spots It
Common symptoms are redness, a feeling that something is in the eye, and grittiness.27EyeWiki. Corneal Dellen Some people notice mild light sensitivity.28EyeCare Center OC. Dellen (Corneal Thinning): Causes, Symptoms & Treatment | EyeCare Center OC Others notice nothing at all, especially when the dellen is small.29PubMed Central. Complications of Strabismus Surgery The dip sits at the edge of the cornea, outside the line of sight, so vision is rarely affected.30EyeCare Center OC. Dellen (Corneal Thinning): Causes, Symptoms & Treatment | EyeCare Center OC
The doctor examines the eye with a slit lamp, a microscope with a bright thin beam.31EyeWiki. Corneal Dellen Under it they see a sharply outlined dip with a steep wall on the cornea side and a gentle slope toward the white of the eye.32EyeWiki. Corneal Dellen Yellow fluorescein dye drops pool in the depression, making it stand out.33EyeWiki. Corneal Dellen
The dye can tint your tears yellow for a short time, which is harmless. The doctor will also look for the raised spot beside the dip, because treatment depends on what is causing it.
A dellen differs from a corneal ulcer, which is more urgent. In a dellen the surface cells over the dip are usually intact, while an ulcer is an open sore in the cornea, often with infection. An ulcer is more likely to cause real pain, a white spot on the cornea, discharge and blurred vision, though a dellen with a milder version of these symptoms is still worth a check. If you have those features, get same-day eye care instead of waiting for your next scheduled visit.
How Corneal Dellen Is Treated
The first goal is to restore a wet surface quickly with frequent artificial tears and lubricating ointment.34EyeWiki. Corneal Dellen In one case after pterygium surgery, lubricating drops 8 times a day plus ointment 4 times a day with patching healed the dellen in one week.35PubMed Central. Corneal and Scleral Dellen after an Uneventful Pterygium Surgery and a Febrile Episode The doctors there also stopped the other eye drops being used, which can help the surface recover.36PubMed Central. Corneal and Scleral Dellen after an Uneventful Pterygium Surgery and a Febrile Episode Don’t stop, switch or add any eye medicine on your own.
Using drops well matters. If you need artificial tears many times a day, preservative-free ones are usually preferred, because the preservatives in some bottles can irritate the surface with heavy use. Ointment is thicker and blurs vision for a while, so it is often used at bedtime. Leave a few minutes between different drops so the second doesn’t wash out the first. Keep going for the length of time your doctor set, even when the eye feels better, because the dip may not yet have refilled.
Patching or a bandage lens keeps the spot covered. After eye muscle surgery, dellen cleared in about 10 to 15 days with antibiotic drops and a firm eye bandage worn at night.37PubMed. Corneal ‘dellen’ as a complication of strabismus surgery A bandage contact lens is a large soft lens worn as a protective cover, not for vision.38PubMed. Treatment of corneal dellen with a large diameter soft contact lens In one reported case it started shrinking the dellen the next day and it was gone in 4 days.39PubMed. Treatment of corneal dellen with a large diameter soft contact lens
With one eye covered, depth judgment is off, so avoid driving and take care on stairs. A bandage worn only at night, as in the muscle surgery cases, leaves the eye uncovered by day. A bandage lens lets you see while protecting the spot; the doctor puts it in and takes it out. Report pain, discharge or worsening redness while wearing one, as lenses can raise infection risk.
Because the dellen comes from a nearby bump, the bump itself may need treatment, for example inflammation calmed or swollen tissue allowed to settle. In one case a raised patch of swollen surface channels was treated with a small electrosurgical device, and the dellen resolved.40PubMed Central. Successful treatment of conjunctival lymphangiectasia accompanied by corneal dellen using a high-frequency radiowave electrosurgical device
How Long Healing Takes and When It Turns Serious
Mild dellen can clear within about 48 hours once the surface is wet again.41American Journal of Ophthalmology. Pathological Dimples (Dellen) of the Cornea Dellen after eye muscle surgery took about 10 to 15 days.42PubMed. Corneal ‘dellen’ as a complication of strabismus surgery About 1 in 5 of those eyes kept a faint permanent change in the cornea’s clarity at that spot.43PubMed. Corneal ‘dellen’ as a complication of strabismus surgery Because the spot is at the edge, such a mark rarely affects sight.
Rarely, a dellen after pterygium surgery thins until the cornea develops a hole, called a perforation.44PubMed Central. Dellen and corneal perforation after bilateral pterygium excision in a patient with no risk factors That is repaired surgically with a partial-thickness corneal graft.45PubMed Central. Dellen and corneal perforation after bilateral pterygium excision in a patient with no risk factors For stubborn dellen that won’t heal, doctors can cover the area with a thin membrane graft from donated placenta tissue.46PubMed. Application of Preserved Human Amniotic Membrane for Corneal Surface Reconstruction
During recovery, pain that suddenly gets worse, instead of slowly easing, is a reason to call the eye doctor that day. A sudden gush of fluid from the eye or a sudden drop in vision needs emergency eye care. A white spot, discharge or redness that spreads over days of treatment can mean infection or an ulcer. If the eye hasn’t improved by the time your doctor expected, say so rather than waiting.
Follow-up visits check whether the dip is getting shallower and the bump beside it is settling, since the dip can’t stay healed if the bump persists. Then the doctor decides whether drops can be reduced or a bandage lens taken out.
Preventing a Dellen From Coming Back
Keeping the surface wet while a bump exists lowers the risk. Once a bump from surgery swelling or a bleed goes away, the dellen usually doesn’t return. A growth like a pterygium or a filtering bleb stays, so the risk can persist.
After eye surgery, use lubricating drops as prescribed even when no one has mentioned a dellen, because they keep the tear film even while the surface is swollen. Mention new grittiness or a dry feeling near the cornea’s edge at follow-up, since early treatment is quick. Keep fans and air vents from blowing straight at your eyes, because moving air dries the surface faster.
If you wear contact lenses, follow the replacement schedule and daily wearing hours your eye doctor set. Take lens-free days when your eyes feel dry or gritty. After a dellen, ask whether a different lens fit or material would suit you better.
If you can’t fully close your eye, nighttime ointment and taping or a moisture shield help keep it covered. Your doctor may also treat the lid problem itself to protect the cornea.