What a persistent epithelial defect is
The cornea (the clear front window of the eye) is covered by a thin surface layer called the epithelium. It is the cornea’s barrier against infection and gives the eye a smooth surface to see through. Normally it renews itself constantly, fed by stem cells at the limbus, the ring where the cornea meets the white of the eye.[1]
Most scratches and surface wounds close quickly. When a wound hasn’t healed after about two weeks despite standard treatment, doctors call it a persistent epithelial defect.[1] It isn’t one disease. It’s a sign that something is stopping the surface from repairing itself. Common reasons include:[1]
- Loss of corneal sensation, as in neurotrophic keratitis. The nerves help the surface heal.
- Damage to the limbal stem cells, as in limbal stem cell deficiency or after a chemical injury.
- Severe surface inflammation, as in Stevens-Johnson syndrome or ocular pemphigoid.
Eyelids that don’t close properly can also lead to wounds that won’t heal (exposure keratopathy).[2]
Why it matters. An open wound leaves the cornea exposed to infection, ulcers, and in severe cases perforation. Delayed treatment can lead to scarring, new blood vessels on the cornea, and permanent vision loss.[1] A defect like this is managed by an eye doctor, usually a cornea specialist, who looks for the cause while treating the wound.
How a scleral lens helps a wound heal
A scleral lens is a large rigid gas-permeable lens. It rests on the sclera (the white of the eye) and arches over the whole cornea without touching it. Before insertion it is filled with sterile, preservative-free saline, so a pool of fluid sits over the wound.
Researchers who first used extended scleral lens wear for these wounds concluded that healing seemed to come from a combination of three things: oxygen, moisture, and protection of the fragile new cells.[3]
- Moisture. The wound sits in fluid all the time instead of drying between blinks.
- Protection. Each blink drags the eyelid across the cornea. Over a fragile wound, that friction can strip away new cells as they form. With the lens in place, the lid moves over the lens instead.
- Oxygen. The lens is made of a gas-permeable material, so oxygen can reach the cornea through it.
How it’s used is different from everyday wear. Because the goal is to keep the wound protected, several published protocols use the lens around the clock, including overnight, for a short time until the wound closes. The lens is taken out briefly every day to be cleaned and refilled, and a preservative-free antibiotic drop is added to the saline. In one protocol, patients then moved to long-term daytime wear once the wound had healed.[5][4] This is a medical treatment run by your eye doctor. It is not a reason to sleep in scleral lenses in general.
PROSE (prosthetic replacement of the ocular surface ecosystem) is one scleral lens treatment model used in much of this research. Other studies used commercially available scleral lenses.[7]
What the research shows
There are no randomized trials. The evidence is a handful of small case series, each from one center. Most patients had already failed standard treatment, often including a bandage soft contact lens.
Many wounds heal, but not all. In one series, 20 eyes with persistent defects were treated with overnight PROSE wear and a preservative-free antibiotic in the reservoir. Seventeen of the 20 healed. The median length of overnight treatment was 8.5 days, and 12 eyes healed within a week.[4] In an older series that included 15 eyes with active defects at the time of fitting, 8 healed and 7 stayed unchanged.[8]
Small standardized protocols report high healing rates. A New York series treated eight eyes with around-the-clock PROSE wear, daily cleaning, and an antibiotic in the reservoir. All eight healed, and none developed an infection.[5] A series of eight eyes using three different scleral lens designs reported that all healed, on average in about 11 days, with no complications.[7]
The benefit can depend on keeping the lens in. In a series of nine patients from Houston’s Cullen Eye Institute whose wounds had failed to heal with bandage soft lenses, all healed with PROSE and vision improved in eight. But eight of the nine had their wounds come back when PROSE was stopped. They healed again when it was resumed.[6] In the New York series, four eyes had recurrences, and all responded when continuous wear restarted.[5]
Infection risk has shaped the method. In an early series from 2000, 14 eyes wore scleral lenses continuously to heal persistent defects. Eight healed, but four developed a corneal infection, and those eyes needed another corneal transplant.[3] The same center later made a preservative-free antibiotic in the reservoir standard practice. In 20 eyes treated that way, there were no infections, and the authors concluded the infection rate had come down.[4] Those are small numbers, so the risk hasn’t gone away.
Other options, compared
Treatment usually starts with simpler measures, and a scleral lens is often tried when those fail. Treatments are frequently combined, and the cause decides a lot.
| Option | What it does | Typically suited to |
|---|---|---|
| Preservative-free lubricants | Support the surface without preservatives | Every defect, as a first step |
| Bandage soft contact lens | Covers the wound short term | Early or uncomplicated defects, with close monitoring |
| Autologous serum or other blood-derived drops | Supply growth factors from the patient’s own blood | Defects not healing with lubricants |
| Scleral lens | Holds saline over the wound and shields it from the lids | Defects that fail other treatment, or need long-term protection |
| Cenegermin (Oxervate) drops | Nerve growth factor that promotes healing | Defects caused by neurotrophic keratitis |
| Amniotic membrane | Tissue placed over the cornea to aid healing | Defects not responding to other treatment |
| Tarsorrhaphy | Partly closes the eyelids | Severe defects, especially with poor lid closure |
Questions to ask a scleral lens fitter
- How many patients with persistent epithelial defects have you treated with scleral lenses?
- Will you work with my cornea specialist on the treatment plan?
- Will I wear the lens overnight, and for how long?
- Will an antibiotic go in the lens, and which one?
- How often will you check the wound, and who do I call out of hours?
- What happens once the wound heals: do I keep wearing the lens during the day?
- What are you doing to find and treat the cause of the wound?
Common questions
Is it safe to sleep in a scleral lens while a wound heals?
Only if your eye doctor has specifically planned it. In the published studies, overnight or around-the-clock wear was a short-term treatment with daily cleaning, fresh saline, an antibiotic, and frequent checks. Outside a plan like that, don't sleep in your lenses.
Why would my doctor put an antibiotic in the lens?
An open wound under a lens is vulnerable to infection. An early study had a high infection rate, and later protocols that added a preservative-free antibiotic to the saline reported no infections in small groups. Use exactly what your doctor prescribes and nothing else in the lens bowl.
How long does healing take?
It varies with the cause. In one series of 20 eyes, the median time on overnight lens treatment was 8.5 days, and most eyes healed within a week. Some take much longer, and some don't heal with a lens at all.
Will the wound come back after I stop the lens?
It can. In one series, wounds reopened in 8 of 9 patients when the lens was stopped and healed again when they started wearing it again. Some people move from round-the-clock treatment to long-term daytime wear for this reason. Your doctor will also look for and treat the cause.
What should I do if my eye gets more painful while I'm wearing the lens?
Take the lens out and call your eye doctor the same day. Increasing pain, redness, discharge, light sensitivity, or a white spot on the cornea can be signs of infection. If your cornea is numb, you may not feel much at all, which is why scheduled checks matter.
Can putting the lens in or taking it out hurt my healing cornea?
Rough handling can scratch the surface, so be gentle and follow your fitter's technique exactly. If a lens feels stuck, stop, use the drops your fitter recommends, and call them rather than prodding repeatedly with the plunger. If the eye feels scratched or bruised afterward, leave the lens out and call your eye doctor today.
Can serum tears go in the lens while my eye heals?
Some doctors do direct patients to add serum tears to the fill, but it's off-label and depends on your eye and your treatment plan. Never add anything to the lens bowl that your doctor hasn't prescribed. Ask how any drops you use should be timed around the lens.
The defect healed and then came back in the same spot. Why?
There can be several reasons, including the underlying condition, the lens fit, or other treatments the eye is getting. Tell your eye doctor and fitter right away, since they may need to check the lens clearance over that area and look again for the cause. Don't restart or extend wear on your own.
If I end up in urgent care or the emergency room, what should I tell them?
Tell them you wear a scleral lens and why, and bring your lens case and the lens if it's out. Ask whether an eye doctor can see you, and call your fitter's after-hours line too. Being clear about the lens helps them examine and treat your eye properly.