Cornea

Dellen: Symptoms, Causes & Treatment in Orange CountyExpert Eye Care from Orange County’s Leading Specialists

A dellen is a saucer-shaped area of thinning in the peripheral cornea caused by localized drying of the tear film, rather than by infection or inflammation. It develops when an elevated lesion sitting immediately next to the cornea — most commonly a pterygium or pinguecula, a filtering bleb from prior glaucoma surgery, or localized post-surgical conjunctival swelling — physically disrupts the smooth tear film and eyelid blink mechanics over an adjacent stretch of cornea. Because the elevated tissue prevents the eyelid from spreading a normal tear layer across that section, the underlying corneal stroma dries out and thins, creating a shallow, well-demarcated depression that can resemble a small crater when viewed under the slit lamp. Dellen formation can occur within days of a new elevation appearing, which is why any sudden corneal thinning adjacent to a bleb, pterygium, or post-operative swelling should prompt a same-week evaluation. Patients typically notice a foreign-body sensation, mild irritation or grittiness, and occasional light sensitivity, but true dellen rarely cause significant vision loss because the thinning stays outside the visual axis and the epithelium usually remains intact over the depression. Treatment is aimed at two things at once: rehydrating the dried stroma and removing the mechanical cause. Aggressive lubrication with preservative-free artificial tears during the day and a thick lubricating ointment at night is the first-line approach, and in more pronounced cases a temporary pressure patch or bandage contact lens can restore normal tear coverage while the cornea recovers. Equally important is addressing the adjacent elevation itself — reducing bleb height, treating an inflamed pterygium or pinguecula, or allowing post-surgical swelling to resolve — since the dellen will recur if the underlying cause is not corrected. With prompt treatment, a true dellen typically resolves completely within days to a couple of weeks and rarely leaves permanent scarring. The reason a same-week exam matters is that a dellen must be distinguished from more serious causes of peripheral corneal thinning, including a corneal ulcer, sterile corneal melt, or early Mooren's ulcer, which require very different — and more urgent — management. An exam with fluorescein staining and careful slit-lamp evaluation of the epithelium is the only reliable way to tell a benign, self-limited dellen apart from a condition that could progress to corneal perforation if left untreated.

At EyeCare Center of Orange County, we specialize in the diagnosis and treatment of dellen. Our experienced optometrists use state-of-the-art technology to provide comprehensive care and help preserve your vision.