Slit lamp evaluation shows the patient's presentation.
A 30-year-old male who wore gas permeable hard contact lenses presented to the clinic with pain in his right eye that, he said, started that morning. He had last worn his lenses 2 days earlier. Upon history, he explained that he had been rubbing his eye. His best corrected visual acuity was 20/25 OD, 20/20 OS. A slit lamp exam of his right eye exposed an area of temporal corneal thinning that holds fluorescein. He also has a slightly adjacent raised red area on the temporal limbal conjunctiva.
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The photo demonstrates a depression on part of the patient’s cornea. A corneal dellen is a focal area of corneal thinning caused by a break in the precorneal oily tear film from a paralimbal elevation. You can see this paralimbal conjunctival elevation in the slit beam in the photo. This resulted in a localized tear instability, and particularly, a focal absence of the mucin layer. This layer is the glue that helps tears stick to the eye. The corneal epithelium is hydrophobic and, in the absence of mucin, will repel water. This will cause localized stromal dehydration which will result in corneal stromal thinning.
On examination, fluorescein will pool in this depressed area, as this patient demonstrates, rather than stain the cell tissue. Corneal dellen are located adjacent to areas of conjunctival tissue elevation or inflammation. The areas of elevation can be due to many things including strabismus or pterygium surgery, severe conjunctival chemosis, elevated subconjunctival hemorrhage, or even vigorous eye rubbing. The eye rubbing the patient described likely caused this localized inflammation of the conjunctiva.
Treatment consists of aggressive corneal lubrication with both ointments and tears. A corneal dellen typically resolves within 4 to 7 days of treatment.
Matthew Garston, OD, is an adjunct professor at the New England College of Optometry and a senior staff optometrist in the medical department at MIT.
Mohan M, Mohan S, Mohan S. Corneal dellen. Eyewiki: The American Academy of Ophthalmology. Published online May 31, 2020.