Q: My friend was diagnosed with a corneal ulcer, and the doctor said she needed aggressive treatment and daily checkups for a week. I scratched my cornea last year, but it only needed antibiotic drops for a week and it healed fine. Why the difference?
A: It sounds like you had a corneal abrasion, but your friend had a corneal ulcer. I will discuss these in today's column.
The cornea is the transparent area in the front of the eye that covers the pupil (the black part that allows light into the eye) and the iris (the colored part), and consists of five layers. A corneal abrasion is a scrape of the top layer, the epithelium, but does not go through Bowman's layer underneath this. A corneal ulcer is an open sore/erosion (from inflammation or infection) that goes through Bowman's layer into the deeper layers of the cornea.
Think of this as the difference between a scraped knee (an abrasion) and a deep laceration in the knee that may (or has) become infected. You would treat the abrasion by keeping it clean and putting some antibiotic ointment on it. The infected deep cut would require much more aggressive treatment.
Trauma to the eye (from direct contact or from a foreign body) can cause a corneal abrasion or an ulcer. Abrasions are from superficial scrapes. Ulcers are from deeper "gouges," or from invasion/infection of a more superficial injury by bacteria or another pathogen (fungus for example).
Corneal ulcers can also develop in a previously intact cornea from certain viral infections (such as getting shingles in the eye from a herpes virus) or as a complication of a systemic disease such as an autoimmune disease (like rheumatoid arthritis) or from other illnesses such as Hepatitis C.
Complications of corneal ulcers can include scarring or even erosion into the eye leading to perforation with possible spread of infection inside the eye. These can threaten the patient's vision, so it is not surprising that a corneal ulcer is an emergency condition requiring aggressive treatment and evaluation by a specialist.
Thankfully, corneal ulcers are not that common, affecting about 25,000 Americans per year. Risk factors for developing corneal ulcers include the systemic conditions already noted above as well as trauma to the eye, vitamin A deficiency (more common in developing countries) and wearing contact lenses. Contact lens wearers have up to a 10 times increased risk of developing a corneal ulcer.
Both corneal abrasions and corneal ulcers may manifest as a red and painful eye, sometimes with blurry vision and/or light sensitivity. Patients with corneal ulcers may also have a pus-like discharge from their eye.
Antibiotic eye drops are usually prescribed for both corneal abrasions and corneal ulcers. However, the types of antibiotics required may be different, with a broader coverage used for a corneal ulcer. Furthermore, prior to starting antibiotic therapy, a patient with a corneal ulcer will usually have a culture done (not typically indicated for a corneal abrasion). Severe corneal ulcers may require hospitalization and intravenous antibiotics, and, in very severe cases, might even require surgery and a corneal transplant.
Corneal abrasions usually heal within several days and with no loss of vision.
Most promptly diagnosed and appropriately treated corneal ulcers also heal well. The ultimate prognosis of corneal ulcers depends on many factors, including the size, depth and cause of the ulcer. Because of the increased risk of complications that can affect vision from a corneal ulcer, very close follow-up is required. The ophthalmologist will evaluate the patient over time to ensure the ulcer is healing. If, instead, the ulcer seems to be worsening, consideration of other factors, such as an infection not covered by the antibiotics the patient is being treated with, will be considered.
If you develop eye pain, redness and/or visions changes, you should be seen immediately to be evaluated. Early treatment, especially for corneal ulcers, can possibly save your vision.
Jeff Hersh, Ph.D., M.D., F.A.A.P., F.A.C.P., F.A.A.E.P., can be reached at DrHersh@juno.com.
author: Dr. Jeff Hersh