A 75-year-old white woman presented with intermittent episodes of blurry vision, burning, and foreign body sensation. She was not able to identify any particular triggers. She was told by one ophthalmologist that she had dry eye, and she therefore tried aggressive lubrication drops and ointments, including cyclosporine (Restasis, Allergan). However, the patient had no improvement.
She sought the opinion of a second ophthalmologist, who said she might have blepharitis. She began a regimen of warm compresses, lid hygiene, omega-3s, and doxycycline but, again, experienced no improvement. She then saw a third ophthalmologist, who inserted punctal plugs, but they too proved unsuccessful.
When the patient presented to me for a fourth opinion, she was understandably very frustrated. Her anterior segment examination appeared benign. The corneal examination showed no epithelial defects or irregularity, no visible anterior basement membrane dystrophy, and no abnormal uptake with fluorescein or rose bengal staining. The conjunctival examination did not reveal any significant abnormalities. Schirmer testing was 14 mm OD and 15 mm OS, and tear osmolarity was 288 mOsm/L OD and 279 mOsm/L OS.
Within minutes, I was able to identify the patient’s issue using a simple but little-known diagnostic technique to treat the underlying cause. She was both elated and relieved that I was able to fix the problem. With tears in her eyes, she told me how maddening it had been to do everything the doctors told her to do yet feel no relief. She hugged me and called me a hero. This is the case that changed how I practice.
OCCULT EROSIONS
The clinical scenario described above is one of hundreds I have encountered for a second opinion and one most of us have faced or will face. Although easy to dismiss as dry eye or blepharitis, this, in fact, was a corneal erosion. I will go a step further and coin it an occult erosion because it was hidden, with no obvious clinical findings. Unlike dry eye and blepharitis, which are chronic diseases, erosions are not chronic and are curable. Therefore, we have a responsibility and opportunity to truly help these patients. In my experience and opinion, these occult erosions are grossly misdiagnosed, and many patients walk around unnecessarily suffering from erosion symptoms.
Traditionally, we are taught to focus on the history of presentation, such as previous corneal trauma, preexisting epithelial basement membrane dystrophy, or herpes keratitis. Classically, symptoms of eye pain, redness, photophobia, and tearing occur during the night or upon first awakening with varying severity and duration. However, these occult erosions are far from typical. They do not follow the usual history and lack physical findings. There are no areas of atypical corneal staining, no visible epithelial basement membrane dystrophy, no scarring—nothing.
CORNEAL SWEEP TEST
Several years ago, I developed a technique for detecting these occult corneal erosions directly without the need for any of the standard diagnostic testing. With this technique, I use a blunt-edged instrument to gently paint the surface of the cornea. Thus far, I have been using a corneal spud, which is traditionally used to remove corneal foreign bodies. However, I have found that this is not the ideal tool for the technique, so I have partnered with an instrument company to develop and design a better-suited one.
The technique is as follows (Video 1): I first apply anesthetic drops and then retract the eyelids with my finger or with a lid speculum. I begin painting the corneal surface with the backside of the spud. Because it is the backside, I am able to sweep the corneal epithelium very gently. A complete surveillance of the corneal surface is necessary; therefore, I begin at the bottom of the cornea and work my way upward. Invariably, I will find an area of loose epithelium. Interestingly, these erosions are often very small—1 to 2 mm in size—and invisible. But when sweeping these areas, the spud will catch the epithelium and reveal the blister.
Video 1 | The corneal sweep test for detecting occult corneal erosions.
Video 2 | Once the occult erosion is identified, a superficial keratectomy can be performed.
Once the occult erosion is identified, a superficial keratectomy can be performed (Video 2). The small area of erosion is often just the tip of the iceberg, and adjacent sheets of epithelium typically begin to slough off as well. I always peel all of the loose epithelium, even if the defect becomes quite sizable. I apply topical 5% povidone-iodine before the procedure and place a bandage contact lens at the end. Topical antibiotics are used for 1 week.
CONCLUSION
The corneal sweep test changed how I practice and diagnose occult corneal erosions because it allows me to directly and decisively identify the problem. There is no more postulating, which has been the traditional approach with corneal erosions. However, there is no need to put patients through this. If you learn to employ the corneal sweep test, I am certain your patients will begin calling you a hero, too.
