Corneal sweep test for recurrent corneal erosion

Cornea
June 2022

by Ellen Stodola
Editorial Co-Director

New diagnostic techniques are often developed when a need in the clinic or OR arises. That is what led D. Brian Kim, MD, to develop the corneal sweep test and a new diagnostic tool to identify recurrent corneal erosion.

Several years ago, Dr. Kim noticed that after draping the eye at the start of cataract surgery, some patients would have an area of loose corneal epithelium. Patients don’t feel it because the eye is numb, but it seemed strange because they never had corneal epithelial disease, he said.

The Kim Corneal Sweeper is oriented with the round profile in view.
The Kim Corneal Sweeper is oriented with the round profile in view.
The tip is rotated 90 degrees with the flat profile in view. Note the tapered edges for a smooth design and thin profile, which enables a clear view of the cornea during the sweep maneuver.
The tip is rotated 90 degrees with the flat profile in view. Note the tapered edges for a smooth design and thin profile, which enables a clear view of the cornea during the sweep maneuver.

He also noticed that some patients after seemingly uneventful cataract surgery would develop a persistent ocular pain syndrome. These observations led Dr. Kim to use the back end of a corneal spud, often used to pull out foreign bodies stuck in the cornea, to sweep the corneal surface of these patients.

He did this on the post-cataract surgery patients who were having persistent symptoms, foreign body sensation, burning, irritation, and sharp pain, after having tried and failed standard dry eye and blepharitis therapy.

Dr. Kim called this method the “corneal sweep test,” adding that after finding these areas of loose epithelium, he would often treat by debriding with superficial keratectomy, and he discovered that it would improve the symptoms.

One reason that Dr. Kim thinks the corneal sweep test is needed is because of the current way to diagnose recurrent corneal erosion. This is done using slit lamp biomicroscopy and vital stains such as fluorescein dye to inspect the surface of the cornea and to look for negative staining or irregularities on the cornea. “If there’s nothing there, we’re taught to say that there is no recurrent corneal erosion, and that’s the gap in our teaching,” he said.

Dr. Kim realized that he would need to use a different instrument to test for these recurrent corneal erosions, especially if he wanted to encourage others to do the same. This led to the development of an instrument with Katena called the Kim Corneal Sweeper designed specifically for this purpose. Dr. Kim described the instrument as “an M&M candy on a stick.” It’s curved and smooth all around, but it has sidedness; one side is flatter. “You can sweep the cornea and because it’s rounded, it’s atraumatic, and because of the thin profile, you can see what’s happening as you’re indenting the cornea,” he said.

Fluorescein dye is instilled, and the cornea is illuminated with cobalt blue light at the slit lamp. The Kim Corneal Sweeper is applied to the wet surface of the cornea with gentle pressure. Note that the normal corneal epithelium is not disrupted during the sweep maneuver, illustrating its safety.
Fluorescein dye is instilled, and the cornea is illuminated with cobalt blue light at the slit lamp. The Kim Corneal Sweeper is applied to the wet surface of the cornea with gentle pressure. Note that the normal corneal epithelium is not disrupted during the sweep maneuver, illustrating its safety.
The instrument is held showing the thin profile to enable a clear view of the corneal surface. When the instrument encounters an area of loose epithelium, a visible wrinkle or fold is induced, which highlights the recurrent corneal erosion. Source (all): D. Brian Kim, MD
The instrument is held showing the thin profile to enable a clear view of the corneal surface. When the instrument encounters an area of loose epithelium, a visible wrinkle or fold is induced, which highlights the recurrent corneal erosion.
Source (all): D. Brian Kim, MD

Since adopting this technique in 2017, Dr. Kim has performed a retrospective chart review that has been published in the journal Cornea.1 This includes his data from July 2018–June 2020 and highlighted 58 eyes of 51 patients.

In Dr. Kim’s experience, 49 of the eyes needed the corneal sweep test in some form to help confirm the diagnosis. His data determined that 34 of 58 eyes had completely normal appearing corneas on slit lamp examination. Additionally, in 28 of those 58 eyes, the most common presumed mechanism of injury was clear corneal cataract surgery.

“In the pathology of recurrent corneal erosion, the classic teaching is that it’s typically caused by accidental trauma. The injury disrupts the epithelium and scrapes it off the basement membrane underneath, then as the eye heals back, it may not heal with good adhesion to the sub-floor,” Dr. Kim said. “It has this loose attachment, and anything that can pull the epithelium off, like dry eye or nocturnal lagophthalmos, can cause the eyelid and epithelium to stick together, and upon opening the eyelid, the epithelium can separate abruptly and cause sharp pain.”

He added that it requires a paradigm shift to think that clear corneal cataract surgery can be one of the causes of these corneal erosions. “We don’t understand the disease process fully,” Dr. Kim said. “But among those 28 eyes [in the retrospective chart review], 20 of them only developed symptoms after their cataract surgery.” Furthermore, when sweeping the cornea, the erosions were right over the cataract incisions.

For those questioning “how do you know you’re not causing trauma with the corneal sweep test?” Dr. Kim said he further looked at 40 eyes of 20 patients. “We excluded everything,” he said. There was no prior corneal surgery, no prior corneal injury, no history of contact lens wear, no history of diabetes or ocular surface disease. When looking at this group, 38 of the 40 eyes had completely normal corneas when their corneas were swept. None of the 40 had complications from the sweep maneuver, and none had symptoms after the numbing drops wore off. Dr. Kim said that 2 of the 40 had a small 2–3 mm area of loose epithelium along the superior limbus, and he admits it’s hard to know what that means. “This could be a form of forme fruste epithelial basement membrane disease. The truth is, we don’t know, and further research is needed.”

As a result of the new technique and instrument, Dr. Kim has created a completely new classification for these patients, which he refers to as “occult corneal erosion.” This term is used because the erosions were missed by standard diagnostic techniques.

“I think a lot more research needs to be done, and I think there’s a lot more to learn about this disease,” he said. He recognized that many might still question this technique and the conclusions drawn, specifically noting that there might be a question of how you know that the loose epithelium that is found with the corneal sweep technique is, in fact, a recurrent corneal erosion.

While Dr. Kim said that’s a tough conclusion to draw, one metric that can be used is treatment response. “If the patient has symptoms consistent with a recurrent corneal erosion and you look at their cornea and everything looks normal, you’re done based on current standard diagnostic methods, but if you move forward with the corneal sweep test and find this loose epithelium, you’ve effectively found the erosion that would have otherwise been missed.”

To treat these patients, there are several options, including hypertonic saline, bandage contact lens, superficial keratectomy, and anterior stromal micropuncture.

In his data, Dr. Kim said more than 35% of patients had complete resolution of symptoms after treatment, and 50% showed improvement but continued to have ocular irritation, suggestive of chronic ocular surface disease. So in total, more than 85% had some positive response to treatment. This is compelling data that suggests that the loose epithelium is responsible for the patients’ symptoms, he said.

Among the people who had the occult corneal erosion that would have been missed, more than 38% of them only developed symptoms after cataract surgery. Additionally, more than half of those patients who had the occult corneal erosion came in to see Dr. Kim as a second opinion. “I think that as surgeons we need to acknowledge the fact that some at-risk patients can develop a recurrent corneal erosion after surgery. I want my colleagues to know about this so that they can be better equipped to handle these patients who are desperate for answers and seeking relief.”

Dr. Kim stressed that while there is still research to be done, the technique is safe, and he has used it on hundreds of patients without complications. When thinking about when to incorporate the technique into practice, Dr. Kim suggested all it takes is a high index of suspicion. “Any patient with persistent ocular surface symptoms recalcitrant to standard treatment should undergo the corneal sweep test.

“Another great aspect of the corneal sweep test is if you do it and it’s normal, you can tell the patient with confidence that they do not have a recurrent corneal erosion,” he said. “I think ruling out is just as important to be a successful diagnostician.” Currently, Dr. Kim’s approach is if a patient comes in with ocular surface symptoms, he will initiate standard therapies first. But if they fail those therapies, he proceeds straight to the corneal sweep test.

He compared incorporating this instrument and technique into practice as similar to gonioscopy: It’s for select patients, it’s not invasive, it takes just a few minutes, it gives you immediate results, and there is no special training or learning curve.


About the physician

D. Brian Kim, MD
Private Practice
Professional Eye Associates
Dalton, Georgia

Reference

  1. Kim ME, Kim DB. Implementation of the corneal sweep test in the diagnosis of recurrent corneal erosion: A 2-year retrospective study. Cornea. 2022. Online ahead of print.

Relevant disclosures

Kim: Katena

Contact

Kim: kim@professionaleye.com