8 EyeWorld Asia Pacific | June 2024 neuroprotective agents, all resulting in dry eye and damage to the ocular surface that can be perceived as FBS. Furthermore, aberrant regeneration of the severed nerves and possibly neuroma formation can result in persistent FBS. Dr. Kim also discussed how cataract surgery can exacerbate the problem. “First, a whole host of medicated eye drops are given preoperatively, intraoperatively, and postoperatively, and these drops contain preservatives, which are toxic to the ocular surface. Betadine can also irritate the eye,” he said. “Second, the very act of surgery severs corneal nerves, which can reduce corneal sensation. Moreover, cutting the cornea can damage the epithelial basement membrane adhesions and result in a recurrent corneal erosion.” He added that typically, recurrent corneal erosion is associated with accidental injury, but it’s important not to forget that surgery is also a form of trauma to the cornea, particularly clear corneal phaco. “The most important precaution is to identify comorbid conditions and counsel patients during the preoperative discussion, so they are made aware and begin treatment before surgery.” Presentation and common complaints In some cases, patients will explicitly say, “I never had FBS until after you did my cataract surgery,” Dr. Kim said. This is a challenge because even if you improve the patient’s visual acuity, they may dwell on the FBS, which they will reiterate only began after you performed surgery. Some of this can be subclinical dry eye or blepharitis manifested from surgery, while others can have an underlying epithelial basement membrane dystrophy or corneal erosion. “A good history including a good description of symptoms, when they began, how they’ve progressed, and any factors that seem to worsen or alleviate the discomfort, underlying health issues, and environmental exposures can be very helpful,” Dr. Sayegh said. “In addition, resolution of the FBS with instillation of a drop of anesthetic in the office is often helpful in narrowing the differential diagnosis. Slit lamp examination, which includes eyelid eversion as well as use of vital dyes, can help make the diagnosis in the great majority of patients.” Dr. Sayegh said that more specific diagnostics such as tear osmolarity, MMP-9, meibomian gland imaging, and confocal microscopy can also be helpful. When diagnosing FBS, Dr. Kim said it’s important to first treat the common conditions, namely dry eye and blepharitis. However, even after aggressive treatment, patients may not improve, and the patient and physician can be left perplexed and frustrated, he said. “It’s important to consider that these cases could actually be a form of recurrent corneal erosion not visible on slit lamp examination.” Typically, Dr. Kim said that recurrent corneal erosions are diagnosed by identifying irregular or negative staining with fluorescein dye or looking for irregularities on corneal topography. However, he noted that identification relies on a high index of suspicion since there is no good definitive diagnostic tool. A dried Weck-Cel sponge has been used to touch the corneal surface to identify areas of loose epithelium, but the dry sponge can stick to the cornea and induce an abrasion. “As a result, I developed the Kim Corneal Sweeper [Corza Medical], which is a handheld instrument with a straight handle and fusiform shape tip with rounded edges,” he said. “The smooth texture enables safe use on the corneal surface. Fluorescein dye is instilled, and the cornea is examined under the slit lamp with cobalt blue light. The sweeper is held like a pencil and pressed Foreign objects, such as contact lenses or even bugs, can get stuck in the eye or under the eyelid, causing FBS. Source: Rony Sayegh, MD Certain systemic drugs can also cause corneal changes and FBS. The slit lamp photograph shows microcyst-like epithelial changes in a patient on Mirvetuximab soravtansine, an antibody drug conjugate used for the treatment of ovarian cancer. Source: Rony Sayegh, MD CATARACT
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