49 EyeWorld Asia-Pacific | March 2025 CORNEA Stephen Pflugfelder, MD, also shared the concern of corneal and conjunctival epithelial toxicity with preservatives. This is most relevant to drops preserved with benzalkonium chloride (BAK), he said, which can cause corneal barrier disruption leading to an irregular and dry corneal surface that can reduce visual function and cause irritation. It can also cause death of conjunctival goblet cells, thus reducing secretion of tear-stabilizing mucin from these cells. Dr. Pflugfelder said that if possible, reducing the frequency of instillation or switching to a preservativefree formulation should be considered to help with the effects of these products. The risk of toxicity is related to the frequency of use and the BAK concentration. Usually, most patients can tolerate one drop with BAK preservative per day. Dr. Pflugfelder said there aren’t many circumstances where you would need to use a product with preservatives. Theoretically, BAK-preserved antibiotic drops may be more effective for treatment of bacterial keratitis because the preservative can provide added bactericidal activity. However, severe corneal infections are often treated with compounded preservative-free fortified antibiotics. John Sheppard, MD, noted two sets of concerns to consider with preservatives—short term and long term. In the short term, normal people will be fine with preservatives, he said. One example is antibiotics. In the past, companies have advertised a synergistic effect between the preservative and antibiotic. In short-term use, they’re fine for a normal surface. “If the patient has ocular surface disease, even the short-term use of a preservative can exacerbate ocular surface disease,” he said, adding that moxifloxacin is a preservative-free option. In a situation where you’re concerned about toxicity, this could be a good option because it has a tremendous track record of safety and efficacy, he said. “Due to hyper concentration that is unachievable by oral anti-microbial medications, any antibiotic in the tear film many times supersedes the minimum inhibitory concentration sensitivity threshold. Often, I’ll have a patient treated for an acute ulcer, doing well with infiltrate resolution but delayed epithelialization, and I want to accelerate surface healing but prevent any future infections. I will frequently use a bandage contact lens,” Dr. Sheppard said. It’s important to consider intermediateterm antibiotic prophylaxis, and moxifloxacin is a wellmatched partner for the clinician and the patient. Another example, he said, is Eysuvis (loteprednol etabonate 0.25%, Alcon), which is indicated for intermittent treatment of episodic dry eye disease. Chronic diseases are notoriously age related, recalcitrant, and incurable, but they benefit from long-term therapy, Dr. Sheppard said. The classic examples are glaucoma and dry eye, and many in this cohort also have cataracts. These patients require intervention for long periods of time, and continuous use of preserved glaucoma medications are known to create changes in the ocular surface. He added that infiltration of inflammatory cells into the conjunctiva can cause a hypersensitivity reaction that can be exacerbated by the preservative themselves. Patients who have sensitivities to the active ingredient may become even more sensitive because the preservative is a wellknown way to enhance permeability, so medications with continuous insult to the ocular surface are more efficacious because they enter the corneal or conjunctival tissues more readily. On the other hand, you have to be very cautious in this population because they tend to be older, and therefore more likely at risk for dry eye disease and trabecular meshwork outflow damage. Central corneal fluorescein staining in patient with aqueous deficient dry eye and history of using latanoprost for glaucoma for 5 years; corneal staining and vision improved when latanoprost was exchanged for preservative-free tafluprost. Source: Stephen Pflugfelder, MD In vivo confocal microscopy demonstrating nerve tortuosity and a few activated dendritic cells in a patient with long-standing glaucoma medication use. Source: Anat Galor, MD, MSPH
RkJQdWJsaXNoZXIy Njk2NTg0