Awareness can reduce challenges associated with preservatives in glaucoma treatment
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Key takeaways:
- Preservatives in eye drops are associated with adverse events and should be minimized or avoided.
- Navigating glaucoma treatment options can be difficult for patients.
Eye drops for glaucoma are associated with various adverse effects on the ocular surface that often lead to treatment nonadherence and poor outcomes with surgery, according to a report published in Ocular Surface.
“Therefore, communication about the importance of the treatment is crucial for patients to continue the treatment despite the side effects,” Miriam Kolko, MD, PhD, of Copenhagen University Hospital and University of Copenhagen, Denmark, and colleagues wrote.
Active substances, phosphate content, pH and viscosity, in addition to preservatives, may be associated with adverse effects on the ocular surface. Image: Adobe Stock
The Tear Film & Ocular Surface Society in collaboration with Kolko convened a 1-day meeting in October 2022 that focused on the impact of glaucoma medications on the ocular surface and how ocular surface disease may influence glaucoma treatment.
It is well known that preservatives are associated with adverse events and should be minimized, but it is also important to know that the active substance and factors such as phosphate content, pH and viscosity of the eye drops may be associated with adverse effects on the ocular surface.
“Many of the challenges that patients with glaucoma experience can be reduced by [eye care providers] being aware of the challenges that come with the treatments,” Kolko and colleagues wrote.
A significant challenge is the use of preservatives in eye drops.
“Preservatives cause unnecessary side effects and should at least be reduced or at best avoided,” they wrote. “Another challenge is the use of generic eye drops that come with different packaging, different solvents and, not least, different preservatives. For those patients who must undergo glaucoma surgery, there is a greater risk of an unsuccessful result if the conjunctiva is affected due to adverse effects from many years use of eye drops.”
Navigating the various treatment options for glaucoma can be difficult for patients.
“That is why information is so important,” Kolko and colleagues wrote. “Also, patients with glaucoma are often in a difficult position. They may have lost their driving license, which can affect their sense of freedom and quality of life. All in all, it is important to see the patient as a whole person and to find the treatment with the least possible side effects, which is also understandable for the patient.”
Perspective
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Glaucoma poses a significant risk for ocular surface disease (OSD), with approximately 50% of glaucoma patients affected, and 20% to 30% experiencing severe cases. The signs and symptoms of OSD worsen with the number of anti-glaucoma drops used. Among glaucoma patients, corneal staining is observed in 25.6% of those using preserved drops, compared to only 8.9% using nonpreserved drops. OSD associated with glaucoma can range from mild dry eye disease (DED) to visually threatening conditions such as pseudo-pemphigoid, cicatricial conjunctival scarring, limbal stem cell deficiency or neurotrophic keratitis. Additionally, glaucoma surgeries like trabeculectomies have been linked to increased conjunctival and corneal staining, as well as reduced tear breakup time. Nevertheless, it is important to acknowledge that glaucoma surgery, as a replacement for topical medications, has been shown to improve OSD overall.
In the context of glaucoma, the use of IOP-lowering eye drops remains the main threat to the ocular surface. Prostaglandins upregulate matrix metalloproteinases, compromising the membrane integrity of conjunctival cells and damaging corneal epithelial cells. They also release pro-inflammatory mediators, cause conjunctival hyperemia, harm meibomian glands, impair meibum quality and reduce tear production. Beta-blockers contribute to conjunctival irregularity, decrease goblet cell density, lower tear production, reduce tear film stability and may affect meibomian gland function. Combination drops commonly possess at least one mechanism that leads to dryness. Essentially, all glaucoma drops have some level of cytotoxic effect on corneal epithelial cells. Moreover, benzalkonium chloride is the most common preservative used in glaucoma drops, which, as we know, has detrimental effects on the ocular surface, including inflammatory cascades, epithelial and goblet cell toxicity, oxidative stress, trigeminal nerve ending toxicity and decreased corneal sensitivity.
Here are a few key points for clinicians to consider: Both glaucoma drops and surgery pose a significant risk to the ocular surface, switching to nonpreserved drops or procedures improves the ocular surface, and uncontrolled OSD can lead to nonadherence with glaucoma drops, underscoring the crucial role of managing OSD in preserving long-term vision.
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