Glaucoma is the leading cause of irreversible blindness worldwide, affecting more than 70 million people. The most well-recognised risk factor for glaucoma is elevated eye pressure or intraocular pressure (IOP). The IOP is the balance between production and drainage of aqueous fluid, which is the fluid that bathes the internal structures of the eye. The aqueous fluid is produced by the ciliary body, a tidy gland inside the eye. The fluid subsequently is removed from the eye by being absorbed and drained by the trabecular meshwork which is microscopic sponge that absorbs the fluid and passes the fluid the canal of Schlemm which removes the fluid from the eye.  Increased IOP is thought to be the result of increased resistance to drainage in the trabecular meshwork.

Treatments for glaucoma are aimed at lowering IOP. Treatment options include eye drops, and laser treatment or surgery.  The most common treatment utilised by glaucoma patients are eyedrops which work by lowering IOP. Patients with glaucoma are likely to receive chronic treatments over a longer duration.

Most glaucoma eyedrops are comprised of two components: the active ingredient and a preservative.  Benzalkonium chloride (BAK), a quaternary ammonium molecule, is the most commonly used ophthalmic preservative.  There is a recognised harm from the preservative in the eye drops. The most common being ocular surface irritation.  However, there is also preliminary evidence that the preservatives in the eye drops may cause inflammation and damage to the trabecular meshwork. As a result, preservative free eye drops have been developed and are readily available in most developed countries.  New Zealand is one of the only countries in which there is no access to preservative free eye drops because it is not accepted by PHARMAC that patients receive a significant benefit.

“This is an exciting and interesting area of glaucoma research, and I am so fortunate to be part of a department that aims to provide optimal patient care with the most innovative and up-to-date research evidence.” – Gabriela Bantas


This study aims to investigate the effects of preservatives on the trabecular meshwork cells. Our hypothesis is that the preservative in eye drops causes significant damage to the cells in the trabecular meshwork that lead to toxic changes and may actually impair the ability of the trabecular meshwork to work adequately in glaucoma leading to exacerbation of the disease. Our team will be the first to compare the effect of the most commonly used glaucoma drops and their preservative on the trabecular meshwork.

Gabriela is completing a Masters Degree in the department of Ophthalmology at the University of Auckland.  She is passionate about research that improves the current treatment management or processes that will enhance the patient experience and health outcomes.

Gabriela Bantas – Masters student

Your research update – MARCH 2024

We’re excited to let you know that the lab research above was completed.

Findings suggest that BAK in the BAK-preserved antiglaucoma eyedrops induces the inflammasome pathway and may introduce inflammatory effects at subclinical doses. The BAK-free eyedrops describe a more protective impact in comparison.

Despite the growing body of evidence suggesting the adverse effects of BAK, there is a paucity of well-designed clinical trials specifically addressing the inflammatory consequences of BAK exposure in the context of glaucoma medication use.

A new study aims to bridge this gap by conducting a case-control clinical trial, focusing on the comparison of inflammatory markers in patients using BAK-containing glaucoma medications and their preservative-free counterparts.

This research holds significant implications for eye care policy in New Zealand. The evidence generated from this study will provide a robust foundation for Glaucoma NZ to approach Pharmac, advocating for the funding of preservative-free glaucoma drops. This has the potential to improve the accessibility of safer alternatives for glaucoma patients and contribute to long-term ocular health outcomes.

Donate here to support this vital clinical trial so kiwis have affordable and fair access to preservative-free glaucoma drops.

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