Doctors Warn a Widely Used Eye Ointment Can Damage Glaucoma Implants

Scientists have discovered that petrolatum-based eye ointments can cause a popular glaucoma implant to swell, weaken, and even burst. The risk appears only when the ointment directly touches the implant, raising concerns about routine eye care after surgery. Credit: Stock Photographic comparison of MicroShunt illustrating size changes.Top: MicroShunt explanted from a patient, exhibiting diffuse swelling with fracture and loss of one fin.Middle: MicroShunt explanted from another patient, showing localized swelling around the fin.Bottom: Unused MicroShunt (control).Scale: 1 division = 1 mm.Credit: Ryo Tomita Progression of visual field loss (from left to right) due to glaucoma. Credit: Ryo Tomita A common eye ointment may quietly damage glaucoma implants-sometimes to the point of rupture-by making them swell from the inside. New research from Nagoya University in Japan suggests that widely used eye ointments may pose a serious risk for some glaucoma patients. The study shows for the first time, using both patient data and laboratory testing, that petrolatum-based eye ointments can damage the PRESERFLO MicroShunt, a glaucoma implant used in more than 60 countries. The findings raise concerns about a routine eye care product that may unintentionally weaken or even rupture a device designed to protect vision. Understanding Glaucoma and How It Is Treated Glaucoma is a condition that damages the optic nerve and can eventually lead to vision loss. It is often caused by increased pressure inside the eye when fluid does not drain properly. Researchers estimate that glaucoma affects about 76 million people worldwide. One modern treatment option is the MicroShunt, a tiny filtration device surgically placed in the eye to help fluid drain more effectively. Compared with traditional glaucoma surgeries, the MicroShunt generally leads to fewer complications and reduces the need for additional medications after surgery. Top: MicroShunt explanted from a patient, exhibiting diffuse swelling with fracture and loss of one fin. Middle: MicroShunt explanted from another patient, showing localized swelling around the fin. Bottom: Unused MicroShunt (control). Scale: 1 division = 1 mm. Credit: Ryo Tomita Why the MicroShunt Is Vulnerable to Certain Ointments The MicroShunt is made from a specialized styrenic thermoplastic elastomer derived from a polystyrene-block-polyisobutylene-block-polystyrene (SIBS) block polymer. This material is valued for its flexibility, biocompatibility, and low risk of triggering inflammation or scarring. However, the same properties that make the material effective inside the eye also make it susceptible to oil-based substances. Because the polymer has a strong attraction to oils, petrolatum-based eye ointments can seep into the implant. When this happens, the device may swell and its shape and flexibility can change. The manufacturer specifically warns against this risk. According to official instructions, “the MicroShunt should not be subjected to direct contact with petrolatum-based (i.e., petroleum jelly) materials, such as ointments and dispersions.” Despite this guidance, the warning is not always widely known or followed in everyday clinical care. Surgeons Observe Implant Rupture in Real Cases “Swollen MicroShunts can be structurally fragile,” said ophthalmologist and Assistant Professor Ryo Tomita of Nagoya University Graduate School of Medicine, the study’s first author. “During surgery, I...

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