Researchers continue to seek safe and effective sustained-release drug delivery systems to combat the common compliance issues associated with long-term glaucoma treatment. However, a new study suggests they may have more to prove than they thought.

After surveying 150 glaucoma patients about their willingness to accept alternatives to drops—including drug-eluting contact lenses, ring inserts, punctal plugs and subconjunctival injections—they found the therapies’ ability to obviate surgery was key to patient acceptance. Even then, patient acceptance of these alternative treatments wasn’t resounding. Slightly more than half of participants would accept contacts (59%), rings (51%), plugs (57%) and subconjunctival injections (52%) if they eliminated the need for surgery. Even fewer said they would be willing to use sustained-release therapies if they only reduced (23% to 35%) or eliminated (27% to 42%) drops.

Of the devices, contact lenses, punctal plugs and even subconjunctival injections were preferable to ring inserts.

“Our results reiterate the importance of studying acceptance rates of sustained delivery methods based on the outcomes of treatment in comparison with standard glaucoma therapies,” the study says. “With acceptance rates of sustained devices dropping when less efficacious than eye drops, there may be clinical implications for the sustained delivery enterprise, given that these devices have generally not shown to confer an increased benefit relative to drops in some early trials.”