JAMA Spotlight on the ‘Flying Cannula’

Published by a team from the Wilmer Eye Institute at Johns Hopkins, and titled ‘In pursuit of safer eye care – the case of the flying cannula’,¹ it argues that the detachment of a cannula from a luer lock syringe during intraocular surgery is more common, more dangerous, and more preventable than the profession has acknowledged.

Writing on behalf of a seven-centre Academic Ocular Safety Consortium, the authors report that every institution in the group had experienced these events. Their central conclusion is uncomfortable: education and human verification of the connection, however diligent, cannot reliably prevent the complication, and the durable answer lies in engineered, system-level solutions. They call explicitly on the surgical consumables industry to prioritise safety in cannula-syringe design.

The piece opens with a cautionary case. During routine cataract surgery, a cannula on a balanced-salt syringe dislodged inside the eye, dislocating the intraocular lens and causing a vitreous haemorrhage; neither the surgeon nor the assisting practitioner had confirmed the connection was fully engaged. It is, the authors suggest, a scenario familiar to most who operate.

The clinical consequences are severe: posterior capsule rupture, vitreous loss, retinal injury, intraocular lens displacement and, in the worst cases, permanent visual loss in what should be a routine, high-success procedure.

The failure is deceptively simple. A luer lock holds by friction on a tapered fitting. Yet during injection, the connection is routinely flooded with viscoelastic, a substance engineered to be slippery. That lubrication works against the very joint relied upon to stay together and blunts the tactile feedback by which a scrub practitioner judges a connection secure. We lubricate the joint with our initial anterior chamber fill and wait for it to do its work in loosening the connection before injecting again to fill the capsular bag. Under the pressure of injection or wound hydration, a junction that felt sound at assembly can loosen and let go, sending a fine cannula into the eye with the potential of significant visual loss.

The clinical consequences are severe: posterior capsule rupture, vitreous loss, retinal injury, intraocular lens displacement and, in the worst cases, permanent visual loss in what should be a routine, high-success procedure. Detachment is reported, most often during wound (stromal) hydration, but can occur at any step that demands sustained injection through a fine-gauge cannula.

What makes the problem so intractable is that its true scale is largely invisible. A peer-reviewed survey of anterior segment surgeons found that 84% had experienced cannula detachment and 78% had witnessed resulting patient harm, with 87% agreeing that a dedicated safety device was needed.² Published health-economic analysis has put the global burden in the order of US$204 million a year.³ Yet almost none of these events reach a regulator or a manufacturer.

The reason is structural. When a cannula detaches, neither the syringe nor the cannula has individually malfunctioned; the failure occurs at the interface between two separately compliant devices. No single manufacturer is notified, no adverse-event category captures it, and the event is typically logged as a surgical complication and attributed to assembly technique. The recorded cases, the JAMA authors note, exclude the unreported events and near misses that every theatre quietly accumulates, making published counts the visible tip of the iceberg.

The ‘Viewpoint’ adds weight to a growing international conversation. The complication has featured in the peer-reviewed literature for more than two decades; in the United Kingdom the Royal College of Ophthalmologists has issued a formal safety alert on it,⁴ and it has surfaced in adverse-event databases⁵ and in at least one regulatory recall of an ophthalmic cannula system.⁶ It is increasingly drawing the attention of professional bodies and patient-safety advocates, and the question now being put is no longer whether cannula detachment is a genuine, recurring hazard, but when the industry that supplies surgical consumables will act on it.

That question lands squarely in Australia and New Zealand. The Royal Australian and New Zealand College of Ophthalmologists (RANZCO) has set itself the goal of eliminating avoidable blindness, and few complications fit that description more precisely: foreseeable, documented, and arising from the equipment handed to surgeons rather than from any failure of skill. The pack providers and viscoelastic manufacturers supplying ANZ theatres are as well placed as any to design the risk out and, increasingly, will be expected to do so.

For now, the message from JAMA Ophthalmology is blunt. The flying cannula is not a training problem to be solved by asking surgeons to try harder. It is a design problem, and responsibility for fixing it rests with those who make and assemble the devices, not with the teams left to catch them when they fail.

Mr Amar Alwitry is a consultant ophthalmologist and anterior segment surgeon and a medicolegal expert holding a Masters in Medical Law. He is the author of Complaints, Litigation and Clinical Errors (CRC Press) and has published peer-reviewed survey and health-economic analyses of cannula detachment in the Journal of Cataract & Refractive Surgery and Eye. He declares a research and commercial interest in surgical safety device design.

References 

1. Woreta FA, Agrawal A, Schein OD. In pursuit of safer eye care—the case of the flying cannula. JAMA Ophthalmol. Published online 4 June 2026. doi: 10.1001/jamaophthalmol.2026.1805.
2. Alwitry A. Prevalence of cannula dislocation during cataract surgery: a survey. J Cataract Refract Surg. 2025;51(11):1034-1036. doi: 10.1097/j.jcrs.0000000000001724.
3. Alwitry A. Cannula detachment — a solution to a significant patient safety and health economic issue. Eye (Lond). Published online 24 March 2026. doi: 10.1038/s41433-026-04428-x.
4. The Royal College of Ophthalmologists. Ophthalmic safety alert — detachment of cannulas during ophthalmic surgery. April 2018. Available at: rcophth.ac.uk/news-views/ophthalmic-safety-alert-detachment-of-cannulas-during-ophthalmic-surgery [accessed June 2026].
5. US Food and Drug Administration. Manufacturer and User Facility Device Experience (MAUDE) database — cannula detachment adverse-event reports (report IDs 22529117, 9217957, 12316769, 12093077). Available at: accessdata.fda.gov [accessed June 2026].
6. US Food and Drug Administration. Class I device recall: Bausch & Lomb 27G disposable cannula packed in Amvisc and Amvisc Plus ophthalmic viscosurgical devices. Recall no. 114567, 2013. Available at: accessdata.fda.gov [accessed June 2026].