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The science of cannual detachment
and why the eyes are in the firing line

CE Certified EU MDR Compliant FDA Class 1 Exempt Patent WO2025/163287A1
A Luer-lock connection is trusted across the whole of medicine. So why does it fail, repeatedly, in the operating theatre of the eye? The answer lies not in the surgeon's hands, but in the physics of the connection itself.
Based on a peer-reviewed mechanical analysis - Amar Alwitry · FRCS FRCOphth MMedLaw
THE PUZZLE

A connection that works everywhere - except the eyes

When a cannula detaches during intraocular surgery, the assumption is almost always the same: someone failed to tighten it. The event is logged as a surgical complication, and the surgeon carries the consequences. Yet the very same Luer-lock fitting is used safely millions of times a day, for intravenous and spinal injections across medicine. Spontaneous disconnection under load is rare - almost unheard of - outside ophthalmology.

The contradiction is the starting point. If the connection is sound enough for the rest of the body, the explanation for its failure in the eye cannot simply be carelessness. It must be something about the conditions of eye surgery itself. A first-principle analysis of the forces at the connection reveals three mechanisms - each unremarkable on its own - that combined only in intracocular surgery to turn a reliable fitting into a hazard.

The cannula detaches not because the surgeon failed, but because the eye the one place where the connection is asked to do the impossible

Download The Science of Cannual Detachment PDF