A 27-gauge cannula can be inadvertently ejected from a pressurized syringe during cataract surgery when excessive force is applied to the plunger or when the cannula–hub connection is not fully secured. Small cannulas create significant resistance to fluid flow, so even a brief, forceful push can generate enough back-pressure to dislodge the tip. If this occurs inside the anterior chamber, the cannula may shoot forward unexpectedly, striking intraocular structures before the surgeon can react. The iris is particularly vulnerable: a sudden impact can create focal tears in the stroma, avulse vessels at the pupillary margin, or even shear off peripheral iris tissue. Because the iris is highly vascular, even a small mechanical insult can produce immediate hyphema. The resulting blood can obscure visualization, complicate capsulorhexis creation or phacoemulsification, and increase postoperative inflammation. Preventive steps include always checking the luer connection, using controlled injection force, and employing larger-bore cannulas when appropriate. Has this ever happened to you?
