Sir,

It is easy to become complacent when using such widely used medical instruments as needle and syringes. Needle and syringe systems have many uses in modern day ophthalmic surgical practice. There are two main types of system commonly used: push-fitting ‘slip-lock’ systems, where the needle hub is pushed onto the tip of the syringe and held by friction, and screw-fitting ‘luer-lock’ systems. Iatrogenic orbital needle stick injuries have been reported, especially with slip-lock systems where needles have become accidentally dislodged during procedures, some with sight threatening consequences.1, 2, 3 This case report describes a situation where a slip-lock cannula dislodged under high pressure during the stromal hydration step of what was otherwise a routine cataract procedure. It entered the eye at high velocity and resulted in iris perforation, zonule rupture, hyphaema, and vitreous haemorrhage. This case and others emphasise the need to change over to luer-lock systems for intraocular procedures.

Case report

A 57-year-old caucasian male underwent elective left eye phacoemulsification procedure under topical anaesthesia for a symptomatic posterior subcapsular cataract. Preoperative snellen acuities were 6/9 in the right eye and 6/60 in the left eye.

The operation was performed under topical anaesthesia via a superior 2.7 mm clear corneal incision. After an uncomplicated capsulorrhexis, phacoemulsification, and manual irrigation/aspiration, the corneal wound was then extended up to 2.9 mm for implantation of a 26 D Acrosoft intraocular lens (IOL). Insertion of the lens was without any problems and healon was then removed from the anterior chamber and capsular bag.

A 5 ml plastic syringe containing balanced salt solution attached to a slip-lock lacrimal cannula was prepared with the intention of hydrating and sealing the corneal wound. Tight fit of the cannula was confirmed before starting. With the end of the needle approximated inside the nasal aspect of the patients’ corneal section, pressure on the syringe driver was steadily increased to achieve stromal hydration. Everything was proceeding routinely, then suddenly and unexpectedly the needle flew off the syringe at high velocity before vanishing from sight. The patient was examined instantly. Small amounts of vitreous and blood had appeared in the anterior chamber and there was a small hole in the iris in the 3 o’clock position. The capsular bag and IOL seemed secure and no obvious initial retinal damage was seen with the indirect ophthalmoscope. The needle was found in the plastic side pocket of the sterile drape covering the patient and must have ricochet back out of the eye, perhaps after colliding with the plastic lens.

After a few minutes the bleeding ceased and the anterior chamber was washed out to clear the debris. The patient was kept for observation for a couple of hours following which slit lamp examination showed no significant problems. He was sent home to come back the next day for a further review.

The next day the patients’ vision was 6/60 in the pseudophakic left eye, and no improvement with pinhole. The anterior chamber was cloudy and there was a 2 mm hyphaema present, plus the small perforation in the iris at 3 o’clock. Intraocular pressure was 15 mmHg. The IOL appeared stable. The fundal view was hazy secondary to a large vitreous haemorrhage. A B-mode ultrasound scan was performed and the underlying retina appeared flat. The hyphaema was treated with bed rest and topical therapy and he was closely monitored over the next few weeks.

His vision steadily improved and as the media cleared there was no sign of retinal damage. At 5 weeks postoperative his vision was 6/9 with no adverse outcomes.

Comment

This is not the first time that slip-lock cannulae have been reported to be involved in ophthalmic surgical accidents after dislodging under pressure. Exactly the same scenario during stromal hydration has been described before.1 There has also been a report of a cannula flying loose inside the eye during injection of viscoelastic during cataract surgery, resulting in a retinal break.2 It is probable that there have been other cases which have been unreported.

From time to time, we are reminded of the potentially devastating consequences that can arise from a mechanical failure of instruments during surgery. Needle and syringe systems have multiple uses in ophthalmology and are possibly the most commonly used instruments in modern intraocular surgery. Corneal stromal hydration, involves significant force, and that the joint between the tip of the syringe and cannula should be able to withstand the pressures involved. Since this accident happened, we have changed all needle and syringe systems used in our department to the more secure luer-lock screw fitting type to reduce the risk of future accidents.