How to avoid explosive silicone oil injector separation

February 18, 2016

Article

Ensuring correct alignment between the syringe and the cap during silicone oil injection can prevent complications during vitrectomy, said Jay M. Stewart, MD, (San Francisco) presenting during the Retina Subspecialty Day of the 2015 American Academy of Ophthalmology meeting.

LAS VEGAS – Ensuring correct alignment between the syringe and the cap during silicone oil injection can prevent complications during vitrectomy, said Jay M. Stewart, MD, (San Francisco) presenting during the Retina Subspecialty Day of the 2015 American Academy of Ophthalmology meeting.

Case details

A 54-year-old female presented with severe proliferative diabetic retinopathy and current retinal detachment after recent vitrectomy. A 20-gauge pars plana vitrectomy was performed.

After removing the gas, there was a large hole in the center macula and further vitreoretinopathy. It was decided to perform an inferior retinectomy in order to flatten the retina.

The retina was flattened under air and under laser was applied. Silicone oil was chosen for the tamponade and the injection was initiated according to the clinic’s usual method.

“The silicone oil injection was proceeding uneventfully and the fill was almost complete. During the last part of the silicone oil injection, there was a very loud popping noise and the silicone oil tubing and cap separated from the syringe forcefully,” Dr. Stewart said.

“Not only was there a sudden drawing motion of the syringe and cannula while it was in the eye, but the tubing and cap flew across the room narrowly missing me and the staff.”

At this point, it became obvious the sclerotomy had traumatically enlarged. In addition, blood could be seen coming into the pupil and entering the anterior chamber.

“The patient was in distress due to both pain and shock from the loud noise. The surgeons and staff were also unnerved,” Dr. Stewart said.

On post-op day one, the patient had no pain and her vision had no light perception. The view of the fundus was obscured by blood in the pupil.

At post-op month two, the patient reported improvement in vision from pre-op and the retina was attached under oil. There is no residual hemorrhage in the eye.

Typically, pressure in the eye is measured in millimeters of mercury, but silicone oil is measured in psi. 50 psi (a typical pressure when injecting silicone oil) equates to 800-1,000 mm Hg, the panelists said.

Thoughts on the complication

In cases of acute trauma-and this appeared to involve a corneal rupture-controlling the intraocular pressure is a key aspect of successful management, said Raymond Iezzi, MD, who was one of the panelists.

Once the blood started entering the anterior chamber, Dr. Iezzi would have closed the sclerotomy and re-evalutated the options, including potentially using endoillumincaiton with wide-angle viewing.

“We decided to recreate the scenario in the laboratory to access risk factors for this occurrence. It is critical that the syringe be aligned with the BFC cap. The wings of the syringe must be entirely covered by the cap. If the syringe is partially rotated, even a normal hand movement during the injection could result in a complete disaster. We believe that this is what occurred in this instance,” Dr. Stewart said.

During the surgery, Dr. Stewart had used 5,000 cs silicone oil, but the complication has not changed his preference to 1,000 cs, he said.

“The issue here was the misalignment and I think the hand movement during the injection procedure ended up dislocating those two portions of the equipment and that's what led the separation to occur,” he said. “I think that because of the emulsification that we see with 1,000 cs, we tend to prefer 5,000 cs.”

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Dr. Stewart and the panelists agreed surgeons should double-check the syringe to ensure proper alignment and this complication was an oversight. For example, if air bubbles are in the syringe, that can also result in the propulsion-type of explosion that occurred in this case.

Post-op day one NLP was a concern, but Dr. Stewart’s staff “took a leap of faith” that since there had been a full silicone oil fill before the explosion, “everything would be okay in the back of the eye.”

Unable to view fundus

He was, therefore, not completely surprised with being unable to view the fundus due to the blood in the pupil obscuring the view.

“It was like those cases where you have a choroidal hemorrhage and there’s a ton of blood; the patient is initially NLP but eventually resolves,” he said.

In Europe, a common technique is a direct exchange of silicone oil, but a component of that procedure is to ensure the suction is in the perfluoron and not the silicone oil, the panelists said.

Ensuring a full oil fill does not necessarily have to be complicated, said Cynthia A. Toth, MD, who was another panelist.

“If it's a giant tear and I'm doing a chlorofluorocarbon to oil exchange, observing the optic nerve is a simple procedure to get a good fill. If there’s an air fill dye and running oil in, watch for that bubble to come up and across the pupil,” she said.

“Tilting upward and letting the air bubble come out. It doesn't bother me to have a small air bubble at the end as long as there’s stable pressure. Under-fill hasn't been an issue.”

Overall, if there is a gas fill (even if it is an under-fill) it is possible to still get a tamponade, the panelists said. With silicone oil, even at levels as low as 80%, there can be a “spit of oil” inside the eye relegating it to a zero tamponade.

Dr. Stewart had no financial interests to declare. He may be reached at (415) 353–2800.