Is the risk of endophthalmitis too high in sutureless transconjunctival vitrectomy?

Yes, even now there is not enough evidence to prove the opposite.

Bill Aylward

In 2005 I reported the first case of endophthalmitis following 25-gauge vitrectomy. Since then, several authors with large series have suggested that the risk is up to 11 or 12 times higher than that of 20-gauge.

Even with this increased rate, endophthalmitis remains a rare complication, but to me it is still too high a price to pay for the fairly minimum advantages of 25-gauge.

A lot of the advantages of 25-gauge that are usually promoted are more for the surgeon than for the patient. The only advantage so far proven for the patient is increased comfort, but the absolute degree of discomfort with 20-gauge is very small. The difference may be statistically significant, but it is not clinically significant.

There are at least three theoretical reasons for the increased rate of endophthalmitis in 25-gauge vitrectomy: You are leaving the wound open, the flow of fluid is much less and more vitreous is left in the eye. The other side of the debate will say the studies that sounded the alarm on endophthalmitis are fairly old, that now techniques have changed and endophthalmitis risk is less. If problems remain, they will say they can be fixed. They might be right, but it is the onus of the proponent to prove that now the technique is safe.

There is an interesting contrast between surgical techniques and drugs. Before you introduce a new drug you need massive trials. But complete changes in surgery, such as in vitrectomy, are often introduced without proving safety.

It looks as if 23-gauge may not have the same increased risk. However, it is still too soon to provide convincing evidence of this. If it is proven to be as safe as 20-gauge, then it will be reasonable to adopt it, but I believe that 25-gauge will eventually fade out.

Twenty-gauge vitrectomy is a well-established, very safe technique that has been around essentially unchanged for almost 40 years. Personally, I don’t believe I should change this approach before the safety of the new approaches is proven.

• Bill Aylward, MD, is a consultant vitreoretinal surgeon and medical director at Moorfields Eye Hospital in London.

Not if recommendations for wound construction and prophylaxis are followed.

Russell Phillips

When we started performing 25-gauge vitrectomy, we did not use subconjunctival antibiotics but topical treatment at the end of the procedure instead. In this early series of 150 patients, we had two cases of endophthalmitis. A 1.3% rate was much higher than we had expected. Since then, we have been using subconjunctival antibiotic prophylaxis with cephalosporin, and not a single case of endophthalmitis occurred in more than 1,000 patients.

Early experiences with mini-incision, transconjunctival sutureless vitrectomy were undeniably related to a higher rate of endophthalmitis compared with the conventional 20-gauge pars plana approach. There are studies reporting an unacceptable 12 times higher risk. Subsequently, a lot of work has been done to investigate the possible causes. Sutureless wounds were found to lead in quite a few cases to leakage, hypotony and vitreous incarceration, creating the conditions for bacterial access and contamination.

A different wound construction, with oblique rather than straight-through entry, is now largely adopted and has proved to produce better self-sealing wounds. The occurrence of hypotony, vitreous incarceration and endophthalmitis has been drastically reduced.

Now I routinely perform, both in 25- and 23-gauge surgery, a two-step 10° to 30° oblique-angled sclerotomy, using the trocar and cannula of the Bausch + Lomb Millennium system. The prophylactic regimen I use is subconjunctival cephalosporin, a small bleb around each of the three ports. If I perform combined cataract and vitrectomy procedures, I do the standard intracameral cephalosporin prophylaxis that I would use for phacoemulsification. I use the smaller gauge in all surgical procedures, with only a few exceptions.

If recommendations for wound construction and prophylaxis are followed, there is no reason why, in the hands of experienced surgeons, mini-gauge transconjunctival vitrectomy should not be at least as safe as conventional 20-gauge.

• Russell Phillips, MD, is a vitreoretinal surgeon at South Australia Institute of Ophthalmology in Adelaide.