Refractory post-cataract endophthalmitis: silicone oil cut recurrence in a small trial

Design

Prospective randomised controlled trial

Population

40 eyes with post-phaco endophthalmitis unresponsive to intravitreal antibiotics

Primary outcome

Change in best-corrected visual acuity (logMAR) at 12 weeks

Effect

Final logMAR 1.5 vs 1.7 (P = 0.289); recurrence 10% vs 40% (P = 0.021)

A randomised trial included 40 eyes with endophthalmitis after phacoemulsification that had not responded to initial intravitreal antibiotics. Eyes had pars plana vitrectomy alone or vitrectomy with 1000-centistoke silicone oil tamponade. The primary outcome was change in best-corrected visual acuity at 12 weeks.

Final vision was slightly better with silicone oil (logMAR 1.5 vs 1.7), but the difference was not statistically significant. Recurrent infection was less frequent with oil: 2 of 20 eyes (10%) against 8 of 20 (40%). Intraocular IL-6 and IL-8 at 8 weeks were roughly halved in the oil group, and recurrence and IL-6 levels both predicted worse vision.

The primary outcome was negative and the trial is small, so this is not enough to make oil routine. But a fourfold difference in recurrence in the sickest eyes is clinically meaningful, and the authors' interpretation — that oil may help in complex cases — is reasonable to weigh, against the cost of a second operation to remove it.

• Consider silicone oil tamponade at vitrectomy for severe post-cataract endophthalmitis that has failed intravitreal antibiotics.
• Discuss the need for a second procedure to remove the oil when choosing tamponade.
• Watch closely for recurrence after vitrectomy alone; it occurred in 40% of eyes in this trial.
• Do not expect a large visual gain from oil alone; the primary outcome did not differ.

Why it matters

Recurrent infection after vitrectomy is a common cause of a lost eye in severe endophthalmitis.

Don't overread it

The primary visual outcome was not significant — recurrence was a secondary outcome in 40 eyes.

The statistics, in plain English

The visual difference (P = 0.29) could easily be chance. The recurrence difference (10% vs 40%, P = 0.02) is less likely to be chance, but with 20 eyes per arm a few events either way would shift it considerably.

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