Clinical Trials in Cataract
Endophthalmitis Vitrectomy Study (EVS)
Arch Ophthalmol 1995;113:1479 | Curr Opin Ophthalmol 1996;7:84 | Arch Ophthalmol 2001;119:650.
The goal was to determine the role of immediate pars plana vitrectomy in managing post-operative endophthalmitis and the role of intravenous antibiotics.
Pars plana vitrectomy provided additional theoretical advantages, including removal/dilution of the infecting organism and toxins, removing opaque vitreous and membranes but potentially inducing retinal detachment. Intravenous antibiotics had been prescribed without evidence.
Participants were randomised to a 2x2 treatment matrix based on vitrectomy vs. vitreous TAP, and intravenous antibiotics (ceftazidime and amikacin) vs. no intravenous antibiotics. All patients received 1) intravitreal vancomycin and amikacin; 2) subconjunctival vancomycin, ceftazidime and dexamethasone; 3) topical amikacin, vancomycin, cycloplegic agent and prednisolone acetate. Patients were permitted reinjection of intravitreal antibiotics at 36-60 hours.
Inclusion criteria were 1) clinical symptoms and signs of bacterial endophthalmitis within six weeks of cataract surgery or secondary intraocular lens insertion 2) VA)between 20/50 and light perception 3) Anterior segment view clear enough to permit pars plana vitrectomy, but enough media opacity to prevent visualisation of second-order retinal arterioles.
Main outcome measures
Primary endpoint: VA. Secondary endpoint: Clarity of ocular media. Follow-up: At three and nine months.
420 patients were randomized. 86% presented with VA worse than 5/200, 26% had perception of light (PL). There was no difference in VA outcome between vitrectomy vs. vitreous tap in those with VA better than PL at presentation. However, in the subgroup of patients with initial PL vision, VIT produced a threefold increase in the frequency of achieving 20/40 or better VA (33% vs. 11%), approximately a twofold chance of achieving 20/100 or better VA(56% vs. 30%), and a 50% decrease in the frequency of severe VA loss (20% vs. 47%) over TAP.
There was a higher rate of phthisis and enucleation in the TAP group (23% vs. 7%) in those presenting with PL vision.
Diabetic patients (n = 58) had a worse vision at presentation and did better with vitrectomy, regardless of VA (57% achieved 20/40 compared with 40% in the vitreous tap group. This was not statistically significant.
The vitrectomy group had a significantly clearer media at 3 months but the same at 9 months.
There was no difference in VA or media clarity with or without systemic antibiotics.
At the time of the study, cataract surgery was routinely performed by extracapsular and vitrectomy was primitive with big calibre, making the relevance to modern-day uncertain.
Nowadays is common to inject intra-cameral cefuroxime at the end of cataract surgery.
The use of steroids is controversial, though most studies commenting on this refer to intravitreal steroids, whereas this study involved subconjunctival injection.
Intravenous antibiotics do not affect the outcome of post-operative endophthalmitis. Pars plana vitrectomy improve results in patients presenting with VA of light perception or in diabetics with any VA.
Pearls for clinical practice
Vitrectomy in endophthalmitis can improve results.