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D. B. Roth, G. Jonna, J. L. Prenner, A. Kheterpal, W. J. Feuer; Inferior Intravitreal Injection Site Associated With Higher Incidence of Endophthalmitis. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3566.
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Despite the low incidence of post-injection endophthalmitis after intravitreal injections, when this complication occurs, the outcome can have severe deleterious effects on visual outcome. Intravitreal injections are all performed at the par plana, however the quadrant of injection is variable. With regard to trabeculectomy filtering procedures, an inferior bleb carries a higher risk of post-operative endophthalmitis, possibly due to bacteria pooling in the inferior tear lake. We sought to determine whether inferior injections had a higher incidence of post-injection endophthalmitis than superior injections.
Consecutive eyes treated with intravitreal injections of pegaptanib, ranibizumab, bevacizumab, or triamcinolone were included. Site of injection, the method of anesthesia and number of injections per patient were tabulated.
10,834 injections in 1302 eyes of 1017 patients were identified. 33 eyes were injected directly superiorly, 8038 superotemporally, 700 supernasally, 1970 inferotemporally, 87 inferioronasally, and 6 eyes directly inferiorly. Any sign of inflammation during the post-injection period was documented. Sterile inflammation associated with triamcinolone injections were excluded. Five eyes developed presumed infectious endophthalmitis; two of which grew positive bacterial cultures from the vitreous samples. Four of the five (80%) eyes with endophthalmitis were injected inferiorly, even though 80.9% of the total study cohort were injected superiorly. The risk ratio associated with inferior location is 17.0 (95% confidence interval: 1.9 to >100) with a p-value = 0.011.
Endophthalmitis after intravitreal injection is rare, occurring in only 0.05% of injections overall and 0.01% of superior injections. Avoiding intravitreal injections in the inferior quadrants may further reduce the rate of endophthalmitis.
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