Dovepress Ranibizumab Bevacizumab Pegaptanip Triamcinolone Table 1 Intravitreal injections and drugs administered Table 3 Characteristics of patients with triamcinolone reaction Azithromycin (n = 4045) 2648 872 52 476 Ofloxacin (n = 4151) 2946 840 42 323 4045 injections in 972 eyes of 701 patients (4.16 injections per eye and 5.77 injections per patient). In the ofloxacin group, there were a total of 4151 injections in 944 eyes of 682 patients (4.39 injections per eye and 6.08 injections per patient). Endophthalmitis cases There were two cases (0.049%) of endophthalmitis (acute endophthalmitis and pseudoendophthalmitis) within a mean time of 4.37 ± 1.33 days after surgery in the azithro- mycin group and five cases (0.12%) within a mean time of 4.41 ± 1.29 days in the ofloxacin group. The characteristics of the seven cases are shown in Table 2. The risk (odds ratio) of presenting with endophthalmitis in the ofloxacin group compared with the azithromycin group was 2.37 (95% con- fidence interval [CI] 1.32–3.72, P , 0.001). When limiting the analysis to culture-positive cases (one case in the azithro- mycin group and three in the ofloxacin group), the estimated relative risk was 3.01 (95% CI 1.97–4.11, P , 0.001). Adverse reactions There were two cases of uveitis after triamcinolone injection in the azithromycin group (0.049%) and two cases (0.048%) in the ofloxacin group. No significant differences were observed in the statistical analysis (odds ratio 0.902, 95% CI 0.622–1.407, P = 0.407). No cases of raised intraocular pressure were recorded. The characteristics of the patients are shown in Table 3. Table 2 Characteristics of patients with endophthalmitis Gender Age Drug Culture Endophthalmitis injected treatment Azithromycin (n = 2) Male 77 Ranibizumab S. epidermidis Intravitreal antibiotics Female 80 Pegaptanip negative Intravitreal antibiotics Ofloxacin (n = 5) Male 76 Ranibizumab S. epidermidis Intravitreal antibiotics Male 72 Ranibizumab S. epidermidis Intravitreal antibiotics + 25-gauge vitrectomy Female 77 Ranibizumab S. aureus Intravitreal antibiotics Female 69 Ranibizumab negative Intravitreal antibiotics Male 76 Ranibizumab negative Intravitreal antibiotics Abbreviations: S. epidermidis, Staphylococcus epidermidis; S. aureus, Staphylococcus aureus. Clinical Ophthalmology 2012:6 Endophthalmitis prophylaxis in intravitreal injections Gender Age Azithromycin (n = 2) Male 78 Female 82 Ofloxacin (n = 2) Female 71 Female 74 Culture negative negative negative negative Ocular pathology Diabetic macular edema Diabetic macular edema Diabetic macular edema Diabetic macular edema Other complications included conjunctival hyperemia (12 cases with azithromycin [0.29%] and none with ofloxacin), punctate keratitis (two cases with azithromycin and none with ofloxacin), subconjunctival hemorrhage (eight cases with azithromycin and six with ofloxacin) and a decrease in acute visual acuity with relapse a few minutes after intravitreal injection (three cases in each group). Discussion With the considerable growth in the use of intravitreal injections in recent years, there has been an increasing interest in determining an effective strategy for endophthalmitis prophylaxis. The incidence of endophthalmitis, which is a poten- tially vision-threatening condition, is currently unclear because very few studies have been conducted. Most data are derived from extended clinical trials that attempted to administer drugs intravitreally, such as the RESTORE (Ranibizumab Monotherapy or Combined with Laser versus Laser Monotherapy for Diabetic Macular Edema) study, in which no endophthalmitis cases were observed after 2415 injections23 or the Diabetic Retinopathy Clinical Research Network24 study in which one patient (0.9%; 95% CI 0.02–4.7) developed endophthalmitis after receiving ranibizumab. According to the meta-analysis by Jager et al,18 the incidence of endophthalmitis after use of intravitreal medicines is 0.3% per injection and 0.9% per eye. The Vitravene Study Group25 described two cases of endophthal- mitis after 1791 injections (0.11%) in 330 eyes (0.60%). A larger study was performed by McCannel et al26 who conducted a meta-analysis of the US literature from 2005 to 2009 and observed a total of 52 cases of endophthal- mitis in 105,536 injections, with an incidence of 0.049% (95% CI 0.038–0.065). In this study, endophthalmitis cul- ture was negative in 24 cases (48.0% [95% CI 34.8–61.5]) and positive in 26 (52% [95% CI 38.5–65.2]). Of the 26 culture-positive isolates, the causative organisms were coagulase-negative Staphylococcus spp. in 17 cases (65.4% [95% CI 46.0–80.6]), Streptococcus spp. in eight cases submit your manuscript | www.dovepress.com Dovepress 1597