Electroretinographic evaluations of bleb-related endophthalmitis after vitrectomy with 0.025% povidone iodine irrigation

Abstract Background Vitrectomy with 0.025% povidone-iodine (0.025% PI) in the irrigation solution was recently reported to be used to treat filtering bleb-associated endophthalmitis. However, iodine is known to be retinotoxic but it depends on its concentration. Electroretinography (ERGs) can be used to evaluate the retinal function, but the contact lens electrodes used to pick up the ERGs can affect the filtering bleb adversely. We performed ERGs with skin electrodes on eyes with bleb-associated endophthalmitis that had undergone vitrectomy with 0.025% PI irrigation. Case presentation: Case 1 was a 46-year-old man who underwent trabeculectomy for steroid induced glaucoma. One month postoperatively, a filtering bleb-associated endophthalmitis was suspected, and vitreal and subconjunctival injections of vancomycin (VCM) and ceftazidime (CAZ), and frequent antibiotic eye drops were started. After three days, an exacerbation of the endophthalmitis was observed and vitrectomy with 0.025% PI irrigation was performed. One month after the surgery, the visual acuity improved from hand movements to counting fingers. Pre- and postoperative ERGs recorded using skin electrodes showed an improvement in the a- and b-wave amplitudes and the b/a ratio was stable at approximately 2.0. Case 2 was a 63-year-old man who had undergone phacovitrectomy for proliferative diabetic retinopathy eleven years earlier and trabeculectomy for glaucoma five years earlier in the left eye. Five years after the surgery, the eye developed blebitis, and frequent antibiotic eye drops and subconjunctival injections of VCM and CAZ were performed. Three days later, vitreous opacities appeared and a high brightness area was observed in the B-mode echo images. A diagnosis of bleb-associated endophthalmitis was made, and vitrectomy with 0.025% PI irrigation was performed. The preoperative visual acuity was hand movements, and it improved to 0.01 one month after the surgery. Comparisons of the postoperative to the preoperative ERGs found that the a- and b- wave amplitudes increased and the b/a ratio was stable at approximately 1.5 postoperatively. Conclusions ERG recordings with skin electrodes are helpful for evaluating postoperative retinal function in cases of bleb-associated endophthalmitis. Vitrectomy with 0.025% PI irrigation is effective and most likely safe for the treatment of bleb-associated endophthalmitis.