Without timely, appropriate treatment, patients with endophthalmitis experience irreversible retinal damage resulting in vision loss. This vision loss occurs within hours to days once pathogens infect the intraocular space, and despite advances in pathogen identification such as polymerase chain reaction and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, bacterial endophthalmitis still remains a major threat to vision. A recent study aimed to identify predictive factors for visual prognosis of Japanese patients with postoperative bacterial endophthalmitis and found that eye pain, bacterial identification and poor baseline VA were risk factors.

The retrospective study included 314 Japanese patients. Of these patients, 278 (88.5%) developed infection unilaterally (84.2% exogenous endophthalmitis and 15.8% endogenous endophthalmitis) and 242 eyes (69.1%) developed exogenous endophthalmitis. In 117 eyes (37.7%), bacteria were identified, and 276 eyes (79.1%) underwent primary vitrectomy. Three months after vitrectomy, BCVA improved significantly.

The researchers compared the characteristics of patients with exogenous and endogenous endophthalmitis. There was a significant difference in age between the two groups: patients with exogenous endophthalmitis were older than endogenous endophthalmitis patients. Additionally, significantly more exogenous endolphthalmitis patients presented with severe clinical symptoms, such as eye pain and ciliary injection, and they had significantly worse initial BCVA than endogenous endophthalmitis patients. Between the two groups, however, final BCVA didn’t differ significantly.

“We classified the pathogens into eight types,” the researchers wrote in their paper. These included coagulase-negative staphylococci (CoNS), Staphylococcus aureus, Genus Steptococcus, Steptococcus pneumoniae, Enterobacteriaceae, Enterococcus, other bacteria and fungus. The researchers noted that age, sex and presence of eye symptoms (eye pain and ciliary injection) didn’t show any significant difference among the eight types of bacteria, but CoNS, Streptococcus pneumoniae, Enterococcus, and other bacteria were detected at significantly higher rates among exogenous endolphthalmitis patients than those with endogenous endolphthalmitis. Patients with fungal-related endophthalmitis had the best baseline BCVA and patients with Genus Streptococcus, Streptococcus pneumonia or Enterococcus had the worst final BCVA.

“Vitrectomy was performed in older patients, and in eyes with exogenous endophthalmitis, shorter duration from onset, eye pain, ciliary injection, bacterial identification and poor initial BCVA, which is consistent with the consensuses of retinal surgeons in J-CREST,” the researchers wrote. “Eyes that needed only antibiotic eye drops and/or intravitreal antibiotics and/or systemic antibiotics had a very good chance of achieving good final vision.”

Their findings suggest severe baseline condition is a risk factor for subsequent visual impairment. “This isn’t very surprising, as the same findings appear in the literature,” they wrote. Ocular pain, bacterial identification and poor BCVA were associated with final visual impairment in this study, as in others before it. The researchers determined that the most important risk factor for visual impairment at 12 weeks was poor initial BCVA.

“If initial BCVA was under 1.7logMAR (Snellen ≥6/300), the final BCVA was likely to stay below 1.0logMAR (Snellen 6/60 or better),” they wrote. “This cut-off value is suggested to be a good parameter for informed consent and for prognosis of final BCVA in patients with endophthalmitis.” Other reported risk factors include: younger age (younger than 85), female sex, presence of an intraocular foreign body, greater number of intravitreal injections, type of injury, retinal detachment and proliferative vitreoretinopathy.

Ishikawa H, Uchida K, Takesue Y, et al. Clinical characteristics and outcomes in 314 Japanese patients with bacterial endphthalmitis: A multicenter cohort study from J-CREST. Pathogens. March 24, 2021.[Epub ahead of print].