Not All that Clouds Is Infection: Intravitreal Precipitation after Sequential Antibiotic Injection

Crystalline opacities appearing after intravitreal antibiotic injections can closely mimic worsening endophthalmitis, potentially prompting unnecessary surgical or pharmacologic interventions. This underrecognized phenomenon, most commonly seen after sequential intravitreal administration of vancomycin and ceftazidime, results from physicochemical incompatibility leading to intraocular precipitation. Despite their alarming appearance, these crystalline deposits are benign, self-limited, and retain antimicrobial activity. Review of the few published human cases reveals favorable outcomes with conservative management once infection is excluded. Recognizing this entity is crucial to avoid misdiagnosis, overtreatment, and medicolegal implications. Awareness of preventive measures-such as using separate syringes, staggered injections, and warmed solutions-can further minimize risk. Ultimately, differentiating true infectious progression from sterile drug precipitation preserves both vision and clinical judgment.