Infectious diseases may lead to ocular complications including uveitis, an ocular inflammatory condition with potentially sight-threatening sequelae, and conjunctivitis, inflammation of the conjunctiva. Emerging infectious pathogens with known ocular findings include Ebola virus, Zika virus, Avian influenza virus, Nipah virus, severe acute respiratory syndrome coronaviruses, and Dengue virus. Re-emerging pathogens with ocular findings include Toxoplasma gondii and Plasmodium species that lead to malaria. The concept of One Health involves a collaborative and interdisciplinary approach to achieve optimal health outcomes by combining human, animal, and environmental health factors. This approach examines the interconnected and often complex human-pathogen-intermediate host interactions in infectious diseases that may also result in ocular disease, including uveitis and conjunctivitis. Through a comprehensive review of the literature, we review the ophthalmic findings of emerging infectious diseases, pathogenesis, and One Health perspectives that provide further insight into the disease state. While eye care providers and vision researchers may often focus on key local aspects of disease process and management, additional perspective on host-pathogen-reservoir life cycles and transmission considerations, including environmental factors, may offer greater insight to improve outcomes for affected individuals and stakeholders.

Coronavirus disease 2019 (COVID-19) is associated with increased risk of microvascular complications; however, reports of ophthalmic manifestations associated with retinal vascular occlusion associated with COVID-19 are limited. In this report, we describe two middle-aged female patients who were admitted for acute hypoxic respiratory failure secondary to COVID-19-induced pneumonia. Following prolonged intensive care unit admission requiring mechanical ventilation and critical care interventions, both patients reported substantially reduced vision upon regaining consciousness. Dilated funduscopic exam showed multiple blot hemorrhages in all quadrants of the posterior pole, bilateral retinal hemorrhage, macular edema, and retinal vascular tortuosity. Both patients were diagnosed with retinal ischemic events owing to bilateral ophthalmic artery occlusion in the first patient, and bilateral central retinal vein occlusion (CRVO) in the second individual. While uncommon, retinal microvascular complications associated with COVID-19 leading to vision loss require prompt evaluation and referral given their potential long-term impact following acute illness.