LYR-220 for Adult Subjects With Chronic Rhinosinusitis (BEACON Study)

Inclusion Criteria: * Diagnosis of chronic rhinosinusitis. * Has had a prior bilateral total ethmoidectomy. * Has computed tomography (CT) ethmoid cavity opacification. * Has a Sinonasal Outcome Test (SNOT-22) ≥ 20 at Screening Visit. * Minimum cardinal symptom score. * Has been informed of the nature of the study and has provided written informed consent as approved by the Institutional Review Board (IRB)/Ethics Committee (EC) of the respective clinical site or regulatory authority if applicable by national law. * Agrees to comply with all study requirements. Exclusion Criteria: * Pregnant or breast feeding. * Known history of hypersensitivity or intolerance to corticosteroids. * History or clinical evidence or suspicion of invasive fungal sinusitis, allergic fungal rhinosinusitis, or atrophic rhinitis. * Known history of hypothalamic pituitary adrenal axial dysfunction. * Had dental procedure/implant on maxillary dentition within 4 weeks of the Screening visit. * Past or present functional vision in only one eye. * Past, present, or planned organ transplant or chemotherapy with immunosuppression. * With prior cataract surgery or presence (in either eye) of posterior subcapsular cataract of grade 2 or higher, nuclear cataract of grade 3 or higher, or cortical cataract of grade 2 or higher or involving a minimum of center optic zone of 3 mm diameter. * Ethmoidectomy that was unilateral or partial. * Currently participating in an investigational drug or device study.