A Clinical Evaluation of the Intersect ENT Sinus Device (ASCEND)

Inclusion Criteria: 1. Confirmed diagnosis of CRS per the 2016, "International Consensus Statement on Allergy and Rhinology" definition. 2. Bilateral disease in the frontal sinuses (Lund-Mackay score ≥ 1 on each side) on CT scan within 30 days prior to enrollment in the PK cohort and prior to randomization in the randomized cohort. 3. Patient has bilateral obstruction of the frontal recess/FSO due to scarring and/or polypoid edema confirmed on endoscopy (patency grade of 0 or 1 for each FSO). 4. Balloon dilation of the FSO judged to be feasible and medically appropriate. 5. Patient has had prior ESS (\> 30 days with a healed mucosa) including bilateral ethmoidectomy (anterior or total) and uncinectomy for better visualization of the FSO. 6. Balloon dilation of the FSO with a 6 mm balloon is judged to be feasible (use light-assisted or image-guided instrument such as a frontal sinus seeker tip to confirm access of each FSO) and medically appropriate. Exclusion Criteria: 1. Expanded amount of ethmoid polyposis (grade \> 2 PK cohort, grade ≥ 2 randomized cohort). 2. Complications from prior ESS or balloon dilation procedure (e.g., cerebrospinal fluid leak or injury to the skull base). 3. History of aspirin exacerbated respiratory disease (AERD). 4. Current smokers. 5. History of allergy or intolerance to mometasone furoate. 6. Oral-steroid dependent condition. 7. Evidence of acute rhinosinusitis, invasive fungal sinusitis or another disease or condition expected to compromise survival or ability to complete assessments during the 30-day follow-up period in the PK cohort and druing the 60-day follow-up period in the randomized cohort. 8. Use of parenteral and injected steroids (e.g., Kenalog) 30 days prior to the baseline procedure. 9. Use of oral steroids, budesonide or other sinus steroid irrigations/rinses or drops, nebulized steroids administered nasally 14 days prior to screening in the PK cohort and prior to baseline in the randomized cohort. 10. Glaucoma or posterior subcapsular cataract.