Patient presents with eye irritation, itching, erythema of the lids. High suspicion for blepharitis; what are other red-flag diagnoses? (Medscape AI)

https://www.medscape.com/ai-search?query=Patient%20presents%20with%20eye%20irritation%2C%20itching%2C%20erythema%20of%20the%20lids.%20High%20suspicion%20for%20blepharitis%3B%20what%20are%20other%20red-flag%20diagnoses%3F&ecd=mkm_ret_260127_mscpmrk_ophth_top-content_etid8058838&uac=148436CN&impID=8058838 Patients with eyelid margin erythema, irritation, and itching often have blepharitis, but several other potentially sight- or life-threatening conditions must be excluded promptly. Key distinguishing “red-flag” features include significant pain, visual changes, photophobia, corneal involvement, or systemic signs.