Efficacy of 0.5% Topical Timolol Eye Drops in the Treatment of Post-Inflammatory Erythema Following Acne Vulgaris

Inclusion Criteria: Participants must meet all of the following criteria: * Age ≥ 12 years with a history of acne vulgaris. * Clinically diagnosed with post-inflammatory erythema (PIE) secondary to acne vulgaris. * Willing and able to provide informed consent (or assent with parental/guardian consent if under 18 years of age). Exclusion Criteria: * Refusal to participate or inability to comply with study procedures (examinations, treatment, follow-up visits), or loss to follow-up. * Presence of post-inflammatory hyperpigmentation (PIH) at the study site that may interfere with accurate assessment of erythema. * Presence of other dermatologic conditions affecting the treatment area (e.g., atopic dermatitis, rosacea, lupus erythematosus). * Known hypersensitivity or adverse reaction to timolol or other beta-adrenergic receptor blockers. * Pregnant or breastfeeding women. * History of cardiovascular or respiratory conditions contraindicating beta-blocker use (e.g., asthma, atrioventricular block, bradycardia \<50 beats per minute, hypotension). * Use of other topical medications or cosmetic products (except sunscreen) on the study area during the study period.