DefinePK

Abstract

Background: Chronic Dry Eye Syndrome (DES) was recognized as a multifactorial ocular surface disorder characterized by tear film instability, hyperosmolarity, and ocular surface inflammation, resulting in discomfort, fluctuating vision, and reduced quality of life. Conventional therapies, including lubricating eye drops, warm compresses, lid hygiene, and pharmacological agents, had provided symptomatic relief but often failed to address the underlying pathophysiological mechanisms. In recent years, non-invasive device-based interventions—particularly light-based modalities—had emerged as promising alternatives for Meibomian Gland Dysfunction (MGD)-related DES. Photobiomodulation and intense pulsed light (IPL) therapies had shown potential to restore meibomian gland function, reduce ocular surface inflammation, and enhance tear film stability. However, robust randomized controlled evidence had remained limited. This trial was designed to evaluate the clinical efficacy of a standardized periocular light therapy protocol under controlled conditions. Objective: The primary objective of this randomized controlled trial (RCT) was to determine the clinical effectiveness of periocular light therapy as a non-invasive treatment for chronic DES, with a focus on improvements in both patient-reported symptoms and objective tear film stability measures. Methods: A two-arm, parallel-group, double-masked, sham-controlled RCT was conducted at Ophthalmology Department of a tertiary care hospital of Peshawar , Pakistan.. A total of 120 adults meeting the TFOS DEWS II criteria for chronic DES were randomized (1:1) to receive either active periocular light therapy—administered via a clinically validated LED-based photobiomodulation device emitting predominantly at 633 nm—or a sham treatment delivered with an identical device producing sub-therapeutic illumination. Treatments were performed at baseline, weeks 1, 4, 8, and 12. All participants adhered to standardized lid hygiene and non-preserved artificial tear use. The primary endpoint was the change in Ocular Surface Disease Index (OSDI) score from baseline to week 12. Secondary endpoints included tear film break-up time (TBUT), corneal and conjunctival staining scores, meibomian gland expressibility and secretion quality, Schirmer’s test results, tear osmolarity, and patient global impression of change (PGIC). Adverse events and ocular/dermatological safety outcomes were recorded. Results: Data were analyzed on an intention-to-treat basis using a mixed-effects model for repeated measures. At week 12, the active treatment group demonstrated a mean OSDI reduction of −12.1 points (95% CI: −14.7 to −9.5) compared with −5.1 points (95% CI: −7.0 to −3.1) in the sham group, achieving both statistical significance and the threshold for clinical relevance. TBUT increased by 3.0 seconds (95% CI: 2.5 to 3.5) in the treatment group versus 1.0 second (95% CI: 0.6 to 1.4) in the sham group. Additional improvements were observed in meibomian gland scores, ocular surface staining, and tear osmolarity. Adverse events were minimal, transient, and non-serious, including mild eyelid warmth and erythema. Conclusion: This RCT provided high-quality, sham-controlled evidence supporting the efficacy and safety of periocular light therapy for chronic DES. The therapy significantly improved both symptoms and tear film stability and represents a viable non-invasive treatment option for patients with persistent symptoms despite conventional management.