This randomized, controlled clinical trial investigates the perioperative use of low-level light therapy (LLLT) to prevent or reduce signs and symptoms of dry eye disease (DED) in patients undergoing cataract surgery. DED is a prevalent postoperative complication associated with ocular surface inflammation, meibomian gland dysfunction, and tear film instability, which can compromise visual outcomes and patient satisfaction.

The study enrolled adult patients scheduled for phacoemulsification, with baseline evidence of mild-to-moderate ocular surface disease. Participants were randomly assigned to receive either LLLT via a polychromatic light-emitting mask (Eye-light® ) or a sham device, administered one week before and one week after surgery. The LLLT protocol is designed to photobiomodulate eyelid and periocular tissues to enhance meibomian gland function and reduce subclinical inflammation.

Clinical assessments were conducted at baseline, one week, and six months postoperatively. The primary endpoint was the change in Ocular Surface Disease Index (OSDI) score at one and six months. Secondary endpoints included tear film stability (TBUT), Schirmer I test, corneal staining, tear osmolarity, and tear inflammatory and reparative biomarkers. The study also evaluated the safety and tolerability of the LLLT intervention.

This is the first prospective study assessing the role of perioperative LLLT in mitigating post-cataract ocular surface disease in consecutive patients. The findings may support the integration of LLLT in perioperative ocular surface management protocols.

This single-center, randomized, single-masked, parallel-group clinical trial was conducted to evaluate the efficacy and safety of low-level light therapy (LLLT) in the perioperative management of dry eye disease (DED) in patients undergoing cataract surgery. The study was carried out at the Department of Ophthalmology, University of Medicine and Pharmacy "Grigore T. Popa" (Iași, Romania) in accordance with the Declaration of Helsinki and ICH-GCP guidelines.

Dry eye disease is a multifactorial disorder characterized by tear film instability and ocular surface inflammation. Cataract surgery is known to transiently exacerbate or precipitate DED through mechanisms including disruption of corneal nerves, exposure to surgical light and irrigation, and postoperative medication use. This can impair visual rehabilitation and reduce patient satisfaction with surgical outcomes, particularly in individuals with pre-existing ocular surface dysfunction.

LLLT is a non-invasive photobiomodulation technique that delivers low-intensity, polychromatic red and near-infrared light to target mitochondrial cytochromes and promote cellular activity. Its application in ophthalmology has shown potential to improve meibomian gland function, enhance tear film stability, and downregulate inflammatory cytokines on the ocular surface. However, its perioperative utility in cataract surgery has not been formally evaluated.

Eligible participants included consecutive adults (≥18 years) scheduled for phacoemulsification. Key exclusion criteria were a prior diagnosis of ocular surface disease (OSD) or dry eye disease (DED), any history of ocular surgery in either eye, ocular comorbidities, and the current or regular use of topical or instrumental ocular treatments.

Participants were randomized into two groups: the intervention group received LLLT using the Eye-light® device (Espansione Group, Italy), and the control group received sham treatment with an identical, inactive device. Treatments were administered one week before and one week after surgery. The mask delivers light in the 600-1200 nm range through closed eyelids for 15 minutes per session, targeting the periocular region and meibomian glands.

Clinical assessments were performed at baseline (T0), one week postoperatively (T1), one month postoperatively (T2), and six months postoperatively (T3) and included:

• Ocular Surface Disease Index (OSDI)
• Non-invasive tear break-up time (NIBUT)
• Schirmer I test (SIT)
• Corneal fluorescein staining (Oxford grading)
• Tear Osmolarity
• Tear Inflammatory and reparative biomarkers

The primary outcome was the change in OSDI score from baseline to 6 months postoperatively. Secondary outcomes included all objective ocular surface parameters. Safety was evaluated by monitoring treatment-emergent adverse events and assessing patient tolerability of the device.

All surgeries were performed by the same experienced surgeon using standard microincisional phacoemulsification technique. Only eyes without significant intraoperative or postoperative complications were included in the final analysis.

Postoperative therapy was identical for all patients and included a combination of topical dexamethasone and netilmicin for 1 week, followed by tapering dexamethasone alone over 2 additional weeks; topical ketorolac tapered over 3 weeks; and preservative-free artificial tears (cross-linked hyaluronic acid, trehalose, sterilamine in liposomes) administered three times daily for 6 months.

Statistical analysis was performed using SPSS (version 30.0.0.0, SPSS Inc., Chicago, IL, USA).. The normality of data was evaluated using the Shapiro-Wilk test. For normally distributed variables, repeated measures ANOVA followed by Dunnett's post-hoc tests were used. For non-normally distributed data, the Friedman test with Dunn's correction was applied. A p-value < 0.05 was considered statistically significant.

This is the first prospective study to investigate LLLT in the perioperative setting of cataract surgery within consecutive patients. The findings aim to provide evidence for integrating non-pharmacological interventions in ocular surface optimization before and after cataract surgery.

Inclusion Criteria:

• Consecutive adult patients (aged ≥18 years).
• Scheduled for routine phacoemulsification cataract surgery.
• Provided written informed consent and agreed to attend all follow-up visits.

Exclusion Criteria:

• Prior diagnosis of ocular surface disease (OSD) or dry eye disease (DED).
• History of ocular surgery in either eye.
• Presence of ocular comorbidities (e.g., glaucoma, uveitis, corneal dystrophies).
• Current or regular use of topical ocular treatments such as lubricants, corticosteroids, or cyclosporine.
• Ongoing or recent instrumental therapies or oral supplements for OSD or DED.
• Use of systemic medications known to be associated with DED (e.g., diuretics, antidepressants, antihistamines, hormone replacement therapy).
• History of autoimmune diseases (e.g., Sjögren's syndrome).
• Regular contact lens wear.
• Any intraoperative or postoperative complications that could interfere with ocular surface evaluation.

De-identified individual participant data (IPD) will be shared, including demographic information (age, sex), baseline and follow-up ocular surface parameters (e.g., OSDI scores, tear break-up time, Schirmer I test, corneal staining, tear osmolarity), and treatment adherence data. No personally identifiable information will be disclosed. Data will be made available only upon reasonable request and for research purposes approved by an ethics committee or institutional review board.