To quantify and compare tear levels of Intense pulsed light (IPL) and traditional dry eye clinical tests in dry eye patients before and after Intense pulsed light (IPL) treatment.

Dry eye is multifactorial, mainly manifested as eye pain, visual impairment (blurred and blurry vision), tear film instability, and tear film hypertonicity, which can cause ocular surface damage. Some possible causes of DED include aging, menopause, Meibomian gland dysfunction (Meibomian gland dysfunction; MGD), Sjogren's syndrome, conjunctival fibrotic disease, refractive surgery, and systemic or topical drugs. Insufficient tear secretion or excessive tear evaporation has been demonstrated to cause precorneal tear concentration or hypertonicity, which disrupts tear film homeostasis. Tear film hypertonicity can cause cell morphological changes, inflammatory cascades, cell death, tear film instability, and further lead to tear hypertonicity. Mgd-induced Evaporative dry eye; EDE) is the most common form of dry eye]. Anti-inflammatory drugs, antibiotics, hot compress, eyelid cleaning and meibomian gland expression are the treatment standards for MGD. However, its long-term efficacy is not satisfactory due to poor patient compliance.

MGD has been found to be associated with eyelid inflammatory disorders. Rosacea affects 5.46% of adults (range 0.09-24.1%) of whom 58% have MGD. Ocular symptoms precede cutaneous rosacea in 15 to 10% of cases, indicating the presence of subclinical variation.

Intense pulsed light (IPL) has mostly been utilized as a dermatological treatment for conditions like facial rosacea, facial erythema, acne, and seborrheic keratosis throughout the last few decades. In 2015, researchers reported the use of IPL for treating MGD to improve the signs and symptoms of DED. Two years later, the TFOS DEWS II report listed IPL as an option for treating DED. Mechanisms of IPL action include liquefication of meibum, regulate inflammation, destroy abnormal blood vessels, inhibit metalloproteinases, and photo modulation. Past studies have reported that IPL treatment modulates tear inflammatory cytokines, with improvements in tear inflammation prior to changes in dry eye signs, however, these studies have been limited by laboratory tests. It is difficult to apply in clinical practice.

Lymphotoxin-alpha (LTA) is a member of the tumor necrosis factor (TNF) superfamily and is expressed by a variety of cells, including T cells, B cells and natural killer cells. LTA secreted to the extracellular space assembles into a homotrimer (LTα3) as a soluble protein, and binds to the tumor necrosis factor receptor to play a role. LTA has been shown to be a diagnostic biomarker for dry eye in past studies. The aim of this study is to investigate the therapeutic mechanism of IPL and provide evidence for the treatment of dry eye by using a point-of-care LTA detection reagent to quantitatively compare the tear LTA levels before and after IPL treatment with traditional dry eye clinical parameters.

Inclusion Criteria:

• age ≥ 18 years
• Fitzpatrick skin types I to IV
• capable and willing to comply with the treatment and follow-up obligations
• a determination of DED based on (a) the Ocular Surface Disease Index (OSDI) ≥13 score represents severe DED, (b) non-invasive tear film breakup time (NITBUT) of ≤5 sec, or conjunctivocorneal staining score (CS) ≥3 points according to the Japanese Dry Eye Consensus

Exclusion Criteria:

• Existing ocular trauma, infectious diseases, recent surgical history
• Skin defects, pigmentation, moles, scars in the treatment area, skin cancer
• Autoimmune diseases, skin allergies.
• Pregnancy or lactation
• Fitzpatrick skin type V or VI.

The study's findings will be shared regardless of the effect's direction. All possible beneficiaries of the research, including patients, carers, family, doctors, advisory boards, and medical boards, will receive trial data. Publications in high impact, open-access medical journals and talks at national and international medical conferences will serve this purpose.

The Steering Committee will write and submit the report for publication at the end of the study

Use in clinical studies