Comparative efficacy of 577-nm high-power, optically-pumped semiconductor lasers (HOPSL) and 532-nm Q-switched lasers in freckle treatment
Objectives: To compare pigment reduction, treatment sessions required, and patient satisfaction between 532‑nm Q‑switched and 577‑nm high‑power optically pumped semiconductor (HOPSL) lasers in Fitzpatrick skin types II–III with freckles. Additional aims included assessing transient hyper/hypopigmentation rates and determining how both modalities align with clinical needs when treating patients with possible concurrent vascular concerns.
Introduction: Freckles (ephelides) often affect individuals with lighter skin. The 532‑nm Q‑switched laser is commonly used due to rapid melanin targeting, but higher rates of transient hyperpigmentation may occur. Meanwhile, 577‑nm HOPSL has been proposed to offer specific hemoglobin absorption and less thermal spread, potentially benefiting patients who also present with rosacea or telangiectasias. Direct comparative data, however, remain limited.
Materials / method: Twenty‑four patients (skin types II–III) with multiple freckles underwent both treatments. Each laser session was performed biweekly, up to four total sessions, or until ≥80% pigment reduction was achieved. The 532‑nm Q‑switched group received 1–1.4 J/cm² (6–8 ns pulse), and the 577‑nm HOPSL group 12–14 J/cm² (16–18 ms pulse, 1mm spot size). Mexameter, VisioFace, Visioscope, and dermoscopy evaluated pigment intensity before and one month after the fourth session.
Results: At one month post‑fourth session, <4% of freckles in the 532‑nm group showed <50% pigment reduction; on average, 2.7 sessions yielded >80% reduction in 85% of freckles. In contrast, 32% of 577‑nm–treated freckles had <50% pigment reduction at the same time point; with an average of 3.7 sessions, 44% exceeded 80% reduction. Patient “very satisfied” rates were 85% (532 nm) vs. 75% (577 nm). Transient hyperpigmentation occurred in 20% of 532‑treated lesions (4% persisted to month three); one 577‑treated freckle showed residual hypopigmentation.
Conclusion: Though the 532‑nm Q‑switched laser produced faster and somewhat more robust freckle clearance, the 577‑nm HOPSL also yielded satisfactory results with fewer long‑term pigment shifts. These findings support both wavelengths as valid therapies. Clinicians might opt for 577 nm particularly when coexisting vascular issues (e.g. rosacea, telangiectasias) are present, balancing overall safety and efficacy considerations.
