Related Experiment Video
Updated: Feb 7, 2026
12:37
Pharmacologic Induction of Epidermal Melanin and Protection Against Sunburn in a Humanized Mouse Model
Published on: September 7, 2013
18.8K
Epidermal Fluence Threshold Determination by Real-Time Melanin Measurements.
Amanda Abramson Lloyd1, Michael S Graves, Edward V Ross2
1*All authors are affiliated with the Scripps Clinic, La Jolla, California.
Summary
Determining epidermal tolerance with melanin measurements improves laser treatment settings for alexandrite (755 nm) and neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers. This enhances safety and efficacy for various skin conditions.
Area of Science:
- Dermatology
- Laser Physics
- Photomedicine
Background:
- Epidermal preservation is crucial for effective laser treatments of vascular lesions, hair removal, and pigmentary disorders.
- Epidermal tolerance to laser energy depends on melanin content, fluence, pulse width, wavelength, cooling, and spot size.
Purpose of the Study:
- To determine the maximum epidermal tolerance for long-pulse alexandrite (755 nm) and neodymium-doped yttrium aluminum garnet (Nd:YAG) (1064 nm) lasers across varying epidermal melanin levels.
Main Methods:
- Melanin index (MI) was measured using a melanin reader.
- Skin was pre-cooled with refrigerated air.
- Alexandrite and Nd:YAG laser spots (5-18 mm) were applied with varying pulse widths (5-50 ms) and ascending fluences.
- Skin reactions were assessed 24-96 hours post-treatment.
Main Results:
- For alexandrite lasers, threshold fluences increased with longer pulse widths (5-50 ms) in subjects with MI 9-25 (Fitzpatrick I-III).
- Nd:YAG laser epidermal tolerance required 6 times the fluence of the alexandrite laser for similar melanin indices (MI 26-35).
Conclusions:
- Quantitative epidermal melanin measurements enable objective determination of optimal laser treatment settings.
- This approach minimizes risks of overtreatment and undertreatment, improving patient outcomes.
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