Picosecond Settings by Pigment Depth: Epidermal vs Dermal Targets
Pigment treatment fails most often from depth mismatch — treating a dermal lesion with epidermal settings wastes sessions, and the reverse causes PIH. Read depth first, then set fluence and spot size to match.
Depth Reading at Consultation
- Epidermal (freckles, lentigines): sharp borders, enhance with woods lamp, sit in the top layers
- Dermal (nevus of Ota-type flat patches, some drug pigmentation): diffuse borders, blue-gray cast, deeper placement
- Mixed (melasma and post-inflammatory pigment): layered — treat conservatively, expect staged progress
Setting Logic
| Depth | Spot size | Fluence approach | Endpoint |
|---|---|---|---|
| Epidermal | 2-4 mm | Moderate, single pass | Light frosting on the spot |
| Dermal | 2-3 mm | Lower per pass, multiple sessions | Minimal or no visible change |
| Mixed/melasma | Large spot (6-8 mm) | Very low, \”toning\” passes | No visible endpoint — by design |
The Depth Rule That Prevents PIH
The deeper the target, the less visible change you should accept per session — chasing visible endpoints on dermal pigment is how rebound pigment happens. Multi-wavelength picosecond platforms let you match wavelength to depth as well as color; pair this guide with the melasma conservative protocol for the mixed category.