Immediate whitening has been the conventional endpoint for picosecond laser treatment of dermal melanocytosis, and it is also the reason post-inflammatory hyperpigmentation is so common in darker skin. This trial tested whether the endpoint could be abandoned without losing efficacy.
Thirty Asian patients with Fitzpatrick skin types III to V and acquired bilateral nevus of Ota-like macules underwent three sessions at six-month intervals in a prospective, randomised, evaluator-blinded, split-face design. One side received a larger spot size and lower fluence, chosen using a melanosome-disruption threshold fluence model to reach a non-whitening endpoint. The other side received a smaller spot and higher fluence to produce immediate whitening.
Clearance after three sessions was comparable and high on both sides, with Global Aesthetic Improvement Scale scores above 3.85 out of 4. But post-inflammatory hyperpigmentation occurred in 22.6% of whitening-endpoint sides versus 4.8% of non-whitening sides (p<0.05), and scabbing in 61.9% versus 9.5% (p<0.05). Sixty-eight per cent of patients preferred the non-whitening side.
This matters more in Indian practice than almost anywhere. Fitzpatrick types IV and V are the norm, post-inflammatory hyperpigmentation is the complication patients most fear and most often present with, and the whitening endpoint is taught as the standard of adequate treatment. A split-face trial showing equal clearance with a fifth of the hyperpigmentation and a sixth of the scabbing is a direct argument for changing technique.
The limitation the authors name is real: a single centre with limited inclusion across types III to V, so the effect in the darkest skin is less certain than the headline suggests.
- Use a larger spot size and lower fluence to reach a non-whitening endpoint in pigmented skin rather than treating to immediate whitening
- Expect equal clearance over three sessions, with post-inflammatory hyperpigmentation falling from about 23% to 5%
- Scabbing fell from 62% to 10%, which is what most patients actually notice in the days after treatment
- Explain the endpoint change to patients who expect whitening as a sign the treatment worked
- Note the single-centre design and limited numbers across skin types III to V; confirmation in darker skin is still needed
The statistics, in plain English
The split-face design is the strongest feature here: each patient is their own control, so differences in skin type, sun exposure, aftercare and healing tendency are eliminated by construction. That is why 30 patients can produce a convincing result where a parallel-group trial of the same size could not. The p values are reported only as below 0.05 without confidence intervals, so the precision of the difference is unknown — treat the direction and rough magnitude as established, and the exact percentages as approximate. Blinding was of the evaluator, not the patient, which matters for the satisfaction figure but not for the counts of hyperpigmentation and scabbing.
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