Physiology of Cutaneous Erythema
Facial redness is primarily driven by blood flow through the superficial cutaneous microvasculature. Capillary dilation in response to temperature, barrier impairment, or inflammatory cascades produces visible erythema, especially across the cheeks and nasal ala.
Skin Tone Adaptive Calibration
Erythema presents differently across skin phototypes. In very light skin (Fitzpatrick I–II), redness appears as vibrant pink; in deep skin (Fitzpatrick V–VI), increased melanin masks superficial erythema, shifting its visual appearance toward purplish or dark tones.
Dr Maher Vision AI v4.0 measures redness against each person's own skin, using a ratio of a* to lightness that shadows do not change, so the same rule applies fairly to every complexion. The skin-tone angle (ITA°) is recorded only to check fairness, never to score.
Frequently Asked Questions
Does facial redness always mean rosacea?
No. Transient redness can be triggered by exercise, spicy food, weather, or temporary barrier irritation. A medical examination is required to diagnose rosacea.