Minimal erythema response (MED) to solar simulated irradiation in normal Indian skin

Phototesting is an essential tool in the investigation of photodermatoses.

The main aim was to study the cutaneous response to UVR in terms of minimal erythema dose (MED) to both UVA and UVB in normal Indian subjects with a solar simulator and to study the relationship of skin type to MED.

One hundred healthy volunteers not on any medication and without any history of photodermatoses were phototested using a solar simulator with whole spectrum irradiation (UVA, UVB and visible light) and only visible and UVA radiation. The tested areas were marked with gentian violet and readings were taken after 24 hrs.

Of the 100 volunteers, 48% were males and 52% were females, with a mean age of 36.6 +/- 11.6 yrs. The most common skin type among Indians was type 5 (46%) followed by type 4 (41%). The mean MED for UVB was 61.5 +/- 17.25 J/cm2. The MED for UVA could not be determined as none of the patients showed any erythema after irradiation for 45 minutes.

As the MED is found to be low in idiopathic acquired photodermatoses, the MED in the normal population could serve as a baseline data in the investigation.