Applications

Patch Testing

Skin irritants (such as detergents, personal care product allergens and fuels) can penetrate the skin and cause damage, local inflammation and irritation. Resultant damage of the skin can be described depending upon the type of damage: structural, chemical or biological. One such change in the skin which is apparent during irritation is sub-epidermal blood flow, changes which are frequently assessed using laser Doppler monitors (De Boer and Bruynzeel 1996; Saary et al. 2005).

Visual assessment of skin irritation via scoring of erythema is common but has the drawback of being very subjective; mild to moderate irritants may not result in the visual differences required for an erythema score (Kanikkannan et al. 2002). It is common for studies of skin irritation, patch testing, and allergy to rely upon a combination of measurements, each of which measure different parameters. These can include, but are not limited to, transepidermal water loss (TEWL), erythema scoring, histological assessment and skin blood flow (Kanikkannan et al. 2002; Jibry and Murdan 2004; Kanikkannan and Singh 2002).

In particular, laser Doppler monitoring has been implicated when mild to moderate irritation is present when the irritation may not be visually apparent and where erythema scoring would not be sensitive (Jibry and Murdan 2004; Kanikkannan and Singh 2002).

In recent years laser Doppler technology has developed and a new improved imaging system is available in place of laser Doppler monitoring for skin irritation, allergy and patch testing studies – the moorLDLS, line scanner (Bal et al. 2008). Laser Doppler imaging with the moorLDLS offers several advantages over monitoring systems:

• Whole areas of irritation are imaged, providing a detailed ‘blood flow map’ of the area of interest and surrounding skin rather than a single point measurement.
• Reproducibility of results is improved: there is no longer the inherent variation in repeat/subsequent measurements introduced when using probes which cannot be replaced in exactly the same measurement position (Jibry and Murdan 2004) on subsequent days/measurement sessions.

The moorLDLS system enables the acquisition of subjective, quantitative data regarding skin blood flow over the entire area of the skin irritant challenge.

Equipment Required - Imaging

• moorLDI2-IR (large area imaging, up to 50cm x 50cm)

Or

• moorLDLS2 (rapid imaging, 64 x 64 pixels in 4 seconds)

• Choose from DS2 / BS1 (desktop stands) or MS2 / MS3b (mobile stand).

Equipment Required - Monitoring

• moorVMS-LDF2 (dual channel recommended to allow comparison of control with stimulated site)
• VP1T combined optic and temperature skin probe(s)
• PAD double-sided adhesive discs
• Laptop or desktop PC
• moorVMS-PC Software

The moorVMS-PC software available with the moorVMS-LDF has a range of user friendly features including;

• The user to remove spikes of data (noise) resulting from movement or other artefacts simply by defining a Region of Interest (ROI) and filtering or deleting it.
• Region(s) of Interest (ROIs) to be selected and statistics for the ROI calculated - providing data averages over a period of time rather than single point.
• Statistics to be saved and exported to Excel (or similar packages) using the File, Save Statistics option.
• Statistics from other moorVMS-LDF files to be appended to a previously exported Statistics file – this enables the user to easily compare data from different allergens/irritants/or days of test.

References

For additional information on this Application or advice for tailoring Moor Instruments products to your specific application contact us for more information.