Sun protection factor (SPF) testing
In vivo: Testing is done according to the Sunscreen Standard (SANS 1557) of Standards South Africa and according to ISO 24444. The test is performed with a Multiport Solar Simulator (Solar Light Co. Pennsylvania, USA) which is fitted with a Xenon arc UV lamp.
Dry and water resistance tests are offered. In vitro SPF testing is currently performed according to SANS 1557. The laboratory is also participating in the ISO ring-test which is refining the COLIPA in vitro UVA test method. Tests are performed on topical sunscreen products with the Optometrics SPF 290 and a Multiport Solar Simulator.
Moisturiser Efficacy Testing (MET)
The moisturisation efficacy of topically-applied products can be measured instrumentally or by expert visual assessment. Instrumental methods measure the amount of water vapour given off from resting skin (transepidermal water loss – TEWL) or the moisture content of skin e.g. via capacitance measurements. Current equipment at the laboratory includes a corneometer (Courage & Khazaka GmbH) for skin capacitance plus two instruments to measure TEWL – the Vapometer (Delfin Technologies™) and Aquaflux (Bioxx). The contour changes in the skin can be measured by special photography (Visia-CR™ with Nikon 10 megapixel camera) or the Visioscan to perform surface evaluation of living skin (SELS). The visual method is still widely used because it is so reliable and repeatable. Skin is graded on appearance and degree of redness on a visual scale. Other techniques such as D-squames™ plus Squamescan , Silflo™ replicas and tape strips are also available.
Irritancy patch test
The irritancy patch test is a safe non-invasive test which has been used for many years to determine the irritancy of topically applied products. A variety of test designs is available, including repeat insult patch test (RIPT). Tests can be conducted occluded using Finn chambers on Scanpore™, or unoccluded.
Skin pigmentation studies:
A variety of test designs is available on a range of ethnic groups to examine the effect of topically applied products on skin colour. Study designs are normally placebo-controlled and double blind. Studies are normally performed on non-UV exposed skin e.g. thigh or inner forearm. Half-face product comparison can be performed. Panels with melasma and post-inflammatory hyperpigmentation are available. Colour assessment is visual and instrumental, using the Minolta Chromameter and the Mexameter (Courage & Khazaka GmbH).
Ophthalmic irritancy studies
Ophthalmic irritancy of shampoos and baby soaps are performed on small panels of volunteers with normal healthy eyes, under the close supervision of an ophthalmologist. Assessment includes expert visual assessment of tears and erythema, plus self-assessment of pain/sting.
Image Assessment and Analysis