Condition of anaemia without drawing blood, can be checked by identifying the presence of pallor in conjunctiva, tongue and nail bed. However, the tongue pallor can be affected by oral hygiene.

Perfusion, which determines the flow of blood to the extremities, also affects the color in the nail bed. The conjunctiva pallor is a reliable factor to detect anaemia.

The ToucHb device captures the picture of conjunctiva and uses the method of reflectance photometry to estimate the haemoglobin content in blood in grams per decilitre.