What does 'madarosis' refer to in eyelash care?

Madarosis specifically refers to the loss of eyelashes and, in some cases, eyebrows. This condition can result from various factors, including medical conditions, hormonal changes, or damage to the hair follicles. In eyelash care, understanding madarosis is crucial for specialists as it impacts not only the aesthetic appearance of the lashes but also the health of the client's hair follicles. Proper care and treatment can help address situations where clients may experience madarosis, ensuring that their eyelash extensions are applied ethically and that the underlying conditions are taken into consideration.

The other options describe different phenomena related to eyelashes but do not define madarosis correctly. For instance, curling, thickening, or having an excess of eyelashes do not relate to the loss of lashes and are therefore outside the scope of what madarosis signifies.