Method for quantifying the water content of a surface of a contact lens having a front surface and a back surface, the method comprising the steps of: - immersing the contact lens in water, and with the aid of an optical inspection system having an optical axis (z) extending from the optical inspection system to the surface of the immersed lens and comprising a water tip objective a front lens of which is immersed in the water: - focusing a laser beam of the optical inspection system into a focal volume in the water extending in the direction of the optical axis (z), and measuring a reflectivity value of the respective focal volume, - advancing the focal volume through the water along the direction of the optical axis (z) by changing the position of the water tip objective until a maximum reflectivity value of the reflectivity values of the focal volumes is measured, - determining a transition from the water to the front surface or to the back surface of the contact lens to determine the location of the front surface or back surface of the contact lens at that focal volume where the maximum reflectivity value is measured, - measuring at that location a reflectivity value of at least one segment of the front surface or the back surface of the contact lens, - storing each measured reflectivity value, - comparing each stored measured reflectivity value with a corresponding reference reflectivity value of a front surface or a back surface of a reference contact lens having known material properties including the refractive index of the material and having a known water concentration, and - from the respective stored measured reflectivity value and the refractive index of the material of the contact lens, from the corresponding reference reflectivity value and the refractive index of the material and the known water concentration of the reference contact lens, as well as from the refractive index of water, quantifying the water content of the front surface or the back surface of the contact lens. - immersing the contact lens in water, and with the aid of an optical inspection system having an optical axis (z) extending from the optical inspection system to the surface of the immersed lens and comprising a water tip objective a front lens of which is immersed in the water: - focusing a laser beam of the optical inspection system into a focal volume in the water extending in the direction of the optical axis (z), and measuring a reflectivity value of the respective focal volume, - advancing the focal volume through the water along the direction of the optical axis (z) by changing the position of the water tip objective until a maximum reflectivity value of the reflectivity values of the focal volumes is measured, - determining a transition from the water to the front surface or to the back surface of the contact lens to determine the location of the front surface or back surface of the contact lens at that focal volume where the maximum reflectivity value is measured, - measuring at that location a reflectivity value of at least one segment of the front surface or the back surface of the contact lens, - storing each measured reflectivity value, - comparing each stored measured reflectivity value with a corresponding reference reflectivity value of a front surface or a back surface of a reference contact lens having known material properties including the refractive index of the material and having a known water concentration, and - from the respective stored measured reflectivity value and the refractive index of the material of the contact lens, from the corresponding reference reflectivity value and the refractive index of the material and the known water concentration of the reference contact lens, as well as from the refractive index of water, quantifying the water content of the front surface or the back surface of the contact lens. - focusing a laser beam of the optical inspection system into a focal volume in the water extending in the direction of the optical axis (z), and measuring a reflectivity value of the respective focal volume, - advancing the focal volume through the water along the direction of the optical axis (z) by changing the position of the water tip objective until a maximum reflectivity value of the reflectivity values of the focal volumes is measured, - determining a transition from the water to the front surface or to the back surface of the contact lens to determine the location of the front surface or back surface of the contact lens at that focal volume where the maximum reflectivity value is measured, - measuring at that location a reflectivity value of at least one segment of the front surface or the back surface of the contact lens, - storing each measured reflectivity value, - comparing each stored measured reflectivity value with a corresponding reference reflectivity value of a front surface or a back surface of a reference contact lens having known material properties including the refractive index of the material and having a known water concentration, and - from the respective stored measured reflectivity value and the refractive index of the material of the contact lens, from the corresponding reference reflectivity value and the refractive index of the material and the known water concentration of the reference contact lens, as well as from the refractive index of water, quantifying the water content of the front surface or the back surface of the contact lens.