A clinical, minimally invasive test used to check for tear volume and production in the eye before and after insertion of lacrimal occlusive devices. During the test, only a soft thread dipped in phenol red dye, is introduced on the surface of the eye. A measurement of 20mm is considered normal, and when the figure is below 11 mm, it is regarded as a sign of dry eyes.

Also Known As

  • Cotton Thread Test
  • Phenol Red Thread Test
  • PRT Test