Phenol red test/ Methyl red thread test for dry eye, true is
Phenol Red Thread test is the test to detect dry eye severity. When in contact with tear film it changes its colour from white to yellow to red. Its main advantage over Schirmertest is: a)It is Less time consuming as compared to schirmer test(15 sec) b)Anaesthesia of cornea is not required c)On the contact of tear strip with the tear it turns red d)Can be done in children easily e)Reflex tearing is minimal f)Differentiates between aqueous deficient & non aqueous deficient eyes
Need instillation of anesthesia before doing the test
Need a ph meter to interpret
Color changes if there is mucin deficiency
Color changes from white to red on contact with tear film and is used to measure the dryness status of eye
Nasolacrimal Disorders