A test to measure the tear volume in the eyes
The doctor might measure the tear production in a patient’s eye with the help of schirmer’s test. In schirmer’s test, the doctor places blotting paper strips under the lower eyelids of a patient. After a few minutes, the doctor measure the quantity of tears absorbed by the bloating strip. Another method to measure the tear volume is the test of phenol red thread. According to the phenol red thread test, the doctor places a thread full of Ph-sensitive dye over the lower eyelid area and wait for wetting with tears for almost 15 seconds and then measure the tear volume. The tears change the color of the thread and a drastic change in dye color of the thread indicates a negative diagnosis of dry eyes and vice versa.
Test for determining the quality of tears
The other diagnostic tests employ special dyes in eye drops to evaluate the surface condition of the eyes. The doctor searches for staining pattern on the eye corneas and gauges how long it takes before the tears start evaporating.
Tear osmolarity test
A tear osmolarity test evaluates the composition of water and particles present in your tears. In case of people with dry eyes, there is less water content in the eyes.
Tear sample to gauge the markers
In some cases, doctors also take additional tear samples to look for certain markers for dry eye disease such as decreased lactoferrin and increased matrix metalloproteinase-9.