Schirmer test: Are your eyes too dry?

When the Schirmer test is performed, small strips of filter paper are placed in the patient's lower conjunctival sac. The filter paper remains in the eye for five minutes with the eyes closed and soaks up tear fluid during this time. In the case of normal wetting, at least one to two centimetres of the filter paper should be damp after these five minutes. However, if the lubricated distance on the strip is shorter, there is a deficiency of the aqueous components of the tear film, which should be treated medically.

For the Schirmer I test, the filter paper is used without prior anaesthesia of the eyes, but the Schirmer II test is also used. Here, a local anaesthetic is applied to the eyes beforehand so that they do not react to the irritation of the paper by producing tears. With this variant, only the basal tear secretion is measured, providing information about the actual tear production.

By testing both eyes, it can be determined whether the extent of wetting is different or equally good or deficient in both eyes. However, the Schirmer test does not provide information about the composition of the tear fluid, but only about the quantity of tears produced during the test phase.

Is the Schirmer test painful?

The Schirmer test is basically a painless examination method. However, inserting the test strip into the lower conjunctival sac can be a little uncomfortable for some patients. To reduce irritation of the surface of the eye, a local anaesthetic may be instilled onto the eye beforehand.

What happens after the Schirmer test has been performed?

Further treatment depends on the test result. If a wetting disorder is clearly detected by the Schirmer test, the eye specialist will start therapy for sicca syndrome. This includes regular lubrication with eye drops to give the eyes the moisture that has been lost from the inadequate tear film.

This is because the natural tear film coats our eyes and protects them from drying out and from pathogens and foreign bodies. If the tear film is intact, it consists of three layers: the inner mucin layer (mucous layer), the middle layer and the oily lipid layer, which stabilises the tear film from the outside. If this composition becomes unbalanced, for example due to a deficiency of the lipid layer or insufficient production of the aqueous component, the tears no longer adhere to the surface of the eye and the eye becomes dry. 

The aim of treatment is therefore to keep the surface of the eye moist and smooth with eye drops, thereby relieving typical symptoms such as itching, burning or redness of the eye.

What causes dry eyes?

The causes of the sicca syndrome are varied and range from environmental influences to pathological changes in the glands. Common triggers of a wetting disorder are:

• working at a computer screen, also known as office eye syndrome
• environmental stimuli such as wind, smoke, fine dust, chemicals
• allergies
• inflammation, e.g. conjunctivitis, corneal inflammation, inflammation of the eyelid margin
• Sjögren’s syndrome
• vitamin A deficiency
• intake of medications
• advancing age
• hormonal changes, e.g. during pregnancy, the menopause or in the case of thyroid problems
• diseases such as diabetes or rheumatism

Anyone suffering from sicca syndrome should avoid triggers such as draughts, air conditioning or dry air in centrally heated rooms, and should always give their eyes short breaks to recover.