To determine whether the eyes have enough tear fluid, the Schirmer test is used. This involves the use of special strips of filter paper that become saturated with the fluid over a period of time. The ophthalmologist can then diagnose a so-called sicca syndrome if the eyes are too dry. In this case, not enough tear fluid is formed and there are also deficiencies in its composition. Thus, the cornea of the eye cannot be sufficiently moistened and protected. The Schirmer test can also detect Sjögren’s syndrome, named after a Swedish physician, in which the conjunctiva and mucous membranes around the eyes are affected by the malfunction of the lacrimal glands. The test strips usually measure five millimeters by 35 millimeters and have an appropriate scale.
What is the Schirmer test?
The litmus paper test method bears the name of German ophthalmologist and university lecturer Otto Wilhelm Schirmer (1864-1917). He came from Greifswald and studied at the university there as well as in Munich and Freiburg. In 1896, the doctor, who had in the meantime received his doctorate and habilitated, took over the chair of ophthalmology in Greifswald. Schirmer later held teaching positions in Kiel and Strasbourg before moving to the United States and working in several clinics in New York. The test of lacrimal gland function, first performed in 1903, is still used today under Schirmer’s name. Two different variants of the Schirmer test are commonly used. In the Schirmer 1 procedure, a small test strip is carefully inserted into the lower conjunctival sac of each eye. The patient then closes his eyes and the filter paper absorbs the respective amount of tear fluid within five minutes. When the strip is full of fluid, it changes color. Based on this color, the ophthalmologist can make his assessment. However, this variant is now only very rarely used. Schirmer 2 is used much more frequently. Here, both eyes are locally anesthetized and show, independently of any possible irritation, the amount of tear fluid secreted without any relevant external influences, such as through the filter paper. If the saturated distance on the test strip is shorter than ten millimeters, the tear flow is in too low a range. Five millimeters or less of wet section indicates an urgent case of dry eyes. The ophthalmologist then examines whether this deficiency is due to possible inflammation of the conjunctiva or other areas of the eye. However, he must be aware that the test results may be inaccurate. The eyes may become so irritated during the test that they tear more than usual, leaving the risk of dehydration undetected. A patient should also not put on contact lenses for two hours after the Schirmer test to protect the eyes.
Function, effect, and goals
The Schirmer test is performed when the eyes are red and cause a burning sensation. Dried eyes can also be when enough tear fluid is produced, but its composition is not in balance. It often happens that the tear fluid, which is formed of three layers, lacks its oily components and thus the protection of the eye deteriorates. In addition, the tear fluid is no longer evenly distributed. However, the Schirmer test is not suitable for this examination. In addition, with Schirmer 2, greater problems with contact lens wear occur from a wetting distance of eight millimeters. In such cases, the lenses are perceived as intolerable by the protective mechanisms of the eye. Corresponding reactions such as redness, inflammation or excessive lacrimation are exacerbated if those affected work frequently and for long periods at a computer screen, are exposed to an unpleasant room climate or strong and gusty winds. As soon as the eyes become noticeably dry or even begin to redden, ophthalmologists and opticians therefore recommend wearing glasses instead of contact lenses.
Risks, side effects and dangers
If the Schirmer test provides a positive result, various diseases can be the cause of this deficient production of tear fluid. Sjögren’s syndrome is an immunodeficiency in which stray immune cells attack the tear glands as well as salivary glands. This disease occurs mainly in women after menopause.Trachoma, an inflammation of the eyes caused by bacteria, continues to affect tear production. Blindness can even develop here if medical intervention is not taken in time. Various types of facial paralysis can also affect the supply of tears to the eye, insofar as they affect the muscles involved. Dried eyes are also often the result of diseases such as diabetes, chronic rheumatism or thyroid dysfunction. Even a room with insufficient humidity can cause dry and painful eyes in sensitive people. Those who suffer from this are well advised to use humidifiers placed in these rooms. When working frequently and intensively at a computer screen, longer breaks should be taken regularly to relieve the eyes somewhat. Incidentally, the Schirmer test is also carried out if a defective vision has developed which is to be corrected by inserting contact lenses. The test also fulfills an important task in veterinary medicine, because dogs, horses and cattle in particular often suffer from dry eyes. The test procedure on the animal is basically the same as for a human and absolutely painless for the quadruped.