The Schirmer Test is explained as a method to evaluate the amount of tear film in the diagnosis of Dry Eye Syndrome.
🇬🇧 Revised English subtitles are available.
👤 J.R. Fontenla, MD-PhD.
Professor of Ophthalmology
🌍 University of Barcelona
►Instagram: @ visus.formacion
📩 visus.formacion@gmail.com
The importance of the tear film lies in the protective function of the eyeball, in such a way that it lubricates its surface, provides the cornea with oxygen and nutrients for its metabolism and finally keeps substances related to the immune defense in suspension.
The tear is composed for the most part by water, the other components being lipids and proteins. The quantitative or qualitative alteration of any of these three elements causes that the tear film is not distributed homogeneously over the eye, appearing dry exposed areas. This leads to the appearance of the conjunctiva and corneal lesions typical of dry eye syndrome. Although it is not uncommon to find primary keratoconjunctivitis sicca, in most cases it is associated with systemic pathologies. These include autoimmune diseases such as Sjögren's syndrome, rheumatoid arthritis or systemic lupus erythematosus. Other pathologies that cause dry eye are certain ocular infections, injuries or trauma to the lacrimal glands, the use of drugs that induce tear hyposecretion or certain mucocutaneous diseases. The importance of dry eye syndrome lies in the high frequency of this pathology, which affects women in greater numbers. Next, we are going to describe the different ophthalmological tests to diagnose a tear film deficit.
Schirmer I test
The Schirmer I test allows the study of total tear secretion, that is, it evaluates the sum of the basal secretion plus the reflex secretion. As for all types of Schirmer tests, whatman No. 41 filter paper of 5 mm wide and 30 mm long is used. They are placed in the lower external conjunctiva, in a low light environment, with the patient with the eyes closed and measured after 5 minutes. Normal values ​​are considered when the wet zone exceeds 15 mm in length. Less than 5 mm indicates tear hyposecretion.
Basal Schirmer test
It measures the basal secretion produced by the accessory lacrimal glands located in the conjunctiva. It is performed a few minutes after the instillation of topical anesthetic to inhibit the reflex secretion produced by the main lacrimal gland. The method and materials are the same as in Schirmer I. Normal values ​​are considered when the wet zone exceeds 10mm in length. Less than 5 mm indicates tear hyposecretion. Between 5 and 10 mm is not diagnostic.
Schirmer II test
It measures the reflex secretion allowing to differentiate between non-Sjögren entities from Sjögren's syndrome. It is performed after the instillation of a topical ocular anesthetic and nasal stimulation (the nasal mucosa is not anesthetized) with a cotton swab, turning it 10 times inside the nose and reading it after 2 minutes.