Sjögren’s Syndrome (SS) is an autoimmune disorder where the body mistakenly attacks its own moisture-producing glands, primarily the lacrimal glands in the eyes and the salivary glands in the mouth. This attack leads to chronic dryness, known as keratoconjunctivitis sicca (dry eyes) and xerostomia (dry mouth). Objective eye tests are an important component of the diagnostic process because the symptoms of dryness can be vague, requiring quantitative measurements to confirm the severity of ocular involvement. These tests provide specific, measurable evidence of reduced tear production, poor tear quality, and subsequent damage to the eye’s surface, which are criteria used to determine if Sjögren’s Syndrome is present.
Measuring Tear Production Volume
The Schirmer test is the main procedure used to quantify the volume of tears produced by the lacrimal glands. This test involves placing a small strip of specialized filter paper, marked with a millimeter scale, into the lower eyelid of each eye. The strip is positioned at the junction between the palpebral and bulbar conjunctiva, and the patient is asked to keep their eyes gently closed for five minutes. The test is performed either with or without anesthetic drops; the version without anesthesia measures both basal and reflex tear secretion, while the anesthetized version measures only basal secretion. A result showing less than 5 millimeters of wetting after the five-minute period is considered an abnormal finding, strongly indicating deficient aqueous tear production associated with severe dry eye.
Assessing Tear Film Quality and Stability
Beyond simply measuring tear volume, other tests assess how well the existing tear film functions and resists evaporation. The Tear Break-Up Time (TBUT) test evaluates the stability of the tear film, which is composed of a complex mix of water, oil, and mucus. A small amount of fluorescein dye is applied to the eye, and the time it takes for the dye-enhanced tear film to show the first dark spot—indicating a break in the film—is measured while the patient refrains from blinking. A healthy tear film remains intact for about 10 seconds or more, but a reading less than 10 seconds suggests instability due to inadequate tear composition.
Another measurement, Tear Film Osmolarity, assesses the concentration of dissolved particles in the tears. High osmolarity, typically above 316 milliosmoles per liter (mOsm/L), indicates that the tear film is excessively concentrated due to high evaporation or low water content, a condition known as hyperosmolarity. This hyperosmolarity drives the inflammation and surface damage characteristic of severe dry eye disease, and is often significantly elevated in those with Sjögren’s Syndrome.
Identifying Damage to the Eye Surface
Chronic lack of moisture and poor tear quality eventually cause damage to the delicate outer layers of the eye, which can be visualized using vital staining techniques. These non-toxic dyes are applied as eye drops and selectively stain damaged or dead cells on the cornea and conjunctiva. Fluorescein dye is used to highlight areas of epithelial defects or tiny abrasions on the cornea, which appear as bright green under a cobalt blue filter on a slit lamp. Lissamine Green, or sometimes Rose Bengal, is used to stain devitalized cells on the conjunctiva. The ophthalmologist then uses a magnified view from a slit lamp to grade the extent and pattern of this staining using a standardized scoring system, providing objective proof of the disease’s physical effect on the ocular surface.
Integrating Eye Test Results into the Overall Sjögren’s Diagnosis
Sjögren’s Syndrome is a systemic autoimmune disease, meaning the diagnosis cannot be made based on eye findings alone. The objective measurements from the eye tests serve to establish the presence of severe aqueous tear deficiency, or keratoconjunctivitis sicca, which is a required ocular sign for diagnosis. Diagnostic guidelines from international groups require a patient to meet criteria from various domains, including ocular signs, oral signs, and the presence of specific autoantibodies. An abnormal Schirmer test result or a high ocular staining score satisfies the objective ocular criteria, contributing crucial points toward the final diagnosis.
Once the ophthalmologist confirms these severe ocular findings, the patient is often referred to a rheumatologist for the systemic workup. This workup typically includes blood tests to check for specific autoantibodies, such as anti-SSA (Ro) and anti-SSB (La), which are markers of the autoimmune process. The eye test results, combined with positive serology and sometimes an abnormal minor salivary gland biopsy, complete the required set of objective criteria needed to confirm a diagnosis of Sjögren’s Syndrome.