Many different sets of classification criteria have been proposed for SS over the past 30 years. Depending on the stringency of criteria used, there can be up to a 10-fold difference in the number of individuals diagnosed. The classification criteria developed by an American-European consensus group are currently the most widely used (Table 4) (1).
Diagnosis of primary SS is more difficult than that of secondary SS because it requires objective findings of the salivary (histopathology, unstimulated whole salivary flow rate, sialography, or scintigraphy), ocular (Schirmer I test or staining with rose bengal or lissamine green), and systemic (anti-SS-B and/or anti-SS-A) components. Subjective findings of salivary and ocular symptoms via patient history can be unreliable (Table 4, points I and II) or can be the result of a disease process other than SS (Tables 1-3).
The ocular component of SS is termed "keratoconjunctivitis sicca" (KCS). The Schirmer I test is used to test tear production. Standardized Schirmer strips 35 mm long and 5 mm wide, composed of sterilized filter paper, are folded at the notched ends and placed over the lateral lid margin of both lower lids and allowed to remain for five minutes, or until the strips are saturated, if sooner. The Schirmer I is preferred because it tests the ability of the lacrimal gland to produce tears under normal conditions of relatively mild stimulation. Application of a topical anesthetic (Schirmer II) creates an artificial situation in which test values are abnormally low, even in some patients without KCS. In most circumstances, less than 5 mm of wetting in five minutes is considered abnormal. Low Schirmer values are also caused by other ocular conditions not associated with SS.
The tear break-up time (BUT) evaluates the stability of the tear film. A drop of 0.5% fluorescein, applied to both eyes, is allowed to equilibrate for three minutes, and then the
Was this article helpful?