Dry eye disease, or keratoconjunctivitis sicca, is one of the most common diseases encountered at ophthalmologic clinics. Patient with dry eye disease commonly presented foreign body sensation, red eye, blurred vision, etc. Numerous treatments for dry eye disease are proposed due to its multifactorial etiology. Sjögren syndrome, which is one of the main etiologies of dry eye disease, is an autoimmune disease characterized by dysfunction of lacrimal and salivary glands. Although dry eye status can be easily examined by ocular surface staining, the methods quantifying salivary flow rate are hard to performed clinically, such as salivary gland scintigraphy and sialometry. Furthermore, disease activity could only rely on serum markers or salivary gland ultrasound. Recently, a portable device measuring salivary conductivity is believed to assess fluid status and renal function. Interestingly, the composition of salivary electrolytes in patients with Sjögren syndrome is different from those with other causes of hyposalivation. Thus, this study aims to evaluate whether salivary conductivity in combination with ocular surface staining can be a non-invasive diagnostic test for primary Sjögren syndrome among people with dry eye disease.