Diagnostic tools allow clinicians the opportunity to effectively assess the underlying cause and diagnose dry eye earlier in the disease process.
Point-of-care testing can be used to detect elevated levels of matrix metalloproteinase-9 (MMP-9), an inflammatory marker for DED. Current tools include the InflammaDry (Quidel) and the TearLab Osmolarity System (TearLab).
A positive MMP-9 test is considered ≥ 40 ng/ml. Osmolarity is considered in the normal range if it is ≤308 mOsm/L; abnormal osmolarity is considered to be above that range or when an inter-eye difference is ≥8 mOsm/L. Both the InflammaDry and TearLab systems have similar positive predictive values of more than 80%.
Sjogren’s syndrome testing
Sjogren’s syndrome is the most common cause of aqueous-deficient dry eye, and it is recommended that all patients with this type of DED be referred for serological testing. Standard blood tests, however, may miss Sjogren’s in the early stages. The Sjö Test (TearWell) is an in-office diagnostic blood test that identifies Sjogren’s biomarkers such as SP1, PSP, CA6, SS-A/Ro, SS-B/La, ANA, and RF, allowing physicians to better treat and identify Sjogren’s in its early stages.
Until a single, definitive test for DED is developed, diagnosing it will remain complex and challenging. Although diagnostic tools are improving and able to identify DED earlier on, a combination of objective tests and patient-reported symptoms continue to be necessary for an accurate, differential diagnosis.
1. Dana R, Bradley JL, Guerin A, et al. Estimated Prevalence and Incidence of Dry Eye Disease Based on Coding Analysis of a Large, All-age United States Health Care System. Am J Ophthalmol. 2019;202:47-54.
2. Schein OD, Tielsch JM, Munoz B, et al. Relation between signs and symptoms of dry eye in the elderly. A population-based perspective. Ophthalmology. 1997;104(9):1395-401.
3. Begley CG, Chalmers RL, Abetz L, et al. The relationship between habitual patient-reported symptoms and clinical signs among patients with dry eye of varying severity. Invest Ophthalmol Vis Sci. 2003;44(11):4753-61.
4. Ngo W, Situ P, Keir N, et al. Psychometric properties and validation of the Standard Patient Evaluation of Eye Dryness questionnaire. Cornea. 2013;32(9):1204-10.
5. Vashisht S, Singh S. Evaluation of Phenol Red Thread test versus Schirmer test in dry eyes: A comparative study. Int J Appl Basic Med Res. 2011;1(1):40-2.
6. Sweeney DF, Millar TJ, Raju SR. Tear film stability: a review. Exp Eye Res. 2013;117:28-38.
7. Craig JP, Nelson JD, Azar DT, et al. TFOS DEWS II Report Executive Summary. Ocul Surf. 2017;15(4):802-12.