While ophthalmic diagnostic lab tests—specifically those targeting ocular surface disorders—have been around for over 20 years, it is only within the past five years that they have begun to gain measurable use.
Still, the number of clinicians who have adopted these diagnostic tools remains quite small—fewer than five percent in the U.S.1
Let’s review the collection of ophthalmic diagnostic lab tests that have received clearance from the FDA for clinical and commercial use, in the order of their release.
Advanced Tear Diagnostic (ATD) Lactoferrin (LF) Diagnostic Test Kit. Cleared in 1995, ATD’s test for lactoferrin (LF) was the first point-of-care diagnostic test specifically designed for ophthalmic diagnostics.2
It requires a small 0.5 µL tear sample (1/100 of a drop) collected via metered micropipette, is a Clinical Laboratory Improvement Amendment (CLIA) Class II moderate complexity lab test, and takes about three to four minutes to produce a result. It provides an accurate assessment of the secretory function of the lacrimal gland as it relates to keratoconjunctivitis sicca (dry eye), is quantitative (provides a number), and is differential.3
Clinically, if the LF concentration is low, as judged against an established range, the patient has aqueous deficient dry eye.
ATD Total Immunoglobulin E (IgE) Diagnostic Test Kit. Cleared in 1999, ATD’s test for total IgE (not allergen specific) is a quantitative test designed to confirm allergic conjunctivitis.4 It also requires a 0.5 µL tear sample.
Clinically, if the concentration of IgE antibodies exceeds the established clinical cutoff, the patient is confirmed to have an active ocular allergen in need of some level of intervention.
TearLab Osmolarity System. Cleared in 2009, TearLab’s osmolarity test requires a 0.05 µL tear sample collected via integrated microcapillary tube.5 It is a CLIA Class I (waived) test and provides a result in approximately 10 seconds.
Clinically, the accurate measurement of ocular osmolarity is useful in confirming dry eye. If the osmolarity reading is over an established clinical cutoff value, the patient has dry eye. It is confirmatory only—it does not provide data that could differentiate aqueous-deficient dry eye, evaporative dry eye, or a possible allergic component to the presenting condition.
Rapid Pathogen Screening (RPS) AdenoPlus. Cleared in 2011, AdenoPlus is a qualitative (yes/no) tear test for confirming adenoviral conjunctivitis.6
RPS InflammaDry. Cleared in 2014, RPS’s qualitative test for matrix metalloproteinase-9 (MMP9) is a clinically relevant nonspecific inflammatory marker often associated with dry eye and conjunctochalasis.7
Note that LF and IgE tests together make up ATD’s TearScan MicroAssay System. It is the only POC measurement that incorporates two tests.
The above tests are important clinical tools, and each provides a level of clinical efficiency and precision not available prior to their introduction. Each is approved for reimbursement, and all require a CLIA certificate before clinical use.