instrumental focus

Tear Test

Osmolarity test quantifies tear film integrity.

Sean P. Mulqueeny, O.D.

Because the medical literature has shown tear osmolarity is a key indicator of tear film quality and can, therefore, reveal the potential for and presence of aqueous deficient and/or evaporative dry eye disease (DED), having a diagnostic device that specifically assesses this marker is extremely beneficial for both the diagnosis and management of DED. This device: the TearLab Osmolarity System, from TearLab Corporation.

Overview

The TearLab Osmolarity System is an in-vitro, objective and quantitative test that provides a tear film integrity measurement. A recent clinical trial on the device revealed that osmolarity values greater than 308mOsms/L are generally indicative of DED.¹ Used in conjunction with other clinical evaluation methods as well as your clinical judgment, this measurement aids you in determining the likelihood and existence of ocular surface disease and the level of a patient's disease. The System has been shown to correctly identify 88% of normal tear subjects, 75% of mild-to-moderate DED subjects and 95% of severe DED subjects.¹

A countertop reader, two electronic tester pens, two reusable blue Electronic Check Cards, two magnetic cardboard pen sleeves and 84 single-use test cards comprise the TearLab Osmolarity System. (You can contact TearLab Corporation for replacement cards, which the company sells at a volume discount.)

Testing procedure

Every day, prior to patient use, you insert the reusable blue Electronic Check Cards into each pen to ensure the System is working properly. (Each pen must be tested singularly.) The additional pen is meant as a backup and to enable simultaneous testing with a separate patient.

The pens' lights turn green and beep once upon proper insertion. When the pens' green light ceases and you hear a second beep, the card has simulated tear collection, and you dock the pen with card into the System's reader. Now, you press “OK” on the reader. A reading of 334mOsms/L (+/− 3) indicates the System is functioning properly. Translation: You're ready for your first patient of the day. If, however, the System's reader doesn't display these numbers, you use the magnetic cardboard pen sleeves to reset the pen or pens, and start the quality control testing from scratch. If the numbers are still off, you contact the TearLab Corporation for troubleshooting.

The TearLab Osmolarity System has been shown to correctly identify 88% of normal tear subjects, 75% of mild-to-moderate dry eye disease (DED) subjects and 95% of severe DED patients.

Either you or your technician can perform the test, and I've found that it takes 60 seconds or less. First, the testing procedure is explained to the patient. Then, the patient is instructed to raise his chin and direct his eyes to the ceiling and blink normally. Now, I remove one of the pens from the System's reader dock, and insert one of the test cards into it. I've found that the pen fits nicely in my hand with a design that enables both practitioner stability and patient safety. That said, if you have an unsteady hand, you may want to gently place it on the patient's cheek for stability.

Once the pen's green light appears and the pen beeps, I approach the patient from the side, place the pen beyond the lashes near the eye's corner and lower it until the card tip's bottom touches the line of moisture on top of the eyelid. You want to touch the top of the eyelid, but avoid the sclera. If the patient has a shallow tear prism, you can achieve tear collection by gently moving the card's tip along the outer one-third of the outer lower lid. However, insufficient tear collection could result in a “Below Range” test result, which is indicated by the System. If this happens, use a new test card, and repeat the test. Something else to keep in mind: Don't pull down on the lower lid. This action will compromise the tear lake, making acquiring a tear sample a challenge.

Once the pen has collected a tear sample—it needs just 50 nano-liters of tear film—the pen's green light disappears and the pen beeps. Next, you dock the pen into the reader within 40 seconds, enter the numeric code of the test card—each card has one—into the reader, and the device will apply voltage to the tear sample and measure the impedance of the fluid through time. The TearLab Osmolarity System then applies a series of calculations to the measured impedance and indicates the resultant osmolarity. Now, you use a new test card to repeat the procedure on the fellow eye. Once you've acquired both measurements, educate your patient on his numbers and how and why you'd like to proceed, in terms of management.

At my patients' initial visit, I perform a baseline test. If I decide to initiate treatment, I obtain a follow-up measurement within three-to-six months, so I can track the success of treatment.

Staff training

The TearLab Corporation offers a device manual and staff and doctor training via teleconference and/or on-site. Supplementary online videos (www.tearlab.com) provide support as well, and the company offers additional training sessions as refresher courses on their website for existing staff and new employees.

In my practice, all personnel using the device must demonstrate competency with the device prior to patient use.

Return on investment

In order to bill for the test, you must become Clinical Laboratory Improvement Act (CLIA) certified. You can bill the device as a private pay elective procedure if the test isn't covered by the patient's insurance. For information on how to become a CLIA director, visit www.tearlab.com/products/doctors/reg/clia/certification.htm. (The company has filed for a CLIA Waiver classification, which would drop this requirement.)

The appropriate CPT for osmolarity is 83861, which is a unilateral code. Always test each eye for maximum diagnostic accuracy. The higher of the two eyes' osmolarity is the reference number, as the physiologic variability in measurements between the two eyes may be indicative of DED. When coding the second eye, use the −59 modifier or R eye/L eye modifier depending on the carrier. (So, the coding for this eye would be 83861-59 to indicate that this is a Distinct Procedural Service.)

Reimbursement varies by state and insurance carrier. We charge $50 per patient, or roughly $24 per eye. The “break even” point for our practice is approximately 330 eyes tested, and depending on the number of DED patients you see, the timeframe for your return will vary. We started using the device roughly a year-and-a-half ago, and we expect to break even by year's end. (Keep in mind that reimbursement is only for the test, not the professional office visits.)

In addition to its clinical application, the device has also enabled me to improve patient retention to appointments and patient compliance with my prescribed treatments. This is because patients are eager to see whether they were able to achieve a “lower score,” or a healthier measurement than before, at subsequent follow-up visits. Further, don't forget that marketing your practice as having advanced DED testing, among other state-of-the-art diagnostic devices and treatment capabilities, creates several patient referrals.

The TearLab Osmolarity System has become a regularly utilized device in my practice. It facilitates my ability to diagnose and manage DED, it's fast and easy for my staff and I to operate, it has improved patient adherence to follow-up appointments and prescribed treatments, and it has reinforced my rep. as a tech-savvy O.D. who, therfore, can provide the best care. These are a lot of benefits for a device created to aid in the diagnosis and management of DED. OM

1. Foulks GN, Lemp MA, Berg M, et al. TearLab Osmolarity as a Biomarker for disease severity in mild to moderate dry eye disease. American Academy of Ophthalmology PO382, 2009.