TearLab™ Osmolarity System: In Vitro Diagnostic Tear Testing Platform

The first CLIA-waived Point of Care (POC) diagnostic device in eye care delivered improved performance and a better patient experience.

Client: TearLab, Inc

Product: TearLab™ Osmolarity System


2009 Medical Design Excellence Award, IVD

Regulatory Requirements

CLIA waiver, FDA

Expertise Used

Experience Design, Usability/HFE, Interfacing to Microfluidic Consumables, Design to Regulatory Standards

Creating patient and user-friendly diagnostics for the ophthalmological space

The Schirmer test has been the gold standard for dry-eye testing for about a century. It consists of inserting strips of paper inside the patient’s bottom eyelids. In addition to many people finding this test unpleasant, false negatives and positives can be facilitated by the application of topical anesthetics or patient reaction to the test.

TearLab saw an opportunity to improve upon this test in ways that benefitted the patient as well as the physician. They developed an innovative method for measuring tear osmolarity which has been shown to be a more effective diagnostic method for dry eye syndrome than traditional techniques (with a PPV of 87 percent versus 25 to 31 percent). The test also takes a fraction of the time of the Schirmer test.

They approached us to design both a product solution that leveraged their intellectual property, and enabled a business solution that would reach the market quickly, respect their budget and meet their profit goals. The resulting osmolarity reader offers improved diagnostic performance as well as a more comfortable experience for the patient. It requires only 50 nL of fluid to take a measurement, reducing the time to administer the test from five minutes to just a few seconds.

The TearLab™ Osmolarity System is also the first CLIA-waived Point of Care (POC) eye care device to make it to market.


Considering human factors led to more comfortable tear sample collection

Using experience design to create purposeful products

For this product, user experience, specifically patient and technician interaction with the device, was key to achieving both differentiation and market success. Our design team initiated the product development process by studying the Schirmer tear test. We used behavioral science techniques including observational research to understand potential user interactions of patients and lab technicians with various solutions.

During the investigation and discussion of what the proposed tear collection solutions might feel like for patients, the research also revealed user experience insights from the technician’s point of view that influenced test performance and usability. Sample collection to analysis needed to be rapid since even minor evaporation of the tear film would alter the osmolarity. In addition, any potential for cross-contamination during the collection process had to be designed out of the product.


Prototypes and iterations led to the design of a simple to-use and ergonomic instrument

Building the right team to build the right product

Along with user experience, three design challenges were presented during the product definition phase of the development process. The technology involved a container or handle unit that held a capillary into which the sample was to be collected, and a base station for holding that unit. We needed to:

  • Establish how to best design the handle reader unit and then how to connect the reader with the base station
  • Determine whether the interpretation and display of the result should happen in the capillary reader or in the base station
  • Create a product that would meet CLIA waived status

We assembled a multidisciplinary team of engineers, designers and usability experts who worked together to develop a number of concepts for the new osmolarity reader. This required a functional analysis approach in designing the solution as a system and breaking it down into its component parts. The team created concepts for components including the base station, the vessel for loading calibration fluid, the pen that held the disposable reader, the connection between the pen and base station and approaches for collecting the sample from the patient.


Engineers, designers and usability experts worked together to develop a number of concepts

Prototyping to create a better design

Our team used prototyping to ensure that both the user problems of patient comfort and technician usability informed the product’s design. The steps they took were to:

  1. Understand the process of extracting a tear sample
  2. Observe user techniques
  3. Perform trials of reader handle interfaces to the eye
  4. Establish design directions

What emerged from these observations was that the testers approached the patient’s eye from various angles and in different ways. After additional testing, it became evident that using a pistol grip-shaped reader handle to collect the tear sample and then loading that reader handle into the base station worked well for both the patient and the technician.

Further trialing yielded further user-focused insights: having a flat surface on the top of the tear-collection cartridge was crucial for precision application, while designing in a ‘bump’ on the underside of the collection device better enabled the physician to rest and pivot the tip of the device as the tear sample was collected. Patients also felt more at ease when the reader approached their eyes from the side and was then rotated along the cheekbone and in toward the eye to make gentle contact.


User testing revealed that a pistol grip-shaped reader handle worked well for both the patient and the technician

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