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The TearLab Osmolarity System is intended to measure the osmolarity of human tears to aid in the diagnosis of patients with signs or symptoms of dry eye disease, in conjunction with other methods of clinical evaluation.

The TearLab Osmolarity System is intended to measure the osmolarity of human tears to aid in the cliagnosis of patients with signs or symptoms of dry eye disease, in conjunction with other methods of clinical evaluation. The device consists of the following components and accessories: One Tearl.ab Reader, Two TearLab Pens, Two TearLab Electronic Check Cards, Sinqle Use TearLab Osmolarity Test Cards, and TearLab Control Solutions.

The TearLab Osmolarity Test Card, in conjunction with the TearLab Osmolarity System, provides a quick and simple method for determining tear osmolarity using nanoliter (nL) volumes of tear fluid collected directly from the eyelid margin.

To perform a test, a new Test Card containing a microfluidic capillary channel is attached onto the Pen. The tip of the Test Card is touched to the inferior tear meniscus located above the lower eyelid and collects 40-50 nanoliters of tear fluid by passive capillary action.

After a successful collection, the Pen in conjunction with the electrodes embedded on the Test Card, measures and stores the tear fluid impedance. The Pen is then docked to the Reader.

The Reader downloads impedance data from the Pen in order to calculate and display the final osmolarity as a numerical value displayed in units of mOsms/L.

The TearLab Osmolarity System simplifies the tear collection process by reducing the required specimen volume to nanoliters, eliminating the need to transfer tear fluid and reducing the risk of evaporation.

Acceptance Criteria and Study for TearLab™ Osmolarity System

This document outlines the acceptance criteria and the study conducted to demonstrate the performance of the TearLab™ Osmolarity System.

1. Acceptance Criteria and Reported Device Performance

The provided document focuses on substantiating the device's performance through comparison with a predicate device and diagnostic accuracy for dry eye disease. The acceptance criteria are implicitly derived from these performance metrics.

2. Sample Size Used for the Test Set and Data Provenance

• Precision Studies: Contrived tear specimens across concentrations of 275–400 mOsms/L were used. The number of individual measurements or specimens per run/instrument/lot/site is not explicitly stated, but "Tear samples were analyzed over 20 consecutive days" for single instrument precision, and "Seven levels of contrived tear solution" for method comparison studies.
• Performance on Patients with Objective Signs of Dry Eye: 140 subjects (45 Normal, 95 Dry Eye) were enrolled.
• Data Provenance:
  • Precision Studies: Not explicitly stated, but likely laboratory-controlled settings given the use of "contrived tear specimens."
  • Method Comparison Studies (Internal & External): "Seven levels of contrived tear solution" were prepared. The external comparison was done "At each of three physician office sites."
  • Performance on Patients with Objective Signs of Dry Eye: "multicenter study." Country of origin is not specified but given the FDA 510(k) submission, it is likely that studies complied with US regulations. The study appears to be prospective for collecting data on device performance with human subjects.

3. Number of Experts Used to Establish Ground Truth for the Test Set and Their Qualifications

• For the "Performance on patients with objective signs of dry eye" study:
  • Ground truth for "Dry Eye patient" vs. "Normal" was established based on clinical criteria: a positive score on the Ocular Surface Disease Index (OSDI) and 2 or more positive indications from a set of tests (Tear Film Breakup Time (TBUT), Schirmer Test, Corneal Staining, Conjunctival Staining, or Meibomian Gland Dysfunction).
  • The number and qualifications of experts (e.g., ophthalmologists, optometrists) involved in performing these diagnostic tests and classifying subjects are not explicitly mentioned in the provided text.

4. Adjudication Method for the Test Set

The adjudication method for categorizing subjects as "Normal" or "Dry Eye" in the clinical performance study is based on a fixed set of objective and subjective clinical criteria (OSDI score and 2+ positive indications from a list of tests). It does not appear to involve a consensus process among multiple independent human readers in the traditional sense of image interpretation, but rather the application of established clinical definitions.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No, a multi-reader multi-case (MRMC) comparative effectiveness study assessing how much human readers improve with AI vs. without AI assistance was not conducted or reported. This device is a standalone diagnostic measurement system, not an AI-assisted interpretation tool for human readers.

6. Standalone Performance Study

Yes, a standalone performance study of the algorithm (the TearLab Osmolarity System) was conducted. This is evidenced by:

• Precision Studies: Demonstrated the device's consistency and reproducibility in measuring osmolarity (Section VI, Precision Studies).
• Method Comparison Studies: Compared the TearLab system's measurements directly against the predicate Wescor 5520 Vapro® Osmometer (Section VI, Internal Method Comparison, External Method Comparison).
• Performance on Patients with Objective Signs of Dry Eye: Evaluated the device's diagnostic accuracy (sensitivity, specificity, PPV, NPV) against clinically established ground truth for dry eye disease, without human intervention in the osmolarity measurement itself (Section VI, Performance on patients with objective signs of dry eye).

7. Type of Ground Truth Used

• Precision and Method Comparison Studies: For these studies, the ground truth was based on contrived tear specimens with known or established osmolarity values, often referenced against a gold standard osmometer (Wescor 5520 Vapro® Osmometer).
• Performance on Patients with Objective Signs of Dry Eye: The ground truth for classifying patients as "Normal" or "Dry Eye" was established through a consensus of clinical evaluation criteria, specifically a positive score on the Ocular Surface Disease Index (OSDI) and 2 or more positive indications from a combination of Tear Film Breakup Time (TBUT), Schirmer Test, Corneal Staining, Conjunctival Staining, or Meibomian Gland Dysfunction. This represents clinically defined outcomes/indicators.

8. Sample Size for the Training Set

The document does not explicitly mention a training set in the context of machine learning or AI algorithm development. The TearLab Osmolarity System uses an "electrical impedance measurement to provide an indirect assessment of osmolarity," and "after applying a lot-specific calibration curve, osmolarity is calculated." This suggests a deterministic algorithm or a model that uses calibration data rather than a machine learning model that requires a distinct "training set" in the common sense.

The "calibration data" mentioned refers to a meta-analysis of historical published data (n=1,436 subjects: 815 normal, 621 dry eye) which was used to determine an osmolarity referent (316 mOsms/L) and its associated sensitivity and specificity for dry eye diagnosis, but this was not for training the device's core osmolarity measurement algorithm. It was for establishing diagnostic thresholds based on osmolarity values, not for training the device's internal impedance-to-osmolarity conversion.

9. How the Ground Truth for the Training Set Was Established

As noted above, a distinct "training set" for an AI algorithm is not explicitly described. However, if considering the "calibration data" from the meta-analysis as a form of reference data to establish clinical thresholds:

• Meta-analysis Ground Truth: The ground truth for the meta-analysis (n=1,436) was derived from "historical published data" on tear osmolarity in normal and dry eye subjects using "earlier osmolarity devices." This implies that the classification of "Normal" or "Dry Eye" in those historical studies would have been based on their respective clinical diagnostic criteria prevalent at the time. Further details on how this ground truth was established within the original studies are not provided in this document.

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