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The OPTICAL BIOMETER AL-Scan is a medical device that optically measures eye components such as:

• axial length;
• corneal thickness;
• anterior chamber depth;
• corneal curvature radii;
• corneal cylinder axis;
• white-to-white distance; and
• pupil diameter.

Axial length and corneal thickness can also be measured using ultrasound.

The OPTICAL BIOMETER AL-Scan also performs calculations to assist physicians in determining the power of the intraocular lens for implantation.

Diagnostic ultrasound imaging or fluid flow analysis of the human body as follows: Ophthalmic (A-mode)

The OPTICAL BIOMETER AL-Scan ("AL-Scan") measures ocular measurements including: axial length, corneal thickness, anterior chamber depth, corneal curvature radii, corneal cylinder axis, white-to-white distance, and pupil diameter. It measures these necessary values successively through a non-contact optical measurement method. The AL-Scan measures as a single unit the values necessary to calculate the power of an IOL for cataract surgery.

Two optional ultrasonic probes (A-scan Probe and Pachymetry Probe) are available for use in the event the optical measurement is unsuccessful. The A-scan probe scans the axial length, anterior chamber depth, lens thickness and the pachymetry probe scans the corneal thickness. Both probes utilize an ultrasonic measurement function by touching the probe to the cornea.

The AL-Scan also has the function to calculate the power of an IOL using measured values such as axial length.

The Nidek Optical Biometer AL-Scan (K133132) was tested for agreement with predicate devices (LenStar LS 900 and PacScan 300A for ultrasound measurements) and its own precision (repeatability and reproducibility).

1. Acceptance Criteria and Reported Device Performance

The acceptance criteria for each measurement were implicitly defined by demonstrating agreement with the predicate devices within calculated 95% Confidence Intervals (CI) for the mean difference and 95% Limits of Agreement (LoA), as well as by achieving acceptable reproducibility and repeatability (measured by Standard Deviation (SD) and Coefficient of Variation (CV)).

Here's a summary of the reported device performance, highlighting key metrics, particularly for the "All Eye Populations Combined" data from Tables 1, 3, and 5. The agreement values represent the difference between the AL-Scan and the predicate device. The precision values (reproducibility and repeatability) are for the AL-Scan itself.

Assessment: The clinical study concluded that the OPTICAL BIOMETER AL-Scan demonstrated agreement to the predicate device, LenStar LS 900, for axial length, keratometry, corneal cylinder axis, central corneal thickness, white-to-white distance, and pupil diameter, and to the PacScan 300A for axial length. Agreement was also shown for anterior chamber depth with both predicates, except for eyes without a natural lens, where the AL-Scan was unable to determine ACD. The precision (reproducibility and repeatability) of the AL-Scan was considered comparable to the predicate device. These findings support that the device meets the implicit acceptance criteria by performing comparably to established devices already on the market.

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

• Test Set Sample Size:
  • Agreement Portion: 80 subject eyes (20 eyes in each of four eye populations: Normal, Cataract, Aphakic/Pseudophakic, and Corneal Abnormality).
  • Precision Portion: 40 subject eyes (10 eyes in each of the four eye populations).
• Data Provenance: Prospective clinical study conducted at a single U.S. clinical site.

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

The study does not explicitly state the number of experts or their qualifications for establishing the "ground truth" for the test set. Instead, the study uses predicate devices (LenStar LS 900 and PacScan 300A) as the reference or "truth" for comparison, which are already legally marketed and established devices for ophthalmic measurements. This is a common approach in 510(k) submissions where substantial equivalence to existing devices is being demonstrated.

4. Adjudication Method for the Test Set

The study summary does not describe any specific "adjudication method" involving multiple human readers for disagreements. The comparison is between the AL-Scan measurements and the predicate device measurements. Discrepancies are quantitatively analyzed using statistical methods like 95% Confidence Intervals for the mean difference and 95% Limits of Agreement, rather than qualitative adjudication between human observers.

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

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not explicitly mentioned or performed. The study focuses on comparing the AL-Scan's measurements directly to predicate device measurements and assessing its own precision, not on evaluating how human readers' performance improves with or without AI assistance. This device is an optical biometer, a diagnostic measurement device, rather than an AI-assisted interpretation or detection system, so an MRMC study would generally not be applicable in this context.

6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study

Yes, the study data presented primarily represent the standalone performance of the OPTICAL BIOMETER AL-Scan. The device mechanically measures ocular components, and its measurements are compared directly to those of other devices. While a human operator uses the device, the reported performance metrics (agreement and precision) are for the device's output itself, not for a human-plus-AI system. The "clinical accuracy and system sensitivity testing," "acoustic output testing," and "software verification and validation" further support its standalone performance.

7. Type of Ground Truth Used

The "ground truth" in this study is established by measurements obtained from legally marketed predicate devices: the LenStar LS 900 (an optical biometer) and the PacScan 300A (an ultrasound reference device). This approach is used to demonstrate substantial equivalence to existing technology, rather than comparing to a histological or pathology-confirmed "true" state.

8. Sample Size for the Training Set

The provided 510(k) summary does not mention a training set sample size. This is expected because the AL-Scan is a measurement device that performs optical and ultrasound biometry, not a machine learning or AI-driven diagnostic algorithm that requires a separate training phase with labeled data. Its underlying physics-based measurement principles do not necessitate a "training set" in the machine learning sense. The clinical study data described above served as verification and validation for its performance.

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

As explained in point 8, the concept of a "training set" and associated "ground truth" for training purposes is not applicable to this device, which relies on established physical measurement principles rather than machine learning algorithms.

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