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The FLEXIENS (hefilcon A) HARRISON Post Refractive Surgery Contact Tens is indicated for Daily Wear use for the correction of refractive ametropia and specialized use such as atypical ametropia following corneal refractive surgery.

The FLEXI.ENS (hefilcon A) Harrison Post Refractive Surgery Contact Lens for daily wear is a soft (hydrophilic) contact lens with a spherical or toric base curve and a spherical front surface. The lens is lathe cut from hefilcon A, a hydrophilic random copolymer of 2-hydroxyethyl methacrylate and N-vinyl pyrrolidone crosslinked with ethylene glycol dimethacrylate. It consists of 55% hefilcon A and 45% water by weight when immersed in normal saline solution buffered with sodium bicarbonate.

Here's a breakdown of the acceptance criteria and study information for the FLEXLENS (hefilcon A) HARRISON Post Refractive Surgery Lens, based on the provided text:

Important Note: The provided text is a "SUMMARY of SAFETY AND EFFECTIVENESS" for a 510(k) submission, which often relies on demonstrating substantial equivalence to a predicate device rather than conducting extensive new clinical trials with detailed statistical analyses for specific acceptance criteria. Therefore, the information regarding acceptance criteria and performance is limited and often inferred from the overall claim of equivalence.

Acceptance Criteria and Device Performance

Study Details

1. Sample size used for the test set and the data provenance:

   • Sample Size: 10 patients (12 eyes)
   • Data Provenance: A small clinical study run in Canada. Retrospective/Prospective status is not explicitly stated, but "a small clinical study that was run" suggests it was a prospective observation of patients fitted with the lens.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

   • Number of Experts: One principal investigator.
   • Qualifications: Keith W. Harrison, FCLSA (Fellow of the Contact Lens Society of America). Specific years of experience are not mentioned.

3. Adjudication method for the test set:

   • Not specified. Given it was a "small clinical study" with one principal investigator, it's highly probable there was no formal, multi-expert adjudication method like 2+1 or 3+1. The principal investigator likely made the assessments.

4. If a multi reader multi case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:

   • No. This is a medical device (contact lens), not an AI-powered diagnostic tool. Therefore, an MRMC study comparing human readers with and without AI assistance is not applicable.

5. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:

   • No. This is a physical medical device. Standalone algorithm performance is not relevant.

6. The type of ground truth used:

   • The "ground truth" for the clinical study appears to be the clinical assessment of visual acuity improvement and patient tolerance/comfort by the principal investigator, potentially based on standard ophthalmic examinations and patient feedback. The text highlights the lens's ability to "improve the visual acuity" for these specific patient groups.

7. The sample size for the training set:

   • Not applicable/Not explicitly stated for this specific device's clinical study. The product claims "equivalence" to other hefilcon A lenses. The "pre-clinical" sections (Toxicology, Microbiology, Compatibility, Stability, Preservative Uptake Tests) refer to data from the original hefilcon A material (N17-976, approved FDA 01/04/1979). This prior approval and accumulated data for the material could be considered a form of "training data" for understanding the base material's safety and effectiveness, but it's not a training set in the context of machine learning.

8. How the ground truth for the training set was established:

   • As noted above, a "training set" as understood in a machine learning context is not relevant here. The ground truth for the underlying hefilcon A material (N17-976) would have been established through a combination of laboratory testing, pre-clinical studies, and prior clinical trials/experience as part of its original FDA approval process in 1979. For the new Harrison design, the "training" for its design came from addressing known issues with conventional lenses in post-refractive surgery eyes, as detailed in the "Device Description" section.

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The FLEXI.ENS 55 (methafilcon A) HARRISON Post Refractive Surgery Contact Tens is indicated for daily wear use for the correction of refractive ametropia and specialized use such as atypical ametropia following corneal refractive surgery.

The FIFXLENS 55 (methafilcon A) Harrison Post Refractive Surgery Contact Tens for daily wear is a soft (hydrophilic) contact lens with a spherical or toric hase curve and a spherical front surface. The lens is lathe cut from methafilcon A. a random copolymer of 2-hydroxyethy) methacrylate and methacrylic acid crosslinked with ethylene glycol dimethacrylate. It consists of 45% methafilcon A and 55% water by weight when immersed in normal saline solution buffered with sodium bicarbonate.

The physical properties of the lens are as follows:
Refractive Index: 1.4153
Light Transmittance: greater than 95%T
Water Content: 55%
Oxygen Permeability: Dk=18 X 10-11 at 35 °C (measured by the standard Fatt method)
Specific Gravity: 1.090 g/cc

The FT.FXLENS 55 (methafilcon A) Harrison Post Refractive Surgery Contact Tens for daily wear was developed to improve the visual acuity of those patients who require improved vision after photorefractive keratectomy, radial keratotomy, and other corneal refractive procedures. Other factors taken into consideration were the following:

1. The topographical profile is such that it is difficult to achieve a satisfactory posterior lems surface to cornea alignment with rigid gas permeable contact l enses .
2. Conventional soft (hydrophilic) contact lens designs do not readily align with the visual axis of the PRS or RK eye or supply sufficient masking of the corneal astigmatism.
3. Conventional toric soft (hydrophilic) contact lenses are limited in their ability to provide a stable level of visual acuity on cases of extreme central flattening in conjunction with irregular astigmatism.

The Harrison Post Refractive Surgery Lens differs from the standard spherical FLEXIENS Custom Sphere in that it incorporates a flat central optical zone with a thickness which varies with power (-1.00n will be approximately 0.30mm thick at the center). The size of the optical zone is generally 8.0mm. The peripheral carrier is thinner than most standard soft (hydrophilic) contact lenses, approximately 0.08mm to 0.10mm, to ensure limbal draping which will exhibit the characteristics (on the eye) of a peripheral aspheric design. In some cases the periphery is manufactured with a steeper curvature than the base curve.

The provided text describes a contact lens (FLEXLENS 55 (methafilcon A) HARRISON Post Refractive Surgery Lens) and a clinical study associated with it. However, the document does not explicitly state "acceptance criteria" in a quantitative, measurable format with corresponding "reported device performance." The study described is more of a re-fitting study to compare two versions of the same lens (different water content) on patients who had already been wearing one version.

Based on the information provided, here's an attempt to answer your questions, highlighting where information is not explicitly available:

Acceptance Criteria and Study Details for FLEXLENS 55 (methafilcon A) HARRISON Post Refractive Surgery Lens

1. Table of Acceptance Criteria and Reported Device Performance:

The document does not explicitly define quantitative acceptance criteria for device performance (e.g., minimum visual acuity improvement, maximum complication rate). The clinical study aims to show "no substantial change from one polymer to the other," implying an equivalence or non-inferiority goal rather than specific performance thresholds.

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

• Sample Size (Clinical Study): 10 patients with 12 eyes.
• Data Provenance: Conducted in Canada. The study was a "refitting" study, meaning patients were already using a previous version of the lens and were then switched to the new version. This suggests a retrospective component (initial fitting data for comparison) and a prospective component (follow-up after refitting with the new lens), though the document describes it as a single "small clinical study."

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

• The principal investigator was Keith W. Harrison, FCSSA. His qualifications are listed as FCSSA (Fellow of the Contact Lens Society of America, or similar professional designation, though not explicitly spelled out in the document).
• The document does not specify additional "experts" involved in establishing ground truth for the clinical study beyond the principal investigator who conducted the refitting and follow-up.

4. Adjudication Method for the Test Set:

• The document does not describe an explicit adjudication method (e.g., 2+1, 3+1). The "ground truth" or assessment of "no substantial change" appears to have been determined by the principal investigator, potentially through clinical examination and subjective patient feedback, but specific methods are not detailed.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done:

• No, an MRMC comparative effectiveness study was not done. This was a small clinical study focused on refitting patients with a slightly modified version of an existing product. It did not involve multiple readers assessing cases to determine improvement with AI assistance.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done:

• Not applicable. This device is a contact lens, not an AI algorithm. Therefore, a "standalone algorithm performance" study is not relevant.

7. The Type of Ground Truth Used:

• The ground truth for the clinical study appears to be based on clinical assessment by the principal investigator and implied patient experience/outcomes (e.g., "no substantial change from one polymer to the other" in terms of performance). The document does not specify objective metrics like visual acuity charts or detailed patient-reported outcomes, but these would likely have been part of the clinical assessment.

8. The Sample Size for the Training Set:

• Not applicable. This is a contact lens, not a machine learning model. There is no concept of a "training set" in this context. The manufacturing and design process relies on established material science and contact lens design principles.

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

• Not applicable, as there is no "training set" for this device. The physical properties (Refractive Index, Light Transmittance, Water Content, Oxygen Permeability, Specific Gravity) are inherent material and design specifications, established through laboratory testing and manufacturing processes for methafilcon A, as referenced in prior 510(k) clearances.

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