(134 days)
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
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Primary Indication: Correction of refractive ametropia and specialized use for atypical ametropia following corneal refractive surgery for Daily Wear. | The lens was fitted to 6 PRK, 3 RK, and 1 corneal keratoplasty (aphakic) patient, with an average daily wear of 12.4 hours. The implied performance is an "improvement of visual acuity" (stated in the device description). |
| Material Properties: | |
| Refractive Index | 1.43 |
| Light Transmittance | greater than 95%T |
| Water Content | 45% |
| Oxygen Permeability (Fatt method) | Dk = 16 x 10^-11 at 35 °C |
| Specific Gravity | 0.979 g/cc |
| Safety and Effectiveness Equivalence | "about the same as that of any other hefilcon A lens." and "should be equivalent to any other FLEXLENS (hefilcon A) lens." |
| Physical Design (for PRS/RK eyes): | |
| Accommodation of topographical profile | Designed to improve vision where "difficult to achieve a satisfactory posterior lens surface to cornea alignment with rigid gas permeable contact lenses." |
| Alignment with visual axis | Designed to address issues where "Conventional soft (hydrophilic) contact lens designs do not readily align with the visual axis of the PRS or RK eye." |
| Masking of corneal astigmatism | Designed to address issues where "Conventional soft (hydrophilic) contact lens designs... [do not] supply sufficient masking of the corneal astigmatism." |
| Stability of visual acuity | Designed to address issues where "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." |
| Specific optical zone design | Flat central optical zone, thickness varies with power (e.g., -1.00D approx. 0.30mm thick in center), generally 8.0mm in size. |
| Peripheral carrier design | Thinner than most standard soft lenses (approx. 0.08 mm to 0.10 mm) to ensure limbal draping; periphery can be aspheric with a steeper curvature. |
Study Details
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
§ 886.5925 Soft (hydrophilic) contact lens.
(a)
Identification. A soft (hydrophilic) contact lens is a device intended to be worn directly against the cornea and adjacent limbal and scleral areas of the eye to correct vision conditions or act as a therapeutic bandage. The device is made of various polymer materials the main polymer molecules of which absorb or attract a certain volume (percentage) of water.(b)
Classification. (1) Class II if the device is intended for daily wear only.(2) Class III if the device is intended for extended wear.
(c)
Date PMA or notice of completion of a PDP is required. As of May 28, 1976, an approval under section 515 of the act is required before a device described in paragraph (b)(2) of this section may be commercially distributed. See § 886.3.