(165 days)
The AlphaSphere Orbital Implant is intended to replace orbital volume after loss of an eye through enucleation or evisceration, including secondary implantation after removal of an existing, unsatisfactory, orbital implant. The device is indicated in any situation where silicone, acrylic, polyethylene, coral, glass, or other traditional orbital implants are used.
The AlphaSphere Orbital Implant is aspherical orbital volume replacement prosthesis with a posterior gel hemisphere resistant to tissue ingrowth and an anterior hemisphere with a spongy outer surface designed to encourage tissue attachment. The implant is made entirely of a flexible hydrogel, poly (2-hydroxyethyl methacrylate). (PHEMA). The physical differences between the gel and spongy portions of the implant are created by varying the conditions during the hydrogel polymerization process. The transition between the two hydrogel regions is reinforced with a biocompatible synthetic mesh (MERSILENE) beneath the device surface to improve mechanical strength for the passage of sutures.
Here's an analysis of the provided text regarding the AlphaSphere Orbital Implant, focusing on the acceptance criteria and the study used to demonstrate its performance:
Summary of Acceptance Criteria and Device Performance
It is important to note that this 510(k) submission primarily relies on demonstrating substantial equivalence to predicate devices rather than setting and meeting specific quantitative acceptance criteria for the new device's performance. The "acceptance criteria" here are implicitly tied to the safety, efficacy, and performance of the predicate devices and the AlphaSphere Orbital Implant's ability to demonstrate similar outcomes.
| Acceptance Criterion (Implicitly based on Predicate Equivalence) | Reported AlphaSphere Orbital Implant Performance (from provided studies) |
|---|---|
| Safety: | |
| Biocompatibility of materials | Constituent materials (PHEMA and Mersilene) have a history of use as implanted devices and are of known biocompatibility. Published peer-reviewed studies establish PHEMA's biocompatibility and ability to allow biointegration. |
| Absence of complications (e.g., retrobulbar hemorrhage, infection, extrusion) | All 8 rabbits in the AlphaSphere study retained their implant to the end of the study period (up to 52 weeks) without complications. |
| Performance/Integrity: | |
| Mechanical strength and integrity | Integrity of the device in situ is assured through the strength of the interpenetrating polymer network (IPN). Mersilene mesh provides firm anchorage for extraocular muscle sutures without risking tearing. In vitro studies with a Sintech mechanical tester demonstrated adequate mechanical strength. |
| Secure muscle attachment | Scans demonstrated muscle attachment to the anterior half of the implant. Histology confirmed muscle attachment and cellular/vascular ingrowth. |
| Effectiveness (Tissue Integration): | |
| Fibrovascular ingrowth | Histology confirmed cellular and vascular ingrowth. Initial inflammation and vascularization developed into quiescent fibroblastic tissue. |
| Retention in situ | All 8 rabbits retained their implant to the end of the study period. |
| Facilitates direct muscle attachment without additional measures | Demonstrated that the device can be implanted without prior tissue or mesh coverage, drilling, or soaking. Direct attachment of extraocular muscles by passing sutures through the sponge region. |
Detailed Study Information:
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Sample Size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective):
- AlphaSphere Study: 8 rabbits. The study was prospective as it involved implanting devices and then monitoring them over time. The country of origin for the study is not explicitly stated, but the applicant's address is in Australia.
- Predicate MEDPOR Study (for comparison): 10 rabbits. This was also a prospective animal study. Country of origin not explicitly stated.
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Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience):
- The studies mentioned (Hicks et al. for AlphaSphere and Jordan et al. for MEDPOR) involved animal models and histological examination.
- AlphaSphere: The "ground truth" was established through gadolinium-enhanced Magnetic Resonance Imaging (MRI) and subsequent histopathology (light and electron microscopy) evaluation of the implants after sacrifice. The number and qualifications of the experts performing these assessments (e.g., veterinary radiologists, pathologists) are not specified in the provided text.
- MEDPOR: The "ground truth" involved histopathology to evaluate implant vascularization. The number and qualifications of the experts are not specified.
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Adjudication method (e.g. 2+1, 3+1, none) for the test set:
- The provided text does not describe an adjudication method for establishing ground truth in terms of expert consensus or arbitration. For animal studies with histological and imaging assessments, it's typical for a pathologist/radiologist to interpret findings, but no explicit adjudication process among multiple experts is detailed.
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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, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This device is an orbital implant, not an AI-assisted diagnostic tool, so such a study would not be applicable.
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If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
- Not applicable. This is a physical medical device, not an algorithm.
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The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- For the animal studies, the "ground truth" for assessing device performance (tissue integration, muscle attachment, complications) was primarily based on histopathology (microscopic examination of tissues) and imaging (gadolinium-enhanced MRI for AlphaSphere). The ultimate "outcome data" was whether the implants were retained without complications and exhibited the desired biological responses.
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The sample size for the training set:
- Not applicable. This device is a physical implant, not a machine learning model. There is no "training set" in the context of AI. The development process involved prior research on the materials and prototypes, but this is not analogous to an AI training set.
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How the ground truth for the training set was established:
- Not applicable, as there is no training set in the AI sense. The developmental work and existing literature on PHEMA and Mersilene would have informed the design and expected performance, but this is not "ground truth" establishment for a training set.
§ 886.3320 Eye sphere implant.
(a)
Identification. An eye sphere implant is a device intended to be implanted in the eyeball to occupy space following the removal of the contents of the eyeball with the sclera left intact.(b)
Classification. Class II (special controls). The device, when it is an ocular peg which is supplied sterile only, is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 886.9.