Ophthalmic implants — Ocular endotamponades
1Key Takeaways
This document applies to ocular endotamponades (OE), a group of non-solid surgically invasive medical devices introduced into the vitreous cavity of the eye to flatten and position a detached retina onto the retinal pigment epithelium (RPE), or to tamponade the retina. With regard to the safety and efficacy of OE, this…
2Expert Interpretation
An in-depth interpretation of ISO 16672:2020, the international standard for intraocular fillers, covering key technical requirements such as chemical properties, biocompatibility testing, and clinical evaluation, and analyzing the application specifications and safety controls of three types of fillers: gas, silicone oil, and perfluorocarbon liquid.
Analysis of the core content of the standard
ISO 16672:2020 establishes technical requirements for the entire process from raw material control to clinical application for the special medical device category of intraocular fillers. The standard applies to three main types of fillers: gas, silicone oil and perfluorocarbon liquid.
Comparison of key technical indicators
| Parameters | Gases | Silicone oils | Perfluorocarbon liquids |
|---|---|---|---|
| Density (kg/m³) | Expansion coefficient must be specified | Must be measured | Must be measured |
| Endotoxin limit (EU/ml) | ≤0.2 | ≤0.2 | ≤0.2 |
| Clinical study period | 6 months±2 weeks | 12 months ± 1 month | Requires risk analysis |
Key requirements for biosafety
Chapter 6 of the standard specifies the biosafety evaluation requirements in detail, among which the endotoxin test limit is tightened from 0.5 EU/ml in the 2015 version to 0.2 EU/ml. For perfluorocarbon liquids, the new Annex C specifically regulates the detection method of incompletely fluorinated pollutants (including HF), requiring control below 10ppm.
The animal experiment design emphasizes: The rabbit eye model should be used with caution due to differences in retinal vascularization; it is recommended to use an animal model that is closer to the human retinal structure.
Clinical Evaluation Standards
Appendix B provides clinical study design templates for three types of fillers:
- Gases: primary endpoints include the incidence of intraocular pressure ≥30 mmHg and the rate of macular hole closure
- Silicone oils: focus on monitoring emulsification and the success rate of anatomical reattachment of complex retinal detachment
- Perfluorocarbon liquids: the effect of intraoperative retinal reattachment needs to be evaluated
The standard gives an example of the sample size calculation formula. Taking the silicone oil study as an example, when the incidence of increased intraocular pressure in the control group was 13%, approximately 140 patients in each group were required to prove non-inferiority.
Implementation Suggestions
Manufacturers need to pay special attention to the following:
- The new version has tightened the EO residue limit: EO≤1.25µg/dose, ECH≤5.0µg/dose
- The packaging needs to add the minimum operating pressure label (gas products)
- Silicone oil products must warn about the risks of CO2 laser use
- The transport stability test temperature must not exceed 45℃