Chorioretinal Toxicity of Perfluorooctane (Ala Octa): Results From 48 Surgical Procedures in Geneva

Ala®sil chemical characterization and toxicity evaluation: an example of the need for the Medical Device Regulation 2017/745

Introduction: Ala®sil infusion was on the market for clinical use under the Medical Devices Directive (MDD) 93/42/EEC as an irrigating solution based on polydimethylsiloxane (PDMS). The product was withdrawn in 2016, and to the best of our knowledge, it did not cause any health damage. Methods: A bibliographic review and experimental analysis were conducted to evaluate whether this CE-marked product could have been used in patients under the current Medical Device Regulation (MDR) 2017/745. Analytical results from gas chromatography-mass spectrometry (GC-MS) and matrixassisted laser desorption ionization (MALDI) were performed. Citotoxicity studies were also carried out. Results: Only one study related to Ala®sil clinical use was found, describing a pilot series of five patients. The authors rated the product as not helpful in three out of the five cases for internal searching of retinal breaks and in four out of the five cases for drainage of subretinal fluid. No other scientific papers or documentation was found regarding Ala®sil's safety. Nevertheless, the product was introduced in the market after achieving the CE marking. GC-MS and MALDI showed that the polymer has a low molecular weight of 1,000 g/mol. Several linear and cyclic low-molecular-weight components (LMWCs) were identified as impurities ranging from L3 to D8, with a molecular weight below 600 g/mol. The Ala®sil sample was found to be cytotoxic after 24 h of cell culture but non-cytotoxic after 72 h, probably due to the cellular regeneration capacity of an immortalized cell line. Tissular cytotoxicity revealed an increased apoptosis rate but without morphological modifications. Discussion: Although Ala®sil cannot be classified as cytotoxic, this substance appears to increase retinal cell death processes. This study supports the notion that the MDDwas not functioning adequately to ensure the safety of medical devices. However, the current MDR 2017/745 imposes stricter standards to prevent the commercialization of medical devices without high-quality preclinical and clinical information, as well as precise clinical verification for their use, information not available for Ala®sil infusion.

Heavy Silicone Oil as an Endotamponade in Recurrent or Complicated Retinal Detachment and Macular Hole

Objectives:

To evaluate the efficacy and safety of heavy silicone oil as an endotamponade in patients with recurrent or complicated retinal detachment and macular hole.

Materials and Methods:

Nineteen eyes of 19 patients who underwent heavy silicone oil endotamponade for different indications were included in the study and evaluated by retrospective chart review. At each visit, patients underwent detailed ophthalmological examination and anatomical and functional outcomes, silicone oil emulsification, intraocular inflammation, presence of proliferative vitreoretinopathy, preoperative and postoperative visual acuity, and postoperative complications were recorded.

Results:

The study included 19 eyes of 19 consecutive patients: 13 women (68.4%) and 6 men (31.6%). The patients’ median age was 60 years (interquartile range [IQR]: 44-70 years) and the median follow-up time was 19 months (IQR: 9-31 months). Indications for heavy silicone oil endotamponade were recurrent retinal detachment in 11 eyes (57.8%), inferior retinal detachment in 5 eyes (26.3%), inferior rhegmatogenous retinal detachment, recurrent macular hole in 2 patients (10.5%), and macular hole in 1 patient (5.2%). Median best corrected visual acuity was 2 logMAR (IQR: 1-2.6) preoperatively and 0.99 logMAR (IQR: 0.4-2) postoperatively (p<0.001). Postoperative anatomical success was achieved in all patients. Densiron 68 was used for endotamponade in 14 patients (73.7%), Densiron XTRA in 3 patients (15.8%), and AlaHeavy 1.07 in 2 patients. Heavy silicone oil emulsification was observed in only 3 patients (15.8%).

Conclusion:

Although heavy silicone oil has limitations as an endotamponade, such as intraocular pressure increase, emulsification, intraocular inflammation, and the risk of complications during removal, it is a safe and effective alternative in eyes requiring inferior retinal tamponade for indications like proliferative vitreoretinopathy and recurrent macular holes.

Acute intraocular toxicity caused by perfluorocarbon liquids: safety control systems of medical devices

BACKGROUND

Acute retinal toxicity has been demonstrated to be associated with the intraoperative use of perfluorocarbon liquids (PFCLs), especially perfluorooctane (PFO). Recently, several cases of PFO-associated blindness have been reported in Spain, Holland, France, Italy, the Middle East, and South America.

METHODS

As a result, a new ISO guideline (ISO 16672:2020) was drafted, discussed, approved, and released in 2019. This recent ISO16672:2020 guideline recommends performing direct cytotoxicity tests as an option along with chemical analysis to measure PFCL quality (purity and safety).

RESULTS

In this review paper, it has been emphasized why an appropriate biological test, specifically direct exposure of PFCL to live cells, for measuring cytotoxicity must be performed with each PFCL batch along with chemical analysis.

CONCLUSIONS

The paper intends to compile all available information to discuss possible approaches for avoiding adverse clinical cases in future.

Intraocular perfluorodecalin and silicone oil tamponade (double filling) in the management of complicated retinal detachment: functional and anatomical outcomes using small-gauge surgery

Purpose

To describe the functional and anatomical results of complicated retinal detachment (RD) treated with small-gauge pars plana vitrectomy (PPV) and combined perfluorodecalin and polydimethylsiloxane tamponade (double filling, DF).

Methods

Retrospective analysis of consecutive patients with complex RD (severe proliferative vitreoretinopathy, inferior/posterior/giant retinal tears, and traumatic detachments) treated with small-gauge PPV, membrane peeling, and DF at the Department of Ophthalmology at San Gerardo Hospital, Monza, Italy. Main outcome measures included best-corrected visual acuity (BCVA), rates of retinal reattachment, and complications.

Results

This study included 15 patients with a median follow-up (FU) of 6 months (range 1–22). Three patients with early retinal redetachment under tamponade and FU shorter than 3 months were excluded from the final functional analysis, but they were considered anatomical failure. At the last examination, BCVA improved in 50% of patients and remained stable in 25% of patients and anatomical success was achieved in 73% of eyes, 64% of them without any endotamponade. Three eyes had retinal redetachment after perfluorodecalin/silicone oil exchange because of diffuse proliferative vitreoretinopathy (PVR) and required reoperation to achieve retinal attachment. In eyes with anatomical success, macular pucker was the most frequent long-term complication (27%).

Conclusion

In the management of complex RD, small-gauge pars plana vitrectomy, and double filling endotamponade using wide-angle viewing systems was a well-tolerated and effective technique to preserve visual acuity and achieve anatomical success.

Intraocular toxicity caused by MEROCTANE perfluorocarbon liquid

Serious intraocular toxicity cases have been reported worldwide after the use of different perfluorocarbon liquids. The current study reports for the first-time the clinical pictures of cases of acute intraocular toxicity caused by MEROCTANE, a perfluoro-octane commercialized by a Turkish company and distributed in many countries. A series of 18 cases from Chile and Spain was retrospectively analysed. To evaluate the impurity profile, a suspicious MEROCTANE sample (lot OCT.01.2013) was analysed by gas chromatography mass spectrometry and compared with a non-suspicious sample of the same commercial perfluoro-octane (lot OCT 722011). Cytotoxicity was tested following a direct-contact method, taking into consideration the high volatility and hydrophobicity of perfluoro-octane and following the ISO 10993 guideline. Cytotoxicity test showed clear cytotoxic effects of the analysed batch (less than 9% of cell viability). Moreover, chemical analysis demonstrated the presence of many contaminants, some highly toxic (acids and alcohols). Perfluorocarbon liquids are useful tools for intraocular surgery but companies and Agencies of Medical Devices must implement measures that guarantee the safety of these products based on both chemical and cytotoxicity analysis for every batch. Medical staff should be encouraged to report any suspected case to their respective National Agencies.