As a manufacturer, we would like to comment on the article written by Wijnants et al. on late-onset toxic anterior segment syndrome with Cutting-Edge Synthesis intraocular lenses (IOLs), which we read with great interest.1

The technical analysis performed was an attempt to explain the occurrence of observed adverse events that may be inappropriate: (1) Energy-dispersive x-ray spectroscopy provides a qualitative elemental analysis. Energy-dispersive x-ray spectroscopy peak heights provide semiquantitative elemental results on 1% or 2% of the total surface that is not proportional to detected atom quantity or to any toxicity threshold and does not provide a quantitative result about the total lens surface. (2) Photographs provided in the article of dried IOLs are normal salt deposits from balanced salt solution that preserve the IOL, dehydrated under vacuum. Photographs should not be misinterpreted as a massive particle contamination.

We present hereafter the total quantification of trace elements found within different IOLs, manufactured by our company or from competitors, using inductively coupled plasma mass spectrometry and/or inductively coupled plasma atomic emission spectroscopy. Those techniques can establish the total amount of an element present on and in an IOL by efficiently detecting, identifying, and reliably quantifying trace elements. There were 36 elements screened, and aluminum and silicone contents were extracted from the results and reported in this study. All measurements were performed by an independent laboratory (Aveyron Labo, France).

Pools of packaged IOLs (200 mg mini) were weighed, transferred to a microwave digestion vessel, and 9 mL of nitric acid (67% to 69%) was added. The vessel was capped, sealed, and left at room temperature for 30 minutes and placed into the microwave chamber. The temperature was ramped to 190°C, over 15 minutes, held for 25 minutes with a power of 12 000 W for digestion. After cooling, the digested sample was rinsed with Milli-Q (Purelab Flex, ELGA/VEOLIA) water, and internal standard was added (0.5 mL) and aliquoted with Milli-Q water. The resulting solution was clear, colorless with no particulates. A control (blank sample) was prepared similarly without the test article. The aluminum and silicone trace assessments are summarized in Table 1. The synthesis outcomes did not differ from those found with competitors' IOLs.

Table 1. - Silicone and aluminium compounds measured with AES/MS IOL studied Silicone (μg/g) Aluminum (μg/g) Hydrophilic  Competitive A 31 (AES) 1.5 (MS)  Competitive B 21 (AES) 3.1 (MS)  Competitive C 21 (MS) 1.57 (AES)  Synthesis preloaded   0.0 D 22 (AES) 1.3 (MS)   8.0 D 28 (AES) 1.2 (MS)   14.0 D 16 (AES) 1.3 (MS)   16.5 D 32 (AES) 2.9 (MS)   17.0 D 23 (AES) 2.1 (MS)   17.5 D 21 (AES) 2.1 (MS)   18.0 D 26 (AES) 1.6 (MS)   21.5 D 26 (AES) 1.5 (MS)   24.0 D 28 (AES) 1.9 (MS)  Synthesis toric preloaded Not measured 1.59 (AES) 1.10 (AES) 1.35 (AES) Hydrophobic  Competitive D 36 (MS) 1.93 (AES)  Competitive E 27 (MS) 1.65 (AES)  Competitive E preloaded 23 (MS) 1.78 (AES)

AES = atomic emission spectroscopy; MS = mass spectrometry

As for the aluminum toxicity threshold, Calogero et al. did not find any statistically significant different inflammatory response from the control group after an aluminum injection of 0.2 μg into the anterior chamber of rabbits at all timepoints.2 An IOL weighing a maximum of 30 mg would correspond to 6.6 μg/g. None of the findings described in Table 1 reaches this limit.

However, the absence of rinsing preloaded IOLs may result in injecting hundreds of microliters of the preservative solution into the eye, that is, 10 to 50 times more than in the case of a nonpreloaded lenses. Rinsing the IOL is a surgical gesture that is part of inflammatory reaction prevention.

1. Wijnants D, Delbeke H, Van Calster J, Beerlandt N, Nijs I, Werner L, Mamalis N, Saelens I. Late-onset toxic anterior segment syndrome after possible aluminum-contaminated and silicon-contaminated intraocular lens implantation. J Cataract Refract Surg 2022;48:443–448 2. Calogero D, Buchen SY, Tarver ME, Hilmantel G, Lucas AD, Eydelman MB. Evaluation of intraocular reactivity to metallic and ethylene oxide contaminants of medical devices in a rabbit model. Ophthalmology 2012;119:e36–e42