Sir,

Calcification of an intra-ocular lens (IOL) is an infrequent but clinically significant event. We report four cases of late calcification of Rayner (Hove, UK) hydrophilic acrylic intra-ocular lenses (HA-IOLs) after Descemet’s stripping automated endothelial keratoplasty (DSAEK).

Case details are outlined in Table 1. All patients were pseudophakic with clear IOLs before DSAEK surgery. Opacification over the centre of the optic occurred between 7 and 26 months post DSAEK, necessitating IOL exchange. Ultrastuctural analysis on three explanted lenses with Alizarin red staining, X-ray spectroscopy, and scanning electron microscopy confirmed calcification as the cause (Figure 1).

Table 1 Details of four cases with intra-ocular lens calcification
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Figure 1
figure 1

(a) Opacification of the IOL optic in Case 1, (b) scanning electron microscopy (SEM) cross-section demonstrating calcium crystals within the IOL optic just below the surface and (c) SEM of the IOL surface showing discrete elevations associated with sub-surface deposition of crystals leading to focal disruption of the anterior lens surface in places.

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Our case series adds to the growing body of evidence that HA-IOLs in general are at risk of calcification post DSAEK. Besides Rayner, reports have recently implicated Akreos Adapt1 (Bausch and Lomb Inc., Rochester, NY, USA), Memory Lens2 (Ciba Vision, Duluth, GA, USA), EasyCare6002 (Tekia Inc., Irvine, CA, USA), 47c2 (Acrimed, now Oculentis, Berlin, Germany), and CF Acrylic lenses2 (Humanoptics, Erlangen, Germany) in post-DSAEK calcification.

All of our patients required repeat injection of intra-cameral air to achieve graft attachment (‘re-bubbling’), which is a consistent risk factor across these reports. Isolated cases of HA-IOL calcification in non-DSAEK patients where intra-cameral gas was used for other indications—such as C3F8 and SF6 for a Descemet’s tear3 and SF6 for ocular hypotony1—support the role of intra-cameral gas in the pathogenesis of HA-IOL calcification.

We propose that the trauma of repeat surgery involved in re-bubbling may disrupt the blood–aqueous barrier, increasing the concentration of calcium ions. The consistent finding of calcification restricted to the central part of the optic not protected by iris, suggests that the gas bubble in physical contact with the IOL surface is an important biochemical trigger for calcification.

We have never encountered HA-IOL calcification in patients after routine cataract surgery or after DSAEK with only one bubble of air. However, an institutional audit identified 10 patients with a Rayner HA-IOL who required a re-bubble after DSAEK. That four of these (all described in this report) developed subsequent lens calcification suggests a significant risk. We now use hydrophobic IOLs in patients with corneal pathology who may require DSAEK in future, given that IOLs with lower water content are less prone to calcification.4, 5