Between 2002 and 2004, surgeons in UK hospitals began to see calcification of Bausch and Lomb Hydroview foldable lens implants, usually progressing to the need for explantation (Figure 1).1, 2, 3 None of the affected hospitals were routinely using Viscoat, known by this time to be associated with calcification of Hydroview lenses.4, 5

Figure 1
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Hydroview lens implant exchanges by month of original impantation. Department names are followed by the year of latest available figures.

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A total of 474 implants, out of 8239 lenses implanted between September 2000 and April 2001 at the seven hospitals, were explanted because of calcification (5.8%, Table 1). The wide geographical variation might be due to Na2HPO4 in the viscoelastics (Table 2). One of the authors, NH, noticed that more of his patients (Provisc) were affected than those of his colleague (Healon).

Table 1 Explantation rates for lenses implanted over the risk period of September 2000 to April 2001
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Table 2 Levels of constituents of several viscoelastic agents used by hospitals affected by calcification of Hydroview lens implants
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The lens exchange rate at Epsom and St Helier Hospitals in Surrey was much lower than elsewhere. An intriguing coincidence was that the Sutton and East Surrey Water Company was the only one in the country to soften the water it supplied. This possible explanation, however, was shown to be unlikely by a small study (Research Ethics Committee Ref 05/Q0104/171), which showed that the aqueous calcium levels of routine cataract patients at Peterborough, where the exchange rate was 40 times higher, were 0.72 mM±0.18, (mean±SD, n=20) compared with 0.73±0.19, n=12 at Epsom and St Helier Hospitals.

The absence of an explanation of the timing of this problem leaves the ophthalmic community less certain that a similar outbreak will not occur again. The recent report of calcification of an Akreos Adapt (another Bausch and Lomb hydrophilic acrylic lens) is hopefully a one-off.6

The authors and others believe that the reporting of cases of calcification to the Medicines and Healthcare Products Regulatory Agency (MHRA) has been less than ideal. A dedicated electronic link to report device issues to the MHRA now appears on the website of the Royal College of Ophthalmologists. In time, the electronic patient record (EPR) might incorporate a button for explantation of a lens for bioincompatibility reasons, which could automatically alert the MHRA.