Sir,

We read with interest the recent correspondence by Yusuf et al1 describing the factors influencing black intraocular lens (IOL) selection for intractable diplopia.

We present retrospective data on our experience with opaque IOLs over a span of 11 years (2003–2014) at our tertiary strabismus and vitreoretinal referral centre in Scotland. Our findings are summarised in Table 1.

Table 1 Patient characteristics
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Five of our six patients were phakic, and underwent routine phacoemulsification surgery, with insertion of a custom-made Ophtec 0.0D black polycarbonate Ani II (‘no hole’) IOL into the capsular bag. This lens takes ~12–14 weeks to manufacture, and technical specifications are shown in Figure 1. Its 9-mm optic diameter allows implantation in the capsular bag, and limits side illumination in scotopic conditions. However, as it is not foldable, implantation requires a proportionately larger corneal incision, which could potentially prolong postoperative recovery and increase the risk of future infection and globe rupture.

Figure 1
figure 1

Custom-made Ophtec Ani II 0.0 Dpt. Black. Polycarbonate, nonfoldable, posterior chamber IOL (incision >9 mm). Reformatted image, reproduced with permission from Ophtec BV.

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Whilst we have not formally tested for its near-infrared (NIR) properties, other opaque polycarbonate IOLs in use, such as Ophtec ‘pupil occluder’ iris claw IOLs, have been shown to be NIR-blocking, thereby providing total light occlusion and minimising the risk of treatment failure.1, 2 Clinically, all five patients had good resolution of intractable diplopia, albeit with variable light perception. The absolute occlusion with consequent symptomatic reduction of field resulted in explantation of the opaque IOL in one patient. This highlights the importance of considering loss of visual field with complete occlusion, and subsequent poor adaptation to monocular vision.

One patient had known Type II diabetes mellitus. Implantation of opaque IOLs in diabetics may be considered a relative contraindication,3 and has not previously been described in the literature to our knowledge. Systemic conditions like diabetes tend to cause bilateral symmetrical ocular pathology.4 In the authors’ opinion, regular fundus surveillance of the fellow eye provides a reasonable proxy that predicts development of diabetic eye disease in the occluded eye. However, we concur that higher risk patients may benefit from longer-term follow-up with posterior segment imaging including optical coherence tomography, for example, those with choroidal naevi, suspicious discs, or lattice degeneration.