Response to ‘Comment on The evidence informing the surgeon’s selection of intraocular lens on the basis of light transmittance properties’

Sir,

We thank Professor Hammond for his correspondence, which serves to strengthen our conclusion that there is no evidence base that can justify anyone to advocate for blue-blocking intraocular lenses (IOLs) over ultraviolet (UV)-only blocking IOLs.

Professor Hammond takes issue with our conclusion (that is, ‘In terms of photoprotection, there is no Level 2b([or higher) evidence in support of blue-filtering IOLs vs UV-only filtering IOLs.¹’) on the basis that we did not cite select publications, which he has now kindly brought to our attention. Accordingly, we would like to bring the Editor’s attention to Table 1, which includes all of the publications alluded to by Professor Hammond, and which clearly illustrates that there remains no Level 2b evidence (or higher) in favour of blue-blocking IOLs over UV-only blocking IOLs.

Table 1 Evidence level

Furthermore, not a single publication (ever) that has advocated for blue-blocking IOLs has measured MP, another prereceptoral filter that absorbs blue light and has profound implications for vision (as demonstrated by Professor Hammond’s own work^{2, 3, 4}) and for macular health.⁵

Accordingly, and in keeping with the findings of Professor Hammond and others, a study designed to comment upon the impact of blue-blocking IOLs vs UV-only blue-blocking IOLs that does not measure and account for MP not only fails to address the research question but even precludes the possibility of addressing the research question.

In conclusion, we thank Professor Hammond for the interest he has shown in our work, an interest, which copperfastens our contention that there is no evidence-based justification for implanting blue-blocking IOLs over UV-only blocking IOLs at the time of cataract surgery.