Blue-light-filtering lens – theory versus empirical experience?

Intraocular lenses (IOL) with a blue light filter were first developed by Hoya Corp. in the mid-1990s. The aim was to improve contrast vision by reducing transmission of the blue segments of light. Only later it was hypothesised that blue-light-filtering IOLs might protect the retina against light of short wavelengths and thus indirectly have a protective effect on age-related macular degeneration (AMD).

The major IOL manufacturers have pursued very different marketing strategies with blue-light-filtering IOLs. While some companies included the blue-light-filtering IOLs in their product portfolio and advertised them more or less vigorously as innovation, other manufacturers did not include any of these IOLs in their programme. Both camps found their experts arguing about the sense and nonsense of blue-light-filtering IOLs and the discourse of specialists, often also working as paid consultants, enlivens many ophthalmological conferences today.

Since the advocates of the blue-light-filtering IOLs regard these lenses as an innovation, the advantage compared with the previous standard (conventional IOL with the usual UV filter) has to be demonstrated. The "burden of proof" rests with the advocates of the new. In view of the very large numbers of cataract surgeries and the high co-morbidity of cataract and AMD, adequate clinical data about the benefits of blue-light-filtering IOLs should have been gained in the last 15 years since the introduction of these IOLs. Such studies should show:

Although there are no clinical studies on the photoprotective effect of the blue-light filtering IOLs, a theoretical need for such lenses could nevertheless be identified, if implantation of conventional IOLs leads to deterioration of AMD. However, this does not seem to be the case: While earlier studies indicated that cataract surgery increases the risk for AMD, this was not proven in a series of current studies. The 25th AREDS report should be particularly emphasised (Risk of Advanced Age-Related Macular Degeneration after Cataract Surgery in the Age-Related Eye Disease Study, AREDS Report 25, Ophthalmology 2009;116:297–303), as no association was found between the pseudophakic status of an eye and the occurrence of neovascular AMD. A (statistically) protective effect of pseudophakia was even detected for the progression of geographic AMD. The results of this study are notable for several reasons. Firstly, the AREDS is probably the largest and most complex prospective epidemiological study of AMD (8050 eyes, average follow-up time 9.5 years).

Secondly, some of the co-authors contradict their own results from earlier studies, namely the Beaver Dam and Blue Mountain studies. In these, the data were still interpreted as cataract surgery being a risk factor for progression of AMD. It can be assumed that these earlier results were revised only on the basis of particularly solid data. The authors discuss the causes of the conflicting results and see possible reasons in modern cataract surgery.

A large proportion of the patients in the older studies were left aphakic following cataract extraction. In addition, all modern IOLs already feature an UV filter. Thus, the new AREDS data argue against the fact that there is any need for the implantation of blue-light-filtering IOLs.

The potential disadvantages of such lenses have also to be considered as there are, for example, possible disturbances of circadian rhythm, higher costs, possible elution of the yellow dye from the IOL and possibly toxic effects on intraocular structures. Just recently, a blue-light-filtering IOL was recalled by the manufacturer because the dye dissolved out of the lens material.

In summary, the current data show:

So, implantation of blue-light-filtering IOLs does not appear to make sense.

The only exception might be patients whose second eye is operated and who have already received a blue-light-filtering IOL in the first eye. That way, disturbed colour perception due to different IOLs may be avoided.