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:
- whether pseudophakia with conventional UV filter IOLs poses a risk for the onset
or
- progression of AMD
- whether epidemiological data are available showing that IOLs with an additional blue filter reduce the rate of AMD
and
- what side effects due to the use of blue-light-filtering IOLs have been described.
On reviewing the literature, it is initially striking that there are no clinical data to support a protective benefit of the
blue-light-filtering IOLs. Rather, there are studies of phototoxicity, which were conducted mainly on cell cultures and in
nocturnal rodents (which do not have a macula). The applicability of data obtained this way to humans is extremely problematic,
especially as low light exposure over years was simulated by brief high-intensity light exposure. To provide an analogy with
heat exposure: ten years of exposure at 25 ºC would be replaced by two days at 300 ºC. It sounds reasonable that the effect
on the organism (human, animal or cell culture) can not be compared. 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:
- no necessity
- no benefit
- possible undesirable side effects of blue-light-filtering IOLs
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.
