Blue light-blocking IOLs unnecessary

There is no current proof that blocking blue wavelengths guarantees retinal protection and, couple this with the fact that blocking this form of light causes an actual loss in visual quality, Alessandro Franchini MD, suggests we concentrate our efforts on blocking UV and violet radiations instead.

It has been an acknowledged fact for more than 25 years that UV radiation is potentially harmful to the retina and more recent studies have suggested that there is also a relationship between violet and blue radiations and macular degeneration. Franchini, of the University of Florence Eye Institute, Italy, discussed the results of a study comparing three light blocking IOLs: the AMO ClariFlex silicone lens with UV block, the Alcon AcrySof Natural lens that blocks UV, violet and 50% of blue light and the AMO OptiBlue which blocks UV and violet wavelengths. The aim of the study being to assess which lens provides the best protection whilst also retaining good visual results.

Using dedicated software and a pseudophakic eye model, the CIE (Commission Internationelle d'Eclairement) day and night curves were calculated. The curves define the average efficiency of the standard eye according to wavelength, taking into consideration photopic and scotopic conditions. First the ClariFlex and Alcon Natural lenses were compared; the difference in their day curves was negligible, however, their night curves were significantly different, with the Clariflex proving to be more sensitive. A similar result was seen when comparing AMO OptiBlue and Alcon Natural, the OptiBlue was considerably more sensitive in scotopic conditions.

The lenses were then given an efficiency value (EV): Clariflex was given an EV of 100%, in scotopic conditions, OptiBlue was given an EV of 97% and the Natural lens just 90%.

The clear conclusion seems to be that, while blocking UV and violet wavelengths is both efficient and safe, blocking blue light is unnecessary since it is not guaranteed to offer further protection and it can cause a loss in the quality of vision.

Ophthalmology Times Europe reporting from the XXIV Congress of the ESCRS, London, 9-13 September, 2006.