Age‐related pupillary miosis should be considered in pseudophakic circadian photoreception analysis ‐ Authors’ reply

performance of blue-blocking, yellowtinted IOLs in pseudophakic vs. crystalline lenses in phakic eyes. Retinal illuminance is proportional to the square of pupil diameter. For specific illumination, much less light passes through smaller 70-year-old pupils than larger 20-year-old pupils, especially in diabetics. Thus, age-related miosis progressively reduces retinal illuminance. Additionally, older adults typically receive less daily bright light exposure than younger adults. Moreover, retinal ganglion photoreceptor populations or sensitivity may decline with ageing or ocular disease, further reducing older vs. younger adults’ nonvisual photoreception. (Turner & Mainster 2008; Turner et al. 2010). We considered age-related photopic pupil size when we analysed crystalline lens and IOL circadian performance in adults of different ages in our articles dating back to 2008. (Turner & Mainster 2008; Turner et al. 2010) Brøndsted et al., ignore that work predating their initial 2010 report, (Kessel et al. 2010) citing instead other publications that fail to consider age-related miosis in calculating the relative photoreception or phototoxicity of elderly pseudophakes vs. younger pseudophakes or phakic individuals. We found that the equivalent phakic ages for pseudophakes with colourless IOLs are roughly 15–20 years more youthful than those with yellowtinted IOLs. Pseudophakes with blueblocking IOLs need approximately 50% more illumination for the rest of their lives to achieve circadian photoreception equivalent to pseudophakes with colourless IOLs, at an age when their environmental light exposure is often diminishing. (Turner & Mainster 2008; Mainster & Turner 2010; Turner et al. 2010). Ten of twelve major epidemiological studies show that environmental light is not correlated with AMD (age-related macular degeneration). (Mainster & Turner 2010, 2011) Nonetheless, Brøndsted et al., argue that ‘it may take a while before we have the necessary evidence’ presumably to prove that ‘blocking blue light may provide photoprotection to slow or prevent the development and ⁄or progression of AMD’. In essence, they apparently feel that the chromophores they consider to be too optically insignificant to adversely affect circadian photoreception might somehow reduce the risk of AMD. Blue-blocking IOLs eliminate half the light in the third of the visible spectrum between 400 and 500 nm, permanently reducing mesopic, scotopic and circadian photoreception while providing less photoprotection than crystalline lenses that do not prevent AMD. Furthermore, compelling evidence shows that cataract surgery with colourless IOLs does not accelerate AMD’s occurrence or progression. Yellow IOL tints cannot decrease AMD risks if cataract surgery does not cause it. (Mainster & Turner 2010, 2011). We agree with Brøndsted et al., that ‘the ageing process of the natural lens is expected to influence the photoentrainment of circadian rhythm’, as we showed in 2008, (Turner & Mainster 2008) but we also feel that manufacturers and ophthalmologists should not arbitrarily restrict pseudophakic photoreception with blue-blocking IOL chromophores. Prospective, randomized clinical trials will eventually determine the circadian significance of yellow lens chromophores, but age-related pupillary miosis must be considered in any theoretical analysis which compares photoreception or photoprotection in older pseudophakes vs. younger pseudophakic or phakic adults.