The Aging Eye and Circadian light:Brief Overview

Thomas Hornick MD

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Wikipedia, accessed 10/30/09

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Disruption of circadian rhythm

• Poor performance/fatigue (Reinberg et al, 2007, Laposky et al 2008)

• Weight gain(Knutson et al, 2007)• Breast cancer (Stevens et al 2001)• Other conditions

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Eye changes with ageCorneal thickening reduces light

Lens opacifies, increases absorption of light, especially in shorter wavelengths

Decreasing pupillary size.

Decreasing ciliary contraction leads to presbyopia

Loss of retinal and optic nerve cells

Aging and light

• Older adults spend much of their time in muted indoor lighting. • 35 minutes/day of bright light exposure compared to

approximately 58 minutes of bright light per day for middle-aged adults. (Sanchez 1993)

• Reduced light exposure compounded due to physiologic changes • senile meiosis, cataract formation, and/or increased

light absorption by the crystalline lens. (Charmin 2003) • Attenuation of light exposure by more than 80% in

normal older adults relative to young adults.

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Turner et al Br J Ophthalmol. 2008 November; 92(11): 1439–1444

Spectral sensitivity of photopic, scotopic and circadian (melatonin suppression) photoreception

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Circadian light transfer function

Figueiro, et al. 2006

Age related losses in retinal illumination

9Turner et al Br J Ophthalmol. 2008 November; 92(11): 1439–1444

Wikipedia, accessed 5/2010