Proc. Natl Acad. Sci. USA http://doi.org/w48 (2014)
Age may bring wisdom, but it also tends to come with the inability to see things clearly — even when they're right in front of you. Presbyopia is a common condition involving progressive difficulty focusing on nearby objects, and it's associated with a hardening of the lens of the eye. Scattering data reported by Giuseppe Foffi and colleagues may hold the key as to why this is the case: their measurements are consistent with the appearance of a glassy arrested state in solutions of α-crystallin — a protein known to be abundant in the lens.
The transparency of the lens, which is crucial for clear vision, has previously been linked to short-range order between α-crystallin proteins. Foffi et al. found that their protein solutions were structurally liquid-like, consistent with a polydisperse hard-sphere model. And their dynamic light scattering and viscometry measurements pointed toward the existence of a glass transition, corroborated by molecular dynamics simulations and mode-coupling theory. The results suggest that the α-crystallin in our lenses may have a role in the onset of presbyopia.