Using molecular scattering simulations and soft matter physics, a research team in Switzerland demonstrated that a perfect balance between two ocular proteins keeps the crystalline lens clear.1 Because this balance is so exact, any minor alteration may cause the proteins to aggregate, or condense, clouding the lens and obscuring vision.

Several factors, such as advanced age and excessive exposure to ultraviolet rays, can cause the crystalline proteins to modify their usual interaction patterns and begin to aggregate, resulting in cataract development. To date, no cure can reverse this process once it starts.

Three major crystalline proteins comprise the solution that keeps the lens clear. The researchers used a computerized molecular scattering program and found that a specific combination of weak attraction and repulsion between two of the proteins resulted in a balanced matrix that is transparent to visible light. If the molecular attraction becomes too weak, the individual proteins segregate and settle into densely packed homogenous domains. If the attraction becomes too strong, the individual proteins bond and clump together. If either situation occurs, cataracts develop.

Besides cataract, other systemic conditions, such as sickle cell, multiple myeloma and Alzheimers disease, are also caused by similar protein or molecular condensation.2

The results of this study not only provide a much better fundamental understanding of these protein-concentration diseases, the authors say, but also may offer critical information about how to slow or even entirely prevent protein aggregation in the ocular lens.

1. Stradner A, Foffi G, Dorsaz N, et al. New insight into cataract formation: enhanced stability through mutual attraction. Phys Rev Lett 2007 Nov 9;99(19):198103.
2. Benedek GB. Cataract as a protein condensation disease: the Proctor Lecture. Invest Ophthalmol Vis Sci 1997 Sep; 38(10):1911-21.