The reason cataracts form as we get older is not fully understood but a leading theory is that the lens is mostly made up of proteins which have to be organized in a very precise format in order for the lens to remain optically clear. Disruption of this organization causes opacities in the lens and thus a cataract.
Cataracts are the leading cause of blindness in the world. Currently there is no treatment for cataracts other then surgery. There are multiple "homeopathic" eye drops on the market that claim they prevent cataracts but none of them have any significant scientific backing.
That may soon change. In a recent issue of Nature, scientists have a found a chemical called Lanosterol, which is a sterol, that when injected into rabbit and dog eyes the researchers found an improvement in the cataracts that were present in the animal's eyes.
A second group of researchers then took that information and started searching related compounds. Their hope was to find a compound that was more soluble then Lanosterol so it could have the same effect but have the possibility of being delivered through an eye drop rather than having to be injected into the eye.
They found a compound that they are currently calling "compound 29" that when delivered as an eye drop to mice. THe researchers found that the compound could restore transparency to the mouse lenses affected by cataracts.
They also tested the compound on human lenses after they had been removed in surgery and found similar results to the tests on the mice. They published their research in the journal Science.
For now there is nothing on the market that can treat cataracts except surgery. The future, however, looks bright for a potential eye drop solution. Getting from animal research to an FDA approved commercial product usually takes many years so for now your most effective cataract treatment is surgery.