How to setup accessibility color theme on Unity editor?

Hi.

I'm a Java programmer and starting on with Unity 5 Personal planning use it in a game project with some friends. But I have a visual impairment that turns impossible to me use softwares with bright background. I work with many OSs and development tools setting up colors to a dark background and a bright font. But I can't found an option like this on Unity editor...

I found a "Editor skin" option in Colors Preferences but this is unavailable... is this the option that I looking for? And... why this is unavailable?

How can I change the color theme of Unity editor to a bright text over dark background?

Or... how can I change the color theme to use the operating system colors (Windows with accessibility color theme)?

I hope that exists an accessibility config on Unity cause we can't use it without this... this exist, right? =)

Thanks.

Cristiano Alexandre Moretti (Pan Veritrax)