Does indoor tanning cause cataracts?

Any U-V light can. Tanning involves exposure to u-v (ultraviolet) light. This wavelength of light has been connected with increased growth of cataracts, and with progression of macular degeneration. If you are tanning, you should always wear the protective eyewear that they provide, and when you are out in the sun, you should wear hats and/or sunglasses to shield your eyes.
It may. Uv light exposure without protection increases cataract formation. Wear protective eyewear while tanning.