The fibers that comprise the lens of the eye are specialized to transmit light. Damage to these fibers, and particularly to the developing immature cells that give rise to them, can result in dark spots in the lens called cataracts, which can interfere with vision.

Acute exposure of 200 rads (2 Gy) or more can induce the formation of vision-impairing cataracts.

Exposure to 1,000 rads (10 Gy) over a period of months can also cause cataracts.