The problems related to the effect of radiation exposure on the transmission optics used in diagnostic systems of the International Thermonuclear Experimental Reactor (ITER) are considered. These problems are discussed using the example of H-alpha and Visible Spectroscopy (HA&VS) in the equatorial port 11 of the ITER. Using neutron calculations based on the Monte Carlo method, radiation conditions for diagnostic components in the equatorial port, including the port cell area, are determined. A brief review of radiation effects and radiation tests of optical materials is presented. On the basis of the results of these tests and data on the radiation environment, the optical performance of the visible spectroscopy diagnostic components at the end of ITER lifetime is assessed.