A tissue-treating portion of a surgical instrument includes a body defining a cavity and a light-energy transmissible sphere captured within the cavity such that a portion of the light-energy transmissible sphere protrudes from the body. The light-energy transmissible sphere is capable of unlimited rotation in all directions relative to the body. The light-energy transmission cable extends through the body to a position spaced-apart from the light-energy transmissible sphere. The light-energy transmission cable is configured to transmit light energy to the light-energy transmissible sphere. The light-energy transmissible sphere, in turn, is configured focus the light energy towards tissue to treat tissue.