Who can play goalball, and what are the B1, B2 and B3 classes?

Goalball is played exclusively by athletes who are blind or visually impaired, in men's and women's teams. Athletes are placed in one of three sport classes: B1, B2 or B3, with B1 and B2 covering the most severe impairments (B1 is totally blind).

At the international level, players must be legally blind, meaning less than 10% vision. All players wear eyeshades, so athletes with complete and partial blindness compete on equal terms.

Sources: https://canadianblindsports.ca/goalball/about-the-game/ and https://ibsasport.org/sports/goalball/about/classification/