The group's principal activity is to develop and operate value-priced laser vision correction centers. these centers provide the facilities, equipment and support services for performing vision correction procedures using state-of-the-art laser technologies to correct nearsightedness, farsightedness and astigmatism. the group currently utilizes two primary excimer lasers: the bausch and lomb technolas 217 and the visx star s2 laser. laser vision correction procedures are designed to reshape the outer layers of the cornea to correct refractive vision disorders by changing its curvature with an excimer laser. the group operates 34 laser vision correction centers, 31 of which are located in metropolitan markets throughout the united states, two in canada and one in europe. laser refractive surgery accounted for 99% of 2001 revenues and other, 1%.