Sts. Cosmas and Damian are included on Western list of Saints who are counted as intercessors for persons with visual impairments. But they are also very familiar to Eastern Orthodox Christians, for they were from the East.
These brothers were physicians; the Holy Spirit also granted them the gift of healing through prayer illnesses of soul and body. That they were “unmercenary” means that they would take no payment for neither their medical efforts nor for their intercessory prayers.
They were martyred for Christ during the reign of Emperor Diocletian in 303 A.D.
From the website of St. Luke the Evangelist Orthodox Church, Palos Hills, Illinois: http://www.stlukeorthodox.com/html/iconography/cosmasanddamian.cfm
Additional information from other websites. (includes info on their martyrdom): http://en.wikipedia.org/wiki/Sts._Cosmas_and_Damian & http://saints.sqpn.com/saint-cosmas/ & http://saints.sqpn.com/saint-damian/