St. Deochar is considered an intercessor for persons with visual impairments; during his earthly sojourn, a young boy was healed of blindness by his prayers. See http://saints.sqpn.com/saintd2h.htm
(Imperfectly translated from the original German:)
A farmer’s son went blind after the theft of Votivaugen. The intercession of the Holy Father Deocarus restores the son’s sight.Eyes made of wax, wood or metal were taken by blind or visually impaired as votive offerings to the Sanctuary.
Source of the translated story and the image of St. Deochar: http://www.forum-nuernberger-werkstaetten.de/aktionen/ausstellung/mittelalter/ausgegrenzt.aspx
Other sources on St. Deochar:
A translation of a German website which relates St. Deochar’s life: http://translate.google.com/translate?hl=en&sl=de&u=http://www.heiligenlexikon.de/BiographienD/Deochar_Deocarus_Deotker_Dietger_Theotgar.htm&ei=fadyTZnEOIP7lweI8rmAAQ&sa=X&oi=translate&ct=result&resnum=7&ved=0CEsQ7gEwBg&prev=/search%3Fq%3DDeochar%2BOR%2BDeocarus%2BOR%2BTheotgar%26hl%3Den%26lr%3D%26prmd%3Divns
The following post briefly discusses St. Deochar as an intercessor for blind people in the context of a recovery from near blindness which the author considers as a miracle: http://asinnersguidetothesaints.blogspot.com/2010/12/st-deochar-8th-century.html