▁operations ▁were ▁review ed ▁by ▁Mar ius ▁von ▁S enden ▁in ▁his ▁German ▁ 1 9 3 2 ▁book , ▁ ▁which ▁was ▁later ▁translated ▁into ▁English ▁under ▁the ▁title ▁Space ▁and ▁sight . ▁In ▁this ▁book , ▁von ▁S enden ▁arg ues ▁that ▁shapes , ▁sizes , ▁lengths ▁and ▁distances ▁are ▁difficult ▁for ▁blind ▁people ▁to ▁judge , ▁including ▁for ▁a ▁time ▁after ▁their ▁operation . ▁ ▁Ex amples ▁and ▁case ▁studies ▁ ▁Vir g il ▁In ▁his ▁book , ▁An ▁Anth rop ologist ▁On ▁Mars ▁( 1 9 9 5 ), ▁ne uro log ist ▁Oliver ▁S acks ▁rec ount s ▁the ▁story ▁of ▁Vir g il , ▁a ▁man ▁who ▁saw ▁very ▁little ▁until ▁having ▁cat ar act ▁surg ery ▁at ▁age ▁ 5 0 . ▁Vir g il ' s ▁subsequent ▁behavior ▁was ▁that ▁of ▁a ▁" ment ally ▁blind " ▁person — some one ▁who ▁sees ▁but ▁can ' t ▁de ci pher ▁what ' s ▁out ▁there ; ▁he ▁would ▁act ▁as ▁if ▁he ▁were ▁still ▁blind . ▁O ften ▁confused , ▁Vir g il ▁rapidly ▁s ank ▁into ▁de pression . ▁ ▁Sid ney ▁Brad ford ▁In ▁ 1 9 7 4 , ▁Richard ▁Gregory ▁described ▁a ▁patient , ▁Sid ney ▁Brad ford , ▁a ▁ 5 2 - year - old ▁who ▁gained ▁vision ▁from ▁cor ne al ▁gra ft s ▁to ▁both ▁eyes . ▁No ▁experimental ▁psych ologist ▁was ▁informed ▁of ▁the ▁case ▁until ▁after ▁the ▁cor ne al ▁gra ft ing ▁took ▁place