 frontal lobe vision influenc frontal lobe vision discuss base present unusu case oper frontal brain abscess led papilledema pronounc diminut visual capac patient gradual disturb regress point return full visual acuiti remain hemianop field defect psycholog defect sens partial visual agnosia regress well prompt discuss neuroanatom neurophysiolog observ pertin find patient data fronto-occipit connect subhuman primat point role frontal lobe area 8 develop visual disturb sens temporari hemianopia partial visual agnosia intellectu deficit contrari singl observ anthropoid ap case indic aforement combin symptom origin frontal lobe hope prompt long-term follow-up studi patient continu observ patient possibl gain insight role frontal lobe vision assum anim 