hes ia ) ▁of ▁sens itivity ▁of ▁the ▁cor nea . ▁The ▁most ▁common ▁causes ▁of ▁loss ▁of ▁cor ne al ▁sens itivity ▁are ▁vir al ▁in fe ctions ▁( her pes ▁simple x ▁and ▁her pes ▁z oster ▁o ph th alm icus ), ▁chemical ▁burn s , ▁physical ▁inj uries , ▁cor ne al ▁surg ery , ▁neu ros urg ery , ▁chron ic ▁use ▁of ▁top ical ▁medic ations , ▁or ▁chron ic ▁use ▁of ▁contact ▁l enses . ▁ ▁Possible ▁causes ▁also ▁include ▁system ic ▁dise ases ▁such ▁as ▁di ab etes ▁m ell it us , ▁multiple ▁s cl eros is ▁or ▁le pro s y . ▁ ▁Other , ▁al beit ▁less ▁frequent , ▁potential ▁causes ▁of ▁the ▁disease ▁are : ▁int rac ran ial ▁space - occup ying ▁les ions ▁such ▁as ▁neur oma , ▁men ing i oma ▁and ▁an eur ys ms , ▁which ▁may ▁compress ▁the ▁trig em inal ▁n erve ▁and ▁reduce ▁cor ne al ▁sens itivity . ▁ ▁Con vers ely , ▁con gen ital ▁conditions ▁that ▁may ▁lead ▁to ▁this ▁dis order ▁are ▁very ▁rare . ▁ ▁Di agn osis ▁ ▁NK ▁is ▁diagn osed ▁on ▁the ▁basis ▁of ▁the ▁patient ' s ▁medical ▁history ▁and ▁a ▁careful ▁exam ination ▁of ▁the ▁eye ▁and ▁surrounding ▁area . ▁ ▁With ▁regard ▁to ▁the ▁patient ' s ▁medical ▁history , ▁special ▁attention ▁should ▁be ▁paid ▁to ▁any ▁her pes ▁virus ▁in fe ctions ▁and ▁possible ▁sur ger ies ▁on ▁the ▁cor nea