omas ▁of ▁the ▁opt ic ▁n erve ▁have ▁rapidly ▁progress ive , ▁pain ful ▁visual ▁loss ▁accompanied ▁by ▁signs ▁of ▁an ▁opt ic ▁ne urop ath y . ▁Initial ▁visual ▁loss ▁may ▁be ▁un il ater al ▁or ▁bil ater al ▁( ch ias mal ▁invol vement ), ▁but ▁rapid ▁pro gression ▁to ▁bil ater al ▁blind ness ▁and ▁death ▁are ▁constant ▁features . ▁Depending ▁on ▁the ▁initial ▁location ▁of ▁the ▁tum or , ▁visual ▁loss ▁may ▁be ▁accompanied ▁by ▁ex oph th al mos , ▁extra oc ular ▁mot ility ▁ ▁Opt ic ▁n erve ▁mel an oc yt oma ▁does ▁not ▁usually ▁produce ▁sympt oms ▁or ▁grow . ▁If ▁they ▁slowly ▁grow , ▁opt ic ▁n erve ▁mel an oc yt oma ▁can ▁produce ▁af fer ent ▁pup ill ary ▁defect s ▁( 3 0 % ), ▁sub ret inal ▁fluid ▁( 1 0 % ), ▁and ▁an ▁en larg ed ▁blind ▁spot ▁( 7 5 %). ▁ ▁On ▁fund os cop ic ▁exam , ▁the ▁opt ic ▁disc ▁may ▁be ▁sw ol len , ▁at roph ic , ▁or ▁even ▁normal . ▁Central ▁ret inal ▁ve in ▁occ l usion ▁may ▁occur . ▁ ▁If ▁the ▁tum or ▁is ▁next ▁to ▁the ▁opt ic ▁n erve , ▁growth ▁can ▁compress ▁the ▁n erve ▁and ▁cause ▁grad ual ▁loss ▁of ▁vision ▁and ▁un il ater al ▁pro pt osis . ▁ ▁Dy sch rom at ops ia ▁may ▁occur . ▁ ▁G row th ▁can ▁also ▁cause ▁compress ive ▁v asc