parameter group  feaure name  explanation
 3*cup/disc related  vCDR  vertical Cup-Disc Ration
   CupHMM  cup hight in mm
   CupAreaMM  cup area in mm^2
 4*ISNT rule related  I  rim inferior thickness
   S  rim superior thickness
   T  rim temporal thickness
   INST  following ISNT rule
 2*Age related  agegp  age group
   age  age
 IOP related  iopl / iopr  left eye IOP / right eye IOP
 PPA related  AlphaPPA  Alpha PPA observed
 Ocular hypertension related  ocular_htnr  ocular_htnl  Ocular Hypertension right/left eye
Table 3: Common Top Features identified by all 4 feature ranking methods.