In multivariate analyses , adjusting for randomization arm , age , baseline IOP , central corneal thickness , pattern standard deviation , and HRT disc area , the following HRT parameters were associated with the development of OAG : the `` outside normal limits '' classification of the Frederick Mikelberg ( FSM ) discriminant function ( hazard ratio [ HR ] 2.51 , 95 % confidence interval [ CI ] : 1.45-4 .35 ) , larger mean cup depth ( HR 1.64 , 95 % CI : 1.21-2 .23 ) , cup-to-disc area ratio ( HR 1.43 , 95 % CI : 1.14-1 .80 ) , linear cup-to-disc ratio ( HR 1.43 , 95 % CI : 1.13-1 .80 ) , cup area ( HR 1.33 , 95 % CI : 1.08-1 .64 ) , smaller rim area ( HR 1.33 , 95 % CI : 1.07-1 .64 ) , larger cup volume ( HR 1.30 , 95 % CI : 1.05-1 .61 ) , smaller rim volume ( HR 1.25 , 95 % CI : 1.01-1 .54 ) , larger maximum cup depth ( HR 1.18 , 95 % CI : 1.01-1 .36 ) , and cup shape measure ( HR 1.18 , 95 % CI : 1.01-1 .36 ) .