The proportion of the subjects whose IOP are not successfully controlled in the LPI group can be estimated as 60% (Aung T 2001). And the proportion of the subjects whose IOP are not successfully controlled in the phacoemulsification with intra-ocular lens implant group is about 20% under clinical estimation. Hence, the study needs a sample size of 70 patients (Machin, Campbell, Fayers & Pinol, 1997), 35 in each group. This will be sufficient to detect a 60% vs. 20% of proportion of the subjects who develop increasing IOP between two groups with a two-sided test with a power 90% while the significance level is controlled at 5%.