Of the 177 participants ( 88 % ) completing the 6-month primary outcome examination , deterioration occurred in 4.6 % ( 4 of 87 ) of the participants in the observation group and in 2.2 % ( 2 of 90 ) of the participants in the patching group ( difference , 2.4 % ; P = 0.27 ; 95 % confidence interval , -3.8 % to +9.4 % ) .