At the end of 12 weeks , significant improvement in CS was seen in the treatment group in 7 of the 8 testing conditions ( 3 , 6 , 12 , and 18 cpd photopic and 6 , 12 , and 18 cpd mesopic ) , whereas in the placebo group , significant improvement was seen only in 3 of the 8 testing conditions ( 3 cpd photopic , 6 and 18 cpd mesopic ) .