I have a merged vcf file, last 8 columns are about the information of my 8 sample weather variant was there in the respective sample or not ?

3   196139511   .   C   A   122 PASS    VDB=0.101032;RPB=-1.22822;AF1=0.5;AC1=1;MQ=60;FQ=125;PV4=1,1,1,1;DP=13;DP4=3,4,3,3;AN=2;AC=1    GT:PL:GQ    ./.:.:. ./.:.:. ./.:.:. ./.:.:. ./.:.:. 0/1:152,0,175:99    ./.:.:. ./.:.:.
3   196144312   .   C   T   137 PASS    VDB=0.104742;AF1=1;AC1=2;MQ=60;FQ=-45;DP=10;DP4=0,0,4,2;AN=2;AC=2   GT:PL:GQ    ./.:.:. 1/1:170,18,0:33 ./.:.:. ./.:.:. ./.:.:. ./.:.:. ./.:.:. ./.:.:.
3   196144517   .   C   A   101 PASS    VDB=0.078549;RPB=0.317149;AF1=0.5;AC1=1;MQ=60;FQ=104;PV4=0.57,1,1,1;DP=11;DP4=4,2,2,3;AN=2;AC=1 GT:PL:GQ    ./.:.:. ./.:.:. ./.:.:. 0/1:131,0,152:99    ./.:.:. ./.:.:. ./.:.:. ./.:.:.

my question is how can I get to know that if a sample doesnt contain a respective variant than weather there was same allele as reference or there was no read matched at that position ? keeping in mind I have few thousand snps and I cant check each of them indivisualy using IGV or tablet viewer.