Hi Pradeep, your lab cud be having an ulcer in his eye which will need the Vet's attention immediately before it develops any further. You have to start the treatment quickly as this takes months to get healed...This is common with all dogs and if treated in the early stages they will not lose the eye. Generally, the eye is washed with distilled water and then CHLOROMYCETIN APLICAPS is applied to the eye. Depending on the size of the white patch in the eye..the treatment follows..so you cud check with a good Vet. in your area.