I Have Used Lumigan Eye Drops For Some Years Now

I have used Lumigan eye drops for some years now to treat occular hypertension. When I collected my new prescription this week, the pharmacist told me the 0.3 dosage was no longer available and gave me bottles of 0.1 dosage. She told me it would somehow have the same effect as the 0.3, is this true and how is it possible?