Microangiopathic disease - leukoariosis

My dad had a sudden neck pain and headache on 2 Mar'09 morning when he woke up. He then had double vision. Went to the normal GP and the blood pressure was normal. Dad has high blood pressure. My sister took him to see the eye specialist the following day and was referred to the hospital for suspected minor stroke. Based on the MRI result, dad was diagnosed with microangiopathic disease. There is the word leukoariosis as well. Would appreciate your advise on what is this disease, what is the cause, any potential treatment for this as his double vision is still there now. Dad is a smoker and he is 75 this year. He has been given some tablets to control his blood pressure, to thin his blood flow etc.