You should not ignore this episode as it could represent what is called a TIA (transient ischemic attack) and can poor circulation or disease of the eye, heart, brain or blood vessels. It is never normal in a 65 year old nor due to low blood sugar. You should inform your personal physician and set up an appointment for an evaluation ASAP, you also need to be seen by an Eye MD ophthalmologist. Hopefully you have one but if not you can ask your family MD to refer you. If you have anything where all the vision goes out in the eye or you have stroke like symptoms ( slurred speech, trouble moving arms, legs, trouble with balance, etc) you need to call 911 or have someone take you to an ER immediately. There are some causes of this that are not ultra serious but the serious causes need to be ruled out first. You can read more about TIA on WebMD or emedicine.