What you are describing is consistent with ocular migraines, a condition that I not only treat in my office but that I have been dealing with personally for decades.
A typical migraine headache starts with shimmering lights, often times they surround a blurry area or have dots or jaggedly lines associated with them. They tend to progressively increase in intensity and sometimes march across the visual field causing difficulty with reading. Many times this is then accompanied by nausea, irritability, sensitivity to bright lights and/or loud noises. After the onset of the lights (called scintillating scotomas), the headache typically starts and the light show tends to progressively go away.
Many people can have this migraine phenomenon WITHOUT the headache; it is called an acephalgic migraine. Some people even start having these late in life, or may have had a few much earlier in life that behaved differently and haven't had any for decades and then begin to have them; this is not uncommon. A family history of migraines is often present as well.
This is nothing to worry about. It is not a sign of a more serious underlying condition, brain tumor or anything like that. If the episodes become so frequent that they are bothersome there are medicines that can be used to decrease their frequency or stop an episode once it has started.
I, personally, have been suffering from this condition for almost 30 years. I almost never got the headaches after the visual effects.
Now. As to your question.....
It is not uncommon for the symptoms of ocular migraine to change over the years. Mine, for instance, have almost completely stopped since I hit my 50's -- I used to get them at least 4x/week during my 30's.....
I have treated a large number of patients like yourself who suddenly start having these attacks frequently. In the vast majority of patients your age, even after an extensive workup, no pathology is found.
So. What is the take home message? We really don't know why these ocular migraines suddenly become more frequent but it is rarely a sign of anything serious.
If you are concerned you could consult a neurologist......but I do not think, from what you have posted, that it is necessary.
Does this make sense to you, Billie?
Please remember the top 3 ratings are positives [Excellent service is my goal] and this is how we are compensated. Rate my answer when you are satisfied. If you feel the need to rate low, please stop and reply to me via the REPLY TO EXPERT button with the issue you have. I will be happy to continue further and do everything I can to provide you with the service you seek.
Otherwise, a high positive rating is very much appreciated, bonuses are great, and find me anytime for follow up.
Let me know if you have further questions.