Symptoms tend to present between 40 and 70 years of age.

That's because symptoms tend to return if you stop taking medicine.

The symptoms tend to show themselves between the ages of 25 and 40.

With the acquired form, symptoms tend to last for one to two hours.

Also, remember that symptoms tend to calm down in time.

Symptoms tend to start two to five days after exposure and typically last a week.

The symptoms tended to disappear after about a week, the researchers reported.

Symptoms tend to peak during the late teenage years and early 20s.

The symptoms tend to resolve after a period of time, although visual changes sometimes remain.

But these symptoms tend to come on slowly and can easily be mistaken for other conditions.