How is it possible to catch glaucoma early? Had annual eye exams with dilation every 2 years. When diagnosed there was already 30% optic nerve damage

Of course. Glaucoma is a problem in which the internal eye pressure exceeds the eyes capacity to resist that pressure. Almost always there are no symptoms early in the disease but later vision can be affected. That is why we recommend an eye exam every year or two in people over age 40. The course is slow, and there is plenty of time to use corrective drops. Was your pressure always taken?
? 30% I would question further into how they are making the assessment if 30% damage and even if you really have glaucoma. You may only be suspect due to a few findings. See an eye md.