If you wait until glaucoma symptoms are obvious, your hindsight isn't 20/20.
Don't wait for noticeable eye problems. There are few warning signs or symptoms for primary open-angle glaucoma until permanent damage has already occurred. Regular eye exams are the key to detecting glaucoma early enough for successful preventive treatment. 
The American Academy of Ophthalmology recommends a comprehensive eye exam for all adults starting at age 40, and every three to five years after that if you don't have any glaucoma risk factors. After age 60, you should be tested every year. For African-Americans or those with other risk factors for glaucoma, a doctor likely will recommend periodic eye exams starting between ages 20 and 39, and every one to two years after age 40. 
Obvious Glaucoma Symptoms
What is glaucoma and what are the symptoms? The most common types of glaucoma — primary open-angle glaucoma and acute angle-closure glaucoma — have completely different symptoms. Glaucoma is called "primary" when there is no known cause. "Secondary" means it has an identifiable origin such as diabetes, eye injury, inflammation, tumor or advanced cataract.
|Primary Open-Angle Glaucoma||Acute Angle-Closure Glaucoma|
Gradual loss of peripheral vision,
usually in both eyes
|Severe eye pain|
|Tunnel vision in the advanced stages||Nausea and vomiting (with severe eye pain)|
|Severe eye pain|
Sudden onset of visual disturbance,
often in low light
|Halos around lights|
|Reddening of the eye|
Severe headache or pain in your eye or eyebrow, nausea, blurred vision, or rainbow halos around lights may be the symptoms of an acute angle-closure glaucoma attack. Seek immediate medical attention. (Glaucoma is discussed and illustrated in detail on the accompanying anatomy poster, Understanding Glaucoma.)
Natural Ways to Lower Eye Pressure
Dr. Joseph Mercola offers suggestions for lowing eye pressure in persons predisposed to glaucoma. Avoid sugar and grains, the two “food groups” that will inevitably cause surges in your insulin levels. Even whole, organic grains will rapidly break down to sugars, so they too should be avoided. This includes breads and starches like potatoes. Taking an animal-based omega-3 fat supplement. Lutein, which is a carotenoid found in particularly large quantities in green, leafy vegetables, (kale, collard greens, spinach, broccoli, brussels sprouts and egg yolks) acts as an antioxidant, protecting cells from free radical damage.
Strength training can go a long way toward reducing your insulin levels.
Avoid trans fat found in many processed foods and baked goods, including margarine, shortening, fried foods like French fries, fried chicken and doughnuts, cookies, pastries and crackers. The European blueberry, bilberry, is known to prevent and even reverse macular degeneration, and bioflavonoids from other dark-colored berries including blueberries and cranberries are also beneficial. A regular, effective exercise program consisting of aerobics, sprint-burst type exercises, and strength training can go a long way toward reducing your insulin levels and protecting your vision.