Why should adults get their eyes checked once per year and not just when their vision is blurry?
Whenever any of our patients asks this, I always think about Glaucoma, which is an eye disease that can damage the eye and cause vision loss slowly and "silently" in the background often for years without notice (similar to the frog which gets cooked to death when placed in water which comes to a boil slowly).
At the final stage of Glaucoma, you can end up with true tunnel vision, which means that you can see with central vision but not peripheral vision.
This is a printout of an visual field test. This test measures how well you are able to see dim lights in several areas in your peripheral and central vision. The dark squares indicate areas of vision loss.
WHAT IS GLAUCOMA?
Though there are several variants of the disease, the main type of Glaucoma is a disease which affects the optic nerve of the eye. The optic nerve is cranial nerve #2 (of 12) and is extremely important because it takes the visual signals from the eye and relays them from the brain.
If you cut the optic nerve behind the eye, then you would not see anything even if your eye was intact.
The optic nerve damage in Glaucoma is most often due to high fluid pressure in the eye.
Similar to a plumbing problem, if the fluid inside the eye is building up, then the pressure can cause damage to surrounding structures (the optic nerve fibers).
The damage occurs from the peripheral vision areas to the central vision areas, and since it can affect small areas in the beginning of the disease, you may not notice the visual changes. Sometimes the blind spots are so small, the brain "fills in the gaps" automatically, like in your normal physiological blind spot.
So there's vision loss occurring and you don't even notice it.
What about the eye pressure? Surely you'd feel some pain if the eye pressure gets too high.
Well... actually... no. You don't feel the eye pressure either (unless it gets around 40-50 mmHg or higher)
With time, the pressure rises slowly and the blind spots grow larger.
So, there you have two main reasons why you need to get your eyes checked every year, no matter how well they feel they see.
TREATMENT OF GLAUCOMA
Treatment of Glaucoma usually consists of daily eye drop medications to lower the eye pressure. Your eye doctor will usually have "target pressure" in mind to shoot for which will help prevent optic nerve damage and vision loss in the future.
Other forms of Glaucoma may require surgeries such as iridotomy or trabeculoplasty.