This describes how vision works and gives another exercise for tired eyes.

THE EYES HAVE IT

Have you noticed that your vision becomes less clear when you're tired or under tension and strain? Today, we'll look at why that happens.

The retina, which is the light-sensitive, inner area of the eye, is extremely intricate. This amazing, delicate area is made up of eight layers and two membranes. The layer which receives visual impressions is made up of rods and cones.

Rods help determine black and gray sight while cones allow us to perceive colors. Both rods and cones are made of membranes that house tiny discs. These discs are used up at the tip in the continual process of vision and are continuously being replenished at the bottom of each structure. Think of it like an ice cream cone that would push up from the bottom with each lick off the top.

There's a layer of pigment in the retina containing a dark substance called melanin. Melanin stores large amounts of vitamin A which is in constant exchange with the membranes of the rods and cones and is continuously used up in the process of vision.

Close to the center back of the retina is a small circular area called the macula lutea which gets its name from its yellow color. In the center of this spot is a deep depression called the fovea. The fovea contains only closely packed cones. This spot is where we have our sharpest visual perception.

When the eye is under strain or the body is ill, this keen central fixation point of vision deteriorates and the rest of the retina compensates. Another name for that point is the central scotoma. The greatest causes of loss of central vision is emotional or mental strain or the process of aging.

When this happens, the exact spot at which a person is looking becomes somewhat less clearly focused but the eye takes in the area past that a little more clearly. The greater the strain, the more noticeable is the lessening of visual clarity. Letters in words and other objects may seem a bit fuzzier

I first noticed this years ago as a young mother. When I got up to check on the children in the dark, I found that in order to see what was directly in front of me, I could see it best if I looked slightly to the sides or above or below the object. This is partly due to the way night-time vision works but also reflects what can happen in day vision when fatigue, low blood sugar, or eyestrain are most notable.

When this happens, the eyes tire very rapidly because of the effort to see clearly. The eyes seem to make fine irregular movements, from side to side, or in other directions. The white part of the eye or sclera may become reddened and even the margins of the lids may become irritable. Wrinkles may occur around the eyes along with dark circles beneath them. Tearing may become more common.

Some of these symptoms may be due to certain vitamin deficiencies, such as vitamin A or various of the B-Complex family. However, since this problem can occur from strain, we'll look at some things we can do to relieve that strain.

It's not unusual for me to notice eye strain when working on the computer. I noticed that my eyes were beginning to wander among the letters and words and focusing was becoming a strain.

So, I took a brief break, went into another room, sat back in a recliner, and began to relax. If you're like me, you may notice that some of your body relaxes more easily than others. As I noticed tension spots, I realized that part of me was ready to jump up and go back to work. As I focused on these areas, I allowed these areas of tension to be released and then relaxation was complete.

When I got up to return, I noticed that my vision was noticeably sharper and clearer.

For those of you who have computer work or desk jobs, I recommend taking tension breaks. You may not be able to leave the site, but stopping the level of intensity of your efforts and concentrating on relaxing tension spots will refresh and revitalize you as you continue with your work.

One exercise that will benefit your eyes is this head and neck relaxer. It can be done seated or standing.

Let your head hang down toward your chest. You will feel a pull in your shoulders as your chin drops down. Don't force your chin down, but let the weight of your head gently pull itself forward and down.

Then, bring it up and allow it to fall gently backward. Now, very slowly and gently alternate these positions a number of times. It increases relaxation if you close your eyes while doing this.

You can then add sideways tilts to the left and right, again, gently and without strain. We're not trying to lay your ear on your shoulder but just stretch tense muscles. As you do these, the blood flow is increased and toxins that build up in tension spots begin to be removed from the area.

You can add a gentle head roll. Start with your head down and rotate it gently to the right, then back. Roll left and return to the head-down position. We are not trying to force these movements. They are more effective when done rather limply like a rag doll.

These help your eyes and lessen mental strain as well.

References:
Bates, William H., M.D., The Bates Method for Better Eyesight Without Glasses, New York: Holt, 1968. p. 52-56.
Guyton, Arthur C., M.D., Textbook of Medical Physiology, 7th ed. Philadelphia:
Saunders, 1986. p. 711-713.