Views on Vision - by Dr. Charles A. Boulet

(Page 15)

Nearsighted vs Farsighted

We all have a unique pair of eyes that focus light on the retina in their own special way. The shape of the eye from one person to another is fully unique, and so in effect, no one's eyes focus light in exactly the same way as another person. In fact, it is very rare that any one person's left and right eyes work in exactly the same way. Refractive Error (RE), glasses prescription, neutralizing lenses - these are all terms that mean the same thing: A mathematical and optical representation of how the eye focuses light. The three most common refractive errors are nearsightedness, farsightedness and astigmatism. This article will compare and contrast nearsightedness and farsightedness.

In order to see distant objects, the eye tries to relax and release focus. To see things up close, the eye must put some effort in and focus. This takes work. For people who spend little time looking at things within arms reach, this focusing effort is of little consequence. For those who spend much time at a desk or in front of a computer, the effort spent in focusing is much more important. For many, if too much effort is required to simply see clearly at close distances, they will prefer to look elsewhere, far away from whatever is in front of them.

Nearsightedness (myopia) is when your vision is easier at near distances. That is to say, light is improperly focused on the retina (the sensory tissue inside the eye). The result is that things in the near distance, say on your desk, are easier to see than distant objects which appear blurry. It doesn't matter how much you try to relax your vision, you can not see distant object clearly, but the benefit is that it takes less effort to see up close. There is usually little pain or discomfort associated with strong nearsightedness, but oddly enough mild nearsightedness can cause headache in school-aged children especially when they must squint ever so slightly to try to see the whiteboard more clearly.

Farsightedness (hyperopia) is when your vision is easier at far distances. Farsighted people can often see well in the distance and up close, but near vision requires extra effort. When the eyes are allowed to relax, everything looks fuzzy - distance and near. In some cases, seeing clearly takes so much effort, the brain is satisfied with seeing only a fuzzy image and gives up trying to force the eyes to see any better. In the end, vision is poor and reading difficult - even with glasses. (This condition is incorrectly called 'lazy eye' and is better described as 'amblyopia'). Farsighted people often complain of pain around the forehead and eyes, behind the eyes and general headache and fatigue especially near the end of a work day. They also tend to squint a lot and this leads to facial lines.

Children who are nearsighted are easy to spot, relatively speaking. They will have trouble seeing the board from the back of the class, but have little trouble seeing up close. Because nearsighted children see well up close, they handle near work with greater ease and they tend to do better in school. There are proportionally more nearsighted students in universities and colleges than farsighted students.

Farsighted children frequently slip through the cracks of the school system because they are difficult to spot. They will often be able to see far and near, but this requires much effort. For the child, this effort to see is normal so they will not often complain, except for headaches. Copying from the whiteboard to a notebook can be an exceedingly tiresome and frustrating task for a farsighted child. Often enough, farsighted children can also read, so this is another reason teachers and parents miss the problem.

There is no significant difference between the sexes for farsightedness or nearsightedness. Some ethnicities have a higher prevalence of some refractive errors (glasses prescriptions), and there is compelling evidence that uncorrected near vision leads to an increase in nearsightedness during the school years.



Dr. Boulet is an optometrist and owner-operator of Diamond Valley Vision Care in Black Diamond (403-933-5552 or info@dvvc.ca.) He is also a former high school teacher and continues to work with children who have trouble learning.