Over the Counter Reading Glasses (OTC)

The demand for pre-made reading glasses is huge. The idea that you could pick your own Over the Counter (OTC) reading glasses for a fraction of the cost of those purchased through your doctor or Optician is appealing for many presbyope. But are they worth it?

For many they are. But they are not without their limitations. OTC Reading glasses do not take into account certain important factors such as astigmatism, prescribed prism and anisometropia (a condition were the refractive errors greatly differ for each eye). OTC readers are made in what we call spherical power.

How do you know if OTC Readers will work for you? Well the first and most obvious is to head to the drug store and try them out. But if they just don't work there may be a few reasons why.


1) You may not require magnification
If you look at your prescription it may look something like this:

O.D. -5.00 sph

O.S. -5.25 sph

Add 1.25


The 'Add' is the additional power that is needed to assist with near vision. This power is added to the powers above. It's important to note that add powers are always plus powers.

Now lets add +1.25 to -5.00 and we get -3.75 for the right eye and for the left we will get -4.00. In this case it's not the magnification that makes reading possible but the reduction of distance prescription that is needed for near vision.

A person with this prescription will find that a pair of OTC Readers will not work if purchased with a +1.25 power. Remember that the add powers tell the eye care professional how much power to add to the distance RX to get you reading prescription. It is not, by itself, the reading RX.

2) OTC Reading Glasses may not help astigmatic vision

Now many of us out there have an astigmatism. It's a condition in which the cornea or the crystalline lens is football shaped rather than spherical. OTC Readers do not correct for this. If your astigmatic correction is not very strong, you may get along with these readers just fine. However if it is rather significant such as a 1.00 or above you may experience some difficulty.

There are those out there that have certain conditions in which the eye begins to wander or there may be other ocular motor dysfunctions which can be corrected with the use of prisms. The prismatic effect is experienced any time one looks away from the Optical center of the lens. In the case of prescribed prism the doctor has determined that the optical center should be moved either up, down, in or out or any combination of these. OTC Readers do not account for this.


3) Both lenses on OTC Readers are the same prescription

Others with refractive errors don't have the same exact prescription in both eyes. In some cases the power difference is so significant that reading or near vision becomes an issue. This is called anisometropia. Each lens displaces an image either towards the center of the lens or towards the edge enlarging it.

If one lens displaces an image more than the other the experience is intensified as one begins to look away from the optical center, for instance while reading. This condition is often relieved with a lens that is called a slab off lens. In a slab off lens, the prism is ground into the bottom half of one of the lenses to relive the excessive prismatic effect.

If the prescription varies greatly from one eye to the other, OTC Readers may not be a good choice considering that they only come in the same powers for each eye.

If you are one of those people who can get by with OTC Readers, they are well worth it. But as I mentioned earlier, the best way to find out if OTCs are right for you is to try them out.

Source : http://www.eyetopics.com/articles/106/1/Over-the-Counter-Reading-Glasses.html