What are Prism Glasses and Who Should Wear Them?

We see the world with two eyes. But then why do we see a single image instead of two?

This is known as binocular vision. Our brain takes two distinct visual messages from our eyes and combines them to form one 3D vision. This process requires coordination between the eyes, the brain and the optic nerve. But sometimes, the eyes fall out of sync and they don’t work as well together as they should. This gives rise to vision problems such as focus issues or double vision.

If your optometrist finds that your eyes aren’t playing like a team, they’ll include a prism correction in your prescription lenses to give you a more comfortable vision.

What is double vision?

Double vision, also known as diplopia, is a condition where a person sees two images of a single object, either constantly or intermittently. This can occur in one eye (monocular diplopia) or both eyes (binocular diplopia). While double vision in most instances may resolve on its own, if it’s due to an underlying condition, the problem can be serious.

There are 12 muscles responsible for generating all eye movements. When something is wrong with any of these muscles, your eyes fail to coordinate and you see two of everything.

Also, if the vision isn’t developed completely in one eye, your brain shuts down messages from that eye which causes it to weaken further leading to the lazy eye condition.

What are prism glasses?

Prism glasses are a type of prescription glasses used to correct double vision or diplopia. These glasses work by bending the light in a way that it falls on the same point in each retina.

Prism glasses can provide clear and stable vision to people with diplopia. The prism correction in the lenses fuses the two images together and resolves the problem.

Your optometrist may prescribe prism glasses if you experience:

• Frequent headaches
• Strabismus or crossed eyes
• Eyestrain
• Eye fatigue from close-up work

Prism glasses are generally used in the case of eye movement problems such as strabismus. A stroke, diabetes or a head injury can damage the muscles that control eye movements causing double vision.

These glasses have prism lenses that refract light so it falls on the same spot on both retinas even if the eyes are misaligned.

In some cases, these glasses are also used to correct monocular diplopia - a double vision that happens in only one eye or when only one eye is open. This problem is generally caused due to corneal abrasions.

How do prism glasses work?

To give you the clearest vision, your cornea filters the light and properly focuses it on the retina in both eyes.

Even in the case of refractive errors such as nearsightedness or farsightedness, the light is focused on the same but wrong area in both your retinas which gives you a rather blurry vision.

When your eyes are misaligned, the cornea filters light properly but the misalignment causes it to fall on different spots onto the retinas. Thus, each eye sends a different image to your brain causing double vision.

Prism glasses help in this situation by refracting light and focusing it on the same place in both the retinas. This helps your brain to produce a single image and gives you a clear vision.

To get the best vision from your prism glasses, your prescription needs to be up to date. So, if you haven’t had an eye test in a while, you need to schedule one first. You can get a free eye test in any of our stores if you live in Manchester or you can visit your nearest optician.

Prism glasses look the same as normal prescription glasses. However, it’s normal for one lens to be thicker than the other in case of prism correction. If this is a problem with you, you should choose thick designer glasses frames to cover the edges of the lenses or opt for high-index lenses.

Prism correction is added to your regular prescription glasses. The correction depends on the type of double vision you experience - oblique, horizontal or vertical. However, you don’t have to worry that much about all this as this doesn’t make any big difference in the aesthetics of your glasses.