Prism Glasses for Double Vision (Diplopia)

Prism glasses correct diplopia (double vision). It is when someone sees two separate images of a single object. Prism glasses help align the two images and correct the problem.

Standard eyeglasses typically only correct two types of vision conditions, including:

Astigmatism (curved cornea)
Focal distance (farsightedness and nearsightedness)

Prism glasses also have a thicker base and thinner apex than standard prescription glasses.

How Do Prism Glasses Work?

Prism glasses are one of the most common treatments for double vision. They make it easier to focus on an object with both eyes.

Double vision occurs when light falls in different places on a person’s retinas. It distorts and doubles what they see.

Prism lenses bend light before it hits the retina. The light is redirected, helping the brain interpret what it sees into a single clear picture.

Who Needs Prism Glasses?

Your eye doctor (optometrist) may prescribe prism glasses if you struggle with double vision and:

Eye strain
Frequent headaches
Fusing two images together into a 3D view (strabismus)
Tiredness with close-up work, such as looking at a computer
Suppression

Potential Side Effects of Prism Eyeglasses

Prism glasses are an effective tool for correcting double vision, but some people experience side effects while wearing them.

These side effects include:

Headaches
Pain with eye movement
Wandering eyes
Misaligned eyes
Nausea

In most cases, these can be corrected with an adjustment to the lens prescription, a change in eyeglass frames, or medication.

If you experience any problems with new glasses or your old prism glasses stop working, contact your vision healthcare specialist to discuss the issue.

How Much Do Prism Lenses Cost?

The cost of prism lenses varies. It depends on the frames you choose and if your lenses are only designed to treat double vision.

Most temporary (Fresnel) prism glasses cost about $250 to $500. Permanent (ground) prism glasses cost about $600 to $1,500.There are instances in which prism glasses cost several thousand dollars.

Speak to your doctor about how much prism glasses cost and how to reduce the out-of-pocket expenses.

How to Read a Prism Glasses Prescription

Prism eyeglass prescriptions have two values: prism and base.

The prism measurement is a number between 0.5 and 5.0. This refers to the amount of prism correction needed to correct eye alignment issues.

Base (the thickest edge) indicates the direction of the prism and can be:

BO – Base Out (towards the ear)
BI – Base In (towards the nose)
BU – Base Up
BDn – Base Down

What Causes Double Vision?

Double vision can affect one or both eyes. It is caused by numerous conditions, including problems inside the eye.

Double vision caused by a problem in the cornea or lens can come from eye conditions like:

Dry eyes
Astigmatism
Cataracts

Double vision is also caused by problems with the eye muscles or nerves. These problems include:

Stroke
Brain aneurysm
Brain tumor

Summary

Prism glasses correct diplopia or double vision. Double vision is when a person sees two separate images of the same object, and it can affect one or both eyes.

Prism glasses correct this eye condition by bending light before it reaches the retina. It redirects the light so that the brain can register what it sees as a single clear image.

Wearing prism glasses can cause side effects if the prescription is incorrect. These side effects include:

Headaches
Pain with eye movement
Wandering eyes
Misaligned eyes
Nausea

Prism glasses can cost anywhere between $250 and $1,500. Sometimes, they can be more expensive if the glasses are meant to correct other eye problems in addition to diplopia. The cost also depends on whether the glasses are temporary or permanent.

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