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Date issued: November 2023

Review date: November 2025 

Ref: C-421/SP/REI/fresnel prisms v2

PDF:  Fresnel Prisms final November 2023 v2.pdf [pdf] 231KB

What is a Fresnel prism?

A Fresnel prism is a thin transparent plastic material which induces a prismatic effect. This mean it refracts light on the back of your eye in order to resolve your double vision. The prism is used as a resolution of the symptoms rather than treating the cause of the double vision¹. 

Which lens should this go on?

Rather than one eye in particular, the Fresnel prism can go on either eye to potentially remove your double vision. This is due to how the balance between the eyes works.

However depending on your vision in either eye, you may prefer to avoid putting the prism on the eye with better vision. This is due to the striations of the prism may cause slight blurring².

Benefits of a Fresnel prism?

• Immediate correction of your double vision².

• Comfortable and discreet compared to a patch.

• No noticeable weight or thickness to the spectacle, unlike if the prism was incorporated¹.

• They are relatively inexpensive compared to if they were incorporated into glasses¹.

• Easily adjustable if proceeding with surgery or prism incorporation.

Short term or long term?

A Fresnel prism is a temporary treatment option for your double vision. Once measurements are stable the prism can be incorporated into your glasses¹.

Before incorporation of a prism the Orthoptist will monitor for any changes, until your eye measurements are stable for ~6 months. Then depending on the size of prism required, this can be incorporated into your glasses.

However by incorporating a prism this can increase the weight and thickness of your glasses. Therefore depending on the size of prism required, either incorporation or further treatment such as possible surgery can be discussed further with your orthoptist³.

Tips for Fitting and Cleaning the Prism:

• The prism will already be cut to the correct size of your lens.

• Wash your glasses, leaving some water on the appropriate lens to allow the prism to stick effectively. The prism adheres with just water and can be easily repositioned.

• Put the prism onto the lens and press out any air bubbles.

• The prism may slide around while still wet but as this dries it should stick to the lens quite firmly.

• The prism can be put on any pair of glasses you use. For example, reading glasses, distance glasses or sunglasses if necessary.  

The prism should then be correctly fitted to resolve your double vision.

For help or advice, contact:

Orthoptic Department: 01752 439319

For further Orthoptic information in regards to double vision:

https://www.orthoptics.org.uk/patients-and-public/about-orthoptics/#Double2