Synoptophore

A synoptophore is a specialised optical instrument used in ophthalmology and orthoptics to measure how well your eyes work together. The device consists of two tubes fitted with mirrors and lenses, so that each eye sees a separate image. By adjusting the angle between these tubes, the orthoptist or ophthalmologist can determine precisely whether your eyes are parallel, turn inwards or outwards, and whether your brain can merge the images from both eyes into a single, coherent image.

The device is primarily used in the diagnosis and treatment of strabismus, or squint, and in amblyopia, also known as a lazy eye. Using a synoptophore, the specialist can measure the angle at which your eyes are positioned, whether one eye is being suppressed, and whether you have depth perception. In addition, the device can serve as a training tool: through exercises involving alternating images, you learn to make your eyes work together more effectively.

A synoptophore is used exclusively in a professional setting, such as an optometrist’s practice or an orthoptic clinic. The examination is painless and usually takes between a few minutes and a quarter of an hour, depending on the specific assessment required.

When is a synoptophore used?

A synoptophore is used to assess binocular vision, i.e. the coordination of both eyes. Typical situations in which the device is used include:

• Determining the angle of deviation in strabismus, including both manifest strabismus and latent deviations.
• Measuring fusion ability: can your brain merge the images from both eyes into a single image?
• Investigating suppression: does your brain suppress the image from one eye to prevent double vision?
• Assessing depth perception and stereopsis.
• Orthoptic training to improve coordination between both eyes, for example following eye surgery or in children with amblyopia.

How does the examination work?

You place your head in a support and look through the two tubes of the device. Each eye sees a separate image, for example a bird in one tube and a cage in the other. The orthoptist or ophthalmologist asks you if you can see the bird in the cage, and adjusts the angle of the tubes until the images align. This measures the angle at which your eyes are positioned and whether your brain can combine the images.

Sometimes exercises are carried out in which the images move or change, to train your fusion ability. The examination is non-invasive and does not require eye drops or anaesthesia.

Who is a synoptophore suitable for?

The device is used with both children and adults, but is particularly valuable for children with strabismus or a lazy eye, as their visual system is still developing and training can be more effective. In adults, it is used to identify the cause of double vision or reduced depth perception, or to monitor the progress of binocular vision following eye surgery or a stroke.

What can you expect after the examination?

The results of the synoptophore examination help the ophthalmologist or orthoptist to draw up a treatment plan. This may consist of spectacles, prisms in the lenses, eye muscle surgery, patching therapy or further orthoptic training. The examination itself has no side effects and you can go home straight afterwards.

If you have any questions about binocular vision, strabismus or a referral for an orthoptic assessment, please discuss this with your optician, optometrist or ophthalmologist.