People suffering from diplopia, or double vision, see two images of one object at the same time. Whether the images are side by side, overlapping or a combination of the two, double vision is something that should be taken seriously. At Abernethy Owens, we are the leading independent Optometrist locals rely on for high quality eye care. If you have suddenly started to see double, read on to find out about more about possible causes and potential treatments for diplopia.

What is Double Vision?

By definition, double vision is “the perception of two images of a single object seen adjacent to each other (horizontally, vertically, or obliquely) or overlapping”. You can experience double vision in one eye (known as monocular) or both eyes (binocular). To find out which type you have, simply cover one eye. If your double vision is binocular, the double vision will disappear when you cover either eye. If the double vision remains when you have one eye covered, then your double vision is monocular.

The Causes of Monocular Diplopia

Most causes of monocular diplopia stem from poor focusing of light by the eye. Monocular diplopia can be caused by:

  • Astigmatism — an abnormal curvature of the front surface of the cornea.
  • Corneal irregularities such as Keratoconus – this is where the cornea gradually becomes thin and cone-shaped.
  • Pterygium — a thickening of the conjunctiva which extends on to the cornea, the clear part of the surface of the eye.
  • Cataracts —the clouding of the eye's natural lens can cause light rays to scatter in different directions resulting in multiple images being seen.
  • Swelling in the eyelid — can place pressure on the front of the eye.
  • Severe dry eyes — insufficient or poor quality tears can lead to diplopia.
  • Some retinal problems — double vision can happen when the surface of the retina is not perfectly smooth, and this can have a variety of causes.

The Causes of Binocular Diplopia

Binocular double vision usually results from a misalignment of the eyes. These conditions may include:

  • Strabismus —a childhood misalignment of the eyes that usually affects children younger than 6 years of age.
  • Nerve damage – the nerves controlling the extraocular muscles (muscles around the eyeball) can be injured or damaged by infection, multiple sclerosis, stroke, head trauma or a brain tumour.
  • Diabetes — this can cause problems with the nerves that control eye muscle movements.
  • Myasthenia gravis — a neuromuscular illness that can cause the body's muscles, including those within the eyes, to tire easily and become weak.
  • Graves' disease — the most common cause of an overactive thyroid, some people with this disease develop double vision due to swelling and thickening of the muscles that move the eyes within the eye socket.

Diagnosis of Double Vision

An Optometrist will undertake a thorough evaluation of your double vision and they will assess:

  • Onset (whether it has been gradual or sudden)
  • Duration (how long you have been experiencing it)
  • Frequency (is it a constant problem or only intermittent)
  • Does it vary with fatigue, head position or direction of eye gaze?
  • Any associated symptoms such as pain, headache and nausea
  • Past and present medical conditions

You will also undergo a physical eye examination which will include measuring the vision (visual acuity) in each eye, thorough examination of the eyes' alignment in various head positions and in many cases, dilating of the pupils to look for any ocular or orbital abnormalities. In some cases, specialized imaging and further tests may be required to investigate other possible causes.


Treatment for double vision depends on its cause. Double vision caused by a medical or neurological condition will usually improve by treating the disease itself. For double vision caused by eye conditions, special contact lenses or updated prescription eyeglasses may help. Surgery may be an option for people with cataracts and pterygium. Other strategies may also be utilised including vision therapy, medication and injections of Botox to help balance vision.

If you have a sudden or dramatic change in vision, make an appointment with an Optometrist today for a comprehensive eye test as soon as possible. This will help to determine the cause of your double vision and help you to see clearly once again. If you have been searching for ‘the best optometrist near me’ then look no further, the team at Abernethy Owens are the here to help. Book online now.