Double Vision (Diplopia): Causes, Symptoms, and Treatments

When an individual sees a double image where there should only be one, it is referred to as double vision or diplopia. The two images can be side by side, one on top of the other, or a combination of both.
Double vision can affect just one eye (monocular) or both eyes (binocular). Treatments vary depending on the cause and type but include eye exercises, specially designed glasses, and surgery.

Other than the obvious difficulties of navigating the world while viewing a double image, double vision can also cause disruptions in balance, movement and reading ability.

There are a number of potential causes for double vision. As a result, the treatment depends on the particular patient. Some of the underlying causes are minor, others are serious. For this reason, any instances of double vision should be checked by a physician sooner rather than later.
This article will take a look at the potential causes, diagnosis, and treatment of double vision.
Fast facts on double vision (diplopia)
Here are some key points about double vision (diplopia).

  • Double vision can be caused by a number of underlying conditions
  •  Diplopia can affect just one eye or both
  •  A childhood squint can sometimes recur and cause double vision
  •  Temporary double vision can be caused by alcohol or other recreational drugs
  • Treatments can include surgery, eye exercises, or corrective lenses

Causes of binocular double vision

Double vision can be caused by a number of conditions.

 

Each eye creates its own image of the environment. These two representations are combined by the brain so that they are be perceived as one clear picture.
If damage occurs to the muscles that move the eyes or the nerves that control that movement, a double image can be created.
It is necessary for both eyes to be functioning together to create depth of field.
Alternatively, the muscles moving the eyes can become weakened by certain illnesses and produce double vision.
Squint
In some cases, the eyes may not be properly aligned. This condition is referred to as a squint or strabismus. Squints are relatively common in children but do not necessarily result in double vision.
Squints cause the eyes to look in slightly different directions. This might be because the affected eye muscle(s):

  • Are paralysed or weak
  • Have restricted movement
  • Are too strong
  • Have abnormal nerves controlling them

Sometimes, a treated squint in childhood can return in adult life and in some cases, the treatment of a squint can actually cause double vision, despite the individual’s vision being normal before the squint was treated. This is because the brain had been suppressing signals from one of the eyes in an attempt to maintain normal vision.
Temporary double vision
In some cases, double vision can be temporary. Temporary double vision is often caused by alcohol intoxication, benzodiazepines, opioids, or certain types of drugs for seizures and epilepsy. Head injuries, like concussions, can also cause temporary double vision.
Being particularly tired or having strained eyes can bring on temporary double vision. If normal vision does not come back quickly, medical attention should be sought as soon as possible.
Other causes of double vision
Other than a squint, there are a number of potential conditions that can cause double vision. These include:

 


Certain thyroid problems can cause double vision.

  •  Thyroid: the thyroid gland is situated in the neck and produces a hormone called thyroxine. Changes in thyroid function can affect the external muscles that control the eye. This includes Grave’s disease.
  • Stroke or transient ischemic attack: blood vessels supplying the brain or nerves controlling the eye muscles can be affected.
  •  Aneurysm: an aneurysm is a bulge in a blood vessel. This can press on the nerve of the eye muscle.
  • Convergence insufficiency: a condition where the eyes do not work together correctly. The cause is unknown, but it is thought to be due to the muscles that control the eye not lining up properly.
  •  Keratoconus: a degenerative condition of the eye that causes the cornea to thin and become cone-shaped.
  • Diabetes: the blood vessels that supply blood to the retina at the back of the eye can be affected by diabetes.
  • Myasthenia gravis: this condition can cause weakness in the body’s muscles, including those controlling the eyes.
  •  Brain tumour/cancer: a tumour or growth behind the eye can interfere with free movement or damage the eye’s nerves.
  • Multiple sclerosis: a disease that affects the central nervous system, including nerves that supply the eyes.
  • Head injury: physically damaging the brain, nerves, muscles, or eye socket can restrict the movement of the eye and its muscles.

 

Causes of monocular double vision
If double vision is noted when one eye is covered and not when the other eye is covered, this is referred to as monocular double vision.
Monocular double vision is less common than binocular double vision and can be caused by the following conditions:

  • Astigmatism: the cornea is irregularly shaped (the transparent layer at the front of the eye). This causes a refractive error; in other words, the light is bent more, or less, than it should be.
  •  Dry eye: the eye does not produce enough tears, or it dries out too quickly
  •  Black eye: an injury can cause blood and fluid to collect around the eye. This can press on the eye itself or the muscles and nerves around it.
  •  Abnormality of the lens: for instance, cataracts, which are cloudy patches over the lens
  • Abnormality of the retina: for example, macular degeneration, where the centre of an individual’s field of vision slowly disappears.

Diagnosing double vision
Diagnosing double vision can be challenging for an ophthalmologist (eye specialist) because of the vast array of potential causes. These can range from minor causes to some that are potentially more serious.
One of the first questions a specialist will ask is whether the diplopia is monocular or binocular. If the double vision is monocular, it means that the problem is more likely to be within the eye rather than with the nerves that control the muscles of the eyes or with the muscles themselves.

Diagnosing double vision in children
As children cannot always express what they are perceiving, diagnosing double vision in children can be more difficult. Things to watch out for include:

  •  Squinting or narrowing the eyes to see
  •  Covering one eye with their hand
  • Turning their head in an unusual way
  •  Looking at objects from the side rather than facing forward
  • Flicking eyes side to side, between images

 

Treatments for double vision
The course of treatment for double vision depends on the underlying cause:
Astigmatism
Astigmatism refers to an abnormally curved cornea. In many cases, corrective lenses (glasses or contact lenses) can counteract the curvature and correct the passage of incoming light into the eye. In certain cases, surgery may also be an option.

Cataracts
Cataracts commonly occur as we age and can sometimes cause double vision. In most cases, surgery is the best option. During the surgical procedure, the ‘cloudy’ lens which is the cause of the double vision is removed.

Treatments for binocular double vision
Depending on the cause, the treatments for binocular vision vary, but they include:

  •  Wearing glasses
  •  Eye exercises
  •  Wearing an opaque contact lens
  • Fixing thin, plastic, see-through prisms to glasses
  • Botulinum toxin (Botox) injections into the eye muscles cause them to remain relaxed
  • Wearing an eye patch
  • Surgery on the muscles of the eye to correct their positioning

 


Presbyopia – an informative guide

When viewing an object that is far away, the eye – if we are perfectly sighted – is shaped so that the object is clearly focused on the retina. This means that the image is clear. When we look at something close up, for example reading a book, the muscles inside the eye that surround the lens contract to make the lens change shape. This focuses the light from the book onto the retina.

The lens inside a child’s eyes is elastic, and so will naturally alter its shape easily to allow for a change in focus from a distant to near object. As we get older however, the lens will stiffen and so change shape less easily. This means that the distance up to which we are able to focus becomes longer and we are no longer able to focus on things that are close to us, having to hold them further away to see them clearly. This is more noticeable with very close work, for example, when threading a needle. It can also mean that it may take longer for us to focus from looking at something close up to looking at something far away (or vice versa).

This change in focusing tends to become more noticeable when we reach our late thirties or forties as we then find it difficult to focus on things that are at the normal reading distance. It is quite common to see people who are presbyopic holding things away from them in an attempt to see them clearly. As this affects things that are close to us first, our vision of things that are further away – such as the computer – is not affected until later, when the lens has lost almost all of its elasticity.

This loss in elasticity is corrected with spectacles. This may mean having separate pairs for distance and reading and maybe for middle distance such as looking at the computer or reading sheet music.

What is the treatment for presbyopia?

Presbyopia is a natural part of ageing and there is no cure for it. The solution is generally to wear glasses for reading. Because reading glasses focus light from close objects, it is normal to find that distant objects are blurred when looking through them. They can either be removed for distance viewing or alternatively, bifocal or varifocal lenses can be used.

Bifocal lenses consist of two separate areas of the lens which are separated by a line: the top part of the lens focuses light from distant objects, and the bottom part of the lens focuses light from near objects. Varifocal lenses work in a similar way to bifocal lenses but without a visible line on the lens. This is because the power gradually changes from the top to the bottom of the lens, to allow objects at any distance to be seen clearly, simply by moving the head up and down to look through a different part of the lens.

Are there exercises I can do to stop needing reading glasses?

Presbyopia is not caused by muscle weakness but by the lens stiffening as we age. There are no exercises that can help this.

If you have any further questions please contact us

 


Are your eyes looking worse for wear this winter?

Winter can be harsh on our eyes. From the damaging reflection of sun on snow and ice to the discomfort of dry eye, our most precious sense is often under attack during the winter season. Check out our top tips for warding off eye health problems as the cold starts to bite.

Protection against UV rays
Snow and ice are reflective, meaning the sun’s ultraviolet (UV) rays can reach your eyes from below as well as above you. If snow has fallen in your area, or if you’re off on a skiing holiday, you should be considering wearing protective glasses to reduce the damage that can be caused by the sun’s reflection. UV exposure is cumulative so although you may not feel any immediate effects, you could be putting yourself at risk of long term damage to the retina and lens of the eye by increasing the risk of developing conditions such as cataracts and possibly AMD (Age-related Macular Degeneration) over time.
The glare of a low-lying sun on icy roads can also cause difficulty for drivers, even for those with good vision so it’s really important to make sure your windscreen is clean, both inside and out. It’s useful to have a pair of sunglasses in the car to help with this. If you wear spectacles, sunglasses can be made to your prescription, including bifocals and varifocals.
If you are venturing off to the ski slopes then buy good quality, specially designed sunglasses or goggles. Check for confirmation that they comply with the safety standard BS EN ISO 12312-1:2013, or are made by a reputable manufacturer and have a CE mark. The CE mark is the manufacturer’s assurance that they meet European safety standards.

Dry eye
Dry eyes can cause itchiness or scratchiness, as well as blurred vision. The condition is not usually serious, however there are some rare cases where severe untreated dry eye has led to scarring of the eye’s surface. Dry eye may be caused because your eyes do not produce enough tears, or because the tears that you do produce evaporate too quickly or do not spread evenly across the front of your eye. The treatment depends upon the cause, so it is important to speak to your optometrist if your eyes feel dry. If your eyes are dry because they do not produce enough tears you may find eye drops, gels or ointments that contain ‘tear substitutes’, helpful. These are designed to lubricate your eyes and are available from many optometrists or from a pharmacy without prescription.
There are some simple steps you can take to minimise the discomfort caused by dry eyes:
• Lower the temperature in rooms – high temperatures make tears evaporate more quickly
• Blink more – many people find that their dry eye gets worse during tasks such as reading or computer work because we unconsciously blink less when we are doing anything that needs lots of visual attention
• Use a humidifier at work and at home – this will help moisten the surrounding air. If you cannot afford a humidifier, lightly spraying your curtains with water several times a day can help keep the air moist. Opening windows for a few minutes on cold days, and longer in the spring and summer, will also help to keep the air moist.

Watery eyes
In cold and windy conditions, many people complain of their eyes watering more than normal. Typically, the symptoms of watery eye are excessive tearing which is made worse by being outdoors. Wearing spectacles will provide protection against the wind, even if you don’t usually wear them outdoors. In some cases, excessive watering of the eyes may be a sign of blocked tear ducts or infection of the eye. If you are concerned about the health of your eyes, then visit your optometrist who will be able to advise you on the best course of action.

Tired eyes / eye fatigue
People often find doing tasks such as reading, writing and sewing more difficult in the winter because there is less natural light available. There is little evidence to suggest that this causes our eyes any long-term damage, however if our eyes are having to work harder to focus then this may lead to eyestrain. It is normal to find that it is easier to see things when the light is good, so we would recommend having an angle-poise lamp or similar, whilst under taking near vision tasks, as this will help. Your optometrist will be happy to recommend suitable lighting.


Maui Jim Blue Hawaii product update

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The first few frames from Maui Jim’s new Blue Hawaii collection, which feature a blue flash mirror coating, were unveiled last year at the TFWA World Exhibition & Conference in Cannes.

Blue Hawaii coating is applied to a grey base lens to create one of the most protective lenses on the market, claims Maui Jim.

“Blue Hawaii’s high contrast Anti-Reflection coating to eliminate stray light combined with Maui Jim’s proprietary PolarizedPlus2 lens technology – which reduces 99.9% of harmful glare and provides 100% protection from UVA and UVB rays – means that only 19% of light is transmitted to the eye,” says the brand.

Maui Jim says that this high protection lens material makes the Blue Hawaii collection of sunglasses ideal for extra bright days and activities on water.

This month Blue Hawaii just got better!

Maui Jim have recently extended our Blue Hawaii collection so it’s available in more styles. For non prescription wearing, the Blue Hawaii lens is now available in the following styles:

Baby Beach, Cliff House, Ho’okipa, Leia, Mavericks, Peahi, Red Sands, Sweet Leilani, Tail Slide and Wiki Wiki.

The Blue Hawaii lens is also now available for your prescription  in any style.

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College of Optometrists offers advice to skiers and snowboarders to protect their eyes on the slopes

The College of Optometrists offers advice to skiers and snowboarders to protect their eyes on the slopes

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The College of Optometrists is urging winter sports fans to make sure they are adequately protecting their eyes when out on the slopes this winter. Although clear skies and deep powder provide perfect skiing conditions; snow is reflective, so the sun’s ultraviolet (UV) rays are much more powerful  on the slopes than elsewhere – posing a risk to eye health.

 

Dr Susan Blakeney, the College’s Clinical Adviser explains: “It’s important that when snowboarders and skiers are getting kitted out for the slopes they get goggles to protect their eyes. As snow can reflect significantly more light than normal ground surfaces, it is vital that you protect your eyes by wearing goggles or sunglasses that are specifically designed for winter sports, and are made to the relevant safety standard to ensure they absorb sufficient UV.

 

“UV exposure is cumulative so, although you may not feel any immediate effects you could be putting yourself at risk of long term damage as sunlight may damage your eyes, increasing the long-term risk of developing conditions such as cataracts and possibly AMD (Age-related Macular Degeneration). If you are not sure of the best protective eyewear for you, ask your optometrist before travelling.”

 

Here are Dr Blakeney’s top tips for looking after your eyes on the slopes:

  • Wear goggles if possible – sunlight can be reflected off the surface of the snow and sunglasses may not provide sufficient all round protection.
  • If you’re going on a family holiday don’t forget about your children – their eyes are more receptive to UV than adult eyes, so UV protection is particularly important for them.
  • If you do choose sunglasses, look for the stamp that says they comply with the safety standard BS EN ISO 12312-1:2013 and have a CE mark – the manufacturer’s assurance that they meet European safety standards.
  • There are four categories of tint in the BS EN ISO 12312-1:2013 standard. Category 4 (the darkest) is designed for protection against extreme sun-glare for example over snowfields or on high mountains. Ask your optometrist to show you glasses in this category.
  • Choose eyewear that fits comfortably – make sure it is the right size for you, and unlikely to fall off in the event of sudden movements or higher winds.
  • Wear a hat that covers the rim of your glasses to protect your eyes from direct over head sunlight.
  • People who wear glasses can wear sunglasses too – sunglasses can be made to any prescription.