Double vision, also known as diplopia, is a condition when a single object is seen twice as either adjacent or overlapping one another. Some people experience double vision all the time, only sometimes, or specifically during a certain head turn, tilt position, direction of gaze. There is a wide variety of causes for double vision and in the event you are experiencing this, it’s best to check with your doctor to be properly diagnosed. 

Causes of double vision

There are many different muscles, nerves, and parts of the eye that work together to produce a single clear image. Double vision or ghost images happen when one of those processes is malfunctioning due to a neurological or muscular problem or if a part of the eye itself has problems.

The leading cause of this vision impairment is due to the misalignment of the eyes but additional complications related to the cornea, lens, or tear production are some common culprits, too.  

Muscle weakness or nerve conditions may lead to misalignment of the eyes that prevents them from moving smoothly and in conjunction with each another. This can be related to anything from an autoimmune disease, a thyroid condition, diabetes, high blood pressure, high blood lipids levels, or other conditions that affect the brain and nerves. More serious cases of double vision may be caused by strokes, head trauma, aneurisms, meningitis, migraines, or brain tumors.

Irregularities with the cornea, which is the transparent surface layer of the eye, may also cause double vision and can affect one or both eyes. This may be due to corneal irregularities that cause the cornea to have an abnormal surface and therefore distorts the light that enters the eye. Significant corneal scarring may occur while experiencing or recovering from an infection of the cornea or while healing from complicated refractive surgery such as LASIK or PRK.

Eyes are meant to operate in a moist environment, so dry eyes can lead to seeing ghost images. This can occur if there is adecrease in tear production quality or quantity. It may also happen in certain situations such as staring at a computer screen too long without blinking or being exposed to windy or dry air. Without proper lubrication, the surface of the eye cannot remain smooth and clear, which is ideal for accurate vision.  

The eye’s lens, which is inside the eye behind the pupil, is responsible for changing shape and bending light to produce clear images of objects at various distances. If there are problems with the transparent lens, in the case of clouding due to cataracts, the light may scatter and cause double or sometimes incomplete images. 

Diagnostics and treatments available 

The consequence of double vision includes the inability to focus on an object properly or have proper depth perception, which can lead to headaches. The body may also naturally ignore images from one eye so that double vision no longer occurs. This can prevent the proper alignment of both eyes pointing towards the same focal point, which can lead to developing lazy eye in young patients.

In order to determine the cause of your double vision, doctors will conduct a very thorough and complete examination, noting when any associated symptoms are present and asking about your current and past medical history. 

There are a number of treatments available for double vision depending on your diagnosis. For those experiencing dry eyes, often lubricating eye drops (whether over-the-counter or prescribed) or punctual plugs may be offered. In the case of cataracts, ghost images are often treatable with minor corrective surgery. Double vision caused by eye muscle or nerve problems can be corrected by prism glasses or eye muscle surgery. However, seeking medical advice is the first step towards determining the correct treatment.

By  Major Dr. Nuthida Wongwirawat, Pediatric Ophthalmologist and Adult Strabismologist, Eye center, Bumrungrad International Hospital