Diplopia, or double vision, occurs when an individual sees two or more images simultaneously. This condition can emerge suddenly in one or both eyes and often indicates underlying disorders within the visual system. Several common causes are outlined below.

Lens abnormalities

The eye's natural lens focuses light onto the retina, creating clear images. If the lens becomes cloudy or opaque, incoming light distorts, leading to unclear vision and double vision. This condition typically continues until a cataract is treated.

Corneal damage

The transparent dome at the front of the eye, known as the cornea, can sustain damage. Conditions like dry eyes, corneal scarring, infections, or astigmatism create an uneven corneal surface, which can lead to double vision.

Eye muscle problems

Eye muscles control and coordinate both eyes' movements in all directions. If one or more of these muscles weaken or become paralyzed, the eyes lose alignment, resulting in double vision and sometimes strabismus.

Vertical double vision, where one image appears above another, often links to Graves' disease, a thyroid disorder impacting the extraocular muscles. Conversely, horizontal double vision, presenting as two parallel images, frequently occurs with damage to oculomotor nerves, particularly sixth cranial nerve palsy. This condition prevents the eye from looking outward and causes it to turn inward.

Double vision that is more pronounced when looking at distant objects often suggests sixth cranial nerve palsy. Conversely, increased double vision when focusing on nearby objects can indicate discoordination of the extraocular muscles or damage to other oculomotor nerves.

Cranial nerve problems

Cranial nerves three, four, and six control eye movements. Damage or conduction disorders in these nerves disrupt eye coordination, leading to double vision. Potential causes include neurological conditions such as Guillain-Barre syndrome, multiple sclerosis, or neuromuscular disorders like myasthenia gravis.

Brain issues

The brain receives and processes visual signals from the eyes. Disorders such as migraines, tumors, aneurysms, strokes, infections, or head trauma can interrupt this process, resulting in double vision. While some cases of diplopia improve spontaneously, underlying conditions like hyperthyroidism or multiple sclerosis necessitate treatment of the root cause. For eye misalignment due to extraocular muscle disorders, eye muscle surgery may be considered to improve vision.

Bao Bao (According to Very Well Health)