Double vision is when an individual sees two images of one object. Double vision might occur when only one eye is open (also called monocular diplopia) or when both eyes are open (also called binocular diplopia). Binocular double vision disappears when one eye is closed. Other symptoms such as bulging eye, eye pain or muscle weakness could be present depending on the cause of double vision.
Individuals with diabetes may complain about sudden onset of double images. It is important to see an optometrist or ophthalmologist immediately because this can be due to damage to the nerves from the brain to the eye.
What cranial nerves pertain to the eyes?
The second cranial nerve is known as the optic nerve. It sends visual info from the eye to the brain. The third cranial nerve is known as the oculomotor nerve. It’s involved with eyelid movement, eye movement and the function of the pupil and lens. The fourth cranial nerve is known as the trochlear nerve and the sixth cranial nerve is called the abducens nerve. They each trigger an eye muscle involved in eye movement. The fifth cranial nerve is known as the trigeminal nerve. It brings facial and corneal sensation.
What is cranial nerve palsy?
A palsy is a lack of function in the nerve. A cranial nerve palsy might cause a complete or partial weakness or paralysis of the areas served by the affected nerve. If a cranial nerve has multiple functions such as the oculomotor nerve, it’s possible for a palsy to affect all of the various functions or only some of the functions of that nerve.
What are the causes of a cranial nerve palsy?
A cranial nerve palsy can be traumatic, congenital or due to vascular disease such as aneurysms, diabetes, hypertension, and aneurysms. They can also be due to migraines, infections, tumors or elevated intracranial pressure. The age of the patient and clinical findings will help point the opthalmologist toward the correct diagnostic tests needed to determine the etiology.
The symptom can be misinterpreted by the patient or by a non-eye care provider unfamiliar with this ocular complication as a sign of a stroke or other neurological issue. This prompts unnecessary diagnostic procedures such as radiological tests.
Double vision or diplopia might instead be due to mononeuropathy. This is the damage to a single nerve such as cranial nerves VI, III or IV. The sixth and third nerves are the most frequently affected. Third-nerve palsies occur with pupillary sparing in eighty percent of cases. Many diabetic third-nerve palsies typically resolve spontaneously within two to three months and the symptom of double vision can often be controlled with the use of special lenses.
Lack of control of blood glucose levels could lead to a fluctuation in vision. These temporary visual fluctuations happen because of fluid imbalance in the crystalline lens. The lens thickens and causes vision changes that may increase nearsightedness or farsightedness when the glucose level is elevated. When the glucose level returns back to normal, the lens could shrink back to its normal state.
If the glucose level is poorly controlled, the constant state of flux can make it difficult to determine the best lenses for people who need glasses.
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