What is optic neuritis
Optic neuritis is inflammation of the optic nerve, which can be in the front part of the nerve known as papillitis or in the back part, retrobulbar optic neuritis. It is the most common optic nerve disease causing sudden vision loss in young patients.
The optic nerve, transmitter of information
The optic nerve is the structure responsible for carrying information from the eyes, which receive light from objects and transform it into nerve impulses, to the brain, which processes this information and interprets it as images. Contrary to popular belief, what we actually see is not with our eyes, but with our brain. A comparable example is the USB cable that transfers information from a digital camera (which is equivalent to the eye) to a computer (which is equivalent to the brain).
Causes of optic neuritis
It is not known in detail why this optic nerve disease occurs. In its most common form, demyelinating optic neuritis, the myelin sheath, the layer that surrounds the neurons that form the optic nerve, is attacked by the patient’s own immune system, constituting an autoimmune disease.
It is likely that a number of factors have combined to cause the episode of optic neuritis to occur. It may be that a viral infection that may have occurred years ago has altered some reaction of the immune system.
Inflammation of the optic nerve may also occur in isolation without being associated with a more generalized disease. In this case it is idiopathic neuritis or neuritis of unknown cause.
It may also be part of a disease that has inflamed other sites in the body such as multiple sclerosis, syphilis, neuromyelitis optica, systemic lupus erythematosus, Wegener’s granulomatosis, or tuberculosis among others.
Symptoms of optic neuritis
If the myelin sheath is damaged, the signal transmitted by the optic nerve from the eye to the brain will travel more slowly and with lower resolution.
Thus, the main symptom of optic neuritis is loss of vision: you experience blurred vision, obscured vision, as if a piece of vision is missing in the center or on the sides or with a fixed spot in the visual field. This vision loss occurs rapidly and does not improve with glasses.
Other common symptoms are pain in the eye or behind the eye, especially when moving the eye, dim color vision and the appearance of bright flashes.
Some patients even notice blurred or obscured vision for a few minutes or even an hour in very hot weather or after exercise or hot showers: this is Uhtoff’s phenomenon.
Diagnosis of optic neuritis
Diagnosis of this pathology can be complicated, as the eye may appear normal. For this reason it is essential to take into account the patient’s symptoms and their progression since they began, as well as all past illnesses and other data from the patient’s medical history such as diet, consumption of toxic substances, pets, etc. that may be relevant to the current problem.
The specialist in Ophthalmology will perform a neuro-ophthalmological examination and with all the data obtained will assess what complementary examinations are required to complete the study. Usually these tests include ophthalmologic tests such as campimetry, and non-ophthalmologic tests such as cranial resonance imaging. The diagnosis of optic neuritis is initially a diagnosis of suspicion, which will be confirmed with the evolution of symptoms and examination findings.
Treatment of optic neuritis
Fortunately, in the vast majority of patients, vision improves considerably, whether or not treatment is performed. In cases of typical optic neuritis, treatment with corticosteroids accelerates recovery, but the final vision that will remain will be the same whether corticosteroids are administered or not. Therefore, corticosteroids cause the nerve to deflate faster, but the vision will reach the same point. Cases of atypical optic neuritis may require treatment with high doses of corticosteroids, antibiotics or other drugs on a case-by-case basis.