What is optic atrophy?

Optic Atrophy is a condition which affects the optic nerve. This is the nerve that carries impulses from the eye to the brain. This condition can have long-term damage to the fibres in the optic nerves, from various causes and can also cause irreversible issues, such as blindness if left untreated. 

Optic atrophy is estimated to affect around 1 in 35,000 people worldwide, where studies show that prevalence to be higher in Japan, Israel, Scotland and many more.

It is important that your eyes are healthy, this is why you are able to see. The optic nerves send messages from your eyes to your brain to produce visual images, playing an essential role in your ability to see, so any damage can result in you losing your vision either from one or both eyes.^1,2

The anatomy of the optic nerve

Structure and function

The optic nerve is found in the back of the eye. It is also known as the second cranial nerve because it is part of the central nervous system. The optic nerve serves to transfer visual information from the retina to the vision centres of the brain by electrical impulses.³

How does optic atrophy happen?

The optic nerve head is represented as the inner part of the optic nerve. This is where the axons of retinal ganglion cells exit from the eyeball. The blood is supplied to the optic nerve by the capillary net that begins at the retinal arterioles. Because of the capillary network and the total internal reflection of light in the axons, the optic nerve will appear to be yellow/ pink. So, when there is a degeneration of the retinal ganglion cells, axons and the capillaries, then it will appear to be a pale and wide optic disc.^4,5

What causes optic atrophy?

The nerve fibres that send out impulses to the brain form the optic nerve. During optic trophy, there is an interference with the optic nerve not being able to send out signals. There are many factors that can cause this:

Genetic factors

• Hereditary optic atrophy: This is caused by an autosomal dominant gene and the most common one that can be inherited. It is believed to be caused by a premature loss of function of the optic nerve, which then leads to slow loss of vision
• Genetic mutations: other mutations include, Leber hereditary optic neuropathy, and it is caused by an abnormal mitochondrial DNA⁶

Acquired factors

• Traumatic injury: Eye injuries can happening many ways, like car accidents, sports or fighting
• Ischemic damage: Lack of blood flow
• Inflammatory conditions: Inflammation to the optic nerve and or fluid accumulation in the brain (hydrocephalus)
• Infections: Damage to optic nerve from infections, like syphilis and measles.
• Retinal diseases: Diseases affecting your retina¹

What are the symptoms?

Visual symptoms

• Gradual vision loss - can be found to be painful in some cases
• Headache
• Haemorrhage to the blood network
• Reduce colour saturation - commonly found the red colour to be less saturated
• Contrast sensitivity
• Peripheral vision deficits
• Colour vision changes - not being able to identify colours blue and yellow¹

Ophthalmologic findings

• Optic disc appearance: It can be found to be wider and a chalky-white colour
• Visual field testing: It can help to show how you can see in corners of the eyes as well as being able to locate the atrophy
• Fundoscopy: It is a test, much like an eye exam and it allows the specialist to examine the retina. When the pupils are dilated it allows for a complete view of the whole retina

How is it diagnosed?

Medical history 

It is essential to have an appointment with your eye care specialist, to see if there are any issues with your vision. They will first ask you questions about the symptoms you are experiencing and your medical history. Your eye specialist can also ask you about your diet, and any medications you take, including supplements. Then, complete an ophthalmologic examination.⁵

Ophthalmologic examination

During the eye exam, the specialist will look at any changes in the visual sharpness, such as reduced visual sharpness and sensitivity in contrast and an afferent pupillary abnormality. They will also look for a chalky white disk in a more severe form. The surface capillary network will also be examined at a higher magnification, here they will find either no thin or no network present at all.⁵

Imaging studies

To better investigate the atrophy, some imaging techniques can be used:^6,7

• Optical coherence tomography (OCT): It helps to show the stage of the nerve fibre layer and examine the ganglion axons 
• Magnetic resonance imaging (MRI): It helps to further examine the orbits and the brain

How is it treated?

Since there is no cure or treatment for optic atrophy itself, the way to treat it would be to treat the underlying cause of optic atrophy. This is why it is important to have regular eye check-ups and to see your doctor when there are any changes in your vision. To stop the condition from getting worse, it is best to treat the underlying condition causing it. 

If your vision worsens overtime, you can ask your doctor for ways to cope with a decreased vision. Your doctor may advise you to have low-vision aids, such as special lenses and magnifying glasses.¹

What are the complications?

The prognosis for optic atrophy will be dependent on how severe the condition is. If it is partial atrophy, then the visual impact will be moderate or mild, but in total optic atrophy, the prognosis will be poor. But if early treatment is given, then you can have a complete recovery. 

Since optic atrophy is not really a disease in itself, and it is a sign of different conditions, the complications for it will be related to the disease/condition causing optic atrophy and not optic atrophy itself.⁵

What can you expect in the future? 

Currently, the use of newer methods is a lot more popular, because the use of medication for optic atrophy has become ineffective. Stem cell therapy has shown a promising initiative. It aims to replace the damaged fibres and restore the nerve circuits.

Recent studies show that stem cell trophic factors are able to protect the damaged nerves and also allow to produce new interneuronal connections. Also, this therapy is able to slow down the vision loss. When in combination with other specialised therapies, it has helped to better manage the main symptoms of optic nerve atrophy and encouraging regeneration of the tissue.⁸

Summary

Optic atrophy is a condition which causes reduced vision, colour and peripheral vision. Many factors can contribute to causing optic atrophy, such as injuries or trauma and any underlying diseases, so the treatment is also limited by only managing the condition and not treating itself. However, with new research, there is hope and positive outcomes in treating optic atrophy, through stem cell therapy and other specialised therapies.