Optic Atrophy
Optic Atrophy is a condition that affects the optic nerve, and that can cause extensive damage to the visual pathway. Affected individuals will present with a pale optic disc due to this damage. There are several known causes of Optic Nerve Atrophy, and it is important to identify the condition early for a good prognosis. There is no known cure, nor effective treatment for Optic Atrophy, and healthcare is directed at the management of symptoms. Although there is no cure, enhanced vision glasses such as eSight may help individuals living with the condition to experience significant improvement in sight.
Overview
Optic Atrophy (OA) refers to a neuro-ophthalmic condition and is not considered a disease. Atrophy, here, refers to the wasting away or progressive decline of the nerve fiber of the optic nerve.. What is affected is the primary retinal ganglion cells (RGC) and the axons forming the optic nerve. The RGC and axons process visual information which begins as light entering the eye, which then gets transmitted to the brain.
“Optic Atrophy” means that some or all of the nerve fibers of the optic nerve have been lost or simply experienced “optic nerve shrinkage”. This could lead to progressive bilateral degeneration of the optic nerves and subsequent vision loss.
Optic Atrophy is a condition of the nervous system that affects the vision by the shrinking of the optic nerve.
How does it work? Light carries visual information about the world around us. The process of seeing beings with light travels through the clear outer coating of your eye, (known as the cornea), and travels through your pupil to enter your eye. Once inside your eye, the light strikes a light-sensitive layer of tissue that lines the back of your eye. This tissue, known as the retina, absorbs the light and converts the visual information into electrical pulses. These electrical signals travel through a bundle of nerve fibers, known collectively as the optic nerve, to the brain. Your brain then translates the electrical pulses into the images we “see.” With Optic Atrophy, there is an interference with the ability to transmit these pulses.
Prevalence of Optic Atrophy
Optic Atrophy is a condition that affects the optic nerve, and that can cause extensive damage to the visual pathway. Affected individuals will present with a pale optic disc due to this damage. There are several known causes of Optic Nerve Atrophy, and it is important to identify the condition early for a good prognosis. There is no known cure, nor effective treatment for Optic Atrophy, and healthcare is directed at the management of symptoms. Although there is no cure, enhanced vision glasses such as eSight may help individuals living with the condition to experience significant improvement in sight.
Signs and Symptoms
The most common signs and symptoms are dimming of vision and a reduction in the patient’s field of view. Patients typically lose their ability to see in fine detail as well, noted Medline. This might be the first time a person notices something is happening to their vision.
- Dimmed vision
- Reduction in field of view
- Loss of ability to see in fine detail/ color
- Decreased brightness perception
Subtle and progressive damage may present itself with the patient losing their ability to detect contrast or color within their vision. If atrophy occurs in one eye, the patient may have a decreased brightness perception in one eye over the other. Pupils will also become less reactive to light over time and eventually, the individual may experience complete vision loss in the affected eye.
There may be other symptoms present such as eye pain, ataxia, and weakness, but these symptoms would be attributed to the underlying condition that caused the damage, rather than OA itself.
Risk factors of Optic Atrophy range from a family history of neuropathies to increased intraocular pressure (glaucoma), infection, compression (tumors), ischemia, inflammation, medication history, known malignancy, history of diabetes, hypercholesterolemia, and hypertension.
Can Optic Atrophy cause blindness?
Yes, Optic Atrophy can cause blindness. Its effect can be from anywhere mild vision changes to complete loss of vision.
Diagnosis
Diagnosis of Optic Atrophy can be made by using an ophthalmoscope to observe the optic disc. This is done by an ophthalmologist. Pallor of the disc is indicative of limited blood flow, suggesting OA and leading to nerve damage. Further ophthalmologic tests can be done including checking peripheral vision and the ability to distinguish colors from one another.
Additional tests may include:
- Visual field tests to confirm the diagnoses and observe changes overtime
- Magnetic Resonance Imaging (MRI) of the brain can be used to view potential causes of Optic Atrophy, such as lesions, inflammations, fractures, etc.,
- Computed Tomography (CT) scans are used to check for fractures
- Orbital tumors can be seen by using ultrasonography (B-scan)
- Diabetes diagnosis can be made by checking the blood glucose level
- For vascular etiology, blood pressure and other cardiovascular indicators can be tested
- Electroretinography (ERG) results may show abnormalities in the retina
- Nutritional deficiency in vitamin B12 can be evaluated
It is important to diagnose Optic Atrophy early to reduce its progression. This is because Optic Atrophy damage cannot be reversed.
Causes
As Optic Atrophy is a condition that has a number of causes, diagnosis may begin at the primary care provider or in the office of your eye doctor. Generally, an underlying condition is getting in the way of the optic nerve conducting signals to the brain. According to the Cleveland Clinic, the most common causes include:
- Glaucoma
- Optic nerve formed improperly before birth
- Vision loss occurs in one eye first, and then the other, an indication that the patient has an inherited condition called Leber’s hereditary optic neuropathy
- Multiple sclerosis causes optic neuritis, which is a swelling or inflammation of the optic nerve caused by MS
- A growing tumor is pressing on the patient’s optic nerve
Tumors are the most common cause of OA in both eyes, traumatic periocular and head injuries are mostly associated with unilateral Optic Atrophy in men. In individuals over the age of 40, vascular issues such as hypertension commonly cause OA.
Such various potential causes of Optic Atrophy underscore the importance of visiting a primary care provider on a regular basis as well as seeing an eye doctor at least once a year for routine surveillance of eye health. After all, symptoms that present themselves in the eyes can sometimes be the first signs of another undiagnosed health condition, detected by the eye doctor before they are discovered by a family doctor.
Glaucomatous Optic Atrophy
Glaucoma is a common cause of Optic Atrophy. More information on Glaucomatous Optic Atrophy can be found here “Glaucoma”
Hereditary Optic Atrophy
Hereditary Optic Atrophy includes Leber Hereditary Optic and Dominant Optic Atrophy, which are mitochondrial cytopathies, meaning there is a mutation in the mitochondrial DNA. Dominant Optic Atrophy is an autosomal dominant condition and the most common of the neuropathies. It has a prevalence of about 1:10,000 to 1:50,000 and is understood to be a progressive vision loss, because of the premature (usually in the first decade of life) degeneration of the optic nerve.
Leber Hereditary Optic Atrophy occurs due to mitochondrial DNA abnormality which impedes cellular respiration. The primary and typically earliest sign of Hereditary Optic Atrophy is vision loss. It commonly occurs in males (about 80 – 90% of those affected are male), but only females can pass on the abnormality to the next generation.
Treatment
Optic Atrophy is currently irreversible. However, it’s prudent to consult with a doctor to learn about any underlying disease that could cause the condition to progress further. This includes regularly monitoring blood pressure and taking steps to keep it under control, with supervision from primary health care providers. Be sure to schedule eye exams once per year, to be screened for possible glaucoma.
Local support groups can also help when living with Optic Atrophy. The USA Genetic and Rare Diseases Information Center’s page on Optic Atrophy provides local resources for patient support.