Medical Care
No proven treatment reverses optic atrophy. However, treatment that is initiated before the development of optic atrophy can be helpful in saving useful vision.
The role of intravenous steroids is proven in a case of optic neuritis and is controversial in arteritic anterior ischemic optic neuropathy. Early diagnosis and prompt treatment can help patients with compressive and toxic neuropathies.
Idebenone, a quinone analog, has been used and is the only clinically proven drug in the treatment of Leber hereditary optic neuropathy. The drug molecule bypasses the defective mitochondrial complex I, leading to improved energy supply and a functional recovery of retinal ganglion cells during the acute stage of the disease, thereby preventing further vision loss and promoting vision recovery. [13] So far, the results were noted to be modest and the treatment is quite expensive. Klopstock et al conducted a 24-week multicenter double-blind, randomized, placebo-controlled trial in 85 patients with Leber hereditary optic neuropathy. They did not find a statistically significant visual recovery in the intention-to-treat population. They did find, however, evidence that patients with discordant visual acuities are the most likely to benefit from idebenone treatment, which is safe and well tolerated. [14]
Current clinical research in gene replacement therapy has demonstrated a good safety record but poor longevity of therapeutic results. The study results are promising and, with a better understanding of the pathophysiology of the neuropathies, should and will enable the development of future viable strategies in terms of prolonging vision. [15]
de Lima et al were able to restore some depth perception in mice with severe optic nerve damage. In addition, they found that the mice regained the ability to detect overall movement of the visual field and were able to perceive light. They found that using adequate stimulus, the fibers (1) are able to find their way to the correct visual centers in the brain, (2) are wrapped in the conducting insulation known as myelin, and (3) can make connections (synapses) with other neurons, allowing visual circuits to re-form. They discovered a molecule called oncomodulin. They achieved neuroregeneration in mice by simultaneously targeting the protein oncomodulin, elevating levels of the small signaling molecule cyclic adenosine monophosphate (cAMP) and deleting the gene that encodes the enzyme PTEN. [16]
In recent studies using hamster models, anterograde tracing and electrophysiologic responses reveal that a small number of axons can regenerate all the way back to the superior colliculus. [17] In other studies, remapping of the retina was noted in the superior colliculus following axon regeneration. [18] These findings have given hope to clinically meaningful regeneration of axons, which may become a reality in the near future.
Three-year results of gene therapy for LHON suggested that intravitreal injection of rAAV2-ND4 is safe and promising. However, the study sample size was small, and additional patients are currently being enrolled. [19]
At present, the best defense is early diagnosis, because, if the cause can be found and corrected, further damage can be prevented.
Further Outpatient Care
Low-vision aids for patients with some useful vision should be considered for occupational rehabilitation.
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Normal optic nerve histopathology.
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Glaucomatous optic atrophy histopathology.
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Healthy optic disc.
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Nonarteritic anterior ischemic optic neuropathy.
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Arteritic anterior ischemic optic neuropathy, cilioretinal artery occlusion.
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Primary optic atrophy.
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Optic atrophy following papilledema (secondary).
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Glaucomatous optic atrophy.
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Juvenile open-angle glaucoma (JOAG) with optic pallor.
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Consecutive optic atrophy following panretinal photocoagulation (PRP).
Tables
|
Postneuritis |
Ischemic Arteritic |
Ischemic Nonarteritic |
Compressive |
Age |
15-50 y |
Approximately 70 y |
Sixth decade |
Varies based on cause |
Sex |
Multiple sclerosis F>M |
F>M |
F=M |
Varies based on cause |
Visual acuity |
Varies from mild blurring (34%) and moderate loss of acuity (12%) to severe or total loss of light perception (complete blindness) in 54% of cases, to no light perception. The loss of vision is acute and progressive.--Vision usually recovers within 2 mo |
< 20/200 (6/60) |
>20/200 (6/60) |
Varies from mild blurring to no light perception |
Color vision |
Color vision > vision loss |
Color vision loss = vision loss |
Color vision loss = vision loss |
Color vision = vision loss |
RAPD* |
+ |
+ |
+ |
+ |
Motility |
Painful movement in cases of retrobulbar neuritis |
Normal |
Normal |
Depends on the site of compression |
Nystagmus |
In multiple sclerosis, vertical nystagmus (upbeating or downbeating) may be seen |
No |
No |
See-saw nystagmus in optic chiasm compression |
Optic disc |
Temporal pallor |
Pallid disc edema |
Segmental disc edema |
Bow-tie pallor seen in optic chiasm compression; varies in other instances |
Electrophysiologic study |
VEP-increased latency < †> |
VEP-reduced amplitude |
VEP-reduced amplitude |
Reduced VEP amplitude |
Neuroimaging (CT, MRI) |
In multiple sclerosis, hyperechoic lesions are seen in the brain on MRI |
- |
- |
For exact location of compression |
Other associations |
|
Headache, scalp tenderness, jaw claudication |
Hypertension and diabetes |
Headache, vomiting, and focal neurologic deficits |
*RAPD - Relative afferent pupil defect < †>VEP - Visual-evoked potential |
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