Optic Atrophy 

Updated: Apr 01, 2019
Author: Rashmin Gandhi, MBBS, FRCS(Edin), FRCS(Glasg); Chief Editor: Edsel Ing, MD, MPH, FRCSC 

Overview

Background

Optic atrophy is the final common morphologic endpoint of any disease process that causes axon degeneration in the retinogeniculate pathway. Clinically, optic atrophy manifests as changes in the color and the structure of the optic disc (cupping) associated with variable degrees of visual dysfunction. The term "atrophy" is a misnomer, since, in its strict histologic definition, atrophy implies involution of a structure due to prolonged disuse.

Pathophysiology

The optic nerve comprises approximately 1.2 million axons that originate at the ganglion cell layer of the retina. The axons of the optic nerve are heavily myelinated by oligodendrocytes, and the axons, once damaged, do not regenerate. Thus, the optic nerve behaves more like a white matter tract rather than a true peripheral nerve.

The optic nerve is divided into the following 4 parts: 


  • Intraocular part (1 mm) (optic nerve head)
  • Intraorbital part (25 mm)
  • Intracanalicular part (5-9 mm)
  • Intracranial part (10-16 mm)

The average optic nerve head is 1 mm deep, 1.5 mm wide, 1.8 mm high at the retinal level, and a little wider posteriorly. The optic nerve head sits at a major transition between an area of high pressure to an area of low pressure (intracranial pressure) and is composed of 4 types of cells: ganglion cell axons, astrocytes, capillary-associated cells, and fibroblasts.

Normal optic nerve histopathology. Normal optic nerve histopathology.

Light incident from the ophthalmoscope undergoes total internal reflection through the axonal fibers, and subsequent reflection from the capillaries on the disc surface gives rise to the characteristic yellow-pink color of a healthy optic disc. Degenerated axons lose this optical property, explaining the pallor in optic atrophy.

Healthy optic disc. Healthy optic disc.

The blood supply at the optic nerve head is provided by pial capillaries arising from the circle of Zinn-Haller. These capillaries exhibit autoregulation and are not leaky. Alternatively, the loss of these capillaries leads to a pale-appearing disc. The Kestenbaum capillary number index is the number of capillaries observed on the optic disc. The normal count is approximately 10. In optic atrophy, the number of these capillaries reduces to less than 6, while more than 12 suggests a hyperemic disc.

Histopathologic changes noted in optic atrophy include the following:

  • Shrinkage or loss of both myelin and axis cylinders
  • Gliosis
  • Deepening of the physiologic cup with barring of the lamina cribrosa
  • Widening of the subarachnoid space with redundant dura
  • Widening of the pial septa
  • Severed nerve leads to bulbous axonal swellings (Cajal end bulbs); may be observed at the anterior cut end of the fibers

Classification

Optic atrophy is classified as pathologic, ophthalmoscopic, or etiologic.

Pathologic optic atrophy

Anterograde degeneration (Wallerian degeneration)

Degeneration begins in the retina and proceeds toward the lateral geniculate body (eg, toxic retinopathy, chronic simple glaucoma). Larger axons disintegrate more rapidly than smaller axons.

Retrograde degeneration

Degeneration starts from the proximal portion of the axon and proceeds toward the optic disc (eg, optic nerve compression via intracranial tumor).

Trans-synaptic degeneration

In trans-synaptic degeneration, a neuron on one side of a synapse degenerates as a consequence of the loss of a neuron on the other side (eg, in individuals with occipital damage incurred either in utero or during early infancy).

Ophthalmoscopic optic atrophy

Primary optic atrophy

In conditions with primary optic atrophy (eg, pituitary tumor, optic nerve tumor, traumatic optic neuropathy, multiple sclerosis), optic nerve fibers degenerate in an orderly manner and are replaced by columns of glial cells without alteration in the architecture of the optic nerve head. The disc is chalky white and sharply demarcated, and the retinal vessels are normal. Lamina cribrosa is well defined.

Primary optic atrophy. Primary optic atrophy.

Secondary optic atrophy

In conditions with secondary optic atrophy (eg, papilledema, papillitis), the atrophy is secondary to papilledema (shown in the image below). Optic nerve fibers exhibit marked degeneration, with excessive proliferation of glial tissue. The architecture is lost, resulting in indistinct margins. The disc is grey or dirty grey, the margins are poorly defined, and the lamina cribrosa is obscured due to proliferating fibroglial tissue. Hyaline bodies (corpora amylacea) or drusen may be observed. Peripapillary sheathing of arteries as well as tortuous veins may be observed. On visual fields, progressive contraction of visual fields may be seen.

Optic atrophy following papilledema (secondary). Optic atrophy following papilledema (secondary).

Consecutive optic atrophy

In consecutive optic atrophy (eg, retinitis pigmentosa, myopia, central retinal artery occlusion), the disc is waxy pale with a normal disc margin, marked attenuation of arteries, and a normal physiologic cup.

Consecutive optic atrophy following panretinal pho Consecutive optic atrophy following panretinal photocoagulation (PRP).

Glaucomatous optic atrophy

Also known as cavernous optic atrophy, marked cupping of the disc is observed in glaucomatous optic atrophy. Characteristics include vertical enlargement of cup, visibility of the laminar pores (laminar dot sign), backward bowing of the lamina cribrosa, bayoneting and nasal shifting of the retinal vessels, and peripapillary halo and atrophy. Splinter hemorrhage at the disc margin may be observed.

Glaucomatous optic atrophy histopathology. Glaucomatous optic atrophy histopathology.

Temporal pallor

Temporal pallor may be observed in traumatic or nutritional optic neuropathy, and it is most commonly seen in patients with multiple sclerosis, particularly in those with a history of optic neuritis. The disc is pale with a clear, demarcated margin and normal vessels, and the physiologic pallor temporally is more distinctly pale.

Etiologic optic atrophy

Hereditary atrophy

This is divided into congenital or infantile optic atrophy (recessive or dominant form), Behr hereditary optic atrophy (autosomal recessive), and Leber optic atrophy.[1, 2] Several hereditary optic neuropathies, including optic atrophy type 1 and Leber optic atrophy, have been attributed to mitochondrial dysfunction in retinal ganglion cells.

Autosomal-dominant optic atrophy type 1 is caused by mutations in the OPA1 gene on chromosome 3q29. The OPA1 protein produced plays a key role in a process called oxidative phosphorylation and in self-destruction of cells (apoptosis). OPA1 is an integral pro-fusion protein within the internal mitochondrial membrane. Mutations in the OPA1 gene lead to vision problems experienced by people with breakdown of structures that transmit visual information from the eyes to the brain. Affected individuals first experience a progressive loss of nerve cells within the retina, called retinal ganglion cells. The loss of these cells is followed by the degeneration (atrophy) of the optic nerve.

X-linked optic atrophy type 2 is caused by mutation in the OPA2 gene with cytogenetic location Xp11.4-p11.21. The patient presents with early-onset childhood vision loss with slow progression of loss.

Hereditary optic atrophy type 3 is caused by mutation in the OPA3 gene with cytogenetic location 19q13.32. The mutation in this gene is associated with childhood-onset vision loss with cataract. It can also be associated with type III methylglutaconic aciduria.

Leber hereditary optic neuropathy results from mitochondrial point mutations in mtDNA 11778G>A, 14484T>C, or 3460G>A mutations.

Consecutive atrophy

Consecutive atrophy is an ascending type of atrophy (eg, chorioretinitis, pigmentary retinal dystrophy, cerebromacular degeneration) that usually follows diseases of the choroid or the retina.

Circulatory atrophy (vascular)

Circulatory is an ischemic optic neuropathy observed when the perfusion pressure of the ciliary body falls below the intraocular pressure. Circulatory atrophy is observed in central retinal artery occlusion, carotid artery occlusion, and cranial arteritis.

Metabolic atrophy

It is observed in disorders such as thyroid ophthalmopathy, juvenile diabetes mellitus, nutritional amblyopia, toxic amblyopia, tobacco, methyl alcohol, and drugs (eg, ethambutol, sulphonamides).

Demyelinating atrophy

It is observed in diseases such as multiple sclerosis and Devic disease.

Pressure or traction atrophy

It is observed in diseases such as glaucoma and papilledema.

Postinflammatory atrophy

It is observed in diseases such as optic neuritis, perineuritis secondary to inflammation of the meninges, and sinus and orbital cellulites.

Traumatic optic neuropathy

The exact pathophysiology of traumatic optic neuropathy is poorly understood, although optic nerve avulsion and transection, optic nerve sheath hematoma, and optic nerve impingement from a penetrating foreign body or bony fragment all reflect traumatic forms of optic nerve dysfunction that can lead to optic atrophy.

Regardless of etiology, optic atrophy is associated with variable degrees of visual dysfunction, which may be detected by one or all of the optic nerve function tests (see Other Tests).

Radiation optic neuropathy

Radiation optic neuropathy more frequently occurs with radiation doses of at least 5,000 centigray. It may be result from radiation damage to the optic nerve vasculature or the optic nerve parenchyma itself.

Epidemiology

Frequency

United States

According to Tielsch et al, the prevalence of blindness attributable to optic atrophy was 0.8%.[3]

According to Munoz et al, the prevalence of visual impairment and blindness attributable to optic atrophy was 0.04% and 0.12%, respectively.[4]

Mortality/Morbidity

Optic atrophy is not a disease but a sign of many disease processes. Thus, morbidity and mortality in optic atrophy depends on the etiology.

Race

Optic atrophy is more prevalent in African Americans (0.3%) than in whites (0.05%).

Sex

There is no sexual predisposition noted.

Age

Optic atrophy is seen in any age group.

Prognosis

Early and intensive treatment in nutritional optic neuropathy can provide patients with near-normal vision.

 

Presentation

History

See Physical.

Physical

When examining a patient with a pale disc, determine primarily if the pallor is physiologic. Nonpathologic disc pallor is observed in the following:

  • Axial myopia: The optic disc has a segmental whitish appearance due to an oblique angle of insertion of the optic nerve and nasal displacement of the optic nerve contents.
  • Myelinated nerve fibers: Feathery margins are due to the superficial location, usually adjacent to the disc.
  • Optic nerve pit: Small colobomas are most often located in the inferotemporal portion of the disc.
  • Tilted disc can cause confusion.
  • Optic nerve hypoplasia is characterized by a small disc and peripapillary double ring sign, and the inner ring is actually the optic disc margin.
  • Scleral crescent areas are devoid of retinal pigment epithelium.
  • Optic disc drusen
  • Fundus viewing through an intraocular lens implant
  • Brighter-than-normal luminosity: The luminosity of an indirect ophthalmoscope is approximately 2000 lux and that of a direct ophthalmoscope is up to 900 lux. A disc appears pale if the luminosity of the instrument is brighter than normal.

Optic atrophy in young individuals

Hereditary and congenital optic atrophy generally presents in the first or second decade of life. They can be broadly classified into the following 3 major groups:

  • Optic atrophy with generalized white matter disease (eg, adrenoleukodystrophy)
  • Optic atrophy with seemingly unrelated systemic features (generally associated with OPA1 gene mutation)
  • Isolated optic atrophy (may be autosomal dominant or recessive mitochondrial inheritance; eg, Leber hereditary optic neuropathy)

Causes

See Pathophysiology.

 

DDx

Diagnostic Considerations

Table 1. Various Common Groups of Disorders Presenting with Optic Atrophy (Open Table in a new window)

 

 

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

Differential Diagnoses

  • Axial myopia

  • Brighter-than-normal luminosity

  • Myelinated nerve fibers

  • Optic disc drusen

  • Optic nerve hypoplasia

  • Optic nerve pit

  • Scleral crescent

  • Tilted disc

 

Workup

Imaging Studies

The type of neuroimaging study depends on the disease process.

  • For tumors located in the orbit, ultrasonography can be performed in addition to CT scanning or MRI. For papilledema, B-scan ultrasonography may show optic sheath dilatation.

  • To find out whether a lesion is cystic or solid (eg, cysticercoids), CT or MRI is recommended. For solid lesions, MRI (with contrast or fat suppression) is preferred in areas in close proximity to the bony wall.

  • For fractures associated with trauma, a noncontrast CT scan is preferred.

  • For multiple sclerosis, a gadolinium-enhanced MRI/fluid-attenuated inversion recovery (FLAIR) sequence is useful to detect hyperechoic areas.

Other Tests

Visual acuity testing

Visual acuity is measured using Snellen optotypes or a LogMAR chart. Visual acuity is reduced, occasionally to no light perception.

Stimulus parameters affecting visual acuity include contrast of the chart, refractive error, pupil size, stimulus eccentricity, duration of stimulus presentation, type of optotype used, illumination, and crowding phenomenon.

Color vision testing

Color vision is more decreased in patients with optic nerve disorders than in those with retinal disorders, especially among individuals with ischemic and compressive optic neuropathy. Prerequisites for color vision testing include proper lighting (both an adequate amount of light and the proper spectral distribution). Color vision is profoundly decreased compared to visual acuity in patients with ischemic and compressive optic neuropathy.

Color vision may be assessed with pseudoisochromatic tests (eg, Ishihara color blindness test, Hardy-Rand-Rittler polychromatic plates, Dvorine plates) or the Farnsworth-Munsell 100 Hues test or Farnsworth panel D-15 test.

Contrast sensitivity test

This test measures the ability to perceive slight changes in luminance between regions that are not separated by definite borders and is a sensitive test for optic nerve function.

Tests used to measure contrast sensitivity include the following:

  • Pelli-Robson contrast sensitivity chart. Each letter subtends an angle of 3 degrees at a distance of 1 meter. Letters are organized in triplets with two triplets in each line. The contrast decreases from one triplet to the next. The log contrast sensitivity varies from 0.00-2.25.
  • Cambridge low-contrast grating test
  • Arden gratings

Factors that affect measurement include suboptimal refractive correction and duration of stimulus presentation.

Pupillary evaluation

Pupil size should be noted, as well as the magnitude and the latency of the direct and consensual responses to light and near stimulation. A relative afferent pupillary defect (RAPD) is a hallmark of unilateral afferent sensory abnormality or bilateral asymmetric visual loss. Occasionally, RAPD is the only objective sign of anterior visual pathway dysfunction. It is a sensitive optic nerve function test.

RAPD can be quantitatively graded by balancing the defect; successive neutral density filters are added in 0.3 logarithmic steps over the normal eye while performing the swinging flashlight test until the defect disappears. The most useful neutral density filters are from 80% (0.1 log unit) to 1% (2.0 log units).

Clinically, it is graded as follows:

  • Immediate dilation of the pupil, instead of normal initial constriction (3-4+)
  • No changes in initial pupillary size, followed by dilation of the pupils (1-2+)
  • Initial constriction, but greater escape to a larger intermediate size than when the light is swung back to normal eye (trace)

Edge-light pupil cycle time

A thin beam of light is shown horizontally across the inferior aspect of the pupillary margin. The light induces pupillary constriction that moves the light out of the pupil. The pupil then redilates until the beam is once again at the edge of the pupillary margin, whereupon it constricts again, creating another cycle.

The time is calculated in milliseconds per cycle. Alternatively, the number of cycles in 1 minute is measured. The rate is normally 900 milliseconds per cycle.

Photostress recovery test

Principle-visual pigments bleach when exposed to an intense light source, resulting in a transient state of sensitivity loss and reduced central visual acuity.

To perform the test, the examiner should note the patient’s best-corrected visual acuity, shield one eye, and then ask the patient to look directly at a bright focal light that is held 2-3 cm from the eye for about 10 seconds. The time needed to return to within one line of best-corrected visual acuity level is measured; this time is the photostress recovery time.

Pulfrich phenomenon

In optic nerve damage, the transmission of impulses to the occipital cortex is delayed. In patients with unilateral or markedly asymmetric optic neuropathy, when an oscillating small target in a frontal plane is viewed binocularly, the target appears to move in an elliptic path rather than in a to-and-fro path.

Cranial nerve examination

All cranial nerves are examined to rule out associated nerve involvement to help determine the site of the lesion.

Extraocular movements

Restriction can be obtained in cases of compressive optic neuropathy due to either the mass effect or the involvement of the nerve supplying the muscle.

Ophthalmoscopic features

Optic disc

Optic disc changes can present with temporal pallor (as seen in toxic neuropathy and nutritional deficiency), focal pallor or bow-tie pallor (as seen in compression of the optic chiasma), and cupping (as seen in glaucomatous optic atrophy).

In the early stages of the atrophic process, the optic disc loses its reddish hue, and the substance of the disc slowly disappears, leaving a pale, shallow concave meniscus, the exposed lamina cribrosa. In the end stages of the atrophic process, the retinal vessels of the normal caliber still emerge centrally through the otherwise avascular disc.

Optic disc cupping also develops in patients with normal intraocular pressures and optic atrophy from various causes, including ischemia, compression, inflammation, hereditary disorders, and trauma.

Focal or diffuse obliteration of the neuroretinal rim with preservation of color of any remaining rim tissue is specific for glaucoma.

Peripapillary retinal nerve fiber layer

Early focal loss of axons is represented by the development of dark slits or wedges in the peripapillary retinal nerve fiber layer. These slits or bands appear darker or redder than the adjacent healthy tissue. The slit defects are most easily identified in the superior and inferior arcuate regions, where the nerve fiber layer is particularly thick.

Retinal vessels

In most cases of optic atrophy, the retinal arteries are narrowed or attenuated. In cases of nonarteritic anterior ischemic optic neuropathy, the vessels may be focally narrowed or completely obliterated. Nonarteritic anterior ischemic optic neuropathy is shown in the images below.

Nonarteritic anterior ischemic optic neuropathy. Nonarteritic anterior ischemic optic neuropathy.

Investigations

Visual field testing

Field testing methods include kinetic and static. In the kinetic method, the contours of the island are mapped at different levels, resulting in one isopter for each level tested. In the static method, the vertical contours of the island are mapped along a selected meridian.

As per the areas tested, the visual field is divided into the central visual field, which has a 30-degree radius, and anything beyond 30 degrees is called peripheral visual testing. The central visual field can be tested using an Amsler grid, confrontation techniques, a tangent screen, and a bowl perimeter. Peripheral visual testing includes automated perimetry and manual perimetry. Automated perimetry tests the central 60 degrees of the visual field, whereas manual perimetry tests the entire visual field.

In optic neuropathy, visual field changes can include enlargement of the blind spot and paracentral scotoma (eg, optic neuropathy), altitudinal defects (eg, anterior ischemic optic neuropathy, optic neuritis), and bitemporal defects (eg, compressive lesions, similar to optic chiasma tumors).

Optical coherence tomography

Optical coherence tomography (OCT) measurements of retinal nerve fiber layer provide an objective measurement of nerve atrophy.

Electroretinography

Abnormal electroretinography (ERG) results that can be seen are as follows:

  • Subnormal: Potential less than 0.08 microvolts; seen in toxic neuropathy
  • Negative: When a large a-wave is seen; may be due to giant cell arteritis, central retinal artery occlusion, or central retinal vein occlusion
  • Extinguished: Response seen in complete optic atrophy

Visually evoked response

In optic neuritis, the visually evoked response (VER) has an increased latency period and a decreased amplitude as compared to the normal eye.

Compressive optic lesions tend to reduce the amplitude of the VER, while producing a minimal shift in the latency.

Blood Tests and Other Tests

As optic atrophy is a sign of end-stage optic nerve damage and not a diagnosis in itself, further investigation is required if a cause is not established. The following additional tests may be used:

  • MRI of the brain and orbits with contrast (in addition to space-occupying lesion [SOL], look for sinusitis, hyperpneumatized sinuses, fibrous dysplasia)
  • Blood glucose level
  • Blood pressure, cardiovascular examination
  • Carotid Doppler ultrasonography
  • Vitamin B-12 levels, heavy metal screen
  • Venereal Disease Research Laboratory (VDRL)/Treponema pallidum hemagglutination (TPHA) tests
  • Antinuclear antibody levels
  • Sarcoid examination
  • Homocysteine levels
  • Antiphospholipid antibodies
  • Enzyme-linked immunosorbent assay (ELISA) for toxoplasmosis, rubella, cytomegalovirus, herpes simplex virus (TORCH panel)
  • OPA1 blood testing in patients with a family history suggestive of dominant optic atrophy, especially young individuals with progressive bilateral vision loss and cecocentral scotoma with temporal disc pallor
  • Leber hereditary optic neuropathy testing, especially in male patients with a family history of vision loss in maternal uncles

Histologic Findings

See Pathophysiology.

 

Treatment

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 or 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.[5] 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.[6]

Research in stem cell treatment can hold a key in the future treatment of neuronal disorders. Currently, there are no approved treatments for mitochondrial disease, including optic neuropathies caused by primary or secondary mitochondrial dysfunction.[7]

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. At present, the best defense is an early diagnosis because if the cause can be found and corrected, further damage can be prevented. de Lima et al 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.[8]

The optic nerve fiber is made of axons from the retinal ganglion cells, which usually do not regenerate after injury, resulting in lifelong visual loss. 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.[9] In other studies, remapping of the retina was noted in the superior colliculus following axon regeneration.[10] These findings have given hope to clinically meaningful regeneration of axons, which may become a reality in the near future.

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.

 

Guidelines

Guidelines Summary

In any patient with unexplained optic atrophy, neuroimaging should be performed.

 

Medication

Vitamin, Water Soluble

Class Summary

Essential to normal metabolism and DNA synthesis.

Cyanocobalamin (Nascobal)

Deoxyadenosylcobalamin and hydroxocobalamin are active forms of vitamin B-12 in humans. Vitamin B-12 synthesized by microbes but not by humans or plants. Deficiency may result from intrinsic factor deficiency (pernicious anemia), partial or total gastrectomy, or distal ileum diseases. Deficiency initially and typically manifests as macrocytic anemia, although neurologic symptoms may be present. Can also cause confusion or delirium in elderly patients.

Essential for normal erythropoiesis. Required for healthy neuronal functions and normal functions of rapidly growing cells.

 

Questions & Answers

Overview

What is optic atrophy?

What is the pathophysiology of optic atrophy?

How is optic atrophy classified?

What are the types of pathologic optic atrophy?

What are the types of ophthalmoscopic optic atrophy?

What are the types of etiologic optic atrophy?

What is the prevalence of optic atrophy?

What is the mortality and morbidity associated with optic atrophy?

What are the racial predilections of optic atrophy?

What are the sexual predilections of optic atrophy?

Which age groups have the highest prevalence of optic atrophy?

What is the prognosis of optic atrophy?

Presentation

Which physical findings are characteristic of optic atrophy?

How is hereditary and congenital optic atrophy classified?

What causes optic atrophy?

DDX

Which groups of disorders commonly present with optic atrophy?

What are the differential diagnoses for Optic Atrophy?

Workup

What is the role of neuroimaging in the workup of optic atrophy?

What is the role of visual acuity testing in the workup of optic atrophy?

What is the role of color vision testing in the workup of optic atrophy?

What is the role of contrast sensitivity testing in the workup of optic atrophy?

What is the role of pupillary evaluation in the workup of optic atrophy?

What is the role of edge-light pupil cycle time in the workup of optic atrophy?

What is the role of photostress recovery testing in the workup of optic atrophy?

What does a finding of the Pulfrich phenomenon indicate in the workup of optic atrophy?

What is the role of a cranial nerve exam in the workup of optic atrophy?

What does a finding of extraocular movements indicate in the workup of optic atrophy?

Which optic disc changes are characteristic of optic atrophy?

Which findings in the peripapillary retinal nerve fiber layer are characteristic of optic atrophy?

Which retinal artery findings are characteristic of optic atrophy?

What is the role of visual field testing in the workup of optic atrophy?

What is the role of optical coherence tomography (OCT) in the workup of optic atrophy?

What is the role of electroretinography (ERG) in the workup of optic atrophy?

What is the role of visually evoked response in the workup of optic atrophy?

What is the role of lab tests in the workup of optic atrophy?

Treatment

How is optic atrophy treated?

When are low-vision aids indicated in the treatment of optic atrophy?

Guidelines

When is neuroimaging indicated in the management of optic atrophy?

Medications

Which medications in the drug class Vitamin, Water Soluble are used in the treatment of Optic Atrophy?