Optic atrophy is the permanent loss of retinal ganglion cell axons and death of these cells, resulting in changes to the optic disc such as pallor. It has many potential causes, including diseases that damage the optic nerve or retina. On examination, patients with optic atrophy typically have reduced visual acuity and color vision, as well as an afferent pupillary defect. The optic disc appears pale on ophthalmoscopy.

1. Optic Atrophy
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 associated with variable degrees of visual
dysfunction. Optic atrophy represents the permanent loss of retinal ganglion cell axons in
conjunction with retinal ganglion cell death.
The axons possess a myelin sheath provided by oligodendrocytes. Once damaged, the axons do
not regenerate. 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 which explains the pallor in optic atrophy.
Alternatively, the loss of pial capillaries which supply the optic disc may be the cause of disc
pallor. The Kestenbaum index is the number of capillaries counted on the optic disc, which
normally is around 10. Less than 6 capillaries indicates optic atrophy; more than 12 suggests disc
hyperaemia.
Histopathology changes in optic atrophy1
 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 etiologic1
.
A. Pathologic classification
1) Anterograde degeneration (Wallerian degeneration): In conditions with anterograde
degeneration (e.g. toxic retinopathy, chronic simple glaucoma), deterioration begins in the
retina and proceeds toward the lateral geniculate body (i.e., to the brain).
Axon thickness determines the rate of degeneration. Larger axons disintegrate more rapidly than
smaller axons. The essential feature is swelling and degeneration of the axon terminal in the
lateral geniculate body (LGB), observed as early as 24 hours. Leukocytes rarely present in
Wallerian degeneration.

2. 2. Retrograde degeneration: In conditions with retrograde degeneration (optic nerve
compression by intracranial tumor), deterioration starts from the proximal portion of the axon
and proceeds toward the optic disc (i.e., to the eye). The time course of this degeneration is
apparently independent of the distance of the injury from the ganglion cell body. Thus, damage
to the retrobulbar portion of the optic nerve, the optic chiasma, or the optic tract causes
pathologic and visible degeneration of the ganglion cell body simultaneously.
3. 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. This type of
degeneration is observed in patients with occipital damage incurred either in utero or during
early infancy.
B. Ophthalmoscopic classification
1. Primary optic atrophy: In conditions with primary optic atrophy (e.g. 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.
2. Secondary optic atrophy: In conditions with secondary optic atrophy (e.g., papilledema,
papillitis), the atrophy is secondary to papilledema. 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 fibro glial tissue. Hyaline bodies (corpora amylacea) or
drusen may be observed. Peripapillary sheathing of arteries as well as tortuous veins may be
observed. Progressive contraction of visual fields may be seen as well. Optic atrophy following
papilledema (secondary).
3. Consecutive optic atrophy: In consecutive optic atrophy (e.g., 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 pan retinal photocoagulation (PRP).
4. 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
5. 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.

3. C. Etiologic classification
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.
1. Hereditary: This is divided into congenital or infantile optic atrophy (recessive or dominant
form), Behr hereditary optic atrophy (autosomal recessive), and Leber optic atrophy.
2. Consecutive atrophy: Consecutive atrophy is an ascending type of atrophy (e.g.,
chorioretinitis, pigmentary retinal dystrophy, cerebromacular degeneration) that usually follows
diseases of the choroid or the retina.
3. Circulatory atrophy: 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.
4. Metabolic atrophy: Metabolic atrophy is observed in disorders such as thyroid
ophthalmopathy, juvenile diabetes mellitus, nutritional amblyopia, toxic amblyopia, tobacco,
methyl alcohol, and drugs (e.g., ethambutol, sulphonamides).
5. Demyelinating atrophy: Demyelinating atrophy is observed in diseases such as multiple
sclerosis and Devic disease.
6. Pressure or traction atrophy: Pressure or traction atrophy is observed in diseases such
as glaucoma and papilledema.
7. Postinflammatory atrophy: Postinflammatory atrophy is observed in diseases such as
optic neuritis, perineuritis secondary to inflammation of the meninges, and sinus and orbital
cellulites.
8. 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.
Epidemiology
Optic atrophy can be seen in any age group. There is no sex predisposition noted.
Differential diagnosis
Non-pathologic disc pallor is seen in axial myopia, myelinated nerve fibers, optic disc pit, tilted
disc, and disc drusen. Viewing the disc in a pseudophakic eye, or using a brighter
ophthalmoscope than usual can cause the disc to look paler.
Clinical Work-up

4. Visual acuity: It is measured using Snellen’s optotypes or using a Log MAR chart. Visual acuity
is reduced, occasionally to no light perception.
Color vision: Color vision is more decreased in patients with optic nerve disorders than in those
with retinal disorders especially in patients with ischemic and compressive optic neuropathy.
Color vision may be assessed with pseudo isochromatic tests (e.g., Ishihara color blindness test,
Hardy-Rand-Rittler polychromatic plates, and Dvorine plates) or the Farnsworth-Munsell 100
Hues test or the Farnsworth panel D-15 test.
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 or asymmetric afferent sensory abnormality. Occasionally it
is the only objective sign elicited. RAPD can be quantitatively graded by balancing the defect
using neutral density filters. Clinically, it is graded as follows:
 Initial constriction, but greater escape to a larger intermediate size than when the light is
swung back to normal eye (trace).
 No changes in initial pupillary size, followed by dilation of the pupils (1-2+)
 Immediate dilation of the pupil, instead of normal initial constriction (3-4+)
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. It can be tested using Pelli-Robson contrast sensitivity chart, Cambridge low-contrast
grating test or Arden gratings.
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.
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.
Cranial nerve examination: All cranial nerves are examined to rule out associated nerve
involvement to help determine the site of the lesion.
Ophthalmoscopic features
Optic disc
Optic disc changes can present with temporal pallor, focal pallor or bow-tie pallor (as seen in
compression of the optic chiasma), or cupping (glaucomatous damage). In the early stages of the
atrophic process the optic disc loses its reddish hue. The substance of the disc slowly decreases,
leaving a pale, shallow 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.
Focal notching or diffuse obliteration of the neuroretinal rim with preservation of color of any
remaining rim tissue is characteristic of glaucoma.
Optic disc cupping also develops in patients in non-glaucomatous eyes due to ischemia,
compression, inflammation, hereditary disorders or trauma.

5. Peripapillary retinal nerve fiber layer
Early focal loss of axons produces dark wedge shaped defects (best seen with a red-free filter on
slit-lamp bio-microscopy) in the peripapillary retinal nerve fiber layer.
Retinal vessels
In most cases of optic atrophy, the retinal arteries are narrowed or attenuated. In cases of non-
arteritic anterior ischemic optic neuropathy, the vessels may be focally narrowed or completely
obliterated.
Investigations
Visual field testing: In optic neuropathy, visual field changes can include enlargement of the
blind spot, caecocentral scotoma, altitudinal defects (e.g. anterior ischemic optic neuropathy,
optic neuritis), and bitemporal defects (e.g. compressive lesions, similar to optic chiasma
tumors).
Neuro-imaging: Neuro-imaging is indicated to find the cause of atrophy.
 Ultrasonography is recommended when orbital tumor is suspected.
 For post-traumatic optic neuropathy a noncontrast CT scan is preferred.
 In optic neuritis or multiple sclerosis, a gadolinium-enhanced MRI/fluid-attenuated
inversion recovery (FLAIR) sequence is useful to detect hyper intense areas of
demyelination.
Electroretinogram (ERG)
 Abnormal electroretinogram (ERG) results that can be seen are as follows:
 Subnormal: Potential less than 0.08 microvolts; seen in toxic neuropathy
 Negative: a preserved a-wave but absent b-wave. It May be seen in arteritic AION or
central retinal artery occlusion.
 Extinguished ERG: seen in complete optic atrophy.
 N95:P50 ratio in pattern ERG is low in optic neuropathy and normal in maculopathy.
Visually evoked potential (VEP)
In optic neuritis the VEP has an increased latency period as compared to the normal eye which
persists even after visual recovery. Compressive optic lesions tend to reduce the amplitude and
cause waveform changes of the VEP.
Unexplained optic atrophy
As optic atrophy is a sign of end-stage optic nerve damage, and not a diagnosis in itself, further
investigation is required if the above tests do not reveal its cause.
Clinical features of optic atrophy
 Loss of vision: may be sudden or gradual onset (depending upon the cause of optic
atrophy) and partial or total (depending upon the degree of atrophy).

6.  Pupil is semi dilated and direct reflex is very sluggish or absent. Swinging Flash light test
depicts Marcus Gunn pupil.
 Ophthalmoscopic appearance of the disc varies with type of optic atrophy.
 Visual field loss varies with the distribution of the fibers that have been damaged. In
general the field loss is peripheral in systemic infections, central in focal optic neuritis
and eccentric when the nerve or tracts are compressed. Paracentral, caecocentral or
central scotomas may be present.
Treatment
No proven treatment exists to reverse optic atrophy. At present, the best defense is early
diagnosis. If specific treatment of the cause is initiated before the development of optic atrophy,
useful vision may be salvaged. For example, early diagnosis and prompt treatment can help in
compressive and toxic neuropathies. Neuro-protective agents like gingko biloba have been tried
with anecdotal success. Research in stem cell therapy may provide answers in the not-too-distant
future. Low-vision aids should be considered for occupational rehabilitation.
Low Vision Management
Magnification at both distance and near with the use of low vision devices must be considered
for the patients with reduced visual acuity due to optic atrophy. For distance too, telescopes are
very useful (Handheld versus spectacle mounted clip-on). Direct illumination along with
magnification & Reading stand quite helpful for performing near tasks.
Excessive lighting should be avoided for these patients.
Sun lenses, tints and filters should be used to eliminate glare both outdoor and indoor.
Non optical systems should be demonstrated and let them follow in their dailies.
Orientation and mobility management techniques and devices can be demonstrated for the
patients with low vision. Sighted guide technique, canes, dog guides and electronic travel aids
can be given to the patients for mobility.
Eccentric viewing if central vision is affected. Patients with central scotoma often have to use
eccentric viewing to function more effectively. When a person has a large scotoma, being able to
effectively use an eccentric point can be more difficult with optical magnification. Eccentric
viewing may be easier with an assistive technology device.7
Additionally, as fixation moves further from the fovea, the impact of crowding increases. Using
different types of text presentation can lessen the effects of visual crowding7
. For example,
studies have reported that using text stretching to increase the spacing between letters and words
can reduce crowding and may be beneficial for the person trying to read with a central scotoma
Peak cap and Sunglasses prove to be helpful for outdoors to tackle photophobia.
A patient with severe contrast sensitivity loss may functions better using reverse contrast, which
can only be achieved with electronic magnification assistive technology7
.

7. Bold line paper, Black ink with felt tipped pen for writing.
When color perception is impacted, a person may have difficulty with color contrasts, which may
make text or objects on a colored background more difficult to see. Using electronic
magnification, colors can be converted to black and white, and if necessary, contrast can also be
enhanced. In addition, if a person has problems with color identification, assistive technology
can offer solutions.
Genetic counseling is must for the case of heredodegenerative forms of optic atrophy2
.
References:
1. Optic Atrophy-A major review by Dr. Devendra V. Venkatramani, Dr. Gangaprasad
Muthaiah Amula, Dr. Rashmin A. Gandhi
2. Richard L.Brilliant.Essentials of Low Vision Practice
3. The Lighthouse Ophthalmology Resident training manual by Eleanor, Benjamin Freed, Karen
R. Seidman, Michael Fischer.
4. Wolff’s anatomy of eye and orbit Eighth edition.
5. Comprehensive Ophthalmology bu A K Khurana
6. lowvision.preventable blindness.org
7. website of lighthouse international
Raju Kaiti
M. Optometry (Practioner)
Amity University