Optic neuropathy results from an ischemic insult to the optic nerve. This condition causes loss of vision. There are two types of optic neuropathy depending on which segment of the optic nerve is affected.
The presentation of the arteritic and nonarteritic forms is similar. They are characterized by a rapid and painless loss of vision that can occur over minutes, hours or days . Diminished visual acuity and impaired pupillary response also develop. Additionally, the optic disk and the nerve fibers are swollen. This swelling overshadows the vessels supplying the optic nerve.
The optic disk may appear hyperemic in nonarteritic cases while it is likely to be pale colored in the arteritic form. Additionally, findings include hemorrhages around the disk. Finally, testing of the visual fields reveals inferior and central deficits.
Diagnosis is established through a history, ophthalmic exam, and laboratory studies. The history should include a thorough assessment of risk factors such as hypertension, diabetes, atherosclerosis, and obstructive sleep apnea. Also, the ophthalmic exam consists of a detailed evaluation of the eye including structures such as the optic disk, small nerves, and vessels as well as papilledema and hemorrhage.
The erythrocyte sedimentation rate (ESR) is helpful. In the arteritic type, ESR is increased in approximately 90% of cases. In the nonarteritic variant, ESR is typically normal unless other diseases coexist. Furthermore, the Westergren ESR is preferred over the Wintrobe ESR. Additionally, the C-reactive protein (CRP) is helpful in the diagnosis of giant cell arteritis. The abnormal levels of ESR and CRP are suggestive of inflammation. Finally, a complete blood count (CBC) may reveal anemia.
Biopsy of the temporal artery confirms the diagnosis of giant cell arteritis.
While ultrasonography has been utilized in the assessment of temporal arteries, this modality has not been used routinely in the diagnosis of anterior ischemic optic neuropathy. Another technique, ocular plethysmography, reveals abnormal results in the arteritic variant. MRI and CT scan are not beneficial in older individuals with either form of neuropathy. A possible advantageous test, fluorescein angiography, may differentiate between the two types of neuropathy . Cerebral angiography identifies stenosis or vessel occlusion in giant cell arteritis, however, this procedure is used less commonly now. Optical coherence tomography (OCT) may be used in individuals with anterior ischemic optic neuropathy .
Steroid use in giant cell arteritis
In giant cell arteritis, patients are managed with a steroid course and scheduled tapering. Specifically, the initial dose ranges from 40 to 60 milligrams of prednisone per day, reflecting the patient's weight and level of severity. These patients are monitored with monthly ESR and/or CRP. In cases with recurrent episodes, the tapering is delayed while flare-ups may require small doses. Other regimens are being explored as well. For example, a trial at Mayo Clinic is investigating the intravenous administration of steroids and whether it reduces the need for chronic use of steroids. In cases where steroids are becoming intolerable due to side effects, methotrexate or cyclosporin may be used concurrently to decrease the steroid dosage. Of important note, periodic monitoring of complete blood count and liver function tests are required.
Steroid use in nonarteritic anterior ischemic optic neuropathy
Steroid therapy in these patients is debatable and usually not helpful. The use of this drug may not be justified especially in the context of long-term side effects.
One procedure, optic nerve fenestration, was studied in the Ischemic Optic Neuropathy Decompression Trial (IONDT)  but found to be ineffective .
Spontaneous recovery is observed in approximately 40% of patients with nonarteritic ischemic optic neuropathy. Recurrence in the same eye is very rare while the other eye may develop neuropathy in 20% of cases within the following 5 years.
There are two variants of ischemic optic neuropathy, namely nonarteritic and arteritic. These are attributed to impaired blood supply to the optic nerve. This leads to vision loss.
Nonarteritic ischemic optic neuropathy
This condition presents more commonly in individuals aged 50 years or above. There are predisposing risk factors such as hypertension, tobacco smoking, atherosclerosis, diabetes, and obstructive sleep apnea. Individuals prone to thrombosis formation and nocturnal hypertension are also susceptible to this type of neuropathy . Finally, use of certain medications such as amiodarone is another risk factor .
Arteritic ischemic optic neuropathy
With regard to patient demographics, there is a race preference for the different types. For example, nonarteritic ischemic optic neuropathy is more common in whites than in black people. As for arteritic anterior ischemic optic neuropathy, it exhibits the greatest incidence in the Scandinavian countries.
In the United States, the incidence of nonarteritic anterior ischemic optic neuropathy is 2.3 to 10.3 per population of 100,000 and increases significantly with age as does giant cell arteritis . Furthermore, the arteritic group demonstrates an incidence of 0.36 per 100,000. With regard to age, both types of anterior ischemic optic neuropathy present in patients above 50 years of age . As for gender, the arteritis form is more predominant in women.
The pathogenesis of nonarteritic anterior ischemic optic neuropathy is secondary to the diminished perfusion in the posterior circulation. Furthermore, these blood vessels, the short posterior ciliary arteries, perfuse the optic disk and optic nerve as it exits. The results of the ischemia include visual loss , impaired inferior visual field, swollen optic disk, and hemorrhage. The loss of vision may occur at rapid onset or take a few days.
Arteritic anterior optic neuropathy is observed less often and typically develops subsequently to inflammation.
Posterior ischemic optic neuropathy occurs when the abnormality occurs between the optic chiasm and the globe. This is not common and is usually a disease of exclusion. It features altitudinal visual field abnormalities and visual impairment. Possible causes include diabetes mellitus, connective tissue disease, and trauma.
Individuals with small disks may have an anatomical predisposition for nonarteritic anterior ischemic optic neuropathy. Hence, a reduced blood supply is enhanced by the swelling causing more damage. As for the arteritic form, the arterial supply to the eye and orbit is jeopardized.
If the patient presents with anterior ischemic optic neuropathy, there are no preventative measures to protect the other eye. The use of aspirin has been advocated by clinicians even though its efficacy is unknown.
As for nonarteritic anterior ischemic optic neuropathy, levodopa may be beneficial in improving visual function .
Optic neuropathy refers to the loss of vision secondary to injury of the optic nerve. Causes include ischemia, toxins, hypertension, diabetes mellitus and compression in the orbit. Ischemic optic neuropathy is classified in accordance with the site of the ischemic injury. The anterior type is more common and usually results from an insufficient blood supply to the optic disk while the posterior form is typically diagnosed when other causes are ruled out.
There are the arteric and nonarteritic variants of ischemic optic neuropathy. The former is less common and is due to an inflammatory process in the arteries. Nonarteritic ischemic optic neuropathy is thought to occur with predisposing factors such as hypertension, diabetes, atherosclerosis, and other conditions.
Generally, optic neuropathy presents with rapid onset vision loss as well as deficits in the visual fields. Additionally, there may be changes in the optic disk and other findings such as swelling and hemorrhage.
Diagnosis is determined through history, ophthalmic exam and laboratory studies. Also, certain imaging modalities may be useful. As for management, the treatment depends on the type of optic neuropathy. While corticosteroids are useful in the treatment of giant cell arteritis, they are not effective in other types of optic neuropathy.
Patients with optic neuropathy experience a sudden loss of central and peripheral vision. This occurs due to an obstruction of blood flow to the optic nerve. There are two types known as the arteritic and nonarteritic ischemic optic neuropathy.
The arteritic type results from inflammation in the arteries supplying the eye. An example of this is known as giant cell or temporal arteritis. This type is found in people 70 years old or above. It is most common in Scandinavian countries followed by Germany.
The nonarteritic type occurs in individuals with predispositions such as high blood pressure, smoking, diabetes mellitus, atherosclerosis, obstructive sleep apnea, low nighttime blood pressure and others. This type is observed in people 50 years old or above. It is more common in white people than in blacks.
Symptoms include visual loss that occurs over minutes, hours or even days. This disease is not associated with pain. One or both eyes may be affected depending on the cause of the neuropathy. Also, patients develop visual field defects. Individuals with giant cell arteritis experience pain when chewing and combing the hair. Also, they have headaches, muscle aches, and other pains as well.
The diagnosis of the disease includes a thorough history and detailed assessment of the risk factors. Furthermore, is important to perform an ophthalmic exam to evaluate the eye structure such as the optic disk, and findings such as swelling and hemorrhage. There are helpful tests to guide the diagnosis of giant cell arteritis. A biopsy of the temporal artery will confirm the diagnosis. Also, blood tests such as erythrocyte sedimentation rate (ESR) and the C-reactive protein level are abnormal in this condition suggesting inflammation.
The treatment of giant cell arteritis includes corticosteroids based on a tapering schedule. In certain severe cases, intravenous corticosteroids may be necessary. As for the nonarteritic form, corticosteroids are not as effective. Also, treatment of the risk factors such as high blood pressure, diabetes, atherosclerosis and obstructive sleep apnea are important for the overall health of the patient.