A 70-year-old man presented to the emergency room complaining of
progressive vision loss in the left eye over the last 2 weeks. He described a
gradual decline with no aggravating or alleviating conditions known. The
subjective vision loss was primarily in the inferior field of the left eye; he
also had nonspecific pain around both eyes. The patient denied any temporal
mandibular pain upon chewing or talking.
Further questioning revealed the patient had not taken his hypertension
medication for 3 months. He took the following medications for blood pressure
control: amlodipine 10 mg at bedtime, fosinopril 40 mg at bedtime,
hydrochlorothiazide 25 mg daily, metoprolol tartrate 50 mg twice daily and
clonidine HCl 0.1 mg twice daily. He also took aspirin 81 mg daily as a blood
thinner, glipizide 5 mg twice daily and metformin HCl 1,000 mg twice daily for
diabetes and omeprazole 20 mg daily for gastroesophageal reflux disease.
|Figure 1. On dilated fundus examination, the retina and optic
nerve appeared healthy in the right eye with a cup-to-disc ratio of 0.1; the
left optic nerve head was hyperemic and edematous with no appreciable
Images: Bockin D
On physical examination in the emergency room, his blood pressure was
240/100 mm Hg, oral temperature was 97.9° F (36.6° C), his chest was
clear, heart sounds were regular without murmur, his abdomen was obese and
soft, he had active bowel sounds and was non-tender to palpation, and his
extremities had no significant edema or gross cyanosis or clubbing. His EKG
showed sinus rhythm.
The patient was started on IV hydralazine for hypertension, which
lowered his blood pressure to 171/90 mm Hg. Blood work showed normal platelet
count and erythrocyte sedimentation rate and a glucose level of 143. In
addition, a non-contrast head CT scan was performed to rule out stroke.
|Figure 2. The field loss in the left eye was confirmed with
automated Goldman perimetry using a size III 4E white target; the greatest
restriction was inferior nasal, although the entire inferior field was
|Figure 3. The imagery from the head CT performed earlier was
available after the exam was completed. It was negative for stroke.
The ER sent the patient to the eye clinic for emergent examination for
his vision loss after his blood pressure stabilized. His prior best corrected
acuity from the medical chart was OD +0.75 +1.75 x 160 20/20 and OS +1.25 +0.25
x 015 20/20. On the day of my examination, his acuity was OD +0.75 +1.75 x 160
20/25 and OS +1.25 +0.25 x 015 20/70. There was no improvement with pinhole. In
addition, the patient continued to tip his body forward to see chart.
The patient’s external eye examination was noted for full and
smooth eye movements in all positions of gaze, clear corneas and nuclear
sclerosis in both eyes that was not consistent with the field loss. Applanation
tonometry was 30 mm Hg in both eyes. There was an abnormal pupillary response
in the left eye, and pupillary testing revealed a mild relative afferent
Gross confrontation visual fields showed constriction of the inferior
field in the left eye and a full field in the right. The field loss in the left
eye was confirmed with automated Goldmann perimetry (Zeiss-Humphrey) using a
size III 4E white target; the greatest restriction was inferior nasal, although
the entire inferior field was reduced overall. Goldmann kinetic visual field
was performed because I did not feel the patient had the cognitive ability to
respond to a standard HVF 24-2.
On dilated fundus examination, the retina and optic nerve appeared
healthy in the right eye with a cup-to-disc ratio of 0.1; the left optic nerve
head was hyperemic and edematous with no appreciable cupping.
The imagery from the head CT performed earlier was available after the
exam was completed.
What is your diagnosis?
Differential diagnosis would include nonarteritic ischemic optic
neuropathy, inflammatory optic neuritis, compressive optic nerve tumor, central
retinal vein occlusion, central retinal artery occlusion, arteritic ischemic
optic neuropathy (giant cell arteritis), pseudotumor cerebri and true
papilledema. The diagnosis was anterior non-ischemic optic neuropathy.
The most urgent consideration among this list would be giant cell
arteritis. This was ruled out with normal sedimentation rate and absence of
concordant symptoms. Other vascular events were eliminated by fundus
appearances. Also low on the differential list are the inflammatory optic nerve
etiologies. The patient’s profile is most consistent with nonarteritic
anterior ischemic optic neuropathy (AION).
|Figure 4. Fundus exam revealed a normal optic nerve in the
right eye with a sector optic atrophy in the left eye.
|Figure 5. Hemorrhages and edema have cleared. Repeat visual
fields were ordered and there was no appreciable change in visual field
AION is attributed to ischemia at the optic nerve head due to structural
crowding that may impair perfusion to the nerve and thereby cause edema. The
condition is divided into two sub-categories: non-arteritic (NAION) and
AAION is most commonly associated with temporal arteritis. Patient
demographics for AION are typically older than 50 years; the median age group
for NAION is older than 60, and with AAION the median age is 70 years old.
There is a gender predilection for females, but only in cases of AAION.
Incidence of AAION is 5% to 10% of cases of AION, while NAION accounts for 90%
to 95%, according to Arnold.
Patients with either form of AION typically report a rapid onset of
painless, unilateral vision loss manifested by decreased visual acuity,
decreased visual field or both. Vision loss is more severe in AAION, typically
worse than 20/200. The most common visual field defect with either form of AION
is altitudinal, but it may also present as a general depression, an arcuate
scotoma or a cecocentral defect.
A retrospective study using Goldmann perimetry suggested that the most
common field loss was actually inferior nasal and, when combined with overall
inferior field loss, it is highly indicative of NAION. The inferior nasal
defect is explained by the location of the watershed zone of the posterior
ciliary arteries, which is often temporal to the optic nerve head and the most
susceptible to ischemia.
The left eye showed thinning from 240° to 110° and from 160° to
200°. This indicated more RNFL damage than the larger sector optic atrophy
on physical exanimation.
Signs of an AION are a pale and hyperemic optic nerve head with edema
(diffuse or segmental) in the acute phase and optic atrophy in later stages.
The edema may be present several weeks to months before vision loss is
reported. Arnold suggests that in AAION, the disc is more pallid than
hyperemic, which is more common with NAION.
Flame hemorrhages and narrowed peripapillary arterioles are also
associated with AION. Because the presentation is typically unilateral, a
relative afferent pupillary defect is often expected. Systemic associations
with the arteritic form are symptoms common with temporal arteritis (i.e.,
headache, jaw claudication and scalp tenderness). Vision loss in the arteritic
form may be preceded by episodes of transient vision loss, which is also highly
indicative of arteritis.
The patient presented in this case study appeared to have more factors
associated with the non-arteritic form; therefore, the rest of this discussion
will focus primarily on NAION.
No proven systemic associations
This form of AION has no proven systemic associations; however,
according to Hayreh, studies suggest that a patient with arterial hypertension
(including the malignant form), nocturnal arterial hypotension, diabetes
mellitus, ischemic heart disease, migraines or sleep apnea are at higher risk
for developing a NAION.
Nocturnal hypotension is thought to play a significant role, considering
73% of patients with NAION report vision loss upon awakening. This is
especially true for patients who take their anti-hypertensive medications at
night or some prostatic hypertrophy medications.
A study by Landau and colleagues that focused on 24-hour monitoring of
blood pressure in both hypertensive and control patients found that patients on
medication for high blood pressure tended to have a lower overall reading and
tended to have a slower and unsteady rise to typical daytime levels. This
evidence suggests that the causative factor in NAION is chronic hypoperfusion
of the nerve rather than an isolated ischemic event.
The study also applied the J-curve hypothesis to the control of
hypertension, indicating that there is an optimal level of blood pressure above
which incidence of disease decreases as it approaches the ideal level and below
which it increases.
Ocular risk factors
A crowded optic disc with a small or absent cup-to-disc ratio is
considered a “disc at risk” for developing NAION. According to
Hayreh, other ocular risk factors are the location of the watershed zone for
the posterior ciliary arteries, vascular disorders in the arteries supplying
the optic nerve head, optic disc drusen, cataract extraction and elevated
intraocular pressure. Vision loss in cases of NAION can be “static”
or “progressive,” indicating that the initial loss may stabilize or
worsen over the course of several weeks to months after the primary event.
According to Arnold, the progressive form is found in 22% to 37% of
patients with NAION. In some cases, a patient with NAION may also report
periorbital pain. The risk of the fellow eye developing an NAION is 12% to 19%
over the course of 5 years, Hayreh said.
Several treatments have been proposed for NAION; however, no statistical
support has shown that any of the treatments are particularly effective. The
current options include optic nerve sheath decompression, aspirin (to prevent
occurrence in the fellow eye), levodopa, systemic corticosteroid therapy and
intravitreal injections of bevacizumab.
Optic nerve sheath decompression was first proposed in 1989 for cases of
progressive NAION; however, it has been implemented in all forms of NAION, and
research shows it may be more harmful than helpful because 24% of patients who
had the procedure had further visual loss compared to only 12% of untreated
patients. This is especially hazardous considering 41% to 43% of cases show
spontaneous improvement in visual acuity with no treatment, reported Hayreh.
The use of aspirin after the initial event has been suggested to help
prevent occurrence in the second eye. Again, long-term studies have disproven
this theory, considering aspirin has no effect on nocturnal hypotension, Hayreh
said. Levodopa was another proposed drug therapy but there is not enough
statistical support to show efficacy.
Hayreh reported that systemic corticosteroids have been used effectively
in cases of arteritic AION, but research has shown that patients with NAION
treated within the first 2 weeks of onset, with a visual acuity of 20/70 or
worse, showed improvement in 70% of cases compared to 41% of untreated cases.
Visual field defects also improved in 40% of patients treated with
corticosteroids vs. 25% of the untreated cases.
Intravitreal injections of bevacizumab have been used to treat a variety
of ocular diseases including macular edema and macular degeneration. This drug
was first proposed for use in NAION in 2007 with the intention of reducing
optic disc edema and therefore improving visual acuity. A few cases reports
since then have shown some patients developed NAION after receiving the
injection. However, as mentioned before, disc edema can precede visual loss by
approximately 6 weeks and, therefore, the injections could have precipitated
the NAION by increasing IOP that, in turn, decreases the perfusion pressure to
the eye, reported Hayreh.
AION can be a devastating condition for the patient due to the sudden
loss of vision. As eye care providers, it is vital to understand the mechanism
of this disease and be able to provide support and understanding during the
course of treatment. Though no clear solution is available for NAION, knowing
the patient’s options can provide some clarity and hope for the future.
The patient’s assessment at this visit was anterior non-ischemic
optic neuropathy with elevated IOP, and he was instructed to use Alphagan P
(brimonidine tartrate, Allergan) twice a day and consider adding Travatan Z
(travoprost, Alcon) once at bedtime in each eye after the inflammation has
subsided to help reduce the pressure. He was scheduled to return for a
follow-up in 1 month to monitor IOP and vision in the left eye.
According to Hayreh, treatment of elevated IOP is controversial with
NAION. Because of the patient’s reported systemic medication noncompliance
and elevated IOP on exam, it was elected to treat with ocular hypertensive
On his first follow-up, the patient had no new symptoms. As with his
initial examination, the patient was still again out of systemic medications
and only refilled his prescription that day. He stated he used the Alphagan P
but did not re-fill or ask for more drops. He said he can see better than at
the last visit. His systemic profile improved to an A1c of 6.3% and fasting
glucose of 174 mg/dL.
Visual acuity did not improve with glasses; it was OD 20/25 and OS 20/70
with pinhole. He had to tip forward to see the chart; if he did not, his acuity
was 20/400. Applanation tonometry was 20 mm Hg in each eye.
Fundus exam revealed a normal optic nerve in the right eye with a sector
optic atrophy in the left eye. The hemorrhages and edema had cleared. Repeat
visual fields showed no appreciable change in visual field loss.
The treatment plan was now to use only one bottle of drops. His IOP was
still above normal. The patient continued to be noncompliant with both systemic
medications as well as ocular. I felt some of the noncompliance was due to
possible confusion from mild brain edema as a consequence of uncontrolled
hypertension. I asked him to use brimonidine twice daily.
On the next follow-up exam, ocular coherence tomography showed normal
retinal nerve fiber layer (RNFL) in the right eye and significant loss of RNFL
in the left eye. With the TSNIT images that are overlaid on the age-related
normative data background, the left eye showed thinning from 240° to
110° and from 160° to 200°. This indicated more RNFL damage than
the larger sector optic atrophy on physical exanimation.
At this exam, applanation tonometry was OD 14 mm Hg and OS 16 mm Hg, and
his cognitive abilities were much improved. I asked him to return, ordered a
HVF 24-2 and considered discontinuing the brimonidine.
On the next follow-up examination the patient said he had been
instilling his drops and taking his systemic medication. Once again he was down
to 1 day of medication, and I got his physician and the pharmacy to renew all
His IOP was 18 mm Hg in both eyes. His threshold visual field showed the
right eye as normal and the left eye with complete inferior homonymous
hemianopsia. Once again, because of his history, I did not discontinue the
brimonidine, but he will take a “drop vacation” 30 days prior to the
next follow-up examination, which will be in 60 days.
- Arnold, AC. Ischemic optic neuropathies. Ophthalmol Clinic
North Am. 2001;14:83-98.
- Hayreh SS. Ischemic optic neuropathy. Prog Retin Eye
- Hayreh SS. Management of non-arteritic anterior ischemic optic
neuropathy. Graefes Arch Clin Exp Ophthalmol. 2009;247:1595-1600.
- Hayreh SS, Zimmerman B. Visual field abnormalities in nonarteritic
anterior ischemic optic neuropathy: Their pattern and prevalence at initial
examination. Arch Ophthalmol. 2005;123:1554-1562.
- Landau K, Winterkorn JS, Mailloux LU, et al. Twenty-four-hour blood
pressure monitoring in patients with anterior ischemic optic neuropathy.
Arch Ophthalmol. 1996;114:570-575.
- Donald G. Bockin, OD, can be reached at the Central Texas Veterans
Health Care System, 1901 Memorial Drive, Temple, TX 76504; (254) 743-0733;
- Edited by Leo P. Semes, OD, professor of optometry, University of
Alabama at Birmingham and a member of the Primary Care Optometry News
Editorial Board. He may be contacted at 1716 University Blvd., Birmingham, AL
35294-0010; (205) 934-6773; fax: (205) 934-6758;