This article is more than 5 years old. Information may no longer be current.
Man experiences acute onset monocular visual field loss
Visual field testing showed an arcuate scotoma inferiorly in the right eye, and posterior segment exam showed optic disc swelling.
Click Here to Manage Email Alerts
A 51-year-old man with a history of hypertension and ulcerative colitis complained of acute blurriness in the lower half of his right visual field upon awakening during hospitalization for an ulcerative colitis flare-up. During his hospital course, he had labile blood pressure that dropped as low as 80/50. The blurriness gradually increased over 2 weeks.
He had been taking atenolol but stopped while he was admitted to the hospital due to labile blood pressure. He also was on mesalamine, ciprofloxacin, metronidazole and an oral prednisone taper. His family history was noncontributory. He had a history of alcohol abuse in the past, but he had been sober for about a year. He denied smoking or illicit drug use.
On examination, best corrected central visual acuity was 20/30-2 in both eyes. The pupils were equal and round, but there was a 2+ relative afferent pupillary defect on the right. Color vision tested by Ishihara plates was normal bilaterally, although slower on the right. IOP by applanation was 16 mm Hg in both eyes. Visual field testing showed an arcuate scotoma inferiorly in the right eye and trace peripheral arcuate changes inferiorly greater than superiorly in the left (Figure 1). Extraocular motions were full bilaterally.
Figure 1. 30-2 Visual field of the left eye showing possible peripheral arcuate-like depression greater inferiorly (a). Right eye visual field showing dense inferior arcuate depression (b).
Images: Ho J, Hedges TR
Figure 2. Disc edema in right eye, no hemorrhages noted (a). No disc edema, cotton wool spot along inferior arcade (b). Early phase fluorescein angiography, no gross delay in filling seen (c). Late phase fluorescein angiography showing hyperfluorescence without choroidal non-perfusion (d).
Anterior segment exam of both eyes was significant only for trace nuclear sclerosis cataracts. Posterior segment exam revealed optic disc swelling on the right, more prominent superiorly, without disc hemorrhages or significant blurring of disc vessels (Figure 2a). There was no optic disc swelling on the left, but there was a cotton wool spot inferotemporal to the optic disc, in addition to a crowded appearance (Figure 2b).
What is your diagnosis?
Acute visual field loss
The differential diagnosis for the fundus findings in this patient include non-arteritic anterior ischemic optic neuropathy, ulcerative colitis-related optic neuropathy, optic nerve compression such as from a meningioma, and inflammatory causes such as optic neuritis.
Non-arteritic anterior ischemic optic neuropathy (NAION) is the most common optic neuropathy in adults older than 50 years of age. It usually presents as an acute onset of unilateral, painless vision loss upon awakening. The most common pattern of visual field loss is altitudinal depression. Visual acuity in the involved eye usually ranges between 20/30 and 20/200. Color vision may be affected, and a relative pupillary defect is usually present in the involved eye. Fundus examination usually reveals disc edema, which is usually hyperemic, although there may be sectoral pallor, depending on when the patient is seen. Evaluation of the fellow eye generally reveals a crowded optic nerve with a small cup, a so-called “disc at risk.” The fellow eye may show optic atrophy in patients who have had a previous episode of NAION in that eye, which is termed pseudo-Foster-Kennedy syndrome and resembles optic nerve signs of an intracranial compressive lesion. Optical coherence tomography may show thickening of the retinal nerve fiber layer (RNFL), which may be helpful for tracking the progression of this condition over time. Fluorescein angiography is helpful to differentiate between NAION and arteritic anterior ischemic optic neuropathy (AAION) from giant cell arteritis. In AAION, there may be evidence of choroidal hypofluorescence, secondary to decreased choroidal perfusion. In NAION, fluorescein angiography may show hyperfluorescence of the optic disc; however, the choroidal circulation is generally spared. Additionally, whereas NAION classically presents in people in their 40s to 50s, AAION rarely occurs in patients younger than age 65 years.
Systemic blood pressure fluctuations, especially in the setting of hypertensive emergency, may present with optic disc swelling and cotton wool spots. The involvement is usually bilateral in these cases, and optic nerve swelling may be transiently present. Other findings may include hard exudates, flame hemorrhages, arteriolar narrowing or arteriolar-venular nicking. It is important to gradually lower systemic blood pressure, as aggressive treatment may lead to worsening retinal and optic nerve perfusion and ischemia.
Ocular manifestations of inflammatory bowel disease may include neuroretinitis, papillitis, optic neuritis or NAION. Neuroretinitis and papillitis usually present with painless vision loss. Optic neuritis may occur either as part of inflammatory bowel disease or in association with demyelinating disease, such as multiple sclerosis. Additionally, there are reports of retrobulbar optic neuropathy associated with tumor necrosis factor-alpha agents, occurring within several months of starting the medication. MRI may show increased signal of the optic nerve. Patients present with unilateral vision loss, usually associated with eye pain, especially with eye movement. Fundus examination is usually not revealing because the optic nerve inflammation typically occurs posteriorly, and MRI for confirmation of optic nerve inflammation is necessary.
Diagnosis and management
Additional testing was conducted after initial examination of the patient. Fluorescein angiography showed late phase disc hyperfluorescence without choroidal non-perfusion (Figures 2c and 2d), consistent with NAION. Spectral-domain OCT did not show macular edema in either eye, but there was thickening of the retinal nerve fiber layer superiorly on the right (Figure 3). Ganglion cell layer OCT showed apparent thickening superiorly on the right. Superior and inferior ganglion cell thickness on the left were about equal.
Figure 3. RNFL OCT demonstrating thickening of nerve fiber layer in the right eye.
Figure 4. RNFL OCT on second follow-up, demonstrating decrease in thickening of nerve fiber layer in both eyes.
Given the subjective complaints of progression since the onset of symptoms, intravitreal injection of Avastin (bevacizumab, Genentech) was administered in the right eye after a thorough discussion with the patient of the risks, benefits and alternatives. One week after injection, the patient’s visual acuity remained stable at 20/30-2 in both eyes, and subjectively he reported improvement in peripheral vision in the affected eye. Fundus examination and OCT revealed reduction in right superior optic disc swelling.
On the second follow-up exam a month later, vision was stable in both eyes. Fundus exam remained stable bilaterally. OCT showed progressive decrease in average RNFL and ganglion cell thickness bilaterally (Figure 4). It became apparent that the left eye may have been previously affected but was masked on the first two visits because it was seen at the time point before evident pallor of the optic nerve or RNFL/ganglion cell layer thinning.
Discussion
The exact etiology of the optic nerve ischemia in NAION remains elusive, although it appears to be multifactorial. The onset of symptoms upon awakening raises the question of nocturnal hypotension as a contributing factor, which may be worsened by taking blood pressure medications before sleeping. This case provides further evidence that a drop in blood pressure may play a role in this condition. Sleep apnea has also been established as an associated risk factor. Thus, testing for sleep apnea might be considered. Also, the use of phosphodiesterase-5 inhibitors has recently been indicated as a possible cause of NAION. There appears to be a mechanical factor as well. Patients with NAION often have baseline crowded optic nerves, known commonly as “discs at risk.” Optic nerve ischemia in NAION leads to intracellular axonal swelling. A crowded optic nerve may worsen the mechanical obstruction, leading to further stasis in axoplasmic flow and ganglion cell apoptosis. The association of NAION with underlying vasculopathic factors including diabetes and hypertension suggests that these factors may play a role, as may dysfunction in autoregulation of optic nerve blood flow in patients with hypertension and atherosclerosis.
There is no standard in the treatment of NAION other than controlling the risk factors in order to decrease the chance of NAION occurring in the fellow eye. The use of anti-VEGF agents such as bevacizumab has been proposed to help reduce vascular permeability or vasogenic edema in optic nerve swelling in patients with NAION, but it is still an area of active research. Bennett et al first demonstrated improvement in visual acuity from counting fingers to 20/70 over 10 days in an 87-year-old woman with NAION with involvement in the second eye after treatment with bevacizumab. Rootman et al conducted a non-randomized clinical trial of 25 patients with NAION. They found no significant changes in mean deviation, OCT RNFL thickness or ETDRS letters between the two groups at 6 months. Systemic steroids have been used in the past, and there is recent evidence that they may be helpful, according to Hayreh et al.
According to the Ischemic Optic Neuropathy Decompression Trial, about one-third of patients experience a three-line improvement in visual acuity within 6 months of presentation, about one-third remain stable, and about one-third experience worsening. The second eye may become involved in about 15% of case within 5 years. Recurrences are rare, but NAION may occur in the same eye in 5% of cases.