Blurred vision or field loss: Not explained by visible ocular disease: optic disc/s normal, swollen, pale or “cupped”

  • Contents

  • 28 Introduction

  • 29 Examination checklist

  • 31 Management flowchart

  • 39 Optic neuropathy

  • 40 Acute optic neuropathies

  • 67 Chronic optic neuropathies

  • 82 Suggested investigations for optic neuropathy that cannot be diagnosed clinically

  • 86 Optic chiasmal disease

  • 92 Retrochiasmal disease

  • 98 Occult ocular disease

  • 99 Non-organic visual loss


Blurred vision and/or visual field loss not explained by visible ocular disease can be caused by disease of the:

  • eye

  • optic nerve

  • optic chiasm

  • retrochiasmal brain visual pathway

  • or (rarely) non-organic functional visual loss (the patient is simulating visual loss in the absence of real disease)

A careful history and detailed examination will often give important clues as to the location of the disease.

Eye disease

Eye disease is by far the most common cause of blurred vision and is usually obvious on slit-lamp examination. However, some ocular disorders, such as keratoconus and some macular dystrophies, may be difficult to diagnose in their early stages and may be overlooked on a cursory ocular examination (see “occult” ocular diseases , p. 98).

Optic nerve disease

Disease of the optic nerve can be recognized by the presence of one or more of the following:

  • abnormal visual acuity, color vision and/or visual field, not explained by (or worse than that expected from) visible intraocular disease

  • presence of a relative afferent pupillary defect (RAPD) (unless optic nerve disease is bilateral and symmetric)

  • pallor, swelling or “cupping” of one or both optic discs (in some but not all cases)

Glaucoma is by far the most common optic neuropathy. The next most common optic neuropathies are the acute neuropathies of typical optic neuritis and anterior ischemic optic neuropathy (AION). There are many other causes of optic neuropathy and it is important that they are identified because many are treatable if diagnosed early (before optic atrophy occurs), e.g. compressive, infectious or sarcoid optic neuropathy.

As ophthalmologists, we all need to know the following four things about optic nerve disease:

  • 1.

    How to make a safe clinical diagnosis of typical optic neuritis (p. 35).

  • 2.

    How to make a safe clinical diagnosis of AION (p. 36).

  • 3.

    How to make a safe clinical diagnosis of glaucomatous optic neuropathy (p. 37).

  • 4.

    What to do for all other patients with non-traumatic optic nerve disease who cannot be diagnosed clinically as having typical optic neuritis, AION or glaucoma. We recommend that these patients be referred to a neuro-ophthalmologist for further assessment (urgently if the problem is acute). If prompt referral is difficult due to geographic or patient factors, or if you wish to work the patient up yourself, the necessary initial basic investigations are outlined on p. 38.

Optic chiasmal disease

Optic chiasmal disease can be recognized by the presence of bitemporal visual field defects on perimetry (if unilateral temporal field loss is present, suspect immediately prechiasmal optic nerve disease). Because the most common cause of optic chiasmal dysfunction is compression by a pituitary region tumor, all patients with suspected chiasmal disease require urgent, contrast-enhanced magnetic resonance imaging (MRI) or at least a contrast-enhanced computerized tomographic (CT) scan.

Retrochiasmal disease

Retrochiasmal disease is characterized by the presence of a homonymous visual field defect on perimetry. Because strokes and brain tumors are common causes of retrochiasmal disease, all patients with homonymous field loss require neuroimaging, either a contrast-enhanced CT scan or contrast-enhanced MRI.

Non-organic visual loss

A diagnosis of non-organic visual loss is frequently considered when inconsistencies are found in a patient’s history and examination. Great care must be taken to establish this diagnosis, bearing in mind that some of these patients have “real” organic disease or organic disease plus an overlay of additional simulated visual loss.

Examination checklist

Blurred vision or field loss

Have you asked about, and looked for, all the following key features?


  • the blurred vision or field loss

    • one or both eyes? (how did the patient know; did he/she check each eye separately?)

    • where in the visual field (all over, central, to the side)?

    • when did it start?

    • speed of onset?

    • change over time?

    • is it getting better, staying the same or still worsening?

    • any preceding transient visual loss?

  • other ophthalmic symptoms

    • eye or orbital pain? (if so, does it worsen on eye movement?)

    • facial numbness?

    • double vision? (possible orbital apex or pituitary tumor)

  • previous medical and surgical history

    • cancer? (possible metastasis)

    • potentially toxic medications?

    • vascular risk factors?

  • social history

    • smoker, alcohol, special diet, difficulty sleeping, snoring, drugs for erectile dysfunction?

  • family history: unexplained visual loss or brain disease?

  • if patient over 50: symptoms of giant cell arteritis (GCA)?

  • system review questions

    • neurologic symptoms?

    • any clues to the cause anywhere in the body?


  • visual acuity

  • color vision testing

  • visual field defect to confrontation?

  • limitation of eye movements? (possible orbital apex or pituitary tumor)

  • pupils

    • RAPD? (unilateral or bilateral asymmetric optic neuropathy, or optic tract lesion)

    • is there anisocoria? (possible partial third or Horner’s from intracranial tumor)

  • eyelids

    • ptosis? (possible partial third or Horner’s from intracranial tumor)

    • lid retraction? (possible thyroid eye disease with compressive optic neuropathy)

  • orbits: proptosis, enophthalmos, injection, chemosis?

  • decreased corneal or facial sensation to light touch? (possible orbital apex or cavernous sinus tumor)

  • if patient over 50: palpate temporal arteries for tenderness

  • measure blood pressure:

    • in all cases, especially if disc swelling is present

  • full neurologic examination if:

    • the patient has an unexplained optic neuropathy, unexplained neurologic symptoms or there is suspicion of chiasmal or retrochiasmal disease

Plus: must perform some type of perimetry:


Management flowchart

Blurred vision or field loss NOT explained by visible ocular disease

Clinical diagnostic criteria for chiasmal lesion

The patient must have ALL of the following:


  • normal or reduced visual acuity


  • bitemporal visual field defect

  • visual field defects stop at the vertical midline (unless there is a superimposed unilateral or bilateral optic neuropathy as well, which is common in pituitary region tumors)


Clinical diagnostic criteria for retrochiasmal lesion

The patient must have ALL of the following:


  • normal visual acuity, unless there is coexistent ocular disease causing blurred vision


  • homonymous visual field loss: the same (or similar) area of field loss occurring in the same position in each eye

  • visual field defects stop at the vertical midline (unless bilateral disease is present)


Clinical diagnostic criteria for possible occult ocular disease

The patient must have ALL of the following:

  • no history of neurologic symptoms

  • no proptosis or enophthalmos, no ptosis, normal eye movements, normal corneal and facial sensation

  • no visible optic disc abnormality

  • if there is a field defect on perimetry, it is in keeping with the proposed ocular disease

and ONE OR MORE of the following:

  • history suggestive of macular or retinal disease, e.g. metamorphopsia, hemeralopia (poor vision in bright light) or nyctalopia (poor vision in dim light)

  • signs of keratoconus including abnormal retinoscopic reflex and high astigmatism on keratometry

  • signs of macular disease on careful slit-lamp contact lens examination

  • signs of occult retinal disease, e.g. vascular sheathing or attenuation

If the patient meets ALL these criteria, see p. 98 for management.


Because optic nerve disease carries a higher risk of serious underlying disease (e.g. tumor) than retinal disease, if there is any doubt, the patient must first be investigated with neuroimaging. If this and other investigations for possible optic nerve disease (e.g. optical coherence tomography (OCT) of the peripapillary retinal nerve fiber layer) are negative, further retinal investigations such as OCT of the macula, electroretinography (ERG) and fluorescein angiography can then be pursued.

Beware attributing blurred vision or field loss to subtle macular or retinal disease; if the degree of visual loss is out of proportion to the visible disease, there could also be an underlying optic neuropathy.

Clinical diagnostic criteria for non-organic visual loss

The patient must have ALL of the following:


  • inconsistency between different parts of the examination raises the suspicion that vision loss may be partly or completely non-organic, e.g. there is claimed severe visual loss in one eye with a normal ocular examination, normal optic disc and no RAPD

  • the patient has an up-to-date refraction and this has been checked to be correct

  • retinoscopy and keratometry are normal (no signs of keratoconus)

  • no RAPD (on careful testing with a bright light in a dark room)

  • no proptosis, no ptosis, normal eye movements, normal corneal and facial sensation

  • AND you are able to demonstrate in clinical testing that the patient’s visual function is actually completely normal (see “clinical tricks” , p. 100)


  • if abnormal, is consistent with non-organic field loss, e.g. “spiraling” (see p. 103)

  • if standard perimetry is normal, central field perimetry (Humphrey 10-2 or similar) should also be performed and also be normal

If the patient meets ALL these criteria, see p. 106 for management.


True non-organic visual loss may be very difficult to diagnose, and it is essential that patients with real but rare diseases are not falsely labeled as non-organic. If there is any doubt, refer the patient to a neuro-ophthalmologist (urgently if visual loss is acute).

Clinical diagnostic criteria for typical optic neuritis

The patient must have ALL of the following:


  • AGE: 15–45 (male or female)


    • otherwise well: no history of cancer, vasculitis or autoimmune disease

  • ONE eye only is symptomatic


    • ACUTE onset of blurred vision

    • worsens rapidly over hours to days

  • eye or orbital PAIN (usually, but not always, increased on eye movement)

  • no diplopia

  • no other systemic neurologic symptoms (apart from those consistent with previous episodes of multiple sclerosis [MS], e.g. an area of numbness that lasts days to weeks then resolves)


  • no proptosis or enophthalmos, no ptosis, normal eye movements, normal corneal and facial sensation

  • affected eye:

    • RAPD

    • normal optic nerve head or mild to moderate swelling

    • no disc pallor, hard exudates, cotton-wool spots, hemorrhages, iritis, vitritis or other intraocular disease

  • other eye: entirely normal intraocular examination


  • affected eye: any type of field defect

  • other eye: an asymptomatic field defect of any type may be present

And on follow-up

  • vision stops worsening within 2 weeks

  • vision starts to improve within 4 weeks

If the patient meets all the other diagnostic criteria at the first visit, you can make a provisional diagnosis of typical optic neuritis, but this can only be confirmed as the definite diagnosis if vision behaves as expected on follow-up.


Clinical diagnostic criteria for anterior ischemic optic neuropathy (AION)

The patient must have ALL of the following:


  • AGE: 40 or over (male or female)


    • one or more vasculopathic risk factors (e.g. hypertension, hypercholesterolemia, diabetes, smoking, obstructive sleep apnea, amiodarone, erectile dysfunction drugs)

    • no history of cancer, vasculitis or autoimmune disease

  • ONE eye only is symptomatic


    • VERY SUDDEN visual acuity and/or visual field loss while awake (over seconds or minutes) or visual loss noted first on waking (with normal vision the night before)

    • vision then remains the same, or worsens slowly for up to a week

  • no or very mild eye or orbital pain, no diplopia, no other systemic neurologic symptoms


  • no proptosis or enophthalmos, no ptosis, normal eye movements, normal corneal and facial sensation

  • affected eye

    • RAPD

    • mild to severe optic nerve head swelling (hyperemic or pale swelling, sectoral or diffuse); may have disc margin hemorrhages; cotton-wool spots suggests arteritic

    • NO hard exudates, iritis, vitritis or other intraocular disease

  • other eye:

    • entirely normal examination (no disc pallor, unless previous documented episode of AION in this eye)

    • “crowded” optic nerve head (with absent or small cup) (unless patient over age 50 and symptoms of GCA present)


  • affected eye: any type of visual field defect (but often altitudinal or arcuate)

  • other eye: entirely normal visual field unless previous attack of AION or other pathology

And on follow-up

  • no progressive worsening of acuity or field beyond a week

If the patient meets all the other diagnostic criteria at the first visit, you can make a provisional diagnosis of AION, but this can only be confirmed as the definite diagnosis if visual acuity and field are found to be stable on follow-up.

NOTE: if the clinical diagnosis of AION is made, it must then be decided (by history, examination, erythrocyte sedimentation rate [ESR], C-reactive protein [CRP] and full blood count) if it could be ARTERITIC (usually due to GCA) or NON-ARTERITIC: see p. 46.


Clinical diagnostic criteria for glaucomatous optic neuropathy

The patient must have ALL of the following:


  • the patient does not complain of progressive worsening of vision (unless very advanced disc cupping or notching is present)


  • visual acuity is normal, unless:

    • there is very advanced disc cupping and extensive field loss

    • there is another cause for reduced vision (e.g. cataract) that is consistent with the severity of visual loss

  • color testing is normal (except in patients with very advanced disc cupping and reduced visual acuity, or congenital color vision defect)

  • intraocular pressure (IOP) may be raised or normal

  • increased cup/disc ratio

  • focal or diffuse loss of the neuroretinal rim

  • the intact areas of neuroretinal rim are not pale


  • field loss respects the horizontal midline but not the vertical midline

  • if the other disc looks normal, it should have an absolutely normal field

  • THE DISCS MUST MATCH THE FIELDS (e.g. a superior arcuate scotoma in an eye with an inferior optic disc notch)

  • if there is no correlation between discs and fields (e.g. diffuse thinning of neuroretinal rim with a central scotoma on the field), it is not glaucoma


Suggested investigations for optic neuropathy that cannot be diagnosed clinically

See p. 82 for details.

These investigations are recommended for patients with optic nerve disease who do not meet the above clinical diagnostic criteria for typical optic neuritis, AION or glaucoma and who cannot be referred promptly to a neuro-ophthalmologist, or you choose to investigate yourself.

Investigate urgently if acute onset.

  • 1.

    Basic assessment for all patients: full systemic clinical history and examination, including blood pressure, temperature and urine analysis.

  • 2.

    MRI optic nerves and brain with contrast for all patients, unless there is a medical contraindication. MRV (magnetic resonance venography) should also be requested if bilateral disc swelling is present.

  • 3.

    Blood tests

    • for all patients: full blood count, electrolytes, liver function tests, glucose, ESR, CRP, angiotensin-converting enzyme (ACE), antinuclear antibodies (ANA), syphilis serology

    • plus for atypical optic neuritis: NMO-IgG (neuromyelitis optica) antibodies

    • plus the following blood tests for patients with bilateral symmetric optic neuropathy: red blood cell (RBC) folate, serum vitamin B12

    • plus other tests as required if there is clinical suspicion of a particular disease (e.g. Leber hereditary optic neuropathy [LHON], cat scratch disease, Lyme disease, human immunodeficiency virus [HIV], quantiferon)

  • 4.

    Chest x-ray for all patients (plus chest CT scan or positron emission tomography [PET] scan if sarcoid or tuberculosis suspected).

  • 5.

    Lumbar puncture for selected patients (p. 85).

  • 6.

    Diagnostic trial of 3 days’ intravenous (IV) methylprednisolone for selected patients (p. 85).

Acute optic neuropathies

Typical optic neuritis

Check that your patient meets ALL the clinical diagnostic criteria on p. 35 before you make this diagnosis!

The term “optic neuritis” just means that the optic nerve is inflamed; it does not indicate the etiology of the inflammation. There are many different types of optic neuritis, including sarcoid optic neuritis, infectious optic neuritis, postinfectious optic neuritis, autoimmune disease-related optic neuritis, and typical optic neuritis. Of these, typical optic neuritis is the only one that can be diagnosed on history and examination alone, and the only one that carries an increased future risk of MS.

Please note:

  • not all young adults with an acute optic neuropathy have typical optic neuritis and neither do all patients with optic neuropathy and normal optic discs. Optic neuropathies of many other causes, many of them treatable, are possible in these patients

  • typical optic neuritis can only be confirmed in retrospect, after the patient’s vision is observed to spontaneously recover as expected over time. At the first consultation, a tentative diagnosis of presumed typical optic neuritis can be made if the patient meets all the clinical diagnostic criteria on p. 35; however, confirmation of the diagnosis can only be made after following the patient over the next few weeks


  • age 15–45

  • men or women (but more common in women)



  • ACUTE visual loss in one eye that:

    • rapidly worsens for up to 2 weeks

    • then stays stable

    • then starts to improve by 4 weeks after onset of the symptoms

  • PAIN in or behind the eye that in most (but not all) patients is worse on eye movement. A minority of cases of optic neuritis (<5%) are painless, so such cases should be considered atypical and investigated


  • usually the patient has no other neurologic symptoms at the time of presentation

  • some patients have a past history of transient, spontaneously resolving episodes of neurologic dysfunction suggestive of undiagnosed MS, e.g. episodes of numbness or weakness of an arm or leg lasting days or weeks, then resolving, or an episode of unexplained vertigo or loss of balance


  • variably decreased visual acuity (20/20 to “no perception of light”)

  • variably decreased color vision (color is usually more severely affected than acuity)

  • any type of visual field defect; however, central scotomas and diffuse loss are common

  • an RAPD in the symptomatic eye

  • optic disc on the affected side ( Fig. 2.1 ):

    • two-thirds of patients have a normal-appearing disc (at least in the Western hemisphere)

    • one-third have mild to moderate hyperemic disc swelling

    • no hard exudates or cotton-wool spots


    The optic disc in typical optic neuritis can be normal A or show mild to moderate swelling B . Typical periventricular white matter hyperintensities are shown in the two MRI scans C and D ; these findings increase the risk of a future diagnosis of multiple sclerosis.

  • intraocular inflammation:

    • a minority of patients with typical optic neuritis have mild peripheral sheathing of retinal veins +/− mild “snowbanking” (similar to that seen in “pars planitis”)

    • however, given that an identical appearance can occur in sarcoidosis, vasculitis, cat-scratch disease or syphilis, these patients require especially close and careful follow-up, with the appropriate investigations (as suggested on p. 38, plus uveitis opinion) if the vision does not begin to improve within 4 weeks or if the uveitis worsens

Differential diagnosis

  • neuromyelitis optica (NMO) – see p. 54

  • infectious and post-infectious optic neuritis

  • sarcoidosis

  • there are many other causes of acute optic neuropathy with normal or swollen disc/s – see list on p. 39


  • patients who meet all the clinical diagnostic criteria for typical optic neuritis do not require investigations to confirm the ophthalmic diagnosis

  • it is, however, reasonable to obtain an MRI orbits and brain ( Fig. 2.1 ) for all patients with first-episode optic neuritis, as the presence and number of brain white matter lesions is a powerful prognostic factor regarding the future risk of MS and helps guide discussions as to possible immunomodulatory therapy

  • patients with an acute optic neuropathy who do NOT meet the clinical diagnostic criteria for typical optic neuritis or AION should be thoroughly investigated to determine the cause (see p. 82)

    • these tests should include NMO-IgG blood testing (for NMO)

Visual prognosis

  • the Optic Neuritis Treatment Trial (ONTT) found that 93% of patients (with or without steroid treatment) had recovery of vision to at least 20/40

  • even if visual acuity (VA) returns to normal or almost low-dose normal, color vision may remain abnormal, and an RAPD persist

  • patients usually say that the eye “never sees quite as well again” due to patchy scotomas, color defects and contrast sensitivity problems

  • the chance of recurrent episodes of typical optic neuritis is about 25%; if episodes are severe or many episodes occur, significant and permanent vision loss eventually may result

Treatment for the visual loss of typical optic neuritis

No treatment has been shown to improve the final visual outcome. The ONTT found that:

  • 1 g IV methylprednisolone daily for 3 days followed by oral prednisone (1 mg/kg/day) for 11 days often sped up visual recovery, but the eventual visual recovery was the same whether or not steroids were used

  • oral prednisone (1 mg/kg/day for 2 weeks) alone (surprisingly) was actually found to be harmful, in that it increased the risk of recurrent optic neuritis in the affected eye and new optic neuritis in the fellow eye

Systemic prognosis: relationship of typical optic neuritis to multiple sclerosis

  • one-quarter of MS patients first present with typical optic neuritis

  • long-term follow-up suggests that two-thirds of women and one-third of men with typical optic neuritis eventually develop MS

  • the risk of developing MS is increased if a patient with typical optic neuritis:

    • has one or more white matter lesions visible on brain MRI

    • has had previous non-specific neurologic symptoms

    • has recurrent episodes of typical optic neuritis

    • has a family history of MS

Treatment to delay development of MS


  • do not provide any long-term benefit

  • in the ONTT, 1 g IV methylprednisolone daily for 3 days followed by oral prednisone (1 mg/kg/day) for 11 days delayed the onset of MS for up to 2 years; however, at 2 years, as many steroid-treated as untreated patients had developed MS

Disease-modifying treatments for MS

  • A variety of immunomodulatory agents are now available and many more are under development. Examples of these medications include:

    • subcutaneous injections, e.g. beta-interferon (Betaferon, Avonex), glatiramer acetate (Copaxone)

    • oral tablets, e.g. fingolimod (Gilenya), teriflunomide (Aubagio)

    • intravenous infusions, e.g. natalizumab (Tysabri)

  • these treatments may delay the onset of MS in some patients presenting with first-episode typical optic neuritis and white matter lesions on MRI; however, long-term efficacy is unknown, especially with the newer medications

  • ophthalmologists should be aware that patients taking fingolimod (Gilenya) tablets may rarely develop uveitis and/or macular edema, usually within the first 6 months of commencing treatment. Therefore, patients about to start fingolimod treatment should have an ophthalmic examination and optical coherence tomography (OCT) macula immediately before commencing treatment; 3, 6, and 12 months after commencement; then yearly. Patients should be told to contact their ophthalmologist and neurologist immediately if they develop blurred vision or metamorphopsia at any stage

  • patients taking natalizumab (Tysabri) may rarely develop posterior multifocal leukoencephalopathy (PML) with involvement of the posterior visual pathways and homonymous or diffuse visual field loss. Ophthalmologists should therefore perform a careful evaluation, including perimetry, for any MS patients treated with natalizumab who develop new visual symptoms. In general, patients should have a serum PCR for the presence of JC virus before natalizumab is started

Management recommendations

It would seem reasonable to refer all patients meeting the diagnostic criteria for typical optic neuritis to either a neurologist or neuro-ophthalmologist to discuss:

  • the risk of developing MS

  • if the patient would like an MRI scan to further assess their risk of MS

  • possible steroid treatment (high-dose IV then low-dose oral) for those patients with white matter lesions on brain MRI at presentation, severe visual loss or an occupational need for rapid return of vision

  • possible beta-interferon or other immunomodulatory treatment (where available) for patients with two or more MRI white matter lesions at presentation

Irrespective of other treatment or referral, all patients should be reviewed at 2 and 4 weeks to check that the disease is “still behaving typically”. That is:

  • vision stops worsening by 2 weeks after the initial onset of symptoms

  • vision begins to recover by 4 weeks after the initial onset of symptoms

  • no new ophthalmic, neurologic or systemic symptoms or signs have developed

If atypical features occur at any stage during follow-up, the initial clinical diagnosis of typical optic neuritis should be considered suspect and the patient urgently referred to a neuro-ophthalmologist for further evaluation (or if this is not possible, urgently investigated as suggested on p. 38).

If the disease behaves “as expected” (the patient remains otherwise well and vision rapidly recovers, usually to almost normal), the patient does not require further routine ophthalmic follow-up unless new ophthalmic symptoms occur.

Anterior ischemic optic neuropathy (AION)

Check that your patient meets ALL the clinical diagnostic criteria on p. 36 before you make this diagnosis!

Please note:

  • not all middle-aged or elderly adults with a swollen disc have AION. Optic neuropathies from many other causes, many of them treatable, are possible in these patients

  • AION can only be diagnosed in retrospect, after the patient’s vision is observed to behave as expected over time (sudden initial visual loss, then plateau, sometimes followed by a very slow slight recovery over months). At the first consultation, a tentative diagnosis of AION can be made if the patient meets all the clinical diagnostic criteria on p. 36, but confirmation of the diagnosis can only be made after following the patient over the next few weeks


Infarction or ischemia in the territory of the short posterior ciliary arteries because of:

  • GCA (or rarely vasculitis of other causes): “arteritic” AION

  • atherosclerosis: “non-arteritic” AION

Risk factors

Arteritic AION

  • increasing age is the principal risk factor for GCA; most patients with arteritic AION are 60 years of age or older

Non-arteritic AION

  • age: most patients are over 55

  • the “disc at risk”

    • a small, crowded optic nerve head (with a small or absent central cup) predisposes patients to non-arteritic AION

    • non-arteritic AION is unusual in patients with normal cup/disc ratios

  • optic disc drusen

  • atherosclerosis of the short posterior ciliary arteries: hypertension, diabetes, hypercholesterolemia, smoking

  • rarely: severe hypotension, coagulopathies, sleep apnea, erectile dysfunction drugs (e.g. sildenafil/Viagra, amiodarone)


  • VERY SUDDEN acute visual loss, with vision then remaining stable or slowly declining further over the next week

  • usually painless or with minimal pain; if pain is present, it almost never worsens with eye movement

  • usually unilateral (if bilateral, suspect GCA)


  • variably decreased visual acuity (20/20 to “no perception of light”)

  • variably decreased color vision (extent of color loss usually consistent with acuity)

  • any type of visual field defect, but altitudinal or arcuate defects most common

  • an RAPD in the affected eye

  • diffusely or segmentally swollen optic disc on the affected side: hyperemic (pink) or pale swelling ( Figs. 2.2 and 2.4 )


    AION presents as sudden visual loss with a swollen optic disc.


    Non-arteritic AION presents with sudden loss of vision and a swollen disc A ; disc swelling gradually settles and disc pallor results over the subsequent months B .

Differential diagnosis

There are many other causes of acute painless visual loss with a swollen disc, including infectious or postinfectious optic neuritis, sarcoid optic neuritis and anterior infiltrative optic neuropathy.


  • no investigations are required to diagnose AION if the patient meets all the clinical diagnostic criteria on p. 36

  • all patients with AION require an urgent complete physical examination, with special attention to underlying systemic vascular disease

  • a careful history for symptoms of GCA (see below)

  • blood tests for underlying diabetes, hypercholesterolemia, coagulopathy if non-arteritic AION suspected

  • ESR, CRP and full blood count if arteritic AION suspected

  • sleep studies if history suggests sleep apnea (e.g. snoring, insomnia)

Distinguishing between arteritic and non-arteritic AION

There are no features in the history, examination or blood test results that can completely exclude GCA. However, the presence of one or more of the following in a patient over 50 who has AION is strongly suggestive of GCA.

Symptoms suggesting GCA

  • ophthalmic

    • transient loss of vision preceding permanent visual loss in the affected eye

    • transient or persistent diplopia

    • bilateral (usually rapidly sequential) visual loss

  • systemic

    • onset of a new headache

    • muscle aches, malaise, weight loss, fever, night sweats

    • scalp tenderness (to touch or on hair brushing)

    • jaw or tongue ache on chewing (jaw claudication)

    • neck or ear pain

    • symptoms of systemic complications of GCA: scalp ulceration, Raynaud phenomenon, myocardial ischemia or infarction, transient ischemic attack or stroke, bowel ischemia or infarction

Signs suggesting GCA

  • ophthalmic

    • retinal cotton-wool spots or arteriolar occlusion ( Fig. 2.3 )


      AION due to giant cell arteritis (“arteritic” AION). A Optic disc swelling in arteritic AION is often pale (but may be hyperemic). B The cotton-wool spots visible here (arrows) are highly suggestive of giant cell arteritis. C Prominent, non-pulsatile temporal artery associated with overlying tenderness is a useful sign when present.

    • normal (non-crowded) disc in the fellow eye (in most cases of non-arteritic AION, the unaffected disc is small and “crowded” with little or no central cup)

    • signs of ocular or orbital ischemia (uveitis, corneal edema, low intraocular pressure, dilated retinal veins, midperipheral retinal blot hemorrhages)

    • motility deficit

  • systemic

    • tender and/or non-pulsatile temporal artery on one or both sides

    • scalp tenderness (rarely scalp ulceration)

Blood test results suggesting GCA

  • ESR and CRP

    • most patients with GCA have elevation of both ESR and CRP; however, some patients have elevation of only one, so both should be tested but beware of the following:

      • not all patients with GCA have a raised ESR or CRP: a few patients with biopsy-proven GCA have an absolutely normal ESR and CRP

      • not all patients with a raised ESR or CRP have GCA: there are many causes for a raised ESR or CRP, including cancer, acute or chronic infections, renal failure and other types of vasculitis; some of these other diseases present with headaches and malaise (and sometimes visual loss) that may be mistaken for GCA

  • full blood count: increased platelet count (thrombocytosis) and a normochromic, normocytic anemia are common in GCA

  • biochemistry: alkaline phosphatase (ALP) is elevated in some cases of GCA

Investigation and treatment of suspected arteritic AION (AION due to GCA)


The treatment of suspected GCA may be complex and has significant risks to elderly patients. Refer urgently to a neuro-ophthalmologist at any stage if you are unsure or if the patient is not responding to treatment.

Initial treatment

  • admission to hospital is often advisable, particularly if the patient is unwell or lives alone

  • start high-dose steroid treatment as soon as the diagnosis of GCA is suspected: the risk of a few days’ steroid treatment is low and you can always cease treatment if the diagnosis is ruled out by temporal artery biopsy

  • intravenous methylprednisolone

    • many neuro-ophthalmologists give this for 3–5 days initially, before starting oral prednisone, if:

      • vision has already been lost in one or both eyes

      • the patient has normal vision but is experiencing transient visual loss

      • there are neurologic, cardiologic or gastrointestinal symptoms of GCA complications (urgently consult the relevant specialist physicians)

    • dose: 1 g per day for a 70 kg adult (in single or divided doses) for at least 3 days, starting as soon as diagnosis is suspected and blood is drawn for ESR, CRP, etc.

    • monitor blood pressure; daily blood glucose if not diabetic, frequent blood glucose monitoring with sliding-scale insulin if diabetic

  • oral prednisone (warn the patient about short- and long-term side effects)

    • 1.5 mg/kg single daily morning dose to start

    • if IV methylprednisolone was given first, start the oral prednisone on the final day of IV treatment

  • prophylactic treatment: start the following immediately (continue until steroid ceased):

    • osteoporosis prophylaxis, e.g. calcium plus vitamin D, alendronic acid

    • gastric ulcer prophylaxis, e.g. ranitidine

Temporal artery biopsy

  • the gold standard test for the diagnosis of temporal arteritis

  • every patient with suspected GCA requires a temporal artery biopsy: if an elderly patient is to be exposed to the risks of steroid treatment for a year or more, a definitive diagnosis must be made and a biopsy is the best method for doing this

  • in general, NEVER wait for biopsy results before starting high-dose steroid treatment

  • aim to:

    • perform within a few days of diagnosis

    • obtain a cut artery specimen of at least 2 cm length (specimens less than this length have a decreased yield); avoid crushing the artery

  • it is important that the histopathology lab processes and examines the specimen correctly, if false-negative reports are to be avoided: examination of many sections of the artery by an experienced pathologist is ideal

  • if the first biopsy is negative, but there is still a high clinical suspicion of temporal arteritis, consider biopsy of the other side (in 1–11% of cases, the contralateral biopsy will be positive!)

  • if adequate bilateral biopsies have been obtained early in steroid treatment and expert histopathologic examination shows no sign of active or healed temporal arteritis, the diagnosis is unlikely and steroids should be stopped unless there is overwhelming clinical evidence of GCA; have the patient evaluated for other causes of raised ESR and CRP (e.g. atypical meningitis, infections, cancer)

Further treatment and follow-up

  • natural history

    • temporal arteritis tends to be a self-limiting disease but may persist for many years

    • high-dose IV steroids followed by lower-dose oral steroids usually protect the unaffected optic nerve/s as well as other vessels elsewhere in the body (e.g. heart, brain) while the disease “burns itself out”

    • further vision loss is rare after 1 year, even without treatment, so steroids can usually be safely withdrawn at 12–18 months unless symptoms or raised blood inflammatory parameters persist or recur

  • principles of treatment

    • oral prednisone is a life-threatening drug, especially for elderly patients; side effects can be minimized by:

      • educating the patient and their family about the drug and its complications

      • starting osteoporosis and gastric ulcer prophylaxis immediately in all patients

      • regularly monitoring for side effects throughout treatment

      • tapering and ceasing treatment after 12–18 months, if possible

    • an initial high dose is essential to protect against early bilateral blindness and to put the disease into remission; the dose is then tapered as rapidly as possible, balancing the risks of treatment against the risk of losing vision

    • it is essential that the patient is followed up by a doctor experienced with prednisone treatment for GCA throughout their course: if you do not have this experience, involve a neuro-ophthalmologist or rheumatologist early

    • “resistant” or “recurrent” disease: obtain a neuro-ophthalmic opinion; such patients may benefit from addition of tocilizumab

  • ceasing treatment

    • treatment continues for a minimum of 12 months

    • once prednisone has been withdrawn, the patient needs to be checked for at least a further 12 months to watch for recurrent disease

Visual prognosis

  • recovery of vision in affected eyes is rare

  • second eye involvement can occur within hours; hence, if visual loss has already occurred in one eye, urgent action must be taken to save the vision in the other eye

  • even patients treated early with high-dose IV steroids after acute visual loss in one eye may lose vision in the second eye, but the risk is much lower with treatment than without

Investigation, treatment and prognosis of non-arteritic AION


  • no investigations are required to diagnose non-arteritic AION if:

    • the patient meets all the clinical diagnostic criteria for AION

    • there is no suspicion of GCA on history, examination and blood tests

    • the condition behaves as expected on follow-up (no deterioration of vision beyond a week, no other neurologic symptoms develop); if not, the patient requires investigation as suggested on p. 38)

  • however, all patients with non-arteritic AION require investigation for vascular risk factors (by yourself, their family physician or their internist):

    • blood pressure

    • fasting blood cholesterol and lipids

    • blood glucose, full blood count and electrolytes (including calcium)

    • remember to ask about use of possible precipitating medications, e.g. erectile dysfunction drugs and amiodarone

    • evaluate for possible obstructive sleep apnea

    • note: investigations for embolic sources (e.g. carotid ultrasound) are not required for AION unless there are other symptoms suggesting this process

  • the “young” patient with non-arteritic AION:

    • if a patient younger than 40 fits all the clinical diagnostic criteria for AION except that of age, he or she should be referred to a neuro-ophthalmologist (or failing this, investigated urgently as suggested on p. 38)

    • if no other cause is found (leaving a presumed diagnosis of non-arteritic AION) and the patient is not diabetic, further investigation for vascular disease or coagulopathies should be considered, particularly if the patient has no other known vascular risk factors:

      • the patient could have a familial hyperlipidemia (or just have high cholesterol)

      • hyperhomocysteinemia may be linked to AION at a young age and is treatable

      • vasculitides such as systemic lupus erythematosus (SLE) may sometimes cause AION (or an anterior optic neuropathy mimicking AION)

    • remember to ask about sleep apnea symptoms (ask patient AND spouse/significant other)

    • ask (in private!) about use of drugs for erectile dysfunction (e.g. sildenafil)


  • no treatment consistently improves the visual outcome once non-arteritic AION has occurred

  • treatment to protect the other eye:

    • no treatment is of proven benefit but many neuro-ophthalmologists will start non-arteritic AION patients on aspirin in the hope of reducing the chance that the disc in the other eye will also suffer infarction

    • significant ocular hypertension should be treated if present in one or both eyes, with the intention of improving optic nerve head perfusion pressure; however, again there is no proven benefit to this

    • if systemic hypertension is present (or discovered during the work-up for AION) it should be treated:

      • the patient’s physician should be advised to avoid a “low” blood pressure or a sudden drop in blood pressure, and to avoid nighttime dosing of antihypertensives because transient systemic hypotension, especially during the night when blood pressure is normally at its lowest, could possibly increase the risk of infarcting the other disc

  • treatment to protect the patient against further vascular events

    • non-arteritic AION is a significant “warning sign” that the patient’s blood vessels throughout the body are being damaged by vascular risk factors (affected patients have an increased risk of stroke and heart attack)

    • advise patients to stop smoking and to have other identified modifiable risk factors treated by their physician


  • re-examine the patient 2–4 weeks after onset (to check that any slow progression after the initial sudden episode has stopped)

  • if acuity or field is still worsening, the diagnosis of AION is suspect and the patient should be investigated

  • if ophthalmic findings are stable at 2–4 weeks, re-examine in a further 3–4 months; if still stable, discharge but ask the patient to return immediately if any change occurs


  • affected eye

    • it is unusual for the same eye to have a second episode of AION (3–5%)

    • many patients (about 40%) do have slow recovery of some acuity but improvement in visual field is rare

  • fellow eye: patients with non-arteritic AION have about a one in four chance that the other disc will also develop AION; this can happen days to many years in the future

Note: “diabetic papillopathy”

  • diabetics of any age may develop optic disc swelling, with or without visual dysfunction; this is often called “diabetic papillopathy”

    • it may be that some of these cases represent “mild” non-arteritic AION; however, in contrast to most cases of AION, vision often spontaneously recovers to normal as disc swelling resolves over weeks or months

    • patients in whom visual acuity recovers to normal may nevertheless have a persistent visual field defect

    • alternatively, there may be a metabolic cause for the disc swelling in some patients

  • it is impossible to exclude the other more serious causes of disc swelling (anterior optic neuropathy of any cause or, in the case of bilateral disc swelling, raised intracranial pressure) without the appropriate investigations

    • remember that diabetics, being functionally immunosuppressed, are at greater risk of atypical infections (e.g. fungal sinusitis), that in some cases can present with unilateral or bilateral disc swelling

  • hence, young diabetics with swelling of one or both discs require the same work-up as other patients with unexplained optic nerve dysfunction, even if vision is normal: refer to a neuro-ophthalmologist (urgently if visual loss is acute) or, if this is not possible, investigate as suggested on p. 38

Traumatic optic neuropathy

  • traumatic optic neuropathy is “clinically diagnosable” in that there is an obvious cause (eye or head trauma)

  • however, beware patients who attribute visual problems to minor eye or head “trauma”: the patient often has coincidentally developed a spontaneous optic neuropathy completely unassociated with their “injury”

  • if seeing the person as an outpatient, make sure that other more serious injuries (including intracranial injuries) have first been excluded


  • indirect (transmitted) blunt trauma, e.g. blow to the forehead

  • compression, e.g. by optic nerve sheath or orbital hematoma, or bony fragment

  • direct injury, e.g. stab or bullet


  • usually unilateral

  • blurred vision, ± diplopia if there has been orbital or intracranial injury


  • RAPD in the affected eye

  • the optic disc usually looks normal initially

  • in rare cases, mild disc swelling is present and may be associated with dilation of retinal veins and some intraretinal hemorrhages (a picture of a central retinal vein occlusion)

  • ± motility defect

  • any type of field defect on perimetry


  • urgent thin-section CT ( Fig. 2.5 ) or MRI orbit (if the orbit has not already been adequately imaged), looking for potentially surgically treatable lesions: bony fragments compressing the optic nerve at the orbital apex or intraorbital or intraoptic nerve sheath hematomas (particularly in patients with a fundus appearance of a central retinal vein occlusion [CRVO])


    Traumatic right optic neuropathy after motor vehicle accident. A External appearance of patient; note lack of obvious damage to eye. B CT scan shows right optic canal fracture (arrow) .


  • treatment is controversial: ideally involve a neuro-ophthalmologist early

  • no treatment is of proven benefit

  • many patients improve spontaneously

  • management options include:

    • observation

      • IV methylprednisolone – “conventional” dose, i.e. 1 g/day for 2–5 days (“mega-dose” corticosteroid treatment cannot be advocated following the CRASH study findings)

    • surgery:

      • optic nerve sheath fenestration (consider especially if swollen disc and evidence of a hematoma in the optic nerve sheath on CT or MRI)

      • orbital decompression

      • optic canal decompression

Neuromyelitis optica (NMO)

Neuromyelitis optica (NMO, previously called Devic disease) is a disease characterized by an immune attack on the optic nerves and spinal cord, usually with minimal or no brain involvement.

It is essential to differentiate NMO-related optic neuritis from the much more common MS-related or idiopathic optic neuritis because:

  • NMO is, in general, a more severe disease than MS and can lead to severe disability or death if not treated appropriately

  • although most cases of MS-related optic neuritis will recover without treatment, NMO-related optic neuritis often leads to permanent blindness without treatment

  • the treatment for NMO is completely different from MS treatment; indeed, if NMO is misdiagnosed as MS, MS therapy may make it worse

A cell-based NMO blood test is available that is >95% sensitive. However, in some cases, clinical features and MRI findings will lead to a diagnosis of NMO, despite a negative blood result.


  • more common in females than males

  • can occur at any age, including childhood, but median age of onset is mid-30s

  • affected individuals often have a history of other autoimmune disorders, e.g. Sjögren syndrome


  • acute or subacute vision loss in one or both eyes

  • bilateral involvement may be simultaneous or sequential

  • may or may not have retrobulbar pain

  • transverse myelitis from spinal cord demyelination can present with tingling, numbness and weakness in the limbs, and sometimes bladder control symptoms

  • myelitis may occur weeks, months or years before or after visual loss; or less commonly both may occur simultaneously


Jun 25, 2019 | Posted by in OPHTHALMOLOGY | Comments Off on Blurred vision or field loss: Not explained by visible ocular disease: optic disc/s normal, swollen, pale or “cupped”

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