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)

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.

History

• □
  

  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?

    
    
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    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?

  
  

Examination

• □
  

  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

  
  

Demographic

• •
  

  age 15–45

  
  
• •
  

  men or women (but more common in women)

Symptoms

Signs

• •
  

  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

Investigations

• •
  

  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

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

• •
  

  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 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.

Causes

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

Symptoms

• •
  

  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)

Signs

• •
  

  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.

Investigations

• •
  

  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)

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

Referral

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

Investigations

• •
  

  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)

  
  

Treatment

• •
  

  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

  
  

Follow-up

• •
  

  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

Prognosis

• •
  

  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

Mechanism

• •
  

  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

Symptoms

• •
  

  usually unilateral

  
  
• •
  

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

Signs

• •
  

  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

Investigations

• •
  

  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

• •
  

  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

    
    

  
  

Demographic

• •
  

  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

Symptoms

• •
  

  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

Signs

• •
  

  optic disc/s normal, swollen or (if diagnosis delayed) pale ( Fig. 2.6 )

  
  

  
  

  
  

  

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  2. Abnormal eye movements without visual symptoms
  3. Ptosis
  4. Swollen disc/s, normal vision: (Note: for swollen disc/s with blurred vision or field loss, see)

  

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