Optic Neuritis

OPTIC NEURITIS

Q. 1 Optic neuritis is caused by following, except:
 A Ethambutol
 B Chloroquine
 C Steroid therapy
 D Methanol
Q. 1 Optic neuritis is caused by following, except:
 A Ethambutol
 B Chloroquine
 C Steroid therapy
 D Methanol
Ans. C

Explanation:

Steroid therapy


Q. 2

Optic neuritis is caused by –

 A

Ethambutol

 B

Pyrazinamide

 C

Rifampicin

 D

Chlormycetin

Q. 2

Optic neuritis is caused by –

 A

Ethambutol

 B

Pyrazinamide

 C

Rifampicin

 D

Chlormycetin

Ans. A

Explanation:

Ans. is ‘a’ i.e., Ethambutol


Q. 3

Optic neuritis is seen in all except:

 A

DM

 B

Methanol poisoning

 C

Multiple sclerosis

 D

None

Q. 3

Optic neuritis is seen in all except:

 A

DM

 B

Methanol poisoning

 C

Multiple sclerosis

 D

None

Ans. D

Explanation:

D i.e. None Optic Neuritis

It is an inflammatory or demyelinating disorder of the optic nerve (from the optic disc to the lateral geniculate body

Aetiology

1. Idiopathic

2.          Demyelinating diseases

  • Multiple sclerosis Q
  • Neuromyelitis optica (Devic’s disease)Q
  • Leucodystrophies

Schilder’s adrenoleuco-dystrophy Krabbe’s galacto cerebroside dystrophy Metachromatic sulfatase deficiency Pelizaeus – Merzbacher disease

  • Post viral e.g. measles, mumps, chicken pox, whooping cough &, glandular fever and immunization.

3. Metabolic / Nutritional Deficiency

  • Vitamin B1,135, B12 deficiency Q (beri beri, pellagra & pernicious anemia respectively)
  • Thyroid dysfunction
  • Diabetes
  • Neuropathy with pregnancy & lactation

4.      Leber’s hereditary optic neuritis

Toxic

  • Drugs – Quinine Q, chloroquine Q,
  • Ethambutol Q, Digitalis Q, streptomycin, INH, Amiodarone, Vigabatrin, NSAID’s (aspirin, indomethacin, ibuprofen, phenylbutazon
  • Tobacco Q, ethyl & methyl alcohol Q, lead, cannabis indica, arsenic, carbon di sulphide.

6.          Ischemic

• Arteritic – Giant cell arteritis

• Non arteritic

Takayashu’s disease

PAN

SLE

7.          Infections

  • Infections of the adjacent structures e.g. uveitis, retinitis, meningitis, orbital cellulites, sinusitis etc.
  • Granulomatous infections e.g. TB, sarcoidosis, syphilis etc.

* Peculiar feature of neuroretinitis

Types

Clinical features

Optic neuritis typically affects the patient between 20-40 years of age (but post viral type typically seen in children) and presents with:

 Symptoms

Monocular sudden, progressive and profound (<6/60) loss of vision Q

Visual loss progresses very rapidly & usually maximal by the end of 2nd week.

Pain behind eye ball especially when the eye is moved superiorly due to attachment of some fibres of superior rectus to duramater (this feature is especially seen in retrobulbar & perineuritis)

 Signs

  • Local tenderness at the site of attachment of superior rectus
  • Decreased visual acuity (usually < 6/60) Q Decreased colour vision (red, green are more affected)

Defective contrast sensitivity

Defective depth perception of moving objects (Pulfrich phenomenon)

Worsening of symptoms with exercise or increase in body temperature (Uhthoff sign)

  • Pupillary reactions may be

Sluggish and ill sustained Q

Relative afferent pupillary defect (RAPD or Marcus Gunn’s pupil) Q detected by swinging flash light test.

  • Visual field defects

Most common field defect is central or centrocaecal scotoma Q

Other defects are paracentral, arcuate, sectorial, and altitudinal field defects.

  • Opthalmoscopic features of papillitis resemble early papilloedema. There is hyperemia (1st sign), blurring of disc margins, disc oedema with obliteration of physiological cup; tortuous, congested and distorted retinal veins with or without peripapillary flame shaped haemorrhages. Even in most severe cases however the swelling of the disc rarely exceeds 2-3 D (in papilloedema 3-6D)
  • Visual evoked potential show latency and delay in amplitude Q

 

– It is commonly due to infectious aetiology and not seen in multiple sclerosis (m.c. cause of papillitis & retrobulbar neuritis)

– Macular star is seen due to inflammation of neighbouring retina

Fundus appears normal ophthalmoscopically Q (occasional temporal pallor present) – typically defined as neither the ophthalmologist nor the patient sees anything.

* Specific features of Retrobulbar neuritis

Fundus appears normal ophthalmoscopically Q (occasional temporal pallor present) – typically defined as neither the ophthalmologist nor the patient sees anything.

Mild pain on ocular movements & tenderness at the site of attachment of superior rectus tendon.


Q. 4

All are true regarding optic neuritis except:

 A

Decreased visual acuity

 B

Decreased pupillary reflex

 C

Abnormal electroretinogram

 D

Abnormal visual evoked response retinogram

Q. 4

All are true regarding optic neuritis except:

 A

Decreased visual acuity

 B

Decreased pupillary reflex

 C

Abnormal electroretinogram

 D

Abnormal visual evoked response retinogram

Ans. C

Explanation:

C i.e. Abnormal electroretinogram 

Electroretinogram indicates the activity of retinal (esp. rods & cones) function and has no role in assessing the functional integrity of the optic nerve Q. So it can’t be abnormal in optic neuritis.

Quiz In Between


Q. 5

All of the following can cause Optic Neuritis, except :

 A

Rifampicin

 B

Digoxin

 C

Chloroquine

 D

Ethambutol

Q. 5

All of the following can cause Optic Neuritis, except :

 A

Rifampicin

 B

Digoxin

 C

Chloroquine

 D

Ethambutol

Ans. A

Explanation:

A i.e. Rifampicin

Ethambutol, streptomycin & isoniazid are anti-tubercular agents that cause optic neuritis.Q Rifampicin does not cause optic neuritis.


Q. 6

In optic neuritis the best investigation to be done includes:

 A

Goldman perimetery

 B

Keratoscopy

 C

Ophthalmoscopy

 D

Opthalmodynamometery

Q. 6

In optic neuritis the best investigation to be done includes:

 A

Goldman perimetery

 B

Keratoscopy

 C

Ophthalmoscopy

 D

Opthalmodynamometery

Ans. A

Explanation:

Ans. Goldman perimetery


Q. 7

Which of the following does not result in optic neuritis: 

September 2011

 A

Diabetes

 B

Hypertension

 C

Sympathetic ophthalmitis

 D

Sarcoidosis

Q. 7

Which of the following does not result in optic neuritis: 

September 2011

 A

Diabetes

 B

Hypertension

 C

Sympathetic ophthalmitis

 D

Sarcoidosis

Ans. B

Explanation:

Ans. B: Hypertension

Aetiology of optic neuritis includes immune mediated disorders (local-sympathetic ophthalmitis and systemic-sarcoidosis), metabolic disorders-diabetes etc.

Optic neuritis

  • It is the inflammation of the optic nerve that may cause a complete or partial loss of vision.

Causes

  • The optic nerve comprises axons that emerge from the retina of the eye and carry visual information to the primary visual nuclei, most of which is relayed to the occipital cortex of the brain to be processed into vision.
  • Inflammation of the optic nerve causes loss of vision usually because of the swelling and destruction of the myelin sheath covering the optic nerve.
  • The most common etiology is multiple sclerosis.
  • The presence of demyelinating white matter lesions on brain MRI at the time of presentation of optic neuritis is the strongest predictor for developing clinically definite MS.
  • Some other causes of optic neuritis include infection (e.g. Syphilis, Lyme disease, herpes zoster), autoimmune disorders (e.g. lupus), Inflammatory Bowel Disease, drug induced (e.g. chloramphenicol, Ethambutol) vasculitis and diabetes Symptoms
  • Major symptoms are sudden loss of vision (partial or complete), or sudden blurred or “foggy” vision, and pain on movement of the affected eye.
  • The vision might also look “disturbed/blackened” rather than blurry, like when feeling dizzy.
  • Many patients with optic neuritis may lose some of their color vision in the affected eye (especially red), with colors appearing subtly washed out compared to the other eye.
  • On medical examination the head of the optic nerve can easily be visualised by an ophthalmoscope; however frequently there is no abnormal appearance of the nerve head in optic neuritis (in cases of retrobulbar optic neuritis), though it may be swollen in some patients (anterior papillitis or more extensive optic neuritis).
  • In many cases, only one eye is affected and patients may not be aware of the loss of color vision until the doctor asks them to close or cover the healthy eye.

Epidemiology

  • Optic neuritis typically affects young adults ranging from 18-45 years of age, with a mean age of 30-35 years.
  • There is a strong female predominance.

Treatment and prognosis

  • In most cases, visual functions return to near normal within eight to ten weeks, but they may also advance to a complete and permanent state of visual loss.
  • Therefore, systemic intravenous treatment with corticosteroids, which may quicken the healing of the optic nerve, is often recommended
  • Very occasionally, if there is concomitant increased intracranial pressure, the sheath around the optic nerve may be cut to decrease the pressure.
  • When optic neuritis is associated with MRI lesions suggestive of multiple sclerosis (MS) then general immunosuppressive therapy for MS is most often prescribed (IV methylprednisolone may shorten attacks; initial only oral prednisone may increase relapse rate).

Quiz In Between



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