Toxic Optic Neuropathy

When there is a problem with your pupils – the black part at the centre of your eyeball – you have what’s known as a pupillary abnormality. The main types of pupillary abnormalities include:

• Anisocoria: unequal pupil sizes
• Horner’s syndrome: disruption of a nerve pathway from the brain to the one side of the face and that eye
• Third nerve palsy: one eyelid is completely closed, and that eye has moved outward and downward
• Adie’s tonic pupil: one pupil is permanently dilated and unresponsive to light and other stimulants

Symptoms of a pupillary abnormality include:

• Decreased size of one pupil
• Difficulty focusing on objects in near visual field
• Diplopia (double vision)
• Drooping eyelids (ptosis)
• Eye pain
• Fever
• Headache
• Light sensitivity
• Problems moving your eye
• Reduced sweating

Tests

Comprehensive Exam – Your doctor will conduct a thorough physical examination of your eyes – as well as gather a complete health history – to determine if you have papilledema. Your doctor may use an ophthalmoscope (specialized light with magnifying lenses) to look at the back of your eye.

Imaging – Your eye care specialist may order magnetic resonance imaging (MRI) or computerized tomography (CT) scan to help determine the cause of your papilledema. Your doctor may order ultrasonography of your eye to distinguish between papilledema and other disorders that can also cause swelling of the optic nerve.

Lumbar Puncture – Your doctor may order a lumbar puncture (spinal tap) to measure the pressure of the cerebrospinal fluid. A sample of this fluid may be sent to the laboratory to check for evidence of a brain tumour or infection.

Treatments

None Required – There is no treatment required for anisocoria or Horner’s syndrome.

Eye Patch – If you have third nerve palsy, wearing an eye patch over the affected eye may help reduce double vision (diplopia).

Prism Eyeglasses – Wearing eyeglasses affixed with a prism may help relieve your diplopia.

Sunglasses – If your pupillary abnormality has caused your eyes to be unusually sensitive to light, you should wear protective sunglasses whenever outdoors in sunlight.

Eye Drops – If you have Adie’s tonic pupil, your eye care specialist may prescribe Pilocarpine eye drops to constrict the affected pupil.

Surgery – If you have third nerve palsy that has not resolved after a waiting period of six months, your doctor may recommend you undergo surgery to realign your eyes or to correct drooping of the eyelid.