My female 30-year-old patient who could see 6/6 with each eye at her last exam 2 years ago but only see 6/60 in her right eye now. For the last two weeks, she has felt a little discomfort when she moves her eyes. She denies any general health problems. I can’t see anything that would cause this. What is going on?

This is a catastrophic loss of vision in one eye. The ingredients are young age, female, pain on eye movement and nothing obvious to indicate the cause. This sounds very much like retrobulbar neuritis, in other words, an inflammation of the optic nerve, which hasn’t affected the optic disc. The inflammation is behind the eye, hence the name retro (behind) bulbar (the bulb of the eye) neuritis (inflammation of the nerve).

The inflamed area is between the back of the eye and the brain. It typically occurs more often in women aged 20-40.

Retrobulbar neuritis can be caused by a variety of conditions:

• Infections such as meningitis, syphilis, and various viral illnesses.
• Multiple sclerosis.
• Tumours.
• Exposure to certain chemicals or drugs.
• Allergic reactions.

Often the cause is unknown. Vision loss can be minimal or the disease can result in complete blindness.

Between 20% and 40% of the people who develop optic neuritis will develop multiple sclerosis within 5 years.

 Other common symptoms include:

• Blurred or dimmed vision
• A blind spot at or near the centre of vision
• Colours are less rich
• Tenderness of the eye to touch or pressure.

This person deserves to be referred to a neuro-ophthalmologist.

The next time your patient can’t see anything and you can’t see anything-think retrobulbar neuritis.