Blurred vision - the common causes

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See also Ophthalmology – eyes are very precious


Blurred vision is the commonest eye problem. This has many causes:

  • Weakness of the muscles which pull the lens into shape - this is the commonest cause of blurred vision in CFS.
  • Loss of elasticity of the lens - this is an inevitable result of ageing, but can be slowed by taking antioxidants.
  • Cataracts - often presents with difficulty driving at night because headlights of oncoming vehicles dazzle.
  • Macular degeneration - loss of the light detecting neurones at the back of the eye. This sort of blurring cannot be corrected by glasses as the actual neurones are damaged. Macular degeneration is something I like treating because patients will be told by their physicians that nothing can be done, but correction of micronutrients, especially zinc, magnesium and selenium, can often restore sight.

Problems of the eye which must be dealt with urgently by a professional

  • Any loss of vision (either sudden or over a short space of time), blurring or blindness. (I am thinking of a detached retina, optic neuritis, bleeding into the back of the eye or stroke, glaucoma, temporal arteritis etc)
  • Holes in the field of vision - these are common in patients with poisonings but often go unnoticed.
  • Pain
  • Red eye
  • Double vision
  • Pupils not reacting to light, or reacting unequally.
  • Any infection around the eye - this is a particular problem because the venous drainage of the eye is back into the brain. Therefore, I have a low threshold for using antibiotics in infections around the eye!
  • Foreign bodies in the eye.

What to expect from your doctor when you go to see them with an eye problem

1. A careful visual inspection of the eye, looking for any inequalities, or pus in the iris.

2. Check of the response of the pupils to light and focusing.

3. Check of visual acuities (Can you read newspaper print? With each eye individually?)

4. Fluorescent drops in the eye to look for corneal ulcers.

5. Eyelid eversion to look for foreign bodies.

6. Test of visual field to look for holes.

7. Eye pressure test.

8. Palpation for tenderness of the temporal arteries.

9. Looking in the back of the eye with an ophthalmoscope.


The commonest cause of red eye, grittiness and discharge is conjunctivitis. Vision should be normal although the excessive secretions may cause slight blurring. Conjunctivitis can be infective (viral or bacterial) or allergic (hay fever season). Infectious conjunctivitis often accompanies a cold and gets better on its own (see Viral infections - avoid and treat aggressively). Antibacterial drops are given to prevent secondary bacterial infection.

But what is most important is what not to give. Steroids should never be prescribed unless the eye has recently been examined by a specialist. This is because a particular viral infection, namely herpes, may cause a dendritic ulcer of the cornea and if steroids are given as drops, this allows the herpes to proliferate and may cause a perforating ulcer resulting in complete blindness.

Allergic conjunctivitis clinically is very like infectious conjunctivitis but usually itching is more prominent. If you look closely at the white of the eye, it may look a bit "bubbly", so called "cobblestone" appearance. Inhalent sensitivity can cause this (pollen, house dust mite, animal furs) but increasingly chemicals are responsible, sometimes more as irritants than allergies. The best example is chlorine from swimming-pools but any chemical may have this effect.

If the cause is unknown (and so cannot be avoided) or desensitisation not available, then sodium cromoglycate drops are a benign but usually effective treatment.

Crusting at the bases of the eyelashes can be caused by a fungal infection. Try baby shampoo initially (does not sting the eyes) or, failing that, an anti-fungal cream is required - I use ketoconazole cream.

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