Contrast Sensitivity


The ability to see objects which are not outlined clearly or that don’t stand out from their background and are therefore not easy to see.  For example, looking at grey on a white background.  This ability reduces with age and can be affected by other eye conditions such as cataracts and diabetic retinopathy.  Low contrast sensitivity may also be a temporary side effect of laser eye surgery.  Everyday problems associated with contrast sensitivity include:

  • Finding it difficult to drive by not being able to see cars, traffic lights or pedestrians.
  • Not being able to see marks on clothes or food on dishes or surfaces.
  • Not seeing a flame on a gas cooker hob.
  • Requiring extra lighting to be able to read.
  • Eyes becoming tired when watching TV or using a computer.
  • Stumbling when walking down from a curb.

Contrast sensitivity may be thought of as the ‘crispness’ of vision, which allows us to see objects that don’t stand out from their background. 

Testing Contrast Sensitivity


When testing for contrast sensitivity, size and contrast are measured.  The CSF is the ability to detect objects of different sizes at low contrasts.  This is important in the real world, as often objects appear to blend in the background.  The contrast detection threshold is the lowest contrast at which a pattern can be seen. High scores for CSF are usually found for medium-sized objects.  

Your optometrists may automatically test your eyes for contract sensitivity as part of a routine eye test or you may only be given a test if there are any particular eye conditions or concerns.  Testing is usually carried out while you are wearing your normal glasses or contact lenses.  Both eyes are usually tested at the same time and you may be asked to look at a low-contrast test chart, which has images such as bars or dots.  These will lower in contrast until you cannot see them.  Good contrast sensitivity is when objects can be seen when they are displayed against a low-contrast background.

The results will determine if you have normal vision, if you require special lenses or surgery, or if you may have glaucoma or other eye conditions.  Vision can be improved by wearing a yellow filter to improve contrast.  Intraocular lenses are also an option.  These can be used to replace the eyes natural lens and can be tinted yellow.  Alternatively the IOL may offset low contrast sensitivity associated with higher-order aberrations which some argue can be improve contrast sensitivity.



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