People sometimes report problems in the sharpness of their vision and often describe it as “some strange fogginess” in their eyesight. Visual acuity measurements do not always give an answer and explain such complaints. Specific tests of contrast vision, however, may show that the primary cause for such problems is reduced contrast sensitivity.
Therefore, contrast sensitivity is a better measurement of the real-life functionality than visual acuity, in such cases. The real world is made of subtle changes in contrast (instead of absolute contrast of black on white as e.g. on the Snellen visual acuity charts). Untested contrast sensitivity may leave patients suffer from unidentified vision problem in their daily life.
The clarity of vision is necessary in order to distinguish objects from their backgrounds. One needs to be able to perceive lights, shadows, and shades. If someone has low contrast sensitivity, the person may have problems e.g. when driving in situations of low light, fog or glare, i.e. when the contrast between objects and their background is reduced.
In the worst case, severely reduced contrast sensitivity may lead to serious problems. There is always a risk of missing to see e.g. pedestrians walking alongside poorly lit streets or animals that may suddenly cross the road in rural areas. Otherwise, falls and injuries, and a decreased functionality and quality of life in general are also possible bummers for anyone with reduced contrast vision.
Lowered contrast vision can be improved e.g. by improving lighting or by using the right kinds of sunglasses or lenses for the glasses. Dry eyes may also affect contrast vision, in which case eye drops may help.
Contrast sensitivity needs to be understood as an integral part of a functional and healthy neuro-visual system and tested periodically (among other aspects affecting functional vision).
Mika Mahlamäki, Business Development Manager, Ocusweep