What is the difference between plus and minus lenses? How do they affect light? how must the visual system respond (to continue to see clearly) when a lens is introduced?
plus and minus lenses are used in our vision therapy office to stimulate or relax the accommodative system. “Accommodation” is the focusing power of the eye.
A plus lens which is convex in shape, converges light and the accommodative system must relax in order to keep an image clear. When looking through a plus lens images may appear to be larger and further away. A minus lens which is concave in shape, diverges light and the accommodative system must stimulate in order to keep an image clear. A minus lens may cause images to appear to be smaller and closer to you.
When accommodative deficiencies are present, a person may report blurriness and fatigue. Therapeutically, blurriness and fatigue can be common, as the use of lenses are meant to increase and you will be able to clear blurry images more quickly!
this is a very useful skill for driving when you must look quickly from the dashboard to the road ahead of you, or in a classroom when you are required to quickly copy notes from the white board to your notebook.
-Lauren Banks, COVT