EyeTools Question of the Day #353

I’ve heard it said often that people can read better with good reading light because the light increases the contrast of the print. Is this true?

No it isn’t. The contrast of the print is a function of the difference in reflectance from the print and the reflectance from the background of the page. The reflectance of the print and the background are fixed properties of the ink used to make the print and the type of paper used.

Putting more light onto a page cannot change these fixed properties and it cannot change the difference between the two reflectances so light cannot change the contrast of the page.

What good light on the page does do is change the contrast sensitivity of the eyes. So the effect of the light is in the eye and not on the page.

Good reading light allows people to see things of a poorer contrast than without a good reading light.

The light also reduces pupil size and the associated increase in depth of focus will also allow print to look clearer.

This is especially true for people with age-related macular degeneration. Improving contrast sensitivity of the eye with good illumination allows reading of print 25% smaller than with poor illumination.

As good light allows people to read smaller print it allows for lower power reading glasses and/or magnifiers to be used which in turn allows for increased reading distance and a wider field of view.

There is also a benefit for people with cataracts as the lens opacities block light from reaching the retina. Extra light on the page means extra light into the eye and more light can pass through the lens opacities to the retina, resulting in improvement in contrast sensitivity and reading of smaller print.

For people with cataracts the reduction in pupil size should also help unless the lens opacity is small and central and then as the pupil reduces in size reading may become more difficult as less light can pass around the cataract.

As long as the light is directed on to the page and not directly at the patient’s face there should not be a problem with glare.

Good light is very much underappreciated by patients (surprisingly) and it is up to us as eye care practitioners to demonstrate its benefits and recommend its use.

Support what they do

You can become a member of EyeTools and support them in building a better and more sustainable professional development platform through kindness and appreciation for what them do. It also helps them build a better relationship with you over a longer period of time and you will receive some cool benefits along the way such as Certificates of Completion. To become a member, go to https://eyetools.in/

EyeTools-use it to get even better at what you do. Get the edge and be better than your competitors.Get Frank’s most recent books The Art of Investigating Binocular Vision Anomalies and The Art of Clinical Practice in Optometry for a deeper insight into everyday clinical practice.If you know someone that might benefit from these messages, please forward this to them. We are always looking to bringEyeTools to new people and we could use your help!

#opticians #optometry #ophthalmology #eyecare #QuestionOfTheWeek #eye #eyes #optom #optometrist #opticianmagazine #vision #eyeexam #eyeglasses #Contactlenses #optometrylife #retina #spectacles #optometria #glasses #frame #marketing #digitalmedia #promotions.

 

  • Posted on -
  • Apr 01, 2022
  • 08:50 AM