• The essential DEM tool

Do you want a faster way of measuring eye movement?

The Developmental Eye Movement Test (DEM) is an essential tool for detecting difficulties with reading 1 and eye movement 2. It was invented in 1983 by Dr Jack Richman - Professor at the New England College of Optometry, Boston.

Like many clinicians who value the test, I refer to the manual for results. This was a very time consuming process, which did not allow me to think on the spot. That was why we made the DEM Calculator App.

  • Simple to Use 
  • Gives Instant Results
  • Allows for Fast Decision Making

Looks good and easy to use.

- Dr Jack Richman, Inventor of DEM

This is a great timesaver! Thanks for creating.

- Dr Thomas Rogers, Behavioural Optometrist

The DEM calculator has allowed me to examine my patients quickly and accurately. I have move confidence in my diagnosis when using this App.

- Dr Shaun Chang, Behavioural Optometrist

Very good App, it makes you consider everything ensuring accurate results.

- Dr Chih Chi Lee, Behavioural Optometrist

How to Use the DEM Calculator?

  • Select Age or Grade

  • Press the Start Button to Start Recording

  • Press the Stop Button to Stop Recording

  • Note any errors by pressing the ‘+’ or ‘-’ keys

  • When you are finished, proceed to the next test

  • Your results are ready!

What do the Results mean?

  • Vertical Time:

    This is the patient’s number naming speed.

  • Horizontal Time:

    This is the patient’s eye movement speed after accounting for errors.

  • Errors:

    This is the patient’s accuracy for the three tests.

  • Ratios:

    This is determined by dividing the Adjusted Horizontal Time by the Vertical Time. The ratio score is used to compare automaticity and oculomotor control levels.

  • DEM Type:

    There are four likely outcomes:

    • Type 1: Average Performance
    • Type 2: Oculomotor Dysfunction
    • Type 3: Poor Automaticity of Number Naming
    • Type 4: Deficiencies in both Automaticity & Oculomotor skills
Results highlighted in orange are borderline
Results highlighted in red are abnormal

Available on Android and iOS.


  • Lauren N Ayton, Larry A Abel, Timothy R fricke, Neville McBrien. Developmental Eye Movement Test. What is it really measuring? Optometry and Vision Science Vol 86, No. 6, June 2009
  • Manzoli, MV, Facchin, A. Pregliasco, R. (2014, November 28). “A comparison of objective (Readalyzer) and subjective (DEM test) evaluation of ocular movements”. Retrieved from this article.
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