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March 06, 2017 / by Shaun Chang / In dem /

DEM: Three Common Mistakes to Avoid

Is thirty minutes enough to deliver a quality eye test? Are you cutting corners when interpreting eye movement? Optometrists are often forced to think on the spot but how confident are you? Here are three things I learned after using the DEM Calculator App.

1. Is it Eye Movement?

Difficulty reading a horizontal array of numbers does not always equate to poor eye movement. Poor number naming is a potential cause that needs to be ruled out.

Since using the App I have discovered many cases of poor number naming that were misinterpreted for poor eye tracking. With the appropriate treatment, these patients can look forward to better results.

2. Do Errors reflect Accuracy?

Young children are expected to make errors because their visual system is still developing. A 6 year old child can make 22 errors on the Developmental Eye Movement Test before it is considered suspect. Don’t be alarmed but monitor carefully.

Errors from reading a vertical array of numbers are NOT associated with eye movement accuracy. They can be caused by difficulties with visual-verbal matching, visual discrimination, expressive language and focusing. Additional tests are required to determine the source of these errors.

3. Ratio - Have a second look!

There is an assumption that a ratio greater than 1 equate to saccadic eye movement difficulties. Some clinicians are smarter and compare their findings with the Mean Ratio but there is still a 50% chance of a False Positive. The best thing to do here is to match the ratio with the corresponding percentile.

In summary,

Optometrists are increasingly time poor. Most clinicians calculate horizontal adjusted time but mistakes occur because vertical time, errors are ratio are not considered. We made the DEM Calculator App so NO time are allocated to calculation and MORE time can be allocated for diagnosis and management.

About the Author

Shaun Chang currently practice as a Behavioural Optometrist in the Northern Beaches of Sydney. His sub specialties are visual learning difficulties, myopia control and amblyopia (lazy eye). Shaun regularly presents talks for Young Optometrists and Optometry Australia and recognised as a Men of Influence in 2016 by Men’s Style Magazine. Outside work, Shaun enjoys trekking and runs an eyecare service for Sherpas in the Mt Everest National Park.