Vision screening devices are specially designed tools that help with the early detection of potential visual impairment before the situation worsens. Once identified or suspected, the patient is referred to a specialist for further assessment to ascertain the actual condition.

This is different from the extensive diagnostic equipment that can be found in eye clinics. While these diagnostic equipment are used for full assessment with a view to provide complete diagnosis to enable treatment, vision screening devices only indicate the likely presence of an issue that will require further investigation.

To this end, vision screening tools are usually more portable, easier to use, and deliver quick results. This makes them ideal for use in locations like schools, work places, community outreaches, and primary healthcare centres.

In this article, we will be looking at some of these devices and how they perform their function. Their primary function is to detect any anomalies in visual performance at their very early stages to increase the chance of preventing a decline or treating the condition. Some conditions that can be detected at their early stages using these tools include:

• Poor eye coordination
• Blurred vision
• Depth perception disorders
• Color blindness
• Refractive errors

Each type of device is designed to target a specific function. This means that different devices have to be used for different types of screening.

As stated above, there are different types of vision screening devices and each one is designed to screen a specific function. We will now look at some of the common types of devices available.

Autorefractors

These are pretty advanced devices used to measure the refractive errors. This device is particularly useful, especially for patients like children who may not be able to communicate because it arrives at its estimate without requiring any input from the patient.

Infrared light is projected from the device into the eye where it reflects off the retina back to the sensors in the device. The reflected light passes through the eye’s optical system on its way back to the sensors in the device.

The device arrives at its estimation of the refractive error by analysing the changes that occur in the trajectory of the reflected infrared light after it passes through the cornea and lens. This automated process, which will immediately detect if the patient is nearsighted or farsighted, is completed in just a few seconds.

Visual acuity screening devices

These are the most commonly used screening devices. They are used to measure the distance at which a person can continue to see objects clearly. There are traditional types like the Snellen chart and modern digital versions.

In both types, the function is the same. They show rows of letters in decreasing sizes and have the patient read them. The point at which a patient can no longer clearly read the letters or symbols marks the point where they started losing vision sharpness.

The major difference between the two types is that the letters are printed on charts, in the case of Snellen chart, while for the digital versions, they are displayed on an electronic screen and the results automatically recorded. In addition, the digital versions deliver more accurate results because they strive to eliminate test biases by randomizing the sequence of the letters and also controlling the lighting conditions.

You can learn more about these devices here: https://www.optometrytimes.com/.

Photoscreeners

These devices are used to evaluate refractive errors, eye alignment and visual clarity. They achieve this through the use of special cameras and light reflex analysis. Similar to autorefractors, light is shone into the eyes such that it bounces off the retina. The path and pattern of this reflection provides useful information that the device analysis to arrive at a conclusion on eye alignment, refractive errors and media clarity.

This is another screening device that is effective for use on patients who cannot provide useful verbal response. They can quickly notice risks of eye conditions like cataract-related opacity, strabismus or misaligned eyes, and amblyopia or lazy eye.

Binocular vision and depth perception devices

These devices are used to evaluate how well the two eyes work together. They check for convergence, coordination 3D perception or stereopsis. In many cases, these devices make use of images, filters or virtual depth illusions that can only be formed into one complete image when the two eyes successfully merge the different image each is seeing into one.

Inability to correctly merge the two images shows that there is a binocular vision disorder. This condition can result in reading fatigue, headaches, poor hand-eye-coordination and double vision.

Colour vision screening devices

Screening devices in this category are meant to detect an individual’s inability to detector differentiate between certain colours. These devices can be manual or digital but all operate with the same principle.

Symbols or numbers are inserted in patterns of coloured dots and the patient is required to identify the symbol or number.

Once a candidate consistently fails to identify symbols or numbers in certain colours, their type of color blindness and its severity will be recorded. Certain industries, like the aviation industry, require this assessment.

Digital and AI-powered vision screening devices

In pursuit of portability, increased affordability and efficiency, modern screening devices are now making use of the latest in technology. You can check this out for examples of simple modern screening devices. These digital and AI-powered devices not only deliver more accurate results, they also increase convenience.

There are now devices that can be used for remote screening. This means that a patient can upload certain information and have it reviewed and a result given.

The above are just some examples of vision screening devices currently available. There are others and more still being developed.

Takeaway

Vision screening has been proven to be a critical first line of defense, when it comes to vision management. With new devices emerging every now and again, we expect that more and more cases of preventable vision impairment will prevented or treated because of these early detection tools.

Adam Mulligan, a psychology graduate from the University of Hertfordshire, has a keen interest in the fields of mental health, wellness, and lifestyle.