In my experience, use of the term “visual hygiene” in the exam room tends to be met with a certain degree of confusion. Invoking images of a thorough scrub and rinse for the eyeballs, it probably wasn’t the best way for us as Optometrists to have termed such a critical concept to discuss with our patients. At its core, visual hygiene is about ensuring that the visual system is allowed to operate in the most optimal and comfortable conditions possible – which does however invoke the parallels with cleanliness and hygiene intended by the phrase.
Many of our preceding blogs have discussed the impact that environmental stressors can have on the development, adaptations and the efficiency of our visual systems. Where we position working material, what lenses we use for what task, how often we blink to replenish our tear film and what type of lighting we use can all have a cumulative impact on visual efficiency. Promoting proper habits in these areas is extremely important for individuals at just about any age. While sitting has been cleverly termed the new smoking, compulsively staring at screens could easily be seen as an equivalent concern for our society (see blog, Technology and the Eyes of a Child).
At the core of the “visual hygiene” movement is a term affectionately known as the “20-20-20 rule.” This rule states that for every 20 minutes of near-centred visual engagement (i.e. reading, computer), we should take a 20 second break to stare at objects at least 20 feet away. Cute, right? While it may seem like a fun play on words, it really is important for our visual systems to be given these periodic “distance-looking” tasks as a source of reprieve from the strain that close work puts on us. Whenever we engage with an object closer than 1 metre, there are actually small muscles both inside and outside of our eyes that are contracting to make the targets in front of us both single and clear. These muscles are strong – but definitely earn themselves a break or two throughout the day. An analogy that I find helpful is to think of reading or computer work as asking your eyes to go to the gym and grab a 2 lb set of weights. They can handle it for some time, but periodic breaks are required to ensure they stay functioning efficiently and with the least amount of stress and strain possible. I typically tend to extend the 20-20-20 rule further, as a concept by “prescribing” 20-minute walks outdoors for patients after school or work. These walks need to be devoid of phones and preferably are to be conducted in large open spaces like parks or beaches, which are plentiful in the Okanagan. You’d be amazed at just how helpful this can be for the mind, body and visual system.
What is the first thing you tend to notice from someone getting lost in a good book (or Instagram post)? Arms…creeping…inwards. When we’re visually engaged, we tend to want to increase the relative size of the engaging target and limit peripheral visual stimuli so we can stay locked in. Studies conducted over the past number of decades have demonstrated that while this may feel compulsive, it is not at all the most efficient distance for our eyes to be reading, writing and tracking text. At a length termed the Harmon Distance, our eyes are actually most efficient for reading at the same distance as from our own elbow to fist. Children and adults alike should therefore be encouraged to keep text at least this far away whenever possible. Along with working distance, the angle at which the text is presented can help aid efficiency. Slant-boards angled at 20-25 degrees from the horizontal allow our eyes to scan text at closer to a perpendicular angle – which again, reduces stress and aids performance. At our clinic in Kelowna, we supply all students with a 22 degree slant board for home reading and writing and encourage patients to position themselves symmetrically, with proper lighting and at the proper working distance discussed above.
Is it that easy?
Unfortunately, all of the above (and many other) visual recommendations will have minimal impact if a child or adult does not possess a robust enough eye-teaming system to allow them to be implemented. Aversion to reading, headaches at the end of a school day, reports of text swimming, blurring or doubling, closure of one eye and postural asymmetries (trying to view out of one eye instead of two) can all indicate issues of binocular vision or eye-teaming, and while implementing the above recommendations for visual hygiene will help to a degree, it will not address the root issue. For many of our patients, these recommendations are important – but can only truly be followed once the underlying deficits with eye tracking and teaming are resolved. Once we have established a strong visual foundation, the above guidance however can be extremely helpful for reducing visual stress, negative adaptations, visual fatigue and frustration.
Until next month,