After the child has developed efficient visual skills, they are still ‘at risk’ if exposed to excessive near seeing demand and prolonged adverse stresses on the visual function.
Indeed, stress induced visual co-ordination difficulties can result at any age. Just as our timing and movement management will deteriorate when any of our skills are exposed to excessive demand and adverse stresses, so will the visual co-ordination skills deteriorate. Thus, a stress induced vision problem may result which will limit the person’s ability to visually perform with efficiency, comfort and accuracy for any sustained time.
Avoiding close visual tasks eliminates symptoms, but otherwise, depending on the degree of deterioration of the visual function some or most of the following symptoms are usually produced.
Symptoms due to fatigue caused by extensive demand on the neuromuscular system:
- Headaches or aching eyes; pain referred to the muscles of which an excessive effort is demanded. Such symptoms are often associated with excessive or prolonged use of eyes and will disappear or significantly reduce with withdrawal from, or avoidance of, visually demanding tasks.
- Difficulty changing focus from near to distant objects or vice versa. Inability to quickly make a distant object clear after sustained close reading without blinking or squinting.
- Glare discomfort, usually only partly relieved by sunglasses, but characteristically reduced by squinting one eye.
- Reading comprehension and efficiency drops after a short time on a task.
Symptoms due to failure to maintain constant singular binocular vision:
- Blurring of print (goes funny) or running together of words while reading.
- Intermittent double vision under conditions of fatigue.
- One eye turns without double vision (usually noted by family or friends).
Symptoms due to defective postural sensation:
- Difficulty in judging distances and positions, especially of moving objects.
- Timing judgments for hitting and catching small balls are usually difficult.
- Bumping into objects or misjudgments of position of objects when involved in active visually directed movement and game play.
- Feeling of insecurity when dealing quickly with steps, escalators or parking the car.
At Envision Optical we have children’s vision specialists available who are specially trained in behavioural optometry, where a greater emphasis is placed on holistic assessment and management from a neuro-developmental perspective.