Posture and Visual System

by Federico Bartolomei, picture by Allessandra Soldati

It is not enough to have 10 over 10 for an optimal vision performance, it is also necessary that vision be supported by good body posture.

 

Posture, which can be understood as the position of the body in space, represents the response of the body to the stress by the force of gravity in relationship to the environment around us and with the objectives of movement.
The characteristics of posture are based on various factors: neurophysiological, biomechanical and also emotional and relational. A correct and functional posture is characterized by the absence of abnormal asymmetrical muscular tensions and by appropriate relationships among the various body parts.
An incorrect posture can instead trigger compensations in the body that will alter the physiological structure of the body.
Numerous researchers have drawn attention on how the posture and vision influence each other. Vision is therefore considered independently and separately from the rest of the body
, it is profoundly intrinsic to the whole system of action of man, his posture, and his manual skills.
Today, we hear more and more about the posture problems in school age children, which has become even more important since the general use of personal computers even during children's leisure time, to the detriment of more natural movements. The visual system then has to maintain attention for an extended period of time at a distance of 25-35 centimetres
from the eyes with an important demand on adaptation and convergence.
The habit of keeping very limited distances results in energy loss with a need for adaptation and convergence resulting in visual tiredness which can lead to loss of attention, soreness, pain in the eyes, difficulty in working for extended periods of time. Maintaining over time an incorrect posture can hasten the onset of functional and structural problems to the whole body.
It is common to observe, while studying children, excessive lateral inclination of the head or notable curving forward of the back. Also,
bringing a book closer to the face as the difficulty of a text increases is a common attitude which is adopted in order to put more attention to the document to be read, reducing peripheral stimuli.
Harmon, a nineteenth century scientist, studied extensively the relationship between posture and prolonged proximal visual activity and determined what should be the optimal reading distance: the length of the forearm measured from the elbow to the end of the first phalanx of the index.

Ergonomics: the term comes from the Greek ergo (work) and nomos (law, regulation). Influenced by anatomy, physiology, psychology and engineering, it is the science that studies the planning of domestic and work environments in order to respect man's limits and at the same time strengthen his abilities. There exist various adaptations which allow the optimization of the study and work environments with positive outcome in terms of performance and results.
In regards to appropriate body position during reading and writing activities, it is essential first and foremost to have a chair and a table that have proportionate dimensions to the body of the person. Often, especially at home, children use chairs and tables that are proportionate for adults which make it impossible to maintain optimal stability. It is important that the surface be inclined at about 20 (maybe with the help of a bookrest) to entice a parallelism between the reading surface and the face.
While writing, it is possible to rotate the body from the part opposite to the writing hand in order to allow writing with more ease, but such rotations cannot have a width superior to 30.
The surface of the chair should have the shape of a pail or a cradle, allowing movements and a natural distribution of the weight. The height of the seat has to allow the feet to rest on the floor.
There are exercises to do and precautions to take to reduce visual stress: for example,
raising the eyes at regular intervals, when one writes or turns pages during reading, focusing for a few seconds on an object at a distance allowing the visual system to gain back tone and dynamism so as to give the body system a chance to recover a stable position.
In conclusion: it is not enough to have 10 over 10 for an optimal vision performance, it is also necessary that vision be supported by good body posture.
An inappropriate posture, we have to remember, can be linked to various factors: environmental, visual, psychological, systemic and based on habits.
An appropriate assessment and a follow up intervention plan involve many professionals.
The posturological approach cannot in fact leave out of consideration a multidisciplinary point of view.

Woman reading with correct posture

Children drawing in the wrong posture

Boy writing with the wrong posture