WHEN ONE EYE TURN.
Strabismus is a condition where one eye is turned in a different direction than the eye that is used for seeing. This divergence can be towards the centre and is then called esotropia (from the Greek ese, meaning inward). When the eye turn out it is known as exotropia (from the Greek exo meaning outward). The divergence can be only slight and almost imperceptible to very severe where the pupil is almost hidden in the corner of the eye. The divergence can also by up and is then called hyperphoria (from the Greek hyper meaning above), or it can be down and is then referred to as hypophoria (from the Greek hypo meaning down). Strabismus is usually present at a very early age but can also develop in adults.
Because of the divergent eye stressful double vision is experienced and the brain switches of the image from one eye creating ambliopia. This is one reason why strabismus and ambliopia are associated.
Strabismus occurs because one or several of the eye muscles are held too tight. For example in esotropia, which account for almost 50%, the inner recti muscle is too tense causing the eye to be turned too far inward.
There is also a type of strabismus known as heterophoria which is a deviation that is held in check by normal convergence. Almost everyone has some degree of this, and it is considered to be normal.
The cause of strabismus is not known at the present time. The usual approach is to first treat ambliopia if it is present. Strabismus itself may be treated by inserting prisms in order to correct for the divergence. However there is a limit to how much divergence that can be treated (up to 5 D prism diopters) before the glasses become too heavy. Fresnel lenses are sometimes used since they are lighter and can be constructed to correct higher degree of divergence.
Surgery is another option that is often recommended by ophthalmologists since it corrects the eye position so the cosmetic appearance is improved. However the vision is not always improved with surgically shortening or repositioning the eye muscle. In any case surgery should only be contemplated after all other options have been exhausted.
Ophthalmologist William H. Bates, M.D. (1920) concluded that strabismus was caused, not by the strength of the muscles but by strain, and in that respect was no different than near-sight, far-sight and astigmatism. They are all functional problems that will respond to Vision Training.
Strabismus is usually something that afflicts children. However, it is not uncommon in adults as well. In many cases the individual has been to see a lot of doctors and clinics. Often the traditional treatment procedures lead nowhere and only builds more frustration for all concerned.