Almost everybody is familiar with the terms nearsightedness (myopia) and farsightedness (hyperopia) but not so many people know about the existence of false nearsightedness (pseudomyopia).
Pseudomyopia (false nearsightedness) is also termed spasm of accommodation, accommodative excess, spurious myopia and because of strong eyepain some researchers also use the term painful accommodation and is crucial for understanding prevention of nearsightedness (myopia).
Pseudomyopia is caused by prolonged close work (reading, computers, smartphones) which causes that overstrained focusing muscle (ciliary muscle) get into cramp and the is not able to relax for looking at far distances why it appears blurry.
If eye examination is not done in accordance with lege artis it may result in wrongful diagnosis of myopia and prescription of detrimental minus glasses by which this reversible state of pseudomyopia may become permanent myopia due to elongation of the eyeball caused by visual stress.
Even if somebody has myopia it is still possible that he or she is overcorrected, e.g. somebody who wears -4.5 can be -3 of true myopia and -1.5 of pseudomyopia (cramp of focusing ciliary muscle). Also somebody who is wrongfully diagnosed e.g nearsighted -1 instead might be farsighted +1.
Over-correction can produce asthenopia i.e. eyestrain, pain in and around the eyes, headaches, migraines and even many remote symptoms by interference of the balance in autonomous nervous system which controls accommodation (focusing power of the eye). Pain may radiate to upper neck (occipital) and down the neck to the shoulders.
The only way of finding this is proper examination which is nowadays not followed by the majority of eye practitioners worldwide that is artificially putting accommodation at rest by atropine cycloplegia at least 3 days (in some instances even more then 10 days. It is scientifically proven that short acting cycloplegics such as homatropine, cyclopentolate and tropicamid are not suitable to gaurantee full cycloplegia. Skillful eye care practitioner is able to detect pseudomyopia even without cycloplegia by the fogging method.
However, nowadays majority of eyecare professionals intentionally do not follow lege artis and many people become overcorrected by easily prescribed with wrongful minus (or too strong minus) glasses.
If you have eyestrain, chronic headaches, migraines, occipital neuralgia, trigeminal neuralgia you should take care of this problem as it is scientifically documented that in many cases people were cured by solving the eye strain problem.