A 14 years old boy complains of pain during reading. On examination, his both eyes are normal and vision with Snellen's reading is 6/5. He still complains of pain on occluding one eye. The diagnosis is –
This boy has :-


Eye strain during reading
No refractive error on examination (snellen:s reading is 6/5)


That means patient has compensated for his refractive error by hyperaccommodation, i.e. spasm of accommodation or pseudomyopia

Following facts require some explanation

Actually this boy also has hypermetropia which is compensated by spasm of accommodation.
If the child will be examined for refraction under cycloplegia (relaxing the ciliary muscles) this compensation will not be there and the refractory error can be measured.
So, the boy is having hypermetropia but at the time of presentation, he is presenting with pseudomyopia due to excessive accommodation, i.e. compensatory correction of hypermetropia by excessive spasm of ciliary muscles.
In hypemetropia (when an error is not compensated)
Refractive testing with or without cyclopegia will show hypermetropic type of refractive error.
In Pseudomypia (hypermetropia is compensated)
 Refractive testing without cyclopegia → No refractive error (because of compensation)
Refractive testing with cycloplegia → Hypermetropia is manifested.
It is worth noting here that the above description was for spasm of accommodation which occurs in response to compensate the refractive error (hypermetropia).
In other situation where the spasm of accommodation is due to other causes (e.g. drugs causing ciliary spasm), the eye will become myopic (Pseudomyopia).



So, basically, spasm of accommodation causes myopia which results in:-


If hypermetropia is there → It will be compensated.
If no refractive error is there → Eye will become myopic.
Myopia
Pseudomyopia
Hyperopia
Emmetropia