Normally the eyes are the best friends. They blink together. They move together and always keep the visual axis parallel, how paradoxical it is that healthy eyes visual axis never meet but it is the eyes who make you meet the desired person in your life.
When visual axis is not parallel in any direction of gaze, we call it a squint
Squint can be congenital or acquired. Congenital squints are usually more difficult to treat. Acquired squint may be due to refractive error. They can be traumatic causing paralytic squint which is more difficult to treat.
If both eyes converge (turn inside), we call it convergent squint. If they diverge, we call it divergent squint.
The squint can be constant or inconstant (sometimes).
A squint patient has to be examined fully by a very competent ophthalmologist at the earliest opportunity. The doctor shall find out the type of squint, its degree, and its nature. Fundus has to be examined. Refraction has to be done. Convergent squint patients quite often have a hypermetropic refractive error and sometimes can be cured by spectacles and exercise. Myopic eyes most often have a divergent squint. In some patients, the squint is quite hidden (latent) and it appears occasionally when patient have a strong emotion or absent minded. Most often these squints are divergent.
The challenge in surgery shall depend on a degree of squint, an age of onset, type, and age of surgery. Ideal age of squint surgery is 5-10 years. More the age, unpredictable results. Simply drugs do not cure squint. Paralytic squint more challenging. Earliest the better