Classification Right, left or alternating Someone with<unk>  will squint with either the right or the left eye but never with both eyes simultaneously. In a left<unk> , the left eye 'squints,' and in a right<unk>  the right eye 'squints.' In an alternating<unk> , the patient is able to alternate fixation between their right and left eye so that at one moment the right eye fixates and the left eye turns inward, and at the next the left eye fixates and the right turns inward. This alteration between the left and right eye is mostly spontaneous, but may be voluntary in some cases. Where a patient tends to consistently fixate with one eye and squint with the other, the eye that squints is likely to develop some amblyopia. Someone whose squint alternates is very unlikely to develop amblyopia because both eyes will receive equal visual<unk> imulation. It is possible to encourage alternation through the use of occlusion or patching of the 'dominant' or 'fixating' eye to promote the use of the other.<unk>  is a highly prevalent congenital condition. Concomitant versus incomitant<unk> s can be concomitant, where the size of the deviation does not vary with direction of gaze—or incomitant, where the direction of gaze does affect the size, or indeed presence, of the<unk> . The majority of<unk> s are concomitant and begin early in childhood, typically between the ages of 2 to 4 years. Incomitant<unk> s occur both in childhood and adulthood as a result of neurological, mechanical or myogenic problems affecting the muscles controlling eye movements. Primary, secondary or consecutive Concomitant<unk> s can arise as an initial problem, in which case they are designated as "primary," as a consequence of loss or impairment of vision, in which case they are designated as "secondary," or following overcorrection of an initial<unk>  in which case they are described as being "consecutive". The vast majority of<unk> s are primary.
Esotropia
Cyclotropia
Exotropia
Ocular dysmetria
Heterotopia 
Quadrantanopia
Presbyopia
Pseudomyopia