1. Normally on looking in a particular direction at some point, both eyes move equally & are directed at an object by the delicate muscles. If any of the eye is abnormally directed, squint is said to be there.
2. Stereoscopic vision (three dimensional vision judging accurate depth) is not possible if vision in any one eye is defective or if there is squint as squinting person uses only one eye at a time (practically one eyed person).
3. Squint is of two types :
(i) Paralytic. It results due to weakness or paralysis of one or more muscles of the eye. Occurs usually in adult or old age (causes include diabetes, hypertension, injury, brain disease etc.). Double vision commonly develops. It needs thorough investigation (e.g, Blood Sugar, X-Ray skull, CT Scan, etc.) and aims at treating the primary cause which might result in partial to full cure.
(ii) Concomitant. Is the common squint, starts in childhood usually one eye may be turned `in' (Convergent Squint) or `out' (Divergent Squint). It may be confined to one eye (unilateral) or both eyes (Alternating). In unilateral squint, the vision in squinting eye becomes poor with time & the squinting eye becomes lazy (so called Lazy eye Syndrome or Amblyopia).
4. `Lazy eye' or `Amblyopia' may also develop due to any factor that interferes with normal visual development (occurring in a child in initial years of life) e.g. presence of cataract, squint, refractive error etc. Amblyopia if once developed is not correctable by removing the primary cause alone. In addition, specific amblyopia therapy is required which may be in the form of temporary occlusion of good eye, etc. Amblyopia usually leads to permanent blindness in that eye if not treated by 7 years of age.
5. Squint is aggravated or precipitated by poor vision which may actually be due to the need of spectacles. Hence glasses power checking is the first requisite to treat squint.
6. The earlier is the treatment for squint started, the better are the results.
7. If squint is not correctable by glasses or exercises, surgery may need to be done. In childhood, squint surgery is safe and can not only correct the misalignment but also may restore the vision in squinting eye in some cases; while in long standing squints, surgery can improve cosmetic appearance only.
8. All children must have annual checkup by eye specialist for vision & squint so that both amblyopia and squint are detected & treated in time. Amblyopia usually causes no symptoms and may be detected on routine examination on finding unequal vision in two eyes.
9. Further, `Common Squint' if noticed in a child must be checked by the eye specialist at the earliest and treated urgently to prevent permanent blindness.