Strabismus – squint
Squint is common in early childhood. Up to 1 in every 15 children found to have squints when they start schooling. In special population like child with brain damage or learning disability, the incidence of squint is even higher.
All fixed squints and any squint that persists after 5-6 months of age require careful evaluation. Most cases of squint in children are non paralytic. There is normal range of external ocular movements. In this type of squint, the angle of squint between bilateral eyes is constant in every directions of gaze. Paralytic squint is cause by paralysis of one of the ocular muscle. This is rare in children. Most cases occur due to failure of development of binocular coordination of unknown etiology. However, some may be caused by cataract, glaucoma, retinal disease or retinoblastoma. Latent squint is difficult to diagnose. In this case, there is imbalance of extra ocular muscle. However, the eyes do not deviate the entire time make it not visible on inspection. Decrease visual acuity of one eye may lead to latent squint. It means that the visual acuity or the eyesight should be tested in all children with squint.
Classification of squint:
| Paralytic squint | Squint varies with direction of gaze |
| Non paralytic squint (concomitant) | Squint constant in all directions of gaze. It can be either of these combination:
|
The diagnosis is mainly made from clinical examination. Symmetrical corneal reflection or occlusion testing may assist diagnosis in less obvious cases. Epichontic folds, low nasal bridge and hypertelorism (wide-spaced eyes) such in the Down Syndrome children may give rise to false appearance of squint. This is called pseudo-squint which is not significant
Early recognition and management of squint ensure better prognosis. If not detected early, it will lead to suppression of vision from the squinting eye in order to prevent blurry of vision or double vision. When unused, this deviated eye may end up with amblyopia or diminished acuity of the central vision. The lesion may be permanent and lead to condition of “lazy eye”. The child will have problem in later life. If left alone without treatment, the vision in the squinting eye may be lost permanently, denying the child binocular vision for life. Early treatment before the school age may prevent this problem.
Refractive errors are very common in children with squint. Correction of refractive error and occlusion of the non squinting eye are mandatory. Many cases can be cured with early use of spectacles. Rarely, occlusion of the non squinting eye is done. The occlusion of the eye means to force the child to use the squint eye. This treatment may be need for several months and is unpopular among children. Surgery is sometimes indicated in selected cases.
Reference:
- Simon J Newell et al. Lecture Notes Paediatrics. 8th edition. 2008. Blackwell Publishing.
- Paediatrics Colour handbook. 1999. Mosby Elsevier.
Tags: amblyopia, latent squint, lazy eye, squint
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“Health awareness” is a blog that is designed to increase health awareness among public. It cannot be used as a substitute for health treatment. When necessary, you need to visit your physician regarding your illness.
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