Pediatric Ophthalmology & Squint
Children require specialized techniques of evaluation and testing visual disorders. They, therefore, are seen by team of ophthalmologists and optometrists who are trained to make a quick and fast examination to pick up defects if any.
Ideally, all children must undergo an evaluation by the eye specialist within few months after birth, particularly those who are low birth weight or premature neonates. Routinely, all children should be got examined at one year, then at preschool (4-5 year age), and periodically thereafter to detect refractive errors, squint, etc. Watery eyes, itching and stickiness due to infections and allergy are common ophthalmic problems in Children and require urgent attention to avoid complications.
Refractive errors are the commonest cause of weak eye sight.
When rays of light come to a focus in front of retina, it is called Myopia or Shortsightedness.
If rays focus behind the retina, it is called Hyperopia or Farsightedness.
When the Corneal shape is more egg-like, rather than being an orange, the principal meridia (horizontal & vertical) of the cornea do not simultaneously focus on the retina. This is called Astigmatism.
Refractive errors in children must be diagnosed and treated with spectacles.
Special tests are performed after dilating the pupils with drops or after applying ointment for three days (Cycloplegics).
If there is a strong family history of refractive errors, it is very important to have the child examined before the age of one year and at the time of admission to school.
When a child has poor vision in one or both eyes, which is not improving by glasses, it is called Amblyopia. Other causes of poor vision are due to obstruction of light reaching the retina due to congenital cataract, corneal opacity and other or other congenital diseases of the retina). When detected early, amblyopia can be effectively treated by ‘patching’ exercise for the lazy eye and by the use of certain eye drops.
Congenital and developmental Cataracts are known to occur in children, though not as common as in adults. Certain infections like measles during pregnancy genetic pre- disposition and nutritional deficiency may cause cataracts.
If there is a family history of congenital cataract the child must be evaluated as soon as possible.
Some babies are born with cataracts and these must be tackled as soon as possible. Vision development in the first 4-8 weeks of life is very critical, and any obstruction to the passage of light into the eye hampers this visual development. Hence, early intervention is important to remove the obstacle (cataract) so that visual development may occur. Delays in treatment can lead to poor visual gain in these children.
Normally, when both eyes have good vision and are properly aligned, they both focus on the same object. Each eye sends a picture of the same object, although viewed from a very slightly different angle, to the brain. These two images are fused in the brain to form a single, three dimensional picture with depth perception. This is known as binocular vision. There are 3 levels of Binocular vision, simultaneous macular perception, fusion and stereovision.
When the eyes are misaligned, each eye focuses on a different object and sends its signals to the brain. This leads to confusion in the brain (due to it having to process multiple varied inputs). This may sometimes lead to “double-vision” or diplopia. To overcome this, the brain tends to ignore the image coming from the deviated (squinting) eye. This phenomenon is called Suppression. Suppression, over a period of time results in poor development of vision in the deviating (squinting) eye, and can also cause amblyopia (lazy eye).
When a squint suddenly develops, as sometimes in an adult, the brain is unable to ignore images from both the eyes, resulting in double vision or diplopia.
It is important to remember that eyes of a baby establish alignment at 3-4 weeks of age. Therefore, if a child is noted to have a squint at a young age, it must be immediately evaluated and treated.
When the alignment between the two eyes is imperfect, it is called a squint (or Strabismus). In other words, the two eyes seemingly point in different directions - the eyes may go inwards relative to each other (called Esotropia or Convergent Squint) or outwards (called Exotropia or Divergent Squint). Rarely, there may be a vertical deviation of the eyes (Hypertropia).
Mal-alignment of the two eyes is called a squint. This can be a Psuedo or a true squint.
Pseudosquint: (What “appears like a squint”) in some children, the nasal skin fold and nasal bridge is very broad giving the appearance of a squint. However, every child with a suspected squint must be evaluated by the specialist to diagnose true squint.
In ward positioning of one eye towards the nose is called ‘Esotropia’ (Convergent Squint).
Outward positioning of one eye away from the nose is called Exotropia (Divergent Squint).
The treatment of squint involves ruling out congenital diseases of eye by detailed microscopic and ophthalmoscopic examination of the eyes and evaluation for refractive error. Treatment of squint comprise off correction of refractive errors, special eye exercises to strengthen binocular vision. [Treatment of amblyopia, or surgeries in those cases who do not get cured by non surgical treatment.]
The exact cause of squint is not known. The movement of each eye is controlled by six muscles (total 12 muscles in the 2 eyes). Each of these muscles acts along with its corresponding muscle in the other eye to keep the two eyes aligned at all times. A loss of coordination between the muscles of the two eyes leads to mal-alignment or squinting. Refractive errors such as hyperopia (especially if uncorrected or under corrected) may lead to an inward deviation of the eye. Poor vision in the eye due to some diseases which do not allow full light to enter the eye, such as cataract, etc. can also cause a squint.
Squints can also develop after injury or rarely, due to congenital genetic causes. A thorough check up children before they start going to school is therefore important to rule out subnormal vision, etc.
A squint can be present at all times (constant), or may be noticed only some time (intermittent) during the day (parents typically notice it when the child is tired, unwell or when he is daydreaming).
Squints are primarily treated to:
- Restore vision in the squinting eye.
- Restore alignment of the eyes.
A thorough evaluation of the child to rule out any refractive errors or abnormal eye power, is mandatory. If required, glasses are prescribed to correct the refractive errors. In some cases of accommodative squint, a correction of the refractive error with the correct power of glasses is all that may be required to treat the squint. Special glasses incorporating Prisms may also be considered in the management.
If the child has developed amblyopia (or lazy eye), it is treated vigorously to restore sight to this eye. Amblyopia is usually treated with patching (occlusion treatment) or sometimes additionally with drops.
Once a lazy eye has been treated and proper glasses prescribed, the residual deviation in the eyes is measured (sometimes on multiple occasions) and is treated by surgery on the muscles to realign the eyes.
A low birth weight baby (weight < 1500 gm) or born before 32 weeks of gestation or those kept under Oxygen tent are at risk to develop Retinopathy of Prematurity (ROP). These infants must be regularly screened and treated by the Specialist. Timely intervention in the form of lasers helps to maintain their eyesight for life.
Watery, Sticky Eye(s) at Birth
Some children are born with non-canalization of the naso-lacrimal duct that connects the eye to the nose on one or both sides. These children tend to have watery eyes and frequent eye infections (sticky eye).
Generally, the naso-lacrimal duct canalizes before birth. It may get delayed and canalize naturally up to 6 months after birth. However, during this period it is essential to keep the eye free of infection and help the canalization process by performing lacrimal sac massage. Early diagnosis and treatment helps avoid complications and persistent watering. Our doctors will teach you how to perform effective massage and how to clean the discharge from the eyes.
In some cases, despite the massage being done regularly, the duct does not open up. In such cases, we perform a small procedure called “Syringing and Probing” to open up the naso-lacrimal passage with a probe, under general anaesthesia.
Rarely, a child may have a white reflex from the eye. This is a condition that requires urgent medical attention, as the child may have a Cataract Retinal detachment or a tumour in the back portion of the eye.