In the far corner of the waiting room in the National Eye Hospital in Colombo is a small door which opens into an Orthoptic clinic. It is one of only two in the country (the other is in Kandy) and has existed for 22 years, says Senior Orthoptist Upali Seekkubadu.
On weekday mornings, it’s packed with patients– as many as 40 or 50 may walk through every day. Many of them are children, which is why Mr. Seekkubadu says they’ve taken great care to make their little rooms child friendly. Pictures of cartoon characters are stuck to the walls-- for their young patients it’s no doubt comforting to see the familiar faces of Pooh and Tigger in the hospital.
Orthoptists such as Mr. Seekkubadu and his colleague Ms. Namali Wijesingha evaluate and treat disorders of the vision, eye movements and eye alignment, including cases of lazy eye (amblyopia) and crossed eyes (strabismus). The name of the field comes from the Greek words for straight ‘ortho’ and vision ‘optikas’ – taken together they are a very good description of an orthoptist’s mandate. This week, MediScene speaks with Mr. Seekkubadu about his specialty.
How the eyes work
The cornea and the lens are two transparent layers that cover the front of the eye and allow light to enter. Passing through the retina, a layer of light-sensitive tissue at the back of the eye, the light is converted into electrical signals. These signals are conveyed to the brain by the optic nerve. In the brain the signal is then converted into an image.
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| At the National Eye Hospital Orthoptic Clinic. Pic by M.A. Pushpa Kumara |
Though you might not realise it, each eye works independently of the other, producing its own, unique image. This binocular vision is how we are able to fully appreciate things like depth and motion of objects, explains Mr. Seekkubadu.
The fact that we see only one image is due to the brain’s ability to combine the images produced by each eye into a single image. It is able to do this in part because it exerts exquisite control over the six muscles in each eye. These muscles have to be coordinated so that the eyes point at the object you are looking at.
However, you only see one image because the brain controls the eye muscles and then joins the images that are produced by each eye together into a single image. When someone is diagnosed with a squint, also known by the more medically accurate term strabismus, it’s because their eyes look in different directions. This misalignment could be the result of problems with the eye muscles, an uncorrected vision problem, such as short-sightedness or long-sightedness or even nerve damage.
The development
of a squint
The clearest sign of a squint is when the eyes are not aligned, but in minor squints this misalignment may not be immediately obvious. However, the degree of the misalignment can be misleading – a larger squint does not equate to a greater distortion in vision, cautions Mr. Seekkubadu. Even a small squint can have a profound impact on one’s vision.
Depending on which way the eye turns, there are four different kinds of squints. Where the eye turns inwards, it is known as esotropia; when it turns outwards it is dubbed exotropia. Patients with upward pointing eyes have hypertropia and those with downward pointing eyes have hypotropia. Of the four, the first two are more common. It’s worth noting here that squints need not be present at all times. Those that are, are known as constant squints, while those that come and go are called intermittent.
Squints are common, and though they affect people of all ages, they are particularly common in young children, usually developing before the child is five years old. (Babies under the age of three months also squint sometimes and this is not something to worry about. Check with your doctor though if it persists beyond that point.)
Squints have also been known to run in families. Though the squint can cause blurred or double vision, some children may not even realise there is a problem. In such cases, adults must rely on cues such as the child developing a habit of looking at you with one eye closed or with their head turned to one side.
A squint should not be neglected – if not treated early on, a patient may develop permanent vision problems, explains Mr. Seekkubadu. For instance, the brain copes with double vision by simply ignoring the signals sent from the squinting eye. It relies solely on the normal eye and as the eye with the squint is underutilised it eventually develops into a case of ‘lazy eye’, also known as Amblyopia.
Occasionally, a squint will develop in adulthood. This sudden onset of a squint could indicate serious nervous system problems and should be immediately brought to the attention of a medical professional. They should also be investigated in case they are connected to any infections or an inflammatory condition says Mr. Seekkubadu.
Treating squints
In Sri Lanka, the treatment of a squint is a project that often involves a trio of specialists – the orthoptist himself, an eye surgeon and an optometrist must work together, says Mr. Seekkubadu.
In cases of lazy eye, wearing an eye patch can provide a surprisingly effective remedy. By covering the good eye, an orthoptist encourages the brain to start using the neglected eye. Amblyopia must be treated in early childhood because after the age of five it’s difficult to improve vision and after the age of 8, it’s almost impossible, cautions Mr. Seekkubadu.
Other treatments for squinting include specific drugs and prescription glasses which can be used to correct the vision problems underlying the squint. (Polycarbonate or plastic lenses are more suitable for children to avoid the risk of breakage, he notes.)
Your orthoptist might suggest simple eye exercises that will help the two eyes work in sync. Surgery is a last resort. It is sometimes employed for cosmetic reasons, says Mr. Seekkubadu, explaining that the alignment of the eyes not only help the eyes to work together but can also correct the squint itself, thereby returning a person’s appearance to normalcy. However, it is quite safe as there is no significant risk of eye damage associated with surgery – the focusing parts of the eye are not touched. |
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