What is strabismus?
Strabismus – or more commonly known as squint, is an eye condition where the eyes do not look in the same direction as each other and do not work together as a pair all of the time. Strabismus can be caused by a refractive error – where the eye cannot clearly focus on images, or binocular fusion abnormalities – this is the process where both eyes work together to form a single picture, or neuro-muscular anomalies. Strabismus is also a common cause of amblyopia (lazy eye).
Types of strabismus
There are multiple different types of strabismus including:
Esotropia:
This type of squint is characterised by the inward turn of the eye, this can either be isolated in one eye or in both of the eyes. This can result in near or distant fixations or both. This means that the person would have an intense focus on objects that are either close or far away.
Exotropia:
This one, in particular, is opposite in nature from esotropia, being characterized by the eyes turning outwards instead of inwards.
Hypertropia:
This is characterised by the misalignment of the eyes. Rather than the eyes turning inwards or outward, one of the eyes will turn upwards.
Hypotropia:
Similar to the prior type.
Symptoms of strabismus
- One of the eyes wanders outward or inward.
- Poor depth perception.
- Head tilting.
- The eyes look like they are not working together.
- Shutting of an eye or squinting.
- Abnormal test results on a vision screening.
How is Strabismus Diagnosed?
At around 3 to 4 months of age, a child’s eyes should usually be able to focus on small objects and the eyes should be well-aligned and straight. And a 6-month-old infant should be able to focus on objects close to them and further away. There is a condition called pseudostrabismus (false strabismus) which can make it appear that a baby has crossed eyes when in fact their eyes are pointing in the same direction. This is why it is key that if you have concerns about your child, you contact your doctor.
Anyone older than four months old who appears to have strabismus should ideally have an eye examination by a paediatric opthamologist. This exam would look at the following:
- Patient and family history. This helps provide an insight into have the symptoms relate to other health problems, medications, family history, and also look at other possible causes of any symptoms.
- Visual acuity – this could include reading letters from an eye chart, or examining visual behaviour.
- Examination after dilation (widening) of the pupils to determine the health of internal eye structures.
- Refraction – this involves checking the eyes with a series of corrective lenses to measure how they focus light. Children do not have to be old enough to give verbal feedback when checking for glasses.
- Alignment and focus tests.
Strategies and Tips for Managing Strabismus
Although the main method for managing this condition is through glasses or medications. Remembering these handy hints can also make eyes less sore and help manage the condition more effectively:
- Take regular breaks when using technology like computers, mobile phones, and tablets. Try to take breaks every 15-20 minutes.
- Enlarge text and images on screens or paper when reading this will mean that those with strabismus won’t tend to be incredibly close to screens.
- Always carry a spare pair of glasses!
Treatment Options
- Glasses or contact lenses.
- Prism lenses.
- Orthoptics (eye exercises).
- Medications including eye drops or ointments.
- Eye muscle surgery can help adjust the position of eye muscles, and injections can help to weaken over active eye muscles.
- Patching can help treat amblyopia.
Eye Exercises for Strabismus
An eye doctor or optometrist/ophthalmologist may recommend eye exercises to improve muscle control and brain-eye coordination. Some of these are technical, often requiring special equipment and would be done with your doctor, but others can be done at home. Here is an insight into the different exercises that a doctor would prescribe:
1. The Pencil Exercise
Hold out a pencil or pen directly in front of you and choose a focal point or point to focus on – this could be the tip of the pencil, the eraser at the end or a letter/numeral on the side. Keep both eyes fixed on this area. Slowly move the pen/pencil closer towards you and towards the tip of your nose. Keep the pencil in focus for as long as you can and stop the exercise as soon as everything turns blurry.
2. Brock String Exercise
This exercise aims to help improve your eye coordination and encourage both eyes to work together. Use a piece of string (between 5 and 12 inches long) and thread it with three different coloured beads at equal distance from one another. Stick one end of the string to a rail or pin it to the wall and hold the other end of the string to your nose. Take it in turns to look at each bead and you should see the same thing every time; the bead you are focussing on should appear to be at the intersection of two identical strings forming an “X” shape. If the “X” appears before or after the bead you’re focusing on then it means that one of your eyes is not looking at the bead. Keep practising until you get it right with all three beads.
3. Computer Therapy
Some doctors and optometrists have computer programs that use virtual reality and video games to help correct strabismus. These are called divergence techniques, and your doctor can customise them for you.
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