Paediatrics and Strabismus
WHAT IS AMBLYOPIA?
Amblyopia or ‘lazy eye’ is inability for an eye to see clearly even if the best glasses are worn, due to a problem in development of the nerves from the eye to the brain; it is the commonest cause of poor vision in childhood.
For normal visual development to occur, one must be neurologically normal, have two structurally normal eyes, and receive clear visual stimulation to develop the nerve fibres from each eye to the brain equally. We are not born with all the nerve connections for vision, and fibres of different types carry the various components of our sight. The two eyes compete with each other for these neural connections; if one has better vision, more connections form with the brain from this eye, at the expense of the other eye. If neither have clear visual stimulation; fibres for smaller print do not form with either eye.
An amblyopic eye has poor vision (despite wearing the best possible glasses) because the best potential vision did not develop, and the nerve fibres for clearer vision do not exist for that eye.
Treatment to improve the vision in an eye which is amblyopic, is usually effective until between 6- 8 years of age and can include a combination of glasses, patching or Atropine drops. The sooner treatment is started the better the chance of attaining the best visual potential. The following are treatment regimens used to treat amblyopia:
Patching aims to improve the vision in the amblyopic eye by covering the eye with the better vision.
Atropine drops are sometimes used as an alternative to patching. They blur the sight in the better eye to encourage the weaker eye to work.
Treatment of Amblyopia, such as wearing a patch is most effective at a young age. By the age of approximately 6-8 years of age, the eyes are fully developed and treatment is most successful if treated before this age.
WHAT IS SQUINT?
A squint is the term used to describe when an eye is turned in, turned out, or higher than the other eye. The squint may be present all or only part of the time and may appear to affect only one eye or alternate between the eyes.
Normally when looking at an object in the distance the eyes are looking straight ahead, when one eye is turned, it is described as a squint.
SYMPTOMS of Strabismus
The most obvious sign of a squint is one eye that does not look straight ahead but turns inwards, outwards, upwards or downwards. However, small squints may be less obvious.
If a squint is left untreated, lazy eye (amblyopia) can develop. The vision in the affected eye gradually deteriorates because the brain ignores the weaker message being sent from that eye. It is not usually possible to correct amblyopia after the age of about 7 years, which is why it is so important to treat a squint as soon as possible
There are 2 main components when treating a child with a squint:
(1) Correcting the misalignment
(2) Treating any amblyopia to ensure normal visual development
WHY DO PEOPLE DEVELOP SQUINTS?
The incidence of squints in the population is 2-4%.
Squints can be due to:
• The effort required to focus the eyes;
• It can run in families
• Illness or being tired can make it more obvious
• Structurally abnormal eye
• Rarely, it can be due to other diseases or illnesses.
You should always seek an expert opinion if you are concerned. If you feel it is persisting despite reassurance ask for another assessment.
The aim is to:
(1) Monitor and treat amblyopia if present
(2) Treat the squint
How will the squint be managed?
In some children this involves glasses, in others strabismus surgery is the best option for your child. This will depend on the type of strabismus that your child has, and whether it is turned in (esotropia) or turned out (exotropia). There are other important factors that are part of the decision making process. This includes how frequently your child’s eye is turned – all the time (constant) or intermittently. Other factors that help Dr Shanel Sharma determine if strabismus surgery is the best option for your child is whether the strabismus responds to glasses. Dr Shanel Sharma and our team will discuss this with you further during your consultation in either our Miranda (02 9531 5300) or Bondi Junction (02 9387 5300) offices.
Squint is the common name for ‘strabismus’ which is the medical term used to describe eyes that are not pointing in the same direction. A squint can be convergent (esotropia), divergent (exotropia) or vertical. The squint may be present all or only part of the time, in only one eye or alternating between the two eyes.
It has been estimated that four in every 100 adults suffer from strabismus. Commonly an eye that was straight after childhood squint surgery later drifts in the opposite direction and causes concern over its appearance.
Sometimes a squint develops due to an underlying health issue, such as damage to cranial nerves, following head injury or as a complication of diabetes, stroke, or thyroid eye disease. Therefore, Dr Shanel Sharma may ask you to have some additional tests to exclude an underlying cause.
SYMPTOMS of Squint
Symptoms of adult squint problems include fatigue, double vision, difficulty with near vision and loss of depth perception. To compensate for this, some individuals will adopt an abnormal head position. The appearance of an eye turn (strabismus / squint) can have considerable impact on one’s social relationships and work, for example a teacher in a classroom or someone who does public speaking. Some studies have demonstrated that people with a turn are perceived as less trustworthy, humorous and reliable due to the appearance of a squint. You are not alone if you feel prejudice towards you, please contact our rooms and make an appointment to see Dr Shanel Sharma in either our Bondi Junction (02) 9387 5300 or Miranda Rooms (02) 9531 5300.
CAUSES of Squint
Squints that have been corrected during childhood often recur in adulthood. Different squints may cause double vision as the brain has been trained to collect images from both eyes.
If you develop a new squint suddenly, you need to be seen urgently.
TREATMENT & RECOVERY
Treatments of squint depend upon the cause, the degree and direction of misalignment, how long the squint has been present, and any previous treatment that has been received. Treatment may involve glasses with or without occlusion, prisms, or contact lenses; Botox for strabismus, squint surgery, exercises or a combination of any of the above.
What is Botox?
Botulinum Toxin is commonly known as a cosmetic anti-wrinkle injection, however, it also has uses in treating medical conditions. It has a powerful effect in weakening muscles on a temporary basis. To treat squint, Botox is injected into the eye muscle under guidance from an electrical probe to detect that the needle is correctly located in the muscle.
This is a treatment that has been done at Moorfields Eye Hospital in London since 1982, with over 1300 injections of botulium toxin given annually into the eye muscles to help in attaining ocular alignment. It has been used repeatedly in some patients, and others are able to regain alignment for prolonged periods with one botulinum toxin injection. If you would like to be assessed to determine if this treatment is an option for you, make an appointment with Dr Shanel Sharma who trained to do botulinum injections for strabismus at Moorfields Eye Hospital in London. Appointments can be made in either the Miranda rooms on (02) 9531 5300 or (02) 9387 5300 for the Bondi Junction offices. This treatment can often be an option for patients who have failed other treatment options such as strabismus / squint surgery or prisms.
Br J Ophthalmol doi:10.1136/bjophthalmol-2011-301332
The effect on quality of life of long-term botulinum toxin A injections to maintain ocular alignment in adult patients with strabismus.
. Joanne Hancox, Shanel Sharma, Kelly MacKenzie, Gill Adams
There is considerable evidence to show that strabismus patients report their quality of life (QoL) as lower than normal controls. While the majority of patients with strabismus are treated with surgery there are a number of cases where surgery is not possible and good long-term ocular alignment can be maintained with repeated injections of botulinum toxin.
65 patients who had undergone over 25 injections of botulinum toxin A for long-term control of their deviation were identified and asked to fill in and return the Adult Strabismus questionnaire (AS-20) to assess their QoL.
46 questionnaires were available for analysis. The mean AS-20 score in our patients compared favourably with that reported for normal controls and was much higher than that reported for patients with strabismus.
Long-term injections with botulinum toxin A is a good treatment for maintaining ocular alignment if squint surgery is not indicated and those patients receiving treatment score near the level of normal controls in QoL terms.
What is hemifacial spasm/ blepharospasm? These are two conditions, where a group of muscles, including those around the eyes contract involuntarily. In hemifacial spasm, the muscle groups involved tend to be on one side of the face, whereas in blepharospasm, it is typically the muscles around the eyes that forcefully contract, causing the eyes to close involuntarily.
What is botox? Botulinum Toxin is a medication which weakens muscles on a temporary basis. It is injected into the muscle to weaken it and reduce spasm.
Dr Shanel Sharma is accredited to treat patients with Botox for Hemifacial spasm / Blepharospasm under the Medicare Botox program. She also treats patients with Strabismus with Botulinum Toxin, as well as those with Crocodile tears.
To make an appointment, phone 9387 5300 (Bondi Junction) or 9531 5300 (Miranda).