Orthoptics

Common Problems: Squint, Lazy Eye and Glasses

What is a squint?

A squint or ‘strabismus’ is the medical term for an eye that either turns in, out, up or down in relation to the other eye. It is also known by other terms such as ‘cast’ or ‘lazy eye’. The squint may be present all or part of the time and can exist in one eye only or can alternate between the two eyes.

The main reasons for a squint developing are:

• Need for glasses (focussing problem)
• Eye muscle imbalance
• Family history
• Injury to eye or orbital area
• Disease or illness
• Facial asymmetry/abnormality

Some babies may appear to have a squint but in fact they have what is known as a ‘pseudosquint’, which is not a true squint. The appearance of this ‘pseudosquint’ may be due to ‘epicanthus’ which is caused by folds of skin on a wide nose. The Orthoptist is specially trained to determine whether the baby has a true or pseudosquint.

A squint can either be treated by:

• Wearing glasses
• Surgery
• Eye exercises

Patching does not help with the squint

There are numerous types of squint and each squint is treated differently. The Orthoptist is specially trained to diagnosis and treat each type of squint.

There are three main types of glasses:

• Short-sighted (myopic)
• Long-sighted (hypermetropic)
• Astigmatism

A glasses test for a child is very different from the conventional testing done on adults at an Opticians. The glasses test is carried out without the need to ask the child any questions regarding letters etc.

Eye drops are instilled to dilate the pupil and then the glasses test is performed. This involves the patient looking at a distance vision chart while the doctor shines a light (retinoscope) into the eye. The doctor can then judge from the reflection received back through the pupil as to whether the child is long-sighted, short-sighted or has astigmatism. The doctor then puts up lenses in front of the eye to determine the strength of glasses needed, again using the light. This is done for both eyes.

You will receive a voucher at the end of the test containing the prescription details found by the doctor. This must be taken as soon as possible to any Optician who will then help you choose a pair of glasses for your child.

All children under the age of 16 or under 19 if in full time education are entitled to a voucher for glasses. The voucher value depends on how strong the glasses are. Most Opticians have a range of glasses that are free with the voucher. If you have paid extra on top of the voucher value for a more expensive pair of glasses, you are liable for any repairs and replacements to those glasses. It is therefore advisable to try and choose a pair that are free with the voucher.

If your child breaks his/her glasses, you must contact the Optician that you got the glasses from immediately. They will either repair or replace the glasses using the GOS4 form that they hold at their practice.

If your child’s glasses are getting too small or are suffering from general wear and tear then you must contact the Orthoptic Department so that a voucher can be issued to you.

Do not wait until your next Orthoptic appointment to get a new voucher, the Orthoptist cannot test your child properly if they do not have their glasses with them and another appointment may have to be made.

How many pairs of glasses is my child entitled to a year?

Your child will get a routine glasses test once a year or earlier if the Orthoptist or Doctor feels that it is clinically necessary. If your child is over 5 years of age and the Orthoptist feels that he/she will respond well to the test, you may be offered to go to a local optician of your choice. If this is the case then you should bring a copy of the glasses prescription given by the optician with you to your next Orthoptic appointment.

Unless instructed otherwise by the Orthoptist your child must wear the glasses full time in order to facilitate full visual development.

Every child is entitled to one pair of glasses a year. Only in special circumstances are two pairs issued. You may however buy a spare pair yourself but you will be liable for the full cost of the glasses and any repairs that may be needed.

Your child will get a routine glasses test once a year or earlier if the Orthoptist of doctor feels it clinically necessary. If your child is over 5 years of age and the Orthoptist feels that he/she will respond well to the test, you may be offered to go to a local optician of your choice. If this is the case then it is vitally important that you bring a copy of the glasses prescription with you to your next Orthoptic appointment.

Unless instructed otherwise by the Orthoptist your child must wear their glasses full time, this is to ensure full visual development and vitally important if undergoing occlusion treatment.

Occlusion (patching treatment)

Amblyopia or ‘lazy eye’ is a term used to describe reduced vision in one or both eyes. Amblyopia can be caused by:

• Need for glasses
• Squint
• Droopy eyelid or any eye condition e.g. cataract that blocks the stimulation being received with that eye.

When a child has a squint, the brain switches off that eye to stop the child seeing double. This is due to a child's visual system being very pliable. The longer the eye is ‘switched off’ the less the eye and the part of the brain that is responsible for vision is stimulated. This leads to a reduction in vision. The same happens for a child that needs glasses or has a cataract in one eye. Anything that blocks or distorts the visual stimulus in that eye will ultimately result in amblyopia.

Various observational tests can be used on babies and toddlers to gain an estimation of their level of vision. Once a child can talk we use a picture test to assess the vision and from around the age of 4-5 we use a letter matching test, where the child matches the letters shown by the Orthoptist on his/her card. The letters shown gradually reduce in size. Once the child can name the letters, their vision can be tested using the conventional letter board (Snellen chart) that can be found in GP surgeries or Opticians.

To enable the Orthoptist to tell whether your child has a lazy eye, the vision test must be carried out on each eye. This will usually be done with a patch to ensure no ‘peeking’. The vision test is one of the most important tests your child has at the Orthoptic department so concentration and encouragement is vital.

The only effective treatment for a lazy eye is to cover the good eye to promote the use of the lazy eye. This is done using a patch.

Firstly a glasses test will be performed by the doctor. If glasses are needed then they will be prescribed to be worn full time.

The Orthoptist will retest the vision with the glasses after about six weeks. If the vision improves with the glasses alone then no further treatment is required other than the glasses at that time. If the vision does not improve then patching (occlusion) of the good eye will be commenced.

If glasses are not needed after the test and your child still has reduced vision in one eye, then patching will be commenced.

Yes!!

The results of the treatment is very much dependent on your child wearing the patch as instructed. The Orthoptist appreciates that it can be very difficult especially if the vision is very poor and you must discuss any problems that you may be having as the Orthoptist may be able to come up with some ideas. The Orthoptist is there to support and help you during the patching treatment.

The amount of patching per day is decided on an individual basis for each patient, depending on factors such as the level of vision and age of the patient. The response to patching is assessed at regular intervals, usually once every 6-8 weeks and is continued until the maximum level of improvement is achieved. Occasionally after the patching has been stopped the vision may reduce to some extent. This can also occur if the child's glasses need updating. Therefore it is important to attend all the Orthoptic appointments so that the vision levels can continue to be monitored throughout the visual development period (up to the age of approximately 8 years old).

Be supportive and encouraging. Your child may feel frightened and vulnerable. Extra care must be taken during activities due to reduced vision levels.

Reading, drawing, computer games, anything that can distract the child whilst wearing the patch will help improve the vision.

No !! If left untreated the child may have permanently damaged sight, which cannot be corrected when they are older.