This leaflet is intended to answer some of the questions of parents or carers of children diagnosed with Hypermetropia under the care of University Hospitals Sussex NHS Foundation Trust.
What is Hypermetropia?
When no glasses are required the image of what you are looking at is focussed sharply on the retina at the back of the eye (Fig A picture below). Hypermetropia is often the result of the eyeball being too small or the eye not focussing light sharply on the retina at the back of the eye. In hypermetropia the light is focussed at a point behind the retina (Fig B picture below), making the light that actually falls on the retina blurred.
A child with mild hypermetropia is likely to see things at a ‘long’ distance better than things at a ‘near’ distance. For this reason hypermetropia is also known as ‘longsightedness’ and ‘far-sightedness’. A child with moderate or strong hypermetropia will have blurred vision for both near and distance.
What causes Hypermetropia?
There is usually no particular cause of hypermetropia. Sometimes the child’s parents have hypermetropia and so it is inherited. Rarely the child has a condition which leads to hypermetropia such as microphthalmos (an abnormally small eye).
What are the signs and symptoms?
Children are good at adapting to blurred vision and will often not show any signs of having hypermetropia. Sometimes a child can want to sit closer to the TV than normal, or complain of headaches and blurred vision. In some cases the child’s eyes may start to turn inwards if they are having to exert a large effort to focus. This is occasionally the first indication of hypermetropia.
How will you test the vision?
Vision tests are available for all age groups, ranging from pictures that are simply looked at, to matching pictures or letters on a card, to naming letters or numbers.
How do you know my child needs glasses?
This is done by an Optometrist. Children with hypermetropia are often very good at over-focussing to see as clearly as possible. This can result in false readings as to what the glasses prescription should be. To overcome this young children are often asked to have eyedrops put into both eyes before the optometrists appointment. These eye drops limit the ability to focus for a few hours so that the optometrist can get an accurate reading.
The eye drops also widen the pupils to give the optometrist a good view of the back of the eye.
Can it be treated?
Glasses or contact lenses can be used to make the vision clearer. Glasses are the most common method used in children. The lenses used to correct hypermetropia are called ‘convex’ or ‘plus’ lenses and are indicated by a plus sign on the glasses prescription. Unless told otherwise by your orthoptist or optometrist the glasses are to be worn all of the time.
Children’s vision usually improves gradually and this can take up to 18 weeks to fully adapt to the glasses.
Are there associated complications?
Sometimes the effort to see clearly for someone who is hypermetropic can cause one eye to wander.
An eye that turns / deviates is called a strabismus. The type of strabismus seen in someone who has hypermetropia is commonly an esotropia. This is when the eye turns inwards towards their nose. Glasses can reduce the strabismus and can often fully correct it. Occasionally an operation may be needed if the strabismus persists with glasses.
Another complication can be amblyopia (reduced vision in one eye). This can occur if the glasses prescription is higher in one eye than the other.
Amblyopia can resolve over time as glasses are worn.
If it persists, despite good compliance with glasses, then we need to do some patching treatment.
This involves wearing an eye patch over the better seeing eye for a few hours per day to help encourage the vision to develop. Your orthoptist will advise you if this is necessary.
Will my child need glasses for the rest of their life?
It is impossible to predict how the prescription will change as a person ages.
Regular tests with the optician will keep the prescription up to date.
In mild prescriptions there are some children who can discard their glasses once their vision is fully developed (around the age of 8).
If the prescription is high then it is usually unlikely children will grow out of the need for glasses.
St Richard’s Hospital
St Richard’s Hospital
Orthoptist 01243 831499
Upper Shoreham Road
Orthoptist 01273 446077
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The information in this leaflet is for guidance purposes only and is in no way intended to replace professional clinical advice by a qualified practitioner.