What happens in lazy eye, exactly?

Sorry about the lack of posts! Our internet connection has been horrible lately and a couple of days ago it just stopped working altogether. It should be okay now though. 

What is it?

Lazy eye, also known as amblyopia, is a disorder of sight characterized by the eye and the brain not working well together. It leads to decreased vision in an otherwise normal eye. Many people only become aware of their condition when their vision is tested at older age, because the vision in their other eye is normal. Spatial vision suffers the most.

2-5% of people in western countries have amblyopia. 90% of visual health appointments of children in the UK are related to this condition.

What causes it?

It is relatively common to have misaligned eyes; when one looks straight ahead, the other looks somewhere else. The brain receives two different images and has to decide what to do with them. Adults are not that adaptable anymore, and they usually experience this as double vision. Children’s brains, however, can begin to prefer one eye and suppress the signals coming from the other, and amblyopia develops. The same process can take place if the image from one eye is clearer than from the other.

What happens during it?

Our brains are very responsive to changes in our environment. They remove and add, strengthen and weaken, connections all the time. When our eye registers an image of the outside world, it is first processed separately and then combined with an image of the other eye. It is thought that in amblyopia, the difference in strength of these two images leads to the part of the brain which unifies the images to be more responsive to the stronger image. The neurons compete for connections, and if the signals from, say, the left eye, are constantly stronger, then the left eye neurons get more connections while it’s even harder for the right eye to get it’s message through because of the limited number of recipient neurons.

How can it be treated?

The younger the patient is when treatment for amblyopia is started, the bigger the chances for success are. The two main goals of treatment are to address any underlying eye problems and to encourage the use of the weaker eye. The first step of treatment is obviously dependent on what has caused the amblyopia in the first place, but glasses or surgery are useful in many cases and can sometimes lead to the correction of even the amblyopia. Using the weaker eye can be encouraged by wearing a patch over the stronger one, or using eye drops to blur the vision in it.

 

 

Sources: content.lib.utah.edu/utils/getfile/collection/ehsl-nam/id/…/4893.pdf, https://en.wikipedia.org/wiki/Amblyopia, http://www.nhs.uk/Conditions/Lazy-eye/Pages/Treatment.aspx, http://emedicine.medscape.com/article/1214603-overview#a6

 

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