Wednesday, October 31, 2012

Hypermetropia

Hypermetropia: refractive condition of the eye in which distant objects are focused behind the retina when the accommodation is relaxed. Thus, vision is blurred.


What is Hypermetropia

Hypermetropia  is the technical name for long sightedness. If you are longsighted, your ability to see objects that are close up is affected.

So we know that Myopia, (short sightedness) is when the eyeball is too long.
Hyperopia is when the eyeball is too short, so when a ray of light is passed through, it goes past the retina, causing the image to be focused at the back of the eye.




How is Hypermetropia Treated?

Long sightedness is usually treated with corrective lenses such as contact lenses or glasses, as with shortsightedness.

Laser surgery can also be used, but it is not suitable for children as the eye is still growing.


Complications of long-sightedness

Long sightedness also has its complications, however these are usually very rare in adults
In severe cases of  hyperopia the eye may 'over-focus' leading to double vision.  This can lead to either
  • crossed eyes (strabismus), where the eyes are not properly aligned with each other and focus on different things
  • lazy eye (amblyopia), where one eye becomes dominant over the other

Tuesday, October 30, 2012

Myopia


My name is Keirisha. I’m in my final year of A Levels, hoping to study optometry at University next year. 

I've wanted to study optometry since quite a young age after visiting the opticians for the first time. Ever since then my interest in how the eye works has been ever growing.



What Is Mypoia?


Myopia: Refractive condition of the eye in which the images of distant objects are focused in front of the retina when the accommodation is relaxed. Thus distance vision is blurred. In myopia the point conjugate with the retina, that is the far point of the eye, is located at some finite point in front of the eye.

Well, its not as bad as it sounds. Myopia is the more medical/technical term for used to describe short-sightedness. It usually occurs when the eye ball continues to grow and gets too long, and so the image is formed before the retina. The typical human eye is about 2.2cm in diameter, but people with myopia would have an eye which is slightly longer than 2.2cm. This causes the image of an object that is viewed from a distance to be blurred.




As we can see in the picture above, the normal eye has a longer light ray compared to the myopia eye. This light ray reaches the retina at the back of the eye to allow the image to be focused. However, the light ray passing through the myopia eye, does not reach the retina, causing distant objects to seem blurred.



Who Is Affected By Mypoia?

Mypoia is caused by a combination of both genetic as well as environmental factors so anyone can be affected by it. However, it is more likely to be developed if it runs in the family. 

Types Of Mypoia

If you've ever seen your prescription, you may have seen some numbers with either a + or - sign in front of them. Well, a - sign indicates short-sightedness.

There are 3 types of Mypoia:

Mild myopia - which has a measurement of between -0.5D and -3D. It is the most common type of myopia
Moderate myopia - has a measurement of between -3D and -6D. 
High myopia - has a measurement of more than -6D. 


Can Mypoia Be Treated?

Mypoia can usually be treated  by corrective lenses, such as contact lenses or glasses. The lenses allow light to be focused on the retina rather than in front of the retina
Laser surgery is also another option to correct the defect but it can't be used in children because their eyes are still developing



About Me

My name is Keirisha and I am currently on work experience at Good Looking Optics, Enfiled. I’m in my final year of A Levels, hoping to study optometry at University next year. 

I've wanted to study optometry since quite a young age after visiting the opticians for the first time. Ever since then my interest in how the eye works has been ever growing.