Hypermetropia is an eye disorder in which one can only able to see the far objects(i.e objects far to his eyes) clearly, that is why Hypermetropia is also known as Farsightedness or also as Hyperopia all are same.
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| Eye Test: Farsightedness |
Scientific Explanation In normal cases light that enters our eye will form an image on the retina that means eye lens focuses the light on the retina but in the case of farsightedness instead of retina light focuses behind the retina causes us to see only near objects.
let us understand with a diagram.
Normal Eye Diagram
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| Normal Eye Diagram |
Hypermetropia Diagram / Eye with Farsightedness defect
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| Hypermetropia Diagram |
How the light does propagates inside a hypermetropia eye? (Far Objects)
The light from the far object travels in the usual way. It gets focused on the retina only. No problems there.
How the light does propagates inside a hypermetropia eye? (Near Objects)
First of all the light rays from a near object coming towards the eye are almost parallel to each other. And when these rays enter the eye, they get converged behind the retina instead of on the retina. This is the reason for the blurriness.
What causes the light to converge in front of the retina rather than on the retina?
The small size of the eyeball is one of the reasons which results in this eye defect. Due to the shrinking of the eyeball, the distance between the lens and the retina is less than usual. Because of this less distance between the two, the image is formed behind the retina and not on the retina.
Well, one thing we must note here is that the lens functions in its usual way. It does its work neatly as it is supposed to. The only thing is that the image is formed at a different position.
Causes of Farsightedness Vision
- Shortening of the eyeballs. In this condition eyeballs of the person become too small.
- Change in the Shape of the Cornea or an eye lens.
- Can cause genetically.
- Environmental factors.
- Also caused according to the type of job and stress level on your eye.
- Blurry near vision is the main symptom of farsightedness.
- Headaches.
- More eye strain.
- Water in the eye during reading.
- In this eye condition, you can see far objects clearly but near objects become unclear or different from far objects in the initial stages.
Hypermetropia in children | Hypermetropia in child treatments
Hypermetropia or hyperopia as the other term you might have heard essentially means long-sightedness it's extremely common in children many children are long-sighted and that's because a long-sighted eye is a slightly smaller eye but many children compensate for this by having a very powerful lens that means they can alter their focus to see things clearly but some children particularly those that are more long-sighted may struggle to do that and in order to form a perfectly focused image a pair of glasses may be necessary just to relax the eyesHow will you know that your child's long-sighted?
If you are longsighted then there is a very high chance that your child also has hypermetropic vision because it is genetic and passes in families, a very strong predictor of a child's glasses prescription is the same as their parent’s glasses prescription particularly at the same age.- Convergent squint due to hyperopia
Sometimes being long-sighted can be associated with developing a convergent squint so one eye turns in and the treatment for that kind of squint is just giving a suitable pair of glasses that may well just straighten the eyes out completely.- Lazy eye due to hyperopia
Hyperopia in children sometimes results in a lazy eye because the brain starts ignoring images from the hypermetropic eye or eye with a weaker vision. If this condition is not corrected at a young age then there are very high chances of permanent vision loss of the weaker eye.
Prevention Tips
- Farsightedness is prevented by proper eye care and a healthy diet plan. Nowadays it also becomes more frequent as myopia only in the US it is frequent to approx to 7.6% in children and teenagers because of our daily unhealthy routine and Lifestyle.
- Glasses and Contact Lenses.
- Other methods are also there which include LASIK surgery.
From above all mentioned methods healthy diet, wearing Glasses and Contact lenses are on top and from these two wearing glasses are more used because of the following reasons
- Less complicated.
- Fast results.
- Cheap.
How do we overcome Farsightedness defect?
It can be corrected by using a convex lens. We place a convex lens in front of the hypermetropic eye.
What does this biconvex lens do?
It refracts light, but its main objective is to make sure that the image is formed on the retina only. By changing its shape, the lens controls the direction of the propagation of light. This ability of the lens to change its focal length is defined as the accommodation power of the eye.
Correction of Hypermetropia using power glasses
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| Correction of Hypermetropia using a convex lens |
As we can see from the above diagram that with the Convex lens of a particular focal length remove the Hypermetropia defect in the eye. Convex lens converges the light so that it falls on the retina of the eye and make a clear image of the far as well as near objects.
Formula to calculate the focal length(f)
1/f =1/u + 1/-v
By putting the values,
Q. The near point of hypermetropic eye is 1m. Find focal length and power
v = 1m = 100cm (distance of the image/ near distance)
u= 25cm (distance of the object)
We take u=25cm because normal cannot see the object near 25cm becuase focal length of our eye cannot decrease more than this limit
1/f = 1/(25) +1/-(100)
f= +33.3cm = +0.33 m
Formula to calculate Power(P)
P= 1/focal length (for 'f' in m)P= 100/focal length (for 'f' in cm)
P= 1/0.33
P= +3D
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