Hyperopia, or "far sightedness" can be a more difficult concept to grasp than myopia. Myopes need their glasses to see clearly, but it is not that straightforward for hyperopes. When you think about someone that wears glasses, the classic image is a "Mr. Magoo" type that is bumbling around blind without their glasses. The thing is, hyperopes (in most cases) can see pretty well most of the time. People with only mild amounts of hyperopia generally never even know they have refractive error until their focusing system begins to decline in a condition called presbyopia (more on that later) that occurs around age 40.
In simple terms, hyperopes see better in the distance than they do up close (the opposite of myopes if you recall from this post). Opposite from myopes, light entering the eye falls behind the retina in hyperopia. The focusing system (accommodation) must be used to bring the image back to lie clearly on the retinal cells. Basically, hyperopes have to use their focusing system all the time, distance and near. Known as accommodation, the focusing system must overcome the patient's prescription at distance to see clearly, as well as the prescription AND the near demand of a target when something is held up close. This is why vision is more blurry at near to the patient; their focusing system is just too overwhelmed by the demand.
Why does light fall behind the retina? Well, a patient with hyperopia has either:
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| Mr. Magoo: a man sorely in need of contact lenses |
Why does light fall behind the retina? Well, a patient with hyperopia has either:
- flatter cornea that doesn't bend light as much as an average cornea
- or a shorter eyeball
Hyperopes are corrected by "plus" lenses which act to move the image back to the retina, and thus to relax how hard the focusing system must work to see things clearly.
My biggest challenge as an optometrist with hyperopic patients that still have a functioning accommodative system? Convincing them to wear glasses! Especially if they are children with an active and healthy focusing system. When low hyperopes wear their glasses, they aren't going to see any clearer with their glasses on for most distances. What they will notice is that things look magnified, and this relaxes how hard their eyes have to work for activities especially at near.
What to do if your child is hyperopic? Children through early elementary school are normally hyperopic, and most do not suffer from any visual discomfort do to their healthy focusing system. If your child is getting frequent headaches at school, suffering from discomfort when reading, or seeing double/expressing an eye turn, these are all reasons that a hyperopic prescription would be necessary. Typically these glasses are worn at school and for near activities, and an emphasis is made on balancing the prescription so both eyes are using the same amount of accommodation (or focusing effort). Again, your child may tell you that their glasses don't help them see any more clearly if they are hyperopic and this is normal! The glasses are to ensure that their focusing system does not become overloaded and can continue to provide clear vision to the wearer.
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