Refractive disorders: Hyperopia. (3) Symptoms

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Hyperopia degrees

• Low: 0 - (+2.00) D
• Medium: (+2.25)-(+5.00) D
• High: More than +5.00 D

Behavior of hypermetropic people (symptoms)
Usually, if hyperopia is low, hyperopic people do not have any symptom, and the time can go by until they show any. Besides, the younger the person is, the lesser the symptoms she will have, since her accommdation works perfectly and therefore, she can compensate the problem without any effort.

Either medium hyperopic, or not so young people or in certain cases will show (without wearing the refraction) the following symptoms:

• Constant or intermittent blurred near vision.

• If hyperopia is medium/high, it also affects distant vision.

• Visual inconvenience when she performs close-up tasks.

• Headache, visual strain, ocular pain, burning, itching, tearing, red eyes… (due to incapacity of keeping the effort of accommodation that is demanded).

• In the case of low hyperopia that people have always been able to compensate without any problem (both as from a distance and as close up), as time goes by or in a special period with too many close-up tasks (at work or at school), they show inconvenience and discomfort and they do not know the reasons why they are caused. They have always seen well and have not had any previous visual problems; and they do not think, that this can be the cause of their problems. Before seeing blurred at near (while they can still keep the accommodation with effort), they usually show the symptoms above (headache, visual strain, itching, red eyes,...).

• In the case of children or young people, they usually have problems with the reading: line jumping, jumping letters, letters “seem to dance”, “they don’t stop!”… (presbyopic or old sight people also say these same words). These symptoms cause that they have aversion to reading.

• They as well perform facial contortions or frequent blinking while reading, that shows the effort that they are doing in their close-up tasks.

• Poor eye-hand coordination.

• In children (younger than 3 years old), if hyperopia is high, it can cause accommodative convergent strabismus (crossed-eye). This is because as they are young, they can perform much effort in order to see the image clear; but since accommodation and convergence are related (I will explain this better later), when the eyes perform too much accommodation, they also converge a lot, and one of eyes gets crossed. Consequently, this can also cause lazy eye or amblyopia on that eye.

• In the case of low hyperopic people who have always been able to compensate without any problem and they have always had a enviable sight in their youth, they inevitably undergo presbyopia. But unfortunately for the hyperopic, they suffer it before that the rest of the people, before they are 40 years old. These people will think that their arms are shorter each time, because they need put their reading text farther (but this refractive disorder deserves its own post later).

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Refractive disorders: Myopia or Nearsightedness (1). Vision and Symptoms

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As I wrote two posts ago, myopia is the best known refractive disorder worldwide. And that’s why, I have many things to tell you about this, so, I will need more than one post…

Myopic person’s vision

The typical complaint in myopia is “BLURRED VISION WHEN TRYING TO VIEW DISTANT OBJECTS”.

DISTANT vision:

Therefore, a myopic person placed next to this lamppost in Gran Via at Madrid, looking at distance, she will be able to focus (see clear) this nearby lamppost, but as her eyes look further, she will see in a blurred way more and more. Of course, it will depend on the degree of myopia or quantity of myopia that she does not wear (assessed in DIOPTERS –D-); a myopic person with a little refraction, will be able to see clear further than other that has more myopia.

CLOSE vision:

As with distance vision, this also depends on the degree of the eye refraction:

- If it is compensated (she wears corrective lenses -eyeglasses or contact lenses-), she sees well, but, in the case of a low degree myopia (lower than -3.00D), she will be doing an unnecessary effort with them. In the case of a medium degree myopia (between -3.00 and -6.00D) or a high degree myopia (higher than -6.00D), the optical effect of the lens will decrease the size of the letters very much, and she will need to bring the text very close.

- If it is not compensated, a person with low degree myopia will read without any problem and much more relaxed. In the case of a young person with a medium degree myopia, she will have to do much more effort than any person, but she will be able to do it; and an adult person with medium degree myopia or any person with a high degree myopia, she will see it probably blurred.


Appearance of myopic eye

- The nearsighted eye is usually longer than normal, because of the eye axial length is greater than normal (> 24 milimeters).

- In the other hand, the power of its lenses (cornea -1- and crystalline lens -8-) is higher than normal (cornea: >43.05 diopters and lens: 19.22 diopters), being its surfaces more curved.

According to these two features (and/or others), the image is not focused on the retina, but in a point in front of it, so that the image of the distant object (placed at 20 feet -6 meters-), is seen blurred.



Prevalence

Some data:
- In Spain, as well as in USA and UK, up to 25% of the population is myopic.
- In some Asian areas, such as China or Malaysia, up to 41% of the adult population is myopic to -1.00 dioptre and up to 80% to -0.50 dioptre.
- In Australia, the overall prevalence of myopia (worse than −0.50 dioptres) has been estimated to be 77%.
- However, in countries such as Brazil and India, the prevalence is estimated at 10% or lower.

In general, approximately a quarter of the adult population from Western Countries and 80% of children during school-age years, have myopia.


Behavior of a myopic people (symptoms)

Without wearing her refraction correction:

- She sees blurred at distance.

- A myopic person sees better at distance when squeezing the eye lids making a narrow opening.
- She can not see at distance but she does see very well at near: It is difficult for her, for instance, seeing the chalkboard at school or seeing a sign while she drives; however, she sees very well a book or the directions for using a medicine.

- She sits very close to watch television, computer or chalkboard.

- She brings the writing, reading, painting, drawing, etc., very close to her eyes; it is like if she were eating the paper or what she is looking at, mainly if the myopia is high.

- If the myopia is low, she can work at near in a more comfortable way and for more number of hours without getting tired.

That’s why, they prefer activities as reading, drawing or handicrafts, that is, any activity at near.


- They are shier and more absent-minded, since they are very “focal”, that is, they are not very aware about what surrounds them; they are able to concentrate very much and to be many hours performing a task, so that the world can fall surrounding them and they do not realize, neither whether it gets dark or not, nor whether anyone has arrived at home or not, nor whether it is already the dinner time,… This ability to concentrate (that others, as a hyperopic people, envy), acts against themselves, because, it favors the increase of the myopia, since they do not rest even to have a glass of water. This ability allows them to be good workers and to have a good school/labor performance.

- Related to all previous, they have a reduced peripheral awareness, due to as the “excessive” concentration, as well as to the close working distance that they use sometimes without realizing.
For instance, when they are reading a book, they bring it closer more and more, because, this way, the letters seem bigger. But, in one specific moment, the eye movements are not enough and they need to move their head to be able to read a whole line. If they try to get away from the text, the letters “seem smaller” (therefore, more uncomfortable for them), but the visual field increases and they are able to read faster, because they can cover a whole line just by having a look.

- Sometimes they suffer headaches (mainly in forehead and temples) or eyestrain, and sometimes, they might even squint noticeably when they are physically tired.



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