Physiological defect: Presbyopia.(1) Vision, Appearance and Symptoms

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Presbyopia is what everybody knows as “old sight”. It is not considered as refractive disorder or an ocular illness.

Vision of presbyopic

The typical complaint in presbyopia is “BLURRED VISION AT CLOSE DISTANCE”. A presbyopic person stretches her arms in order to see better, but in a certain moment “THEY ARE TOO SHORT”.

Distance vision may have not any changes, at least in the first stages.

Appearance of presbyopic eye

The shape of the eye is like a myopic or hyperopic or even emmetropic one at young age; but the difference is given by the crystalline lens. When a person looks at objects up close, she is not capable of focusing them on the retina, but behind (as hyperopic people), therefore seeing them blurred.


Prevalence

Everybody will have suffered presbyopia sooner or later, after 45 years old.

As presbyopia is age-related, its prevalence is higher in societies in which larger proportions of the population survive into old age.

For instance, from all Spanish population, 43% suffers “old sight”. And from this 43%, 7% of presbyopic people have never checked their vision in any previous occasion. Because of the increased life expectancy, within 10 years, more than half of the Spanish population will suffer from this condition.

It does not exist any way tested to be true in order to prevent it.


Symptoms

Incipient presbyopia (the first symptoms)

• It is difficult to maintain the performance of near task in a continuous way.
• Headache because of the continuing effort.
• The letters seem to move on the paper.
• More light is necessary in order to see better.Near vision is worse at the end of the day.
• Sometimes it seems that we “do not control” our eyes (as the accommodation and convergence are related, the gradual loss of accommodation involves the progressive worsening of our fusion, resulting in Convergence insufficiency, and even in a double vision when we are more tired).

Evident presbyopia

• We stretch our arms in order to find the distance where we can read whatever we want, until a certain moment where we do not get to read although we stretch them completely.
• At the beginning presbyopia only affects near distance (documents, handicrafts,…), and little by little it starts affecting intermediate distance too (computer,…)
• We tend to avoid the small texts and precision tasks in near vision whenever we can (we do not sew anymore, we do not read so much, we do not perform certain leisure activities that we liked… :-( )
• We always look for natural light or a good light lamp.
• It is usually accompanied by “Dry eye”.

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Refractive disorders: Astigmatism. (4) Symptoms.

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Behavior of astigmatic people

A low degree of astigmatism USUALLY causes more symptomatology, because the visual system tries to compensate it, and does not show blurred vision symptoms; therefore, at the beginning people do not usually associate the symptoms to a vision problem.

• The main symptom is the distorted and blurred vision in high astigmatism; and headache, visual strain, ocular itching and red eyes in low astigmatism.
  
  As I explained in a previous post, a young hyperopic person with the low degree is able to “disguise” her disorder if her accommodative function works correctly. But in the case of an astigmatic person, although her accommodation is in correct condition, it “gets crazy”, because it has several points or images that fall in different planes regarding the retina; accommodation is constantly trying to focus all of them, without distinction. The closest points of the retina will cause less tension, but those that are farther will be more difficult to compensate. Visual system will be exhausted and the symptoms (red eyes, itching, burning, tearing, headache, visual strain,…) will appear.

• Although a person with astigmatism is usually born with it, if this is low, she could compensate it during the infancy. But as the child grows up and the school request is higher (more number of homework or study hours, more reading, more understanding,…), and her accommodation naturally decreases, the child has got more problems to compensate it; and this moment is when the astigmatism is obvious, showing several symptoms. That is why, many people say their astigmatism appeared between 10 and 20 years old.

• So, an astigmatism will cause more symptoms if it is associated with a hyperopia than with myopia, because hyperopic people have a more exhausted accommodative system due to the excessive effort that she makes to compensate her refractive error.
  

• That is why astigmatism can also cause learning disabilities.

• It can develop wrong postural habits, like tilting her head when looking far away or looking up close, since when the astigmatic person tilts her head, can find the position in which she sees better, or where the image is less distorted. This can cause cervical problems in the long run.

• “Blurred” or double vision greater at near than at distance.

• While she reads, she jumps the line or the letters seem to be moving.

• Visual strain and feeling sleepy.

• Headache mainly in the fronthead and in the eyes.

• Photophobia (light sensitivity).

• Frequent conjunctivitis or blepharitis.

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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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Identifying signs and symptoms for a visual problem

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Detection of visual upsets, mainly in childhood stage, is done when we observe and assess the child’s attitude and behavior when he performs a task.

- Itching, stinging or watery eyes

- Blinks or rubs his eyes a lot
- Frowns or scowls in order to seeing better
- Blurred vision at distance or at near

- Rigid body or moves his head forward or backward when reading or looking at a remote object
- Very close distance when watching TV, writing or reading a book
- Has difficulty for copying from the board
- Unusual eyestrain when finishing a task or decline in the reading after long periods
- Omission of tasks at near
- Fatigues quickly during reading, writing or drawing
- Bothered by the sun and lights changes
- Headache and eye pain
- Negative behavior at school or at work
- Bad head or body posture
- One eye drifts or aims at a different direction than the other (look carefully, this can be subtle). This is significant even if it only occurs when the child is tired or stressed
- Closes or covers an eye, or twists or tilts head, when reading and writing or watching TV…
- Double vision

- General difficulties at Reading:

• Moves head when reading instead of to move the eyes
• Words slide together
• Reading speed below chronological age
• Does not understand what he has read or does not remember it
• Loses place, skips lines or rereads words or lines
• Needs to use finger as a marker to keep place
• Reads in loud voice or moving lips
• Omits or adds words or tries to guess them from the fast recognition of one part of them
• Mixes syllables when reading and numbers in maths
• Reverse letters, syllables or words
• Avoids reading or other close-up tasks

- General difficulties at writing or in the hand’s motor skill:

• Irregular and changeable letter size
• Small spacing
• Inability to write in a straight line
• Reverses letters, words and numbers when writing or copying
• Favors the reading with regard to playing or motor activities
• Favors oral exams with regards to the written ones
• When coloring, he can not keep his work inside the lines
• Does not like to draw
• Grabs the pencil badly, or takes out his tongue or does strange gestures with his face when he uses his hand to perform something that requires eye-hand coordination
• He is slow when he has to follow a dictation

- Difficulty to comprehend and perform instructions
- Bumps into things
- Sometimes he appears clumsy
- Becomes easily distracted
- Has a short attention span and needs a lot of rests
- Poor concentration
- Homework takes longer than it should
- Poor visual memory
- Negative and/ or aggressive character
- Troubles for adapting to the changes
- Gives up easily (says “I can’t”, before trying)
- Dizziness, nausea or motion sickness
- Poor posture when sitting down and working
- Incapacity of being kept sat down on a chair more of 5 minutes
- Walks on tiptoe
- Balance troubles
- Confuses right and left in himself and/or in the space past age 7 (and sometimes up and down)
- Poor performance of sports or coordination of hand-eye and foot-eye (ball skills and team games): catching and hitting a ball
- Etc.

These manifestations will help you yourself to detect if any child, in your environment, may have an undiagnosed visual problem.


Moreover, in the optometric office, the professional will give you or ask you a brief questionnaire about the child, his development and his visual habits. Sometimes it is very long and tedious or even sometimes, you do not know what relation, some questions may have with the eyes or with the problem that you bring to the office; but there is not random question in these questionnaires, all of them give very important information that will help the optometrist to achieve a better diagnosis about the problem that the child has got. Therefore, even though everybody thinks that their children are wonderful and perfect, think that if you go to the office is because you suspect something, and if so, being as sincere as possible when you fill in these questionnaires is better, because the lies and half truths or half informations or underestimating the details that show where the child is not so handy, will not help; this information is the most valuable in the questionnaire.

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