Amie wrote:
I noticed my 2.5 year old daughter doing a lot of exaggerated blinking lately, so I took her in for an eye exam. I was told that she needs glasses. Her prescription is +5.75 in one eye and +6.25 in the other with slight stignatisms in both eyes. I was told that the prescription written is lower then she actually needs to give her eyes room to adjust as she grows. I’ve been doing a lot of research on farsightedness and I was wondering if a child with her type of vision problems needs to have glasses. If she doesn’t get them is there more of a chance that she will outgrow some of the farsightedness? Her eyes are straight and she seems to be able to see everything close up and far away. Any insight you can give me into this would be great thanks!
ANSWER
Dear Amie,
This is a very good question. Thanks for asking it.
Your optometrist is perfectly right to say that at +5.75 and +6.25 your child needs glasses. Farsightedness creates an image that is focused back from the retina. Eyes have to adjust their “power” to refocus that image at the appropriate point on the retina. This is done with the effort of the crystalline lens. Over +4.00, many studies have proved that the effort to compensate farsightedness is too demanding for the visual system. At near, you have to add +2.50 to the visual demand at far. That means that your daughter has to compensate +7.25 and +8.75 at near! She can, but she is already rapidly developing visual fatigue… OR she compensates by not looking for a long time at near or doing many things at the same time. Some parents think their children are hyperactive but in fact they are just hyperopes… She also develops a tendency to look at near at a closer distance than normal. This is linked to the fact that for every dioptre the child has to compensate the eyes turn inward by 6 degrees. For a natural demand of +2.50 to +4.00, a regular reading distance is maintained. At +7.00 or +8.00 your daughter is focusing and seeing well at near only if she is at less than 12 cm! Very close. Further than that, she would see double since the eyes crossed at this distance.
In the long term, it is not possible, with such a problem uncorrected to learn to read efficiently and to maintain near work for more than 1-2 minutes. Many children drop out of school simply because their visual system cannot handle the demand.
Even if the child seems to see well, high hyperopia is known to be amblyogenic, meaning that without the appropriate correction the eyes will never develop to their optimal level. We can translate that by the fact that, without correction, these eyes will remain at 80-85% of their capacity and that further on the binocular vision and the 3D vision will be also reduced. This is sad because that can cause reading difficulties, headaches while doing computer work and this reduced capacity can also make the difference in career choices: a policeman, a firefighter or an aircraft pilot have to have 100% percent vision with full 3D vision.
Under +4.00, habitually we do not correct and we observe how the eyes are developing between 2 and 8 years old. This is the critical period when eyes have to be appropriately stimulated in order to fully develop their capacities. This period of development is known as the emmetropization phenomenon. This means that whatever the visual problem is from birth, the eyes tend to compensate for it in order to get perfect unaided vision at 8 years old. When you are under +4.00 this phenomenon should not be altered and to prescribe glasses could interfere with “nature”. This is another story over +4.00, which is the case of your daughter. Considering that the eyes don’t have the possibility to fully develop their potential, emmetropization is cancelled. This is also true for myopia over 5.00D and astigmatism over 1.50. Yes, just 1.50 because astigmatism is way more disturbing for the visual system than spherical refractive errors such as farsightedness and myopia.
The way to prescribe glasses has to take in account the age of the children. This is true that, for hyperopes (farsightedness) we have to lessen the amount of the full correction by the normal visual demand at near. For a younger child, like your girl, a +2.00 reduction is OK. Older than that, this reduction will be +1.25.
To get the right script, it is necessary to perform a cycloplegic refraction. This means that the optometrist or the ophthalmologist will put some drops on the eye of the patient. This aims to alleviate any compensation of the refractive error by the natural lens of the eye, the crystalline lens. Once done, this test allows us to assess the “real” amount of hyperopia on which to base the prescription.
It is not rare to find +2.00 to +3.00 higher values compared to the test done without cycloplegia.
For instance, if with that test your daughter is +6.00 at far, I would start the prescription at +4.00 and see how the eyes will develop. IMPORTANT: These glasses have to be worn ON A FULL TIME BASIS. ALWAYS.
With time, this prescription will be updated according to the evolution of the eyes.
In the long term, most of the hyperopes, well corrected with appropriate glasses, will be back on the emmetropization pathway. This means that the system will adjust to lessen the amount of hyperopia over the years. Most of the hyperopes cease to wear glasses by the age of 12-15 but again this is unique to each patient. Genetics play a big role here.
Some patients will remain hyperopes, no matter if they wear glasses or not at a younger age. Again, glasses will not do anything but good for the development of your children. This is a misconception that eyes can be made stronger by leaving them without correction. The visual system is not built that way.
Consequently, my recommendation are the following:
1) Re-consult your optometrist if the first exam was not performed with drops.
2) Follow his recommendation — it seems that you are in very good hands considering the recommendations he gave to you.
3) Your daughter should wear her glasses on a full time basis. Her future in school depends on the way you deal with her hyperopia NOW.
4) Make regular follow-ups until the age of 8 to confirm the full development of the eyes.
5) Make annual follow-ups thereafter.
6) Contact lenses can be considered by the age of 8 for most of the children. There are a lot of benefits and self-esteem of the children is boosted as a consequence. Many studies were done in the last years that prove this.
Thanks for sharing that with us. Hoping that this will help,
Dr. Langis Michaud, OD, MSc, FAAO (Dipl)
Associate Professor
Université de Montréal
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