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Monday, May 20, 2013
Eye and Vision Care
Strabismus and prescription glasses for kids
Our 5 yr old son was just diagnosed with Strabismus and is farsighted. He seems to have been able to see very clearly all along, but his one eye started turning in. We have never noticed a vision problem (i.e. reading signs, reads books, etc.). The prescription he was given was a spherical +3.00 which seems very strong. He is complaining that everything looks "fatter" and that letters are blurry to that point he can no longer tell what they are. Is the prescription too strong? The Optamologist was adamant at the time that he needs this strength. Please help.
Children who are farsighted can typically see very well both at distance and at near so the term is a bit misleading. Actually, most kids are farsighted when they are infants and toddlers and they grow out of this as they age.
Being farsighted means that the length of the eye is slightly shorter so the child has to accommodate or focus at distance to see clearly, just like everyone needs to do to see clearly at near. The more farsighted the child, the more he or she needs to accommodate at distance.
A child has a high amount of focusing abiliy so in most kids, farsighted is not an issue. In some kids, however, it does cause visual issues. Unless you are farsighted, you only accommodate to see near objects. Because of this, our brain is wired so that when we accommodate, our eyes reflexiively turn in or converge (to point them at near).
To keep objects at distance single, the child must therefore use effort to keep his eyes from turning in by actively diverging (or turning his eyes out). This effort can cause some eye movement problems with reading and it can cause fatigue or it might go completely unnoticed without a coprehensive eye examination. The fatigue is seen when the eyes occasionally turn in when the child is tired, especially when he or she is looking at near objects.
If you notice that the eyes are turning in occasionally, then this is a sign that the visual system is being stressed to near its maximum ability. When we see this in clinic, the treatment is to reduce the amount the child accommodates by prescribing either plus lenses for distance to correct the farsightedness, or distance plus lenses and bifocals.
Plus lenses do magnify the world so objects will appear larger through the glasses. Also, if the child does not wear the glasses regularly or looks over the top of the glasses, then his or her eyes will not adapt to the lenses. The child will have spent his or her whole life focusing or accommodating at all distances before getting glasses. Now with the glasses, the child doesn't have to focus as much. However, some kids will still focus with the glasses on (visual habit) so the glasses are not clear. This should stop being an issue quickly if they wear the glasses regularly. If it continues, then the strength of the prescription should be rechecked.
Also, children often don't like wearing glasses because they can see fine without them (unlike a nearsighted person who can only see with glasses). You have to reinforce that they are wearing the glasses so their eyes don't have to work as hard and not to clear things up. Reading and near work should be easier with the glasses if the prescription is correct. Also, as the amount of farsightedness can change with age, regular follow-up care is essential to make sure the prescription stays accurate.
Michael Earley, OD, PhD, FAAO
Assistant Dean for Clinical Services
Professor of Clinical Optometry
College of Optometry
The Ohio State University