eye muscles strain when wearing plastic lens

[nav999]

My eye power is -4.75 and -4.5. When I wear spectacles (plastic lens) of the correct power or of power -4, I feel a burning and dry kind of feeling on the left side of my left eyeball. This happens on the outer surface of the eyeball, and happens in a kind of a half centimeter wide rectangular patch of burning on the sclera starting from the edge of my iris and extending to the middle left half of the eyeball. Then the burning starts in the lower half of the eyeball (on the sclera). Also, right from the moment I wear the spectacles, the muscles of the orbicularis oculi and the bottom most muscles of the inferior tarsus start getting tense and strained. When I take off the spectacles, I feel those muscles having an instant relief and un-tensing. But if I wear a glass lens of power -3.25, there's no such problem (I'm going to purchase glass lens of higher power today as a trial experiment, but I would be very grateful if you could help with this. I've been facing this problem for 2 years and no ophthalmologist has been able to help. Dry eyes and astigmatism ruled out. No visible eye disease either. Lack of sleep is suspected to be the problem, but I can't understand why I'm unable to wear spectacles of the correct power.

[nav999]

I'm twenty nine years old. I doubt if age would have anything to do with it. Lack of sleep might, but still, it's a bit weird that I'm unable to wear spectacles of the right power.
There's a lady who describes that she has a similar problem, but she blames it on the plastic frame. In any case, even she can't seem to be able to tolerate lenses of the correct power: http://www.youtube.com/watch?v=SzfAJKn8WVU

[rward80]

How old are you?  That could affect your troubles.

[nav999]

Thank you Dr.Doreen, but a pupil dilation test has already been done on me, and the doctor did a computerised eye check which showed very skewered results before and after the dilation. My brother has just completed his MBBS, and he said the results were weird. A week later I went to the same doctor who measured my eye power as -4.5 in both eyes with -0.5 astigmatism of some angle in one eye. Twenty minutes later I went to a different ophthalmologist in the same hospital and he measured it as -5.25 in both eyes. I've been getting different readings from every ophthalmologist. But that's not my point. My point is that -3.25 is definitely not the right power or even close to the right power because vision is not clear. -4.5 or -4.75 is indeed the right power, but as I described earlier, I get strain in those particular muscles when I wear spectacles. My brother says the tarsus and oculi are voluntary muscles and shouldn't be affected. Then why are these muscles getting strained. An important point to consider would be that I have been suffering for two years now. Earlier it was chronic. I've posted about this earlier too: http://www.medhelp.org/posts/Eye-Care/eye-strain-for-two-years/show/2032781#post_9608454

[Doreen Fazio, M.D.]

One possibility is that the -4.50 and -4.75 are overpowered for you and you are having to accommodate to see.  Ask your doctor to do a cycloplegic refraction.  In this exam, your pupils are first dilated in order to relax the focusing (accommodating) muscles, to give an accurate refraction; if you accommodate during the refraction, the result will be more myopic than you need.  A cycloplegic refraction will help to uncover the true amount of myopia, without the accommodated extra amount, and the result may be closer to the -3.25 which is comfortable for you.