Question

[Curious]

Hello. I'd like to ask when the difference is supposed to become noticable if someone has a different prescription for each eye. I have -2.75 and -2.25. I can sometimes feel that my eyes are seeing different things. I think the -2.75 is my dominant eye.

[chip anderson]

If you mean difference in image size, yours is so negligable it's extremely unlikely
that you could possibly be aware of it. You might have a slight muscle imbalence or your Rx may not be be precribed or filled as well as possible. But image differnence with 1/2 diopter imbalence (if this is the exact correct Rx), highly unlikely.

Chip

[Spexvet]

If you mean difference in image size, yours is so negligable it's extremely unlikely
that you could possibly be aware of it. You might have a slight muscle imbalence or your Rx may not be be precribed or filled as well as possible. But image differnence with 1/2 diopter imbalence (if this is the exact correct Rx), highly unlikely.

Chip

I agree:cheers: - on all points

[drk]

What do you mean by your eyes are seeing different things?

[Curious]

Hi Chip. I didn't mean that I experience a difference in image size, although I see how you might have thought that. What I meant - and I hope this answers your point drk - is that the right eye, which is the -2.75 one, seems to be trying harder to see. I can feel the difference between them. The left one isn't uncomfortable like the other. I've always had a bit of a difference between the two prescriptions and wouldn't have thought that .50 would have made much difference.

Chip - you got me thinking about maybe the prescription for the right eye should be stronger. If I compare the right and left the right seems alot worse. I don't wear correction 100% of the time and admittedly the symptoms aren't so obvious when I do. I guess you'll say that's the answer but I am interested in the reason and if I understand it then it may change my wearing habits. Since I got glasses about ten years ago I've been interested in optics so knowing what's going on with my own vision is interesting to me.

Thanks for taking the trouble to read/respond to this.

[Jedi]

Curious, does your RX have your visual acuity referenced on it. If one eye was refracted to 20/20 but the other was only able to be refracted to 20/25, you would be able to detect a variance.

You also say you don't wear the correcting 100% of the time, I hope you mean you alternate between contacts and glasses and not between corrected and uncorrected.

[Curious]

Hello Jedi

I checked my most recent prescription which was from last December but it doesn't show visual acuity.

Yes I do go without correction some of the time but I guess from your tone that you wouldn't recommend it/are surprised that I do. My optician didn't discuss it, he obviously assumed I'd figure it out for myself but he did say he thought this prescription was quite strong. I presume if I was your patient you'd just tell me to wear them all the time? :hammer:

[Ian Jordan]

Whilst image size differences and prismatic effects due to spectacles are negligible it is possible that percpetual effects other than than acuity differences are present. Sequencing may be a problem causing symptoms such as asthenopia (non specific frontal headaches/discomfort/dry eyes), vestibular reflex problems, nerve pathway crossing difficulties e.g. forms of synesthesia.

If centres are incorrect a whole new range of matching problems occur at the cortex (often these are the cause of non tolerance cases). Vertical centres should also be considered as a potential cause of problems as supravergence tolerances can be very small. Torticollis may be introduced as a compensatory strategy and muscle tonus differences are measurable. Magnocellular effects must also be considered.

Even small differnces in Rx can be important in perceptual problems although they are often discounted on the basis that the mathematical differences are small.

[Curious]

Ian - you say

Sequencing may be a problem causing symptoms such as asthenopia (non specific frontal headaches/discomfort/dry eyes),

I'm not sure what you mean by 'sequencing'. I wonder if this is my problem. Thanks.

[Jason Carruthers]

Whilst image size differences and prismatic effects due to spectacles are negligible it is possible that percpetual effects other than than acuity differences are present. Sequencing may be a problem causing symptoms such as asthenopia (non specific frontal headaches/discomfort/dry eyes), vestibular reflex problems, nerve pathway crossing difficulties e.g. forms of synesthesia.

If centres are incorrect a whole new range of matching problems occur at the cortex (often these are the cause of non tolerance cases). Vertical centres should also be considered as a potential cause of problems as supravergence tolerances can be very small. Torticollis may be introduced as a compensatory strategy and muscle tonus differences are measurable. Magnocellular effects must also be considered.

Even small differnces in Rx can be important in perceptual problems although they are often discounted on the basis that the mathematical differences are small.

Dude, that's what I was going to say, except I didn't think the word "whilst" was still in use.

[shellrob]

I'd start with having your eye doctor double check your prescription. Then see your Optician.