Astigmatism and simple tests

[Harry_]

Hi,

It would be great if you could find the time to consider my questions, i have had them for some time and find it tricky to discuss them with a professional.

First, I'm nearsighted, right eye much worse than the other, and the bad eye has a strong astigmatism. I wear glasses some of the time, but they can't correct my right eye fully. But that's not what i want to discuss. What i want to discuss is some simple tests, or rather effects, i noticed.

The easy to explain one first: When i look at a pinpoint light source from a distance with the bad eye i can see a line traced away from that light source. This image is very stable and i could easily draw it.  What it looks like right now is not a straight line (which is how astigmatism is always described), but rather a curved line going first left and curving down where the down travel is about double the left travel. I am not certain, but i believe some time ago this light trace was more like straight down.

Is it normal for astigmatism to see a curved line?

Also, i notice when i put gentle pressure on the area around my eye it changes the shape of the curve. Previously i also noticed applying gentle pressure in some areas will make my vision better and in other spots it will make it worse. I assume this slightly deforms the eye and it is what i would expect. But i would like confirmation if my theory is correct.

The other thing is slightly trickier to explain, but i noticed it many years ago before the pinpoint source thing. When i hold for example a finger in front of one eye (the other closed) and look just over the edge of the finder there is an area, like a band, lust above the finger, in which i can see much more clearly. This band is widest when the edge is horizontal, which coincides with the axis of my astigmatism. As i rotate the finger it gets narrower, and at 180 degree (or if i look under the finger) there is a blurry band instead. I assume this confirms there is some astigmatism, and also indicates the axis? My theory is the edge of the finger obstructs the light going to the area of the eye which has the picture out of place due to astigmatism, thus i see more clearly in that narrow band, is that correct?

I also did the simple test where you look at a pattern of parallel lines, which is rotated, and identify the point where the lines appear most blurry. The axis seems to be vertical, but I'm not sure how this goes together with the curved line i see from the point light source (should that not lead to a slanted axis?).

If you have eyeglasses fitted around here it basically involves looking through a computer controlled machine and trying things (along the lines of "is this better - or that"). Now I'm an engineer by trade, and it frustrates me to do things by plain trial and error. I mean i the glasses i have are perfectly sufficient, but i would still like to know what exactly is wrong with my eyes and if there would be any way to correct it better. I feel like i have some reduction in three-dimensional vision because the one eye is so much worse, and i also don't see as well as i would like in low light condition (e.g. night driving).

Right, this turned out rather longish, but what do those effects i noticed tell me about my eye?

Thank you so much.

Harry

[Harry_]

Thanks anyway.

I can't quite understand why nobody seems able to interpret the most basic symptom - what the patient sees. Maybe one day I'll find someone able to explain it.

[John C Hagan III, MD, FACS, FAAO]

Sorry Harry I can't help you on this one.

JCH III MD