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Dr. James
Dr. James, Board Certified Ophthalmologist
Category: Eye
Satisfied Customers: 2286
Experience:  Eye Physician and Surgeon
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1) Is it theoretically (so according to the laws of optical

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1) Is it theoretically (so: according to the laws of optical physics) possible to do subjective eye testing on a computer screen, e.g. by blurring a picture in such a way that only a person with a specific correction can see it properly?

2) if not, why not? if so what would be the practical problems to overcome?

Can you explain the reasoning behind your question? This will help me provide a better answer.
Is this question regarding a school assignment?
Customer: replied 7 years ago.
I would be interested in looking at developing software for opticians if it is feasible
When we do subjective eye testing, we use 20 feet or 6 meters as the standard for distance visual acuity. That is far away enough to approximate what the vision would be at infinity.

If the letters are brought in closer, then the size of the letters need to be decreased as well. You also need a way to standardize the distance the patient is from the letters. In an exam room, there is a chair. In schools and such, there is line people need to stand behind. So for the computer screen, there needs to be a fixed distance and the ability to occlude one eye.

There are computer programs out there that displays eye charts, but my experience has been they are used at the standard 20 ft or 6 meters as well. If you are trying "computerize" the subjective part, that would be more difficult. When we ask "better 1 or 2" and so forth, we do not always get a reliable answer from the patient and therefore need to make adjustment during exam.

Remember to press the green ACCEPT button. It was a pleasure helping you with your question. Best wishes to you. Feel free to ask any additional questions.
Customer: replied 7 years ago.

Thank you for your answer. So my question refers to the adjustments, not to the "fixed" eyecharts. So, if someone e.g. has -2 prescription in the left eye (no astigmatism) and you want to find out, could one make a program that adjusts a picture on a screen say starting at showing a picture that someone with -1 would see properly, and gradually moving down (0.25 D increments) to -2 in such a way that the person would see it properly?

So the process is basically the opposite of the phoropter: in the phoropter, you change the lenses until someone can properly see a fixed eyechart; instead of changing lenses, would it be possible to adjust a picture on a computer screen in such a way that once the patient indicates that the picture is clear, you can read the correction? Thanks again



I understand your reasoning, however, I don't think you are able to "adjust" the eyechart as oppose to changing lenses. You are still left with the problem of if you will automate the refraction or have a person do the subjective refraction.

To make an invention work, it should solve a problem and fill a need. In my view, the current system of using lenses works out well. This also gives a good approximation of what their vision will be with glasses because the phoropter is essentially a trial pair of glasses for the patient.

Please remember to accept if my answer has been helpful.
Dr. James and other Eye Specialists are ready to help you
Customer: replied 7 years ago.
Thank you for your answer.
Customer: replied 7 years ago.
I did hit the accept button, did you recive money??? (i am new here)
Yes, your deposit was received. Thank you for the accept and asking your question. If you have other questions, please ask. Best wishes.