Sort of. There's a device called an autorefractor which can get a pretty good estimate out of your refractive error. However traditional eyesight tests tend to provide better results.

I believe wavefront guided LASIK uses some kind of automatic method of determining refractive error called an aberrometer. Some ophthalmologists have a device called an i-profiler that they use as part of their assessment which appears to be an aberrometer.

Everything I've read on the matter seems to me to indicate that there is possibly some kind of hybrid automated autorefractor/aberrometer type technology that could be created to give fairly objective and accurate measurements of refractive error with no human operator, but given that legally an ophthalmologist would need to sign off the prescription anyway the upside is probably limited.

I was excited to get lasik when wavefront came out due to one eye having astigmatism. I came out with 20:15 in one eye, 20/20 in the other. Overcorrection is normally avoided, but I jumped when wavefront lasik came out. Totally worth it.

Yes. Last year, I realized I needed glasses, went through two opticians and three pairs of lenses, still wasn't happy, and finally ended up seeking out an office that could measure for free-form lenses (measured objectively with more degrees of freedom in the prescription).

This optician used Zeiss a i-Profiler to make i-Scription lenses (https://www.zeiss.com/vision-care/us/for-eye-care-profession...) They've worked better for me than any of the subjectively-measured prescriptions.

Since vision happens mostly in the brain, simply selecting a lens which focusing light at a certain point in your eye is not the only thing to optimize for. You also have to optimize for the processor behind the sensor which, at least until more advanced vision models are made, is going to be purely subjective.

Is it possible for the lens to focus light perfectly, and the brain to process that as blurrier than if the light were focused imperfectly?

I would imagine that, no matter how the brain were processing the image, the image being focused exactly on the retina is an objective truth, and that an exactly-focused image must be clearer to the brain than a blurry image.

That is true for the spherical part of the lens. When you start to look into the correction of astigmatism (done by the cylindrical component of the lens) it become a whole lot more complicated.

As others have said, yes, with limited accuracy. A big issue is the focus of your eyes is never static.

Imagine creating a lens system for a camera where you can't control for one element. That element is dynamic with a reasonable autofocus that suffers from time varying accuracy and range of performance.

We need dynamic correction. Glasses with auto/adjustable focus.

> isn't it an objective way to measure it

No it's subjective - I think that's the main point of the article.

I know, I though it might a very expensive but precise way to measure that with time or new tech could become afrodable.

I don't see why the entire process couldn't be automated. A machine could ask me "which is better A or B or are they the same?"

There are other parts of the exam that are more related to eye health, but I don't see why they vision prescription process and the eye exam have to be combined. How many people that don't wear glasses ever get their eyes examined?

"Which is better?" is the subjectivity people are hoping can be eliminated, the patient's, not the examiner's. This is an interesting black-box problem, I suppose it's possible that with the examination of enough eyes a system could suggest corrections, but I am skeptical.

> I know, I though it might a very expensive but precise way to measure that with time or new tech could become afrodable.

No it's imprecise - again that's a key point of the article. The author finds that there's a lot of variance in the measurements obtained.

Maybe it's the way I worded it, but I'm not debating the point of the author, sometimes in HN there are people that know more, or have more recent information than the authors of what is posted here.

fwiw, I talked to someone who'd done some research in that area. While using an autorefractor provides you with objective values, predicting the actual values people were most satisfied with was very difficult. Possibly because there's a lot of "post-processing" of visual signals in our brain and that may vary a lot individually.

I totally agree that having an objective way to measure this would be awesome.