How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Coachrobmd Your Own Question
Coachrobmd, Doctor (non-eye specialty)
Category: Eye
Satisfied Customers: 1785
Experience:  Medical Internist
Type Your Eye Question Here...
Coachrobmd is online now
A new question is answered every 9 seconds

When I strain/tense my eye muscles, Im

This answer was rated:

When I strain/tense my eye muscles, I'm able to get my near/far vision clear. When I also add a little astigmatism correction to this (or pin-hole), it gets even clearer.

My understanding is that pin-holing removes the variable of refraction? So the fact that pin-holing does not get my vision clear (only straining does), means my vision issue is not due to refraction error?

What physical change am I'm inducing when I strain to get vision clear? (Again, when I strain, near and far are clear, when I relax, near and far are very blurry.)
this is called Accommodation,it is the way the eye increases optical power (the degree to which the lens converges or diverges light). This is necessary to produce a clear image (focus) on an object when it draws near the eye. A lens that is more convex( fatter in the middle) would refract more light rays than a less convex lens( thinner lens). The lens can change shape because the cells of the lens contain an elastic crystalline protein. The young human eye can change focus from distance to seven centimeters from the eye in 350 milliseconds. The eye focuses on a given object by changing the shape of the eye lens through accommodation. This is controlled by ciliary muscle,which is attached to the lens.
Unless you have any other questions please press ACCEPT so I would get compensated for my time and answer
Customer: replied 4 years ago.
I already know everything you said, as it's basic knowledge. That was not my question.

Also, if I was accommodating, it would expect it to make my near-vision clearer, not infinity distance. I can't find any plus nor minus powers to make my vision clear, but straining does.

(I need a highly skilled Board Certified Ophthalmologist for this question.)
The process of straining the eye muscles is used to change the shape of the lens. This can actually improve near OR farsightedness due to the degree of change of the lens shape. As we age, the lens become less flexible and taken to the extreme, may form cataracts.

The reason pinhole boards work is that the send light through just the CENTER portion of the lens, and prevent refractive error from the edge of the lens, which becomes distorted more rapidly than the central portion of the eye. This refractive error is prevented by taking the full light source down to a very narrow band through the pinhole and sending it through just the CENTER of the crystalline lens.

You should understand something unique about the eye's lens. It is the ONLY tissue in the human body that lays down new cells on the OUTSIDE, so that the older, more senescent cells are trapped. This is what makes the lens thicker and less pliable as we age, and leads to presbyopia.

In the skin we flake off dead skin. In the GI tract, we shed off mucosa and pass it out as waste. With the eye lens, that cannot happen and thus the new cells are laid down in a somewhat uneven pattern, causing the refractive error mentioned above.

Plenty of people who have near sight strain to see things far away. The ciliary body has opposing fibers and can both collapse and expand the eye's lens. I'm doing it at this very moment looking out my window as I try to focus on a distant bird without my glasses on.

Is this the answer you're looking for? If so, please click ACCEPT so I can receive credit for my answer.

If not, could you please clarify your question so I can try further? Thank you so much. (This does not replace a physician visit.)
Customer: replied 4 years ago.
ok, that's interesting the ciliary muscles can exert effort to flatten the lens also; I had thought their flexing could only curve it.

So I'm left with the dilemma of how to get clear vision without straining? None of the lens powers tried have helped. Should a lens help with this, if so, plus or negative?
+ or - is best determined during refraction with a pheropter in the eye doctor's office. It's not possible for me to determine that from a distance and not examining you.

It really seems like you need an eye exam that includes:
1. testing for glaucoma
2. visual field testing
3. anterior chamber evaluation
4. tests of accommodation
5. dilated exam to look at the back (retina) of the eye and the lens itself
6. color blindness testing if it was never done

And the ciliary muscles are much more complicated than people believe. My father was an ophthalmogist for 49 years and we were constantly discussing eye problems.

So, see an optometrist or opthalmologist, get good visual testing, and perhaps glasses. They'll need to check you for +/-, sphere, and axis as well, something that takes a good deal of training, You cannot do that for yourself.

POSITIVE feedback is FREE for you to leave about our session today. It is very important for me to get feedback so I can help customers the best way possible. This is VERY different than an office setting where I can see if you're satisfied with our discussion. Please consider taking one minute to fill this out. Thank you.
Coachrobmd, Doctor (non-eye specialty)
Category: Eye
Satisfied Customers: 1785
Experience: Medical Internist
Coachrobmd and other Eye Specialists are ready to help you
Customer: replied 4 years ago.
Yeah, I've had all those tests done by 9 different opthalmologist in several cities, including Duke, Mayo, etc. and no one can figure out what my prescription is. It's very frustrating, so I was hoping to figure things out with the help of this site.
It's awfully tough for us, who can't examine you, to beat the guy who has you in his office when it comes to diagnosis. The best thing we can do is broaden your horizons by coming up with alternate differential diagnosis that you can then bring in and discuss with your doctor.

Thanks for the positive feedback by the way. I really do appreciate it.

On thing you MIGHT ask is if a prism added to the lens will make a difference. At times, this is overlooked, and it can make all the difference. But I'm sure at Duke and Mayo the considered that option.

Hope I've helped you a little bit.


JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

  • I feel so much better today, and upon further investigation believe that there is a chance that the responses I got saved me from a serious, even life threatening situation. I am very grateful to the experts who answered me. Susan O. USA
< Previous | Next >
  • I feel so much better today, and upon further investigation believe that there is a chance that the responses I got saved me from a serious, even life threatening situation. I am very grateful to the experts who answered me. Susan O. USA
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland

Meet The Experts:

  • Dr. Dan B.

    Dr. Dan B.

    Board Certified Ophthalmologist

    Satisfied Customers:

    Eye surgeon experienced in cataracts, glaucoma, retina & neuro-ophthalmology
< Last | Next >
  • Dr. Dan B.'s Avatar

    Dr. Dan B.

    Board Certified Ophthalmologist

    Satisfied Customers:

    Eye surgeon experienced in cataracts, glaucoma, retina & neuro-ophthalmology
  • Dr. Stan's Avatar

    Dr. Stan


    Satisfied Customers:

    Johns Hopkins Fellowship Trained, Certified and Licensed Medical Physician and Surgeon
  • Dr. Stevens's Avatar

    Dr. Stevens


    Satisfied Customers:

    Board Certified Ophthalmologist
  • Dr. Susan's Avatar

    Dr. Susan


    Satisfied Customers:

    Board Certified & Fellowship trained eye surgeon.
  • Dr. JP's Avatar

    Dr. JP

    Ophthalmology, Oculoplastic Surgery

    Satisfied Customers:

    Harvard Medical School, Massachussetts Eye and Ear
  • Dr-Trace's Avatar


    Board Certified Ophthalmologist

    Satisfied Customers:

    Board Certified in General Ophthalmology
  • Dr. Daniel Jewelewicz's Avatar

    Dr. Daniel Jewelewicz

    Board Certified Ophthalmologist

    Satisfied Customers:

    Glaucoma Specialist, Associate Professor FAU, Teaching Faculty Bascom Palmer Eye Institute

Related Eye Questions