Previous 1 69 70 71 72 73 Next 2,377 Replies Latest reply: Apr 13, 2016 2:01 PM by Gurm42 Go to original post Branched to a new discussion.
  • Jessiah1 Level 1 Level 1

    I think we are all in agreement that there has been recent developments in regards to Hz and PWM controllers that are probably consistent issues for both CCFL and LED back lighting. The reason your Mac's are worse is becuase LED compared to CCFL is like a sharp stick in the eye by comparison, most likely due to high levels of blue light. It's unlikely it has anything to do with the OS, you should try some of the new LED TV's or light bulbs and see how you fair there, if they bother you then you know it is PWM or Blue light spectrum or both. I think it is both for me.

  • Gareth Jones6 Level 1 Level 1

    I fear there is something about the OS, as I have hooked my Macbook up to a CCFL monitor and it still wrecks my eyes. My old XP laptop is fine however.


    I'm interested to know where the cutoff point is in terms of operating systems, because I may consider getting/building a Vista PC if it is going to be ok. My (possibly flawed) memory of earlier in this thread though was that there was a BIOS update which rendered Vista unusable?


    Microsoft is due to withdraw support from XP next year, so probably not worth investing too much in a machine with this on.

  • Jessiah1 Level 1 Level 1

    PWM controller, pulsing to control dimming and power consumption. That would affect any monitor you hooked up to, that or the Hz being set below 75. On some computers you can set the Hz rate and some you cannot, many of us here have a theory that PWM is responsible for many of our issues. If you add that with harsh blue back lighting the result can be unbearable for some, I am one of those

  • Gareth Jones6 Level 1 Level 1

    My external monitor gives me the option of 60 or 75 hz, while the laptop monitor doesn't give me the option. Are there any CCFL monitors I can get that will offer me more options? Preferably ones that don't cost hundreds of pounds/dollars? And are there any settings I can look for to change PWM controller, pulsing to control dimming and power consumption?


    In an ideal world I guess some tech whizz could come up with a programme to allow us to change these settings?:

  • mvanier Level 1 Level 1

    I think there is some confusion here about what the Hz in 60/75 Hz refers to.  Back in the days of CRT (cathode-ray tube) monitors, the refresh rate was very relevant to eyestrain, as the only time you would see light on the screen is when the phosphors were stimulated by the electron beam.  A 60 Hz refresh rate would lead to visible strobing for many people (including me).  I vividly recall how much better it was when I figured out how to adjust the refresh rate from 60 Hz to 85 Hz; it was like night and day and almost all my eyestrain went away.  On an LCD monitor (however it's backlit, LED or CCFL), the refresh rate only refers to how often the LCDs get updated.  If they are showing e.g. a solid color that isn't changing, it really doesn't matter, and LCD refresh rates have almost no effect on eyestrain that I've heard of.  What matters is PWM of the LED backlight or the CCFL backlight, as this determines how constant the light source appears even when the screen image is static.  There are monitors that have 120Hz LCD refresh rates, but I would bet money they would not fix your eyestrain issues.

  • Eric Leung1 Level 1 Level 1

    @Jessiah, may I know where did you get your spectacles coated with Crizal Prevencia?


    I tried to look for it around the shops where I live (Hong Kong), and seems like they don't have it as the product is too new.


    By the way, from what I read about the details of the Crizal Prevencia, it claims that it targets the wavelengths between 415 - 455nm (435nm +/- 20nm), which, hurts the retinal cells most.


    Then, according to the iPhone 5 / new iPad / iPhone 4S spectrographs made in here: up-against-apples-claims/


    The blue spike of iPhone 5 and the new iPad are slightly to the left by around 10nm compared with the iPhone 4S.

    But if you draw a vertical line at around the 440-450nm wavelength (on the white or blue spectrographs), due to the steep blue spike, it looks like the iPhone 5 and new iPad are quite a lot brighter than then iPhone 4S in that particular wavelength.


    That appears to be in line with my personal experience, I feel the iPhone 4S to be a lot more comfortable than the iPhone 5. I don't experience the new iPad long enough to have a good idea on it though.


    Perhaps the problem with the new harsh and ultra bright bluish LED is that they have too much blue at the 415-455nm wavelength? Just a thought.

  • Dovez Level 1 Level 1

    Has anyone on this forum ever had a concussion?

  • Jessiah1 Level 1 Level 1

    Eric, I have emailed my contact at Crizal and I will let you know what he has to say. I agree also the 5 is sooooo much worse for me than the 4S, someone using an Ihpone 5 a few feet away in my peripheral can affect me where the 4S is almost tolerable in my peripheral even up close. My expereince with the Provencia coating was tested heavily this weekend on a trip to Chicago for a wedding, I am currently writting this up for my blog, Southwest airlines has remodeled all of their interiors with LED lighting and it is super bright

  • Jessiah1 Level 1 Level 1

    I have hit my head a few times pretty hard blacking out twice and I would assume I have probably had one without medical confirmation. I have had an MRI done and they have found no issues with my brain such as swelling or aneurysms.

  • Eric Leung1 Level 1 Level 1

    Jessiah1: Thanks a lot for checking for me!!


    I have just read your blog, from your symptoms, I guess I have very similar light sensitivity like you do! Just perhaps a little less serious.


    I too could sense the discomfort from iPhone 5 even at distance. And I'm surprised to see that you mentioned about your voice when feeling uncomfortable with LEDs, as I also have throat issues when looking at certain kind of LED lights!! (I don't usually tell others about this as it just sound so weird that people don't believe.) Though fortunately, my voice don't get affected like you did.


    Seems like the Prevencia have positive effect in your case! That's a very good start to a solution! Now I wonder why it doesn't help you for longer than 15min. Perhaps a small amount of LED light rays got in from the side of your spectacles? Perhaps a stronger coating is required? Perhaps the coating (which blocks 415-455nm) doesn't fully block the spectrum that your eyes are sensitive to?


    Nevertheless, it seems we are starting to have a clearer explanation on how exactly those harsh bright blue LEDs are causing the troubles.

  • Jessiah1 Level 1 Level 1

    I agree, it is difficult to gain acceptance for our issue and there are people who can be very derogatory towards us in their beliefs that we are all "Crazy". It is very real and very life debilitating and only get worse the more LED lights become the new source of light in all things. As for the Prevencia not working for long periods of time I have a theory or two however I am no scientist and Crizal does have scientists researching this very thing.


    I would say in my opinion that the issue may be two fold: Some sort of flicker or imitting of UV or frequency and the Blue light spectrum. I believe if there is something bothering you about the light related to flicker then using a brighter blue/white light source will magnify that issue ten fold.


    If you go back through this thread there are numerous highly intelligent opinions about flicker VS. spectrum or perhaps both.


    Perhaps the next generation of anti-glare coating will be more effective, we can hope

  • Dovez Level 1 Level 1

    Interesting experiment: Those who usually get pain in eyes after 15 minutes with screens could test if they can double their time without pain by closing one eye at the very beginning (or covering it with something). After 15-30 minutes of use will both eyes hurt? Even if only one was used?

  • Sapsombat Level 1 Level 1

    I started using new iMac 27" in the beginning of April and immediately I got severe eye problems, headache, dizziness, aching eyes etc


    My first thought was that it has to do with the new screen, but then I refused to believe it. The problem came worse and I went for an eye specialist, at a well known private clinic. After all tests the outcome was that there's absolutely no defect in my eyesight. I went for blood tests to be sure I don't have any thyroid related problems, but everything was normal.


    Now the problem comes worse and worse. First it only appeared while working at my iMac (at home), then it started to come up also at work (basic PC) and now it can suddenly start anywhere - when using my iPhone or even without any digital device. Sometimes it really hurts to look anything and I can feel my eyes in a bad way all the time.


    I would like to read this thread through more carefully, but in this condition it's not so appealing. I don't know what to do.

  • Eric Leung1 Level 1 Level 1

    Jessiah1: It's glad to know that there is a company (Essilor / Crizal) trying to fix this issue.  I hope in the near future we could identify a clear cause of the problem, and could get back to Apple so that they could fix it in their future products.


    I think, there are currently too much different information in this forum that even if Apple wants to fix, there's no clear answer on what to fix...

  • Eric Leung1 Level 1 Level 1

    Sapsombat:  I have spent quite a bit of time playing with the latest 27" iMac at Apple Store in the past. It appears that it has some "snow flickering" problem, but the "bright harsh blue LED" problem that I talked about in recent posts doesn't seem very bad for this computer.


    I would suggest first to calibrate the color of your screen. Either with a professional calibration device or using your eye (in System Preference -> Displays -> Color -> Calibrate -> "Expert Mode").


    I have tried eye calibrating a few iMac 27" at the Apple Stores, and it appears the contrast could improve slightly to the extent that the texts becomes slightly sharper and lowered the "snow flickering" effect.


    Another thing to try would be change the display to a lower resolution. It seems to help some times.


    But since you appear to feel uncomfortable looking any screens now, I guess your eyes are over stressed... It would probably be best to give them enough rest first. Try spending a weekend outdoors without looking at any devices with a backlight (I know that's almost impossible, but try to minimize the time!) and have plenty of sleep. That's how I "reset" my eyes when they are over stressed.

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