I just returned from the optometrists and my eyesight has improved by 1 step, according to him.
He asked me about the lighting at work. I told him I no longer work in an office environment but I now work at home. He asked the type of lighting I used at home and I told him incandescent light for my home office. He cited the use of incandescent lighting as a reason my eyesight has improved slightly.
His recommendation is to never use fluorescent lighting to read by or to light one's home office. According to the optometrists, the use of cpls' is a marketing ploy and causes more harm than good. I have never converted to compact fluorescent lights and it looks like I never will.
I took a quick look at his office lighting and it was all incandescent lighting. There were no fluorescent lights that I could see. So he seems to practice what he preaches.
So to those pushing compact fluorescent lights, I say get lost. My eyesight is worth a lot more than the very few Pennys I might be saving.
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"If ignorance is bliss, why aren't there more happy people" Anonymous
Fluorescent lights (in general - not just the compact variety) display a flickering that occurs at a frequency that is twice the frequency applied to the bulb itself. This has been a 'known problem' with fluorescent lighting for as long as the technology has existed.
Conventional non-compact fluorescent with magnetic ballasts (typically, the tubular fluorescents that have been around forever) display a flicker frequency of twice the power system line frequency. When fluorescent lighting became popular in commercial offices, workers reported more frequent headaches that were attributed to this flicker. Interestingly, the problem was more pronounced in Europe where the line frequency is 50 hz (causing 100hz flicker) than it was in North America (60hz line frequency leading to 120hz flicker), but one set of experiments showed that it diminished when the line frequency was lowered to 32 hz. That suggests to me that the perception process in the human eye operates at a frequency in the 100-120hz range, and flicker at a similar frequency could set up some kind of resonance-like phenomenon that leads to stress.
In the early 1960s, lighting manufacturers offered so-called 'high frequency' lighting that operated at higher frequencies. When I was in college, I worked for an architect-engineer who purposely installed the most modern facilities in their offices (a showcase for potential clients) and who had 400hz fluorescent lighting in the office areas. This seemed to address the problem, but the motor-generators used to convert line frequency from 60hz to 400 hz were inefficient mechanical devices that required maintenance. And even though the MG sets were in an isolated room, there was a nagging hum throughout the building.
Most (but not all) modern compact fluorescent lights use electronic ballasts that produce (electronically) a high frequency voltage to excite the phosphors in the fluorescent tubes. Typical frequencies for these lamps is 20khz and higher, and of course the flicker frequency is twice that excitation frequency. So if the 400hz solutions of the early 1960 solutions were effective in addressing the physiological problems, then modern CFLs with electronic ballasts will be even better.
However, it is possible to purchase some CFLs that continue to employ line-frequency excitation of the phosphors, and those will produce the same flicker effects as conventional tubular lamps. I suspect it comes down to the old adage - 'you buy cheap, you get cheap'.
Incidentally, the reason there is no flicker effect with incandescent lamps is that light is generated through incandescence - a wire is electrically heated to a very high temperature, causing it to give off light (as well as heat). While the supply does fluctuate at the line frequency, the thermal time constant of the wire is such that it can't change temperature significantly in the 8 millisecond period between fluctuations (10ms in Europe), and therefore the light output also doesn't change.
And for your next game of Trivial Pursuit - the reason that we use 60hz in North America while the Europeans use 50 hz is that in the early part of the 20th century, the more common form of lighting was the arc light. In North America, the practice was for that electric arc to be exposed to air which caused it to cool down more rapidly. Therefore, to avoid perceptible flicker, it was necessary to select a higher line frequency(60hz) so that the arc would be more quickly re-established. In Europe, the practice was for the arc to be enclosed such that it did not cool as rapidly, and therefore 50hz could be used without nuisance flicker.
I can't say that I come down on one side or the other, but I can say that another difference between flo's and incandescents is color spectrum, and by that I don't mean the predominant color temperature, but rather the output of the luminary over the whole spectrum. Incandescents have a spectrum that basically ramps up and falls away smoothly from their predominant output. Flo's on the other hand, display fairly abrupt spikes in different parts of the spectrum not related to their predominant spectrum. I have speculated at times on if this discontinuous spectrum is another reason they seem to be disturbing to some people. I would suspect some people would be more or less sensitive than others. It is, however, speculation.
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--J Brunner, The Prints of Darkness
Well, in the interest of scientific exactitude and against a general consensus, I'll have to say, your optometrist was propagating a myth. There are no scientific data linking types of illumination with development (or improvement) of refractive errors. In fact, there are very few scientific data about possible causes of shortsightedness, farsightedness and so on. The last studies in that regard were done in the 1970-ies on chicken.
I can see possible effects from either the color spectrum or the flickering. I would love to see some scientific analysis. I could say that the CFL's I have put in through most of my house are scaring off bear attacks, as evidenced by the fact that no bears have come around to attack us, but it wouldn't be true.
One thing that I have done in many work environments I have used where fluorescent lighting is the norm is that I use a small incandescent lamp at my desk or work station to add more of the full spectrum and light consistency that I tend to prefer. Fluorescent lighting works really well for general lighting for, say, large rooms or long hallways. I am not convinced that it is the end all-be all for all lighting.
I, generally, do not have a problem with fluorescent lighting unless the ballasts start going and the lights start flickering to the point I can notice.
I just returned from the optometrists and my eyesight has improved by 1 step, according to him...
Exactly what does that mean? What is "1 step?" Does this refer to your distance vision? Close focus (accommodation) ability? Is it in diopters? One line on the wall chart? Or? Difficult to comment usefully without a better definition.
Quote:
Originally Posted by Gary892
...He asked me about the lighting at work. I told him I no longer work in an office environment but I now work at home. He asked the type of lighting I used at home and I told him incandescent light for my home office. He cited the use of incandescent lighting as a reason my eyesight has improved slightly...
If, like most people today, your work involves staring for long periods at a computer screen, and it's a reasonably modern computer, you're using a flat panel monitor. Except for a very few of those, monitor backlight comes from a fluorescent bulb. So I question his assertion that a different environment is responsible for the slight change in your exam results. I've been presbyopic for the last 46 years; annual refractions since then have almost always yielded differing prescriptions. Sometimes stronger, sometimes weaker. The cornea can be in constant flux.
Also, does working at home mean you're better able to give your eyes rest breaks througout the day? That alone might be responsible for increased acuity.
Quote:
Originally Posted by Gary892
...I took a quick look at his office lighting and it was all incandescent lighting. There were no fluorescent lights that I could see. So he seems to practice what he preaches...
I suspect making the merchandise, i.e. frames, more attractive is a significant factor in his choice of office lighting.
Quote:
Originally Posted by Gary892
...So to those pushing compact fluorescent lights, I say get lost. My eyesight is worth a lot more than the very few Pennys I might be saving.
I have also declined to convert, but for purely aesthetic reasons. As CFL performance improves, I'll consider using them in certain areas. Or perhaps they'll be supplanted by LEDs before then. In any case, I am stockpiling some incandescent bulbs. Just not for "eyesight protection" reasons.
Fluorescent lighting works really well for general lighting for, say, large rooms or long hallways. I am not convinced that it is the end all-be all for all lighting.
Lighting technology is in flux. IMHO, fluorescent lighting either has peaked or is about to peak in popularity. LED lighting is more energy-efficient than fluorescent lighting and LED bulbs contain no mercury. The main drawback right now is getting enough lumens out of an affordable bulb, but my understanding is that LED technology is improving rapidly in cost and lumen output. A secondary factor is the color of LED lights, which doesn't match either daylight or tungsten. Although many of the readers of this forum are sensitive to color balance and may never be satisfied with LEDs (or fluorescents!) for this reason, I fully expect that all of these issues will be solved well enough to see LEDs replacing CFLs in homes and offices pretty soon. That is, assuming something else doesn't come along in the meantime....
Your eyes and compact fluorescent lights. 
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