 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Medical Forum / General / Vision / December 2006Are anti-glare or anti-reflective lenses useful?
Hello. I am a 33-year-old male. I need to get a pair of glasses with the prescription -5.00, -5.00 for driving, watching movies in a theater, etc. Would it be useful to buy lenses that have anti-glare or anti-reflective coating on them? What exactly does this coating do? Also, I may buy another pair of glasses to use as reading glasses. These glasses would be used for reading, computer use, etc. Would anti-glare or anti-reflective coating be useful for these glasses? I have had driving glasses and reading glasses before, and I don't think I've ever had anti-glare coating before. I'm not sure, but I don't think that not having this coating has been a problem. The coating can cost as much as an extra $75 for each pair of glasses. So, is the coating worth the price? Thanks for any information. John On 12/20/06 8:06 PM, in article 1166674018.469403.141480@48g2000cwx.googlegroups.com, "midwest_46@yahoo.com" > Hello. I am a 33-year-old male. > > I need to get a pair of glasses with the prescription -5.00, -5.00 for > driving, watching movies in a theater, etc. Would it be useful to buy > lenses that have anti-glare or anti-reflective coating on them? Antiglare lenses have a polarized coating on them that ideally cuts out a bit more than half of the light. In addition, it cuts out some reflected light off of the pavement near what is the Brewster angle. Look that up in Wikipedia. I personally use CHEAP clip-on polarized glasses for that purpose. > What exactly does this coating do? > [quoted text clipped - 8 lines] > The coating can cost as much as an extra $75 for each pair of glasses. > So, is the coating worth the price? Antireflection coatings on glasses are nice but usually not durable. They are anti-FLARE as opposed to anti-GLARE. That is, the typically 4% of light at a lens air surface is reduced to about 1%. This lets more light get through and reduces the multiple reflections that might be annoying. I find antireflection coatings to be more useful in cameras where the stray light can leave a permanent reminder on the picture. For spectacles, you can often, but not always, move your head in a way to minimize the annoyance. > Thanks for any information. > > John -- Fermez le Bush > Antireflection coatings on glasses are nice but usually not durable. They > are anti-FLARE as opposed to anti-GLARE. That is, the typically 4% of light [quoted text clipped - 4 lines] > light can leave a permanent reminder on the picture. For spectacles, you can > often, but not always, move your head in a way to minimize the annoyance. So, let me see if I have this straight. Anti-glare coating keeps light out and decreases the brightness of, say, a computer monitor. Anti-glare coating can be purchased in cheap, clip-on form. Anti-reflection coating allows more light to come in. Thus, if I am wearing glasses with anti-reflection coating, my glasses reflect less light towards the people who are looking at me. So, if I am sitting at a computer, anti-reflection coating will make the monitor appear brighter than it already appears? Also, the lenses that I buy will be transition lenses. That is, when the sun goes up, the glasses become sunglasses. So, on a sunny day, is anti-glare coating necessary if I have transition lenses? And, as for anti-reflection coating, will transition lenses and the anti-reflection coating cancel each other out? Thanks. John On 12/20/06 11:59 PM, in article 1166687943.946994.247740@42g2000cwt.googlegroups.com, "midwest_46@yahoo.com" > So, let me see if I have this straight. > [quoted text clipped - 13 lines] > anti-reflection coating, will transition lenses and the anti-reflection > coating cancel each other out? You would lose about 4% of the light at each of the two lens surfaces (assuming an index of 1.5) or a total loss of about 8%. The additional transmission of light is not really all that useful. It is the prevention of the reflected light from generating confusion that is the big benefit. Simple one layer AR coatings will reduce the reflectivity to about 1% per surface. Multilayer coatings, and I am not familiar with what dispensing opticians can do these days, can improve upon that. If your lens index goes up to 1.65, the total loss is about 6% per surface. Strange as it may seem, single layer coatings will give improved AR performance on such lens surfaces up to a lens index of 1.9 compared to lower index lenses. For monitors, there are other systems for wiping out glare that do not require glasses. Retarding waveplate films can be placed in front of the screen so that light reflected off of a CRT surface does not get back out. Other methods use absorbing screens or meshes that reduce light from reflections off of the screen/ Bill -- Fermez le Bush There you go again. Please don't use confusing terms like glare and flare. Glare refers to distracting light coming from around the object of regard, and cannot be corrected with any eyeglasses. Specular reflection refers to light that is reflected off a relatively smooth surface like a highway, water and computer monitor or eyeglass lenses. These the first two can be fixed with polarized lenses, the second by the use of anti-reflection coatings. Let's keep the terminology straight. In the present case, if he chooses high index lenses, which have significantly higher relflectivity, approaching 10%, anti-reflection coatings will definitely help. High quality ones (over $60) are quite durable and always come with guarantees. w.stacy, o.d. >On 12/20/06 8:06 PM, in article >1166674018.469403.141480@48g2000cwx.googlegroups.com, "midwest_46@yahoo.com" [quoted text clipped - 48 lines] > > On 12/21/06 9:04 AM, in article 78zih.35837$wP1.2987@newssvr14.news.prodigy.net, "William Stacy" <wstacy@obase.net> wrote: > There you go again. Please don't use confusing terms like glare and flare. > Glare refers to distracting light coming from around the object of regard, and [quoted text clipped - 6 lines] > anti-reflection coatings will definitely help. High quality ones (over $60) > are quite durable and always come with guarantees. Again, there is terminology confusion. I take glare to be s (senkrecht) polarized light reflected off of dielectric surfaces, like asphalt, that can be partially blocked (totally at the Brewster angle) by viewing through properly oriented polarized film. Flare is the recording or perception of artifacts in a photograph arising from light reflected at the surfaces of lens elements. Bill -- Fermez le Bush Right. This sci.med.VISION, where we use ophthalmic optics terminology, not precision camera or instrument terminology. But I still think you are using the term glare incorrectly even in that context (see my definition below). And I don't know why you are specifying dielectric below. What has that got to do with anything? Reflected sunlight off any relatively smooth surface anywhere near Brewster's angle will of course be polarized, including glass, water, even the atmosphere, which is why polarized filters are used under those conditions. We do not use the term flare in the eye business, except in the context of warning people not to try to observe the solar variety, and to use protective eyewear when handling the boating or highway hazard varieties. Your use of the term here is showing your, er, obfuscatory flair. w.stacy, o.d. > On 12/21/06 9:04 AM, in article > 78zih.35837$wP1.2987@newssvr14.news.prodigy.net, "William Stacy" [quoted text clipped - 23 lines] > Bill > -- Fermez le Bush On 12/21/06 11:47 AM, in article xyBih.12033$Gw4.828@newssvr23.news.prodigy.net, "William Stacy" <wstacy@obase.net> wrote: > Right. This sci.med.VISION, where we use ophthalmic optics terminology, not > precision camera or instrument terminology. But I still think you are using [quoted text clipped - 7 lines] > protective eyewear when handling the boating or highway hazard varieties. Your > use of the term here is showing your, er, obfuscatory flair. Unfortunately, there are many divergences generated among disciplines that confuse people trying to understand other specialists in related fields. For example, the way the direction of polarization was once arbitrarily assigned was in terms of the direction of the magnetic field in the propagating wave. Later, it was found that interaction with matter was primarily with the electric field. The term direction of vibration was then used to replace direction of polarization. Nevertheless, confusion is still there. I used the term dielectric because metals do not have a (real) Brewster angle. That is, simple metallic reflection does not discriminate with polarization state. That is, polarized glasses could help with sun glare off of the rust on steel plates put in the roadway, but not the reflection from clean shiny steel. Flare is a term used by photographers. It corresponds to the general loss of contrast from scattered light. It also refers to various artifacts in photographs that often come from unwanted and often unrecognizable images generated by specular reflection off of lens surfaces. Bill -- Fermez le Bush > Would it be useful to buy > lenses that have anti-glare or anti-reflective coating on them? I'm no expert, but in my experience, those coatings are more for when other people look at your eyes, they don't see as much reflections off of them. And see less rings around the edges of the lenses. i am sure that in eyeglass store lingo the terms anti glare and anti reflective are being used interchangeably and refer to the same coating. at -5 you are probably getting hi index lenses and therefore anti reflective coatings become more important or the reflections on the lenses will be greater. the coatings do increase light transmission thru the lens and therefore enable brighter view. the coatings are on both surfaces of the lens and therefore offer an esthetic advantage (someone looking at you sees your eyes and not a lot of reflection off the lens) and a functional advantage (the wearer has less kick or reflection in the lens he's looking thru). The idea is the AR coating causes the lens interface to more or less disappear . look at your self in a mirror with wearing a pair of regular lenses and compare with ar lenses. Very obvious difference. > Hello. I am a 33-year-old male. > [quoted text clipped - 18 lines] > > John > i am sure that in eyeglass store lingo the terms anti glare and anti > reflective are being used interchangeably and refer to the same [quoted text clipped - 36 lines] >> >> John I find they make a tremendous difference when driving at night - oncoming headlights etc. - well worth the money. Louise
|
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.