 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Medical Forum / General / Vision / August 2005Plus lens questions
What is the difference, technically, between a reading plus lens and distance plus lens in prescriptions? A +2.00 is written the same whether for distance or reading yet they are not the same, so how is the distinction made? If no notation is made that they are reading glasses, are they automatically made for distance? And how would a single vision plus rx be written for intermediate needs -as a distance lens or near lens? Thanks, C. (hyperopia/presbyopia) Dear Calw, The "preventive" plus lens is sold in the stores -- with no prescription required. If you wrote a prescription for it -- it would be +2 diopters, astigmatism zero and, and therefore no "angle". The preventve plus is intended only for use to keep distant vision clear -- for young children. It is not a "quick fix", and the parents who wish to help their children avoid nearsighedness should understand it in that manner. Some ODs now support the concept by using the plus (before their childeren even become nearsighted). This IS THE SECOND OPINION. You can find furthter reference for this at: www.chinamyopia.org The "majority opinion" ODs on sci.med.sci will post their own opinions shortly. Best, Otis (Preventive engineer) > The "preventive" plus lens is sold in > the stores -- with no prescription > required. And here foolish little me thought they sold those for use as reading glasses! > Otis > (Preventive engineer) Are you trying to prevent people from becoming engineers, or are you seriously claiming that your area of expertise as an engineer is prevention?  SignatureDan Abel Sonoma State University AIS dabel@sonic.net > Dear Calw, > > The "preventive" plus lens is sold in > the stores -- with no prescription > required. Dear Calway, Please disregard Otis's postings. He is not in the medical profession and not in any position to give medical advise. Thank you! Allen wtf! what a stupid reply. Otis you are a moron. +2.00 glasses used for reading are exactly the same as +2.00 glasses used for hyperopes. the only difference would be the pupillary distance (PD). for readers the PD is set for near work while in hyperopes the PD is set for distance. > What is the difference, technically, between a reading plus lens and > distance plus lens in prescriptions? A +2.00 is written the same [quoted text clipped - 3 lines] > single vision plus rx be written for intermediate needs -as a distance > lens or near lens? I'm not a professional here, but I'm absolutely sure that they are identical. The only difference is in their use. The same +2.00 lens can be used for distance,intermediate or close depending on what your eye needs. SignatureDan Abel Sonoma State University AIS dabel@sonic.net Technically, the only difference is the polar separation, or the distance between the optical centers, which is 2 to 4 mm larger in distance Rxs and smaller in near Rxs (due to the eyes' convergence when viewing close objects). w.stacy, o.d. >What is the difference, technically, between a reading plus lens and >distance plus lens in prescriptions? A +2.00 is written the same [quoted text clipped - 8 lines] > > > Technically, the only difference is the polar separation, or the > distance between the optical centers, which is 2 to 4 mm larger in > distance Rxs and smaller in near Rxs (due to the eyes' convergence when > viewing close objects). > > w.stacy, o.d. OK. I was wondering why, if they were the same, "reading" is indicated on the script, and I noticed online sellers require you to check off if the glasses are to be used for distance or near. Thanks for the info. Cal I hope they are asking for pupillary distances. If so, that's good. Unlike the store bought (OTC) glasses where one size "fits" all. Not good, since human p.d.s range from 50 mm to over 70 mm, and that can make a big difference... w.stacy, o.d. > > [quoted text clipped - 14 lines] > > > What is the difference, technically, between a reading plus lens and > distance plus lens in prescriptions? Only the interpupillary distance, the "PD." > A +2.00 is written the same > whether for distance or reading yet they are not the same, so how is > the distinction made? If no notation is made that they are reading > glasses, are they automatically made for distance? And how would a Normally prescriptions are written in the form of a bifocal, essentially two prescriptions, far and near, and opticians calculate the "near" prescription. It's the PD that makes it clear. As you've read, the pupil distance is a little smaller for near prescriptions. Not all doctors record a PD or specify it on the written prescription. When they do, it's usually written "64/61" for distance/near. If I were prescribing single-vision reading glasses, I might write it as "+2.00." But to specify them as reading glasses, I'd have to specify a PD, or I'd write "use near PD" or "NVO" (near vision only). > And how would a single vision plus rx be written > for intermediate needs -as a distance > lens or near lens? Either the Rx would specify a PD, or it would say "use intermediate PD." In practice, at +/-2.00 level, a millimeter or two of horizontal PD doesn't make much difference. Standard male and female PDs are used in over-the-counter reading glasses and they're ok for "most people." A good optician will question you about how you're using the glasses and measure PD as necessary. -MT, OD |
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.