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Medical Forum / General / Vision / March 2007cylinder power
These days it seems like doctors prefer to prescribe progressive lenses instead of bifocals or trifocals. Why is that? Also, do optometrists adjust or change the cylinder power so that the add power for each eye can be the same? If so, wouldn't that mess up the visual acuity to some extent? At least in the distance? > These days it seems like doctors prefer to prescribe progressive > lenses instead of bifocals or trifocals. Why is that? > Also, do optometrists adjust or change the cylinder power so that the > add power for each eye can be the same? If so, wouldn't that mess up > the visual acuity to some extent? At least in the distance? The marketplace demands more progressives every year. Knowledgeable and ethical fitters will still fit bis and tris along with progs, while ignorant or unethical ones will only fit progressives, or will push them when they are not indicated. No we do not change the cyl to effect equalizing the adds. That question really doesn't make optical sense. The only adjustment in cyls we sometimes make is to reduce it somewhat if we think the full Rx will present a challenge to the wearer in adaptation. Some people seem to not handle full cyl corrections very well, and many don't like any large changes in their Rxs at one time. And yes, sometimes we sacrafice a little acuity for perceptual stability. w.stacy, o.d. > cda...@directflatscreen.tv wrote: > > These days it seems like doctors prefer to prescribe progressive [quoted text clipped - 17 lines] > > w.stacy, o.d. What might account for these prescription changes ( I was 44 in 1996 and I could see close up, it was just the distance I needed corrected, I do not have diabetes or a thyroid problem): 07/22/04 Prog. -2.50 +3.00 +0.25 -2.00 x167.00 +3.00 Contact OD -11.00 04/22/04 Prog. PL +2.25 +0.25 -2.00 x167.00 +2.25 Contact OD -11.00 02/27/03 Prog. PL +2.25 -0.25 -2.25 x161.00 +2.25 Contact OD -9.50 01/15/01 Prog. -7.50 -0.75 x66.00 +3.00 with slab-off -0.50 -2.00 x169.00 +3.00 11/24/98 Prog. -7.25 -0.50 x65.00 +2.00 with slab-off -0.50 -2.00 x171.00 +2.00 11/01/96 Bifocals -7.75 +1.25 PL -2.00 x170.00 +1.25 They keep trying to get me to buy smaller frames and lenses but I don't think that anything smaller than 52x38 gives me a good field of view. Thank you for looking at this post. > What might account for these prescription changes ( I was 44 in 1996 > and I could see close up, it was just the distance I needed corrected, [quoted text clipped - 3 lines] > +0.25 -2.00 x167.00 +3.00 > Contact OD -11.00 Is that a soft lens or RGP? It is apparently too weak. The -2.50 should have been added to the CL, not to the glasses. 3.00 add seems a bit high still. > 04/22/04 Prog. PL +2.25 > +0.25 -2.00 x167.00 +2.25 > Contact OD -11.00 Looks pretty good. No big change except the increase in myopia. > 02/27/03 Prog. PL +2.25 > -0.25 -2.25 x161.00 +2.25 > Contact OD -9.50 Makes sense if you're wearing the CL full time. > 01/15/01 Prog. -7.50 -0.75 x66.00 +3.00 with slab-off > -0.50 -2.00 x169.00 +3.00 3 add seems out of line for your age. > 11/24/98 Prog. -7.25 -0.50 x65.00 +2.00 with slab-off > -0.50 -2.00 x171.00 +2.00 No big change. > 11/01/96 Bifocals -7.75 +1.25 > PL -2.00 x170.00 +1.25 Should have had a slab off in that one too. > They keep trying to get me to buy smaller frames and lenses but I > don't think that anything smaller than 52x38 gives me a good field of > view. I disagree with you somewhat, because the larger you go, the bigger the area of your field that is cut off. Yes, smaller brings it closer to your line of sight, but the actual area of loss decreases as the eyesize goes down; going to the limit and making it a contact lens reduces the edge "scotoma" to zero. w.stacy, o.d. > cda...@directflatscreen.tv wrote: > > What might account for these prescription changes ( I was 44 in 1996 [quoted text clipped - 47 lines] > > w.stacy, o.d. Those were soft contact lenses BC 8.7. I am not sure why, on those two prescriptions, cyl. was added while at the same time he backed down on sphere. When I reached -11.0 in the contact lens he didn't want to raise it further for fear of damage to the cornea (my eyes continue to be pronounced "healthy"). I wasn't having problems reading, maybe with computers, definitely with distance. I wore hard contact lenses and then RGP's from 18 to about 35 with no problems. I agree with you about the field of vision. What I meant to say is that in a progressive lens, when the want to put in an add of 2.5 or 3.0, because of the rotation of the reading area they always seem to cut it off when they cut the lens size down. I have a preference toric of +. 50 -2.25 x170 BC 8.4 that I just love for my left eye. I cannot find a multifocal for my right eye in the same material that will let me specify the add power, maybe you know of one? The doctor said it is not possible to fill my prescription in RGP's so I am back to glasses. I could wear reading glasses over the contact lens in the left eye but that is when I was given my present reading glasses of: Reading +2.00 -0.50 x20 +3.50 -2.00 x168 ½ Up They only make my left eye blurry and my right eye ache from the strain. >Those were soft contact lenses BC 8.7. I am not sure why, on those two >prescriptions, cyl. was added while at the same time he backed down on >sphere. Because there was some residual cyl. The soft sphere does not correct any astigmatism, unlike your RGPs. > When I reached -11.0 in the contact lens he didn't want to >raise it further for fear of damage to the cornea (my eyes continue to >be pronounced "healthy"). That was a bogus answer. The difference in thickness is negligible. If he was concerned about your cornea, he should have changed you to a more oxygen permeable lens. > What I meant to say is that in a >progressive lens, when the want to put in an add of 2.5 or 3.0, >because of the rotation of the reading area they always seem to cut it >off when they cut the lens size down. Now that is true. If you must have a progressive, you need to keep some reasonable vertical dimension to the lenses. >I have a preference toric of +. >50 -2.25 x170 BC 8.4 that I just love for my left eye. I cannot find a >multifocal for my right eye in the same material that will let me >specify the add power, maybe you know of one? No, and the pref. toric is not a multifocal either. There is no good multifocal CL for you unless you want to try something like a tangent streak RGP. > The doctor said it is >not possible to fill my prescription in RGP's so I am back to glasses. [quoted text clipped - 8 lines] > > If you are wearing that preference toric, you should not have any cyl in the left reading lens. That Rx is for use with no contact lens on the left eye. w.stacy, o.d. > cda...@directflatscreen.tv wrote: > >Those were soft contact lenses BC 8.7. I am not sure why, on those two [quoted text clipped - 45 lines] > > w.stacy, o.d. Well, I didn't think that would work but he told me it would be fine. Since I didn't have the multifocal for the right eye, I needed something to wear while the contact lens was in my left. I just need the multifocal for the right eye, maybe PL with an add of +2.50, not toric. I need a toric for the left but no add. I am not sure of the optical mechanism whereby I can read but not see the street signs so they give me a reading add, although I am old enough now that I probably need some now. These are my K's: 44.37 x0 44.37 x0 7.61mm 7.61mm 43.25 x175 45.50 x85 7.80mm 7.42mm The K's in my right eye have been measured several times by more than one person and machine and that is what they get.
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