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Medical Forum / General / Vision / July 200550% failure rate in Biomedics Toric?
Intrepid readers may recall me mentioning I have an assortment of soft lenses to try. My left lens is a toric and I was provided three different powers, same brand/bc/dia. Ostensibly the lenses are identical except for the thickness and I imagine the difference is so negligible to the mechanics of the lens as to be irrelevent. So. The first lens was good. Centered well, corrected my vision adequately. Today I popped in the weakest lens and OH MY GOD the thing is horrible - decenters. feels bad, can't see for squat. The first lens is fine, afaic. Am I being overly paranoid in thinking that if one lens of two is crap then possibly 3 in a box of 6 will be as well? And on a side note - it seems to me that everrything I've read, and the little I recall from my last successful foray into soft lenses, says that the contact power is generally a full sphere WEAKER than the spectacles Rx. Is this correct? My right contact and right spectacles Rx are identical and I feel grossly over-corrected. The contact lens dispenser at the eyedoc's office insists it has to be correct since that's how the doc wrote it - but I'm leaning toward the doc having made a transcription error. Comments? +++++++++++++ Reply to the list as I do not publish an email address to USENET. This practice has cut my spam by more than 95%. Of course, I did have to abandon a perfectly good email account... > Intrepid readers may recall me mentioning I have an assortment of soft > lenses to try. My left lens is a toric and I was provided three > different powers, same brand/bc/dia. Ostensibly the lenses are > identical except for the thickness and I imagine the difference is so > negligible to the mechanics of the lens as to be irrelevent. No, if the powers are different, then the thicknesses will be only minutely different (assuming they didn't give you something like -12, -5 and +8! > So. The first lens was good. Centered well, corrected my vision > adequately. Today I popped in the weakest lens and OH MY GOD the > thing is horrible - decenters. feels bad, can't see for squat. Bad lens, or something other than power is different > The first lens is fine, afaic. Am I being overly paranoid in thinking > that if one lens of two is crap then possibly 3 in a box of 6 will be > as well? Not usually. > And on a side note - it seems to me that everrything I've read, and > the little I recall from my last successful foray into soft lenses, [quoted text clipped - 4 lines] > correct since that's how the doc wrote it - but I'm leaning toward the > doc having made a transcription error. Effective powers of CLRxs depend on the corresponding spectacle Rx. If the SRx sphere is less than around +or -3.00, then no corrections for vertex distance need to be made. At about 4.D, a .25 D. correction needs to be made (add for - lenses, subtract for + lenses). This "vertex correction" increases as the powers go up, to around a full diopter at 10.D, and so on. What are your powers? w.stacy, o.d. >Bad lens, or something other than power is different Ok. I have an appointment for a lens check on Friday. I'll simply wear the first left lens to the check as it was *adequate* from my POV. >Effective powers of CLRxs depend on the corresponding spectacle Rx. If >the SRx sphere is less than around +or -3.00, then no corrections for [quoted text clipped - 4 lines] > >What are your powers? My spex OD is a -600 with no astigmatism correction this time around, the CL blister claims to be an aspheric -600. Everything is hyper-clear and I feel like that eyeball is trying to extrude itself from my head, which is essentially the same symptom I had when the optician once switched the lenses in my spectacles and the -8 lens ended up on the (then) -5 eye. My spex OS was a -950 -80 135, the blister from the first CL is a -825 -75 140 and is the CL the doc recommended I try first. The CL I tried today is the -850 and it may very well give me better vision but I couldn't keep the damned thing in for more than 5 minutes. I also have a -875 to try but I may not get around to it. As I said I have a lens check scheduled for Friday. The dispensing optician can't be bothered to ask the eyedoc to clarify the right lens power so I'll do it myself on Friday. This is the first time I've been less-than-impressed with the service at this place... +++++++++++++ Reply to the list as I do not publish an email address to USENET. This practice has cut my spam by more than 95%. Of course, I did have to abandon a perfectly good email account... > My spex OD is a -600 with no astigmatism correction this time around, > the CL blister claims to be an aspheric -600. Everything is > hyper-clear and I feel like that eyeball is trying to extrude itself > from my head Yep, they forgot the little vertex calc. You should have a -5.50 or so on that eye. > My spex OS was a -950 -80 135, the blister from the first CL is a -825 > -75 140 and is the CL the doc recommended I try first. The CL I tried > today is the -850 and it may very well give me better vision but I > couldn't keep the damned thing in for more than 5 minutes. I also > have a -875 to try but I may not get around to it. These left lenses are all torics with the same cyl and axis (2nd and 3rd numbers)?? Are they all biomedics torics? What's that -80? Is this a wave front refraction or what (conventionally, we refract and prescribe in .25 cyl steps)? > As I said I have a lens check scheduled for Friday. The dispensing > optician can't be bothered to ask the eyedoc to clarify the right lens > power so I'll do it myself on Friday. This is the first time I've > been less-than-impressed with the service at this place... The od shouldn't be bothered to hear about this. The disp. should also know better, esp if he/she wants to fit CLs! This isn't exactly rocket science... w.stacy, o.d. > The od shouldn't be bothered to hear about this. What I meant to say, is it shouldn't bother the od to hear about this. I for sure would want to know if someone in my employ was handing out lenses that are too strong! w.stacy, o.d. >> The od shouldn't be bothered to hear about this. > [quoted text clipped - 3 lines] > >w.stacy, o.d. The ophthalmologist apparently wrote the Rx for the -600 and the dispenser is too much of a chit to "bother" him with it. Nevermind that I'm the paying customer wearing the damned lens and ought to know if is too strong ;P I don't know what the -80 is if it isn't the add for my astigmatism. Historically that number on my spex Rx has hung right around -70. Possibly the man's handwriting is inscrutable to me in my badly-corrected state :) +++++++++++++ Reply to the list as I do not publish an email address to USENET. This practice has cut my spam by more than 95%. Of course, I did have to abandon a perfectly good email account... > I don't know what the -80 is if it isn't the add for my astigmatism. > Historically that number on my spex Rx has hung right around -70. > Possibly the man's handwriting is inscrutable to me in my > badly-corrected state :) Maybe, but convention is a SRx is usually written (in the US and many other places) as: -8.00 -1.00 x 165 add +2.00 Where the -8.00 is the sphere power, -1.00 is the cylinder (astigmatic) power, 165 is the axis or orientation of the cylinder power, and +2.00 is the add power for near. All powers are given in diopters, usually in .25 increments but the sphere power is occasionally specified in .12 increments. Axis is given in degrees, starting at 0, the horizontal, progressing counter-clockwise as you look at the patient's face, through 90 (the vertical) and back to 180=0 the horizontal. Thus I was puzzled to see -80 as any power value, although I think in wave front refraction (still a rarity) powers are expressed to the .01 diopter. Anyway, good luck with the fitting and report back. w.stacy, o.d. Hokay. The eyedoc is ordering a range of the new(?) Acuvue torics for me to try on my left eye. I'm wearing an aspheric lens on the left at the moment that she used to check the fit, and the optics are ok, tho I've got a little bit of "wave action" if I turn my head too fast while moving my eyeball - its quite strange, but at least it *fits*. She did agree (saw a diff doc today) that the right lens was too strong and sent me home with several weaker lenses to try. +++++++++++++ Reply to the list as I do not publish an email address to USENET. This practice has cut my spam by more than 95%. Of course, I did have to abandon a perfectly good email account... |
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