Sabbir: On your point #1, I think you are all wet. But I will defend your right to say it.
Sab: Wet Wrong!
[This message has been edited by chip anderson (edited 02-24-2001).]
Sabbir: On your point #1, I think you are all wet. But I will defend your right to say it.
Sab: Wet Wrong!
[This message has been edited by chip anderson (edited 02-24-2001).]
Is being wet right or wrong? And how come they don't do an American to English dictionary, so I don't have to look stupid asking these questions.
Uncle Chip,
Wet in my part of world means a womaniser!
May be in China it means something different again.
Anyway,I also learn American slangs,great indeed.
Sara
In the U.S. "All wet" usually (and in this case) means wrong. In fact now that I have pondered the matter, I don't think that there is a "most important consideration" in rigid lens fitting. At least not before you start. Of course if something is wrong, that becomes the most important part. As to base curve vs. diameter they both make up 1/2 of the specification sagital depth and to have an imbalance of either would make them both wrong.
I think base curve, sagital depth, diameter, posterior optical zone, peripheral curve width/radii, bevel width radii, edge roll/shape, lenticular zone are all important an neglect of any can result in a poor fit, poor comfort or be detrimental to long or short term corneal health.
Chip (Hard to please) Anderson
Where I come from it means something too rude to mention here. :)Originally posted by Sara:
Uncle Chip,
Wet in my part of world means a womaniser!
Sara
Steph,Originally posted by stephanie:
Ah Chip!! I believe me book has some wrong answers. I have for the answers both as being B. Hmmmm... interesting.
Chip is right about the answers to your examples. (45.00D =7.50mm) Do you remember how a couple of us told you how to convert Base Curves to Diopters?
Contact Lens Master Chip:
Starting the thread was a good idea! I mentioned in another post that I was returning to an independent shop; now I won't have to start a whole new thread when I come running to you for advice. It is nice to see that you speak from experience not just a text book. There is too little of that type of knowledge these days.
Jo
Chip:
We get alot of people, especially teenagers, who come in looking for non-Rx cosemetic lenses. We also get alot of expired contact lens Rx's in. Both will get into a shouting match and say they have gotten lenses in other cities without exams or fittings. Short of tossing one of your glass eyes at them, how do you effectively deal with them; they kind of ignore the medical device speech? I know you a good with words and I am looking for optical "fire and brimstone" here.
I know you addressed this to Chip, but with the teenagers I would try pointing out that no-one will fancy them (or whatever the US term is) when they are blind and their eyes are all starey and strange. Use the word 'disabled', as it has good psychological impact. Tell them that you couldn't care less if they go blind, but they're not doing it in your shop. Teenagers can relate to people who couldn't care less :) And shout loudly, because your're older than them and you can.
In fitting of RGP lenses we are taught that lens diameter is important to obtain good centration,base curve is not mentioned.
Sara,
Optical Student(2nd year)
Uncle Chip,
Shabbir asked your view on importance of lens diameter versus base curve in relation to RGP fitting parameters.
You replied base curve.
Shabbir expressed his view that he considers diameter an important parameter in RGP fittings.
You answered him with he is all wet(LOL).
In your later tread posting you said"as to base curve vs diameter they both make up 1/2 of the specification sagital depth and to have an imbalance of either would make them both wrong"
This means in principal you agreed that diameter is important fitting parameter of RGP lenses.
So you were wrong in first place when you replied him that base curve is important parameter in RGP fitting.
You are confusing me uncle!
Your (dry) niece Sara
Sara: I replied that the diameter being the most important concideration was wrong. I did not say it was not important. As you will note I don't think any parameter is unimportant, but if I were forced to say which was most important I would say the relationship of the base curve to the cornea, period.
You may have your parameter that you think is most important, you are entitled to this, as I am entitled to disagree.
[This message has been edited by chip anderson (edited 03-06-2001).]
Can someone please explain me in simple english
Cell Mitosis
Dk
Dk/t
I find it difficult to grasp from textbooks.
Sara
Uncle Chip,
You seem to be upset,that's the reason you not coming up with answers on questions posted in above tread.
Sara
Cells reproduce in two ways, mitosis, in which case a cell divides in two so as to produce two cells, each with the same chromosomes as the parent; and meiosis, which results in two cells each having half the parents' chromosomes.Originally posted by Sara:
Can someone please explain me in simple english
Cell Mitosis
Dk
Dk/t
I find it difficult to grasp from textbooks.
Sara
In simple English: mitosis is cell reproduction by division.
Dk is a measure of the ease with which oxygen can be dispersed (or "diffused")through a material. Dk/L (and I suppose, DK/t) is similar; it's a measure of the actual transmission of oxygen through a material of a given thickness.
"D" is the "diffusion coefficient" and "k" is the "solubility coefficient". Since I don't know how this measurement is actually done, I can't describe these. But "diffusion" and "solubility" seem pretty descriptive.
Regarding Uncle Chip (thank you for that) and the diameter v. base curve issue: I too would regard base curve as the more useful and critical fitting parameter. You can't change the diameter nearly as much as you can the curve, and changing the curve has a more direct and predictable effect on the fit.
That said, I'd rather make bricks without straw than fit contact lenses.
[This message has been edited by shanbaum (edited 03-09-2001).]
Dear Uncle Shanbaum,
Thank you very much for your simple explaination.It was easy to understand.
Regarding Diameter VS Base curve in RGP fittings,I am going to write to my course tutor and association to find it out more.If Shabbir being an international lecturer on cornea & contact lenses does not know simple things like this,I will stop him from coming to Kenya to lecture on this subject.I know Shabbir because we are from same region,Kenya,Uganda and Tanzania makes East-Africa.I have attended couple of his recent presentations in Addis Ababa,Ethopia.He is research optometrist.Now time has come for him to make bricks.
Thanks again uncle.
Sara
optical student
[This message has been edited by Sara (edited 03-09-2001).]
Dearest Sara: I was no upset, I had a page in an old "dictionary of Science" that Illustrates cell division in all four stages. Didn't remember the names and particulars enough to send you a popped off answer. Still haven't located the book, but If and when I will E.Mail it to you.
Chip
Finally getting back to this thread.
Methods of detecting corneal edema.
1) Observation in slit-lamp best seen with retro (light bounced off iris) illumination.
2) Central clearance (or sometimes more obscure areas) deminished under flourcein.
3) Changes in "K" readings from origional pre-fit condition.
4) Patient symtoms:
1)Spectacles seem fuzzy on removal of contacts.
2) Photophobia (sunlight sensitivity) should not be persent in a "perfect fit" of any type contact.
3) Over wearing syndrome, ( pain or discomfort sometime (30 min to several hours) after removal of lenses.
Recommendation: Check all of the above and do something about it if significantly changed at any follow-up. For the most part these things should not change at least on the short term. It is true that as one goes from teenager to middle age+ the cornea is likely to move from with the rule to against the rule cylinder and average corneal radii are somewhat longer, but these should not be short term (less than one decade) changes.
Chip
Hi Sara,
Re-visiting this post.Did you get correct answer from your course tutor you were going to ask about silly but important arguement on RGP=Diam. Vs BC.
I always want to re-learn and want remain student througout my life though however qualified I am!
Your Uncle Chip is qualified & experienced contact lens technician as I have noticed from reading his postings.However,he is arguementative by nature.I appreciate his knowledge in optics.
Shanbaum has no intellect.All his postings I have read;either he pleases posters by putting little flavoured remarks,or copy- repeats the same.
If feel he is here to do postings to increase his optiboard points only.Honestly Sara,you despite being still student,you have better knowledge of optics than Shanbaum.
Dear Shabbir,
Yes, I did get correct answer from my tutor,but I don't like academic conflicts.Both of you are right,OK.
Thanks for the compliments too.
Thanks,
Sara
In the summer months we receive more warped and flattened, or even occasionally steepened (rigid) lenses than any other time of the year. Why: Because the UPS trucks are hotter and the labs are more pressed to turn lenses out in a hurry. It is our DUTY to catch these things before they make it to the patient. How are they detected? Method #1 With a radiuscope, If you get a toric pattern or any reading you don't expect, it's wrong. Method #2
This can be detected with a keratometer and a devise called a contacheck (W/J). Here you supend the lens in water and focus the kerotometer thorugh a 45 front surface degree mirror. How much is too much? 1/4 diopter.
Chip:drop:
Last edited by chip anderson; 10-25-2008 at 06:10 PM. Reason: Front surface
Are You Providing Adequate Service?
I just had a new customer come to see me who had been purchasing contact lenses from my oldest competitor. While the patient was there, I read the Rx, took K readings, examined the corneas in the slit~lamp, examined the presently worn contacts on the cornea in the slit~lamp, and examined the new lenses on the eye in and took a history.
I found that the patient had a lot of corneal vascularization to about two and a half millimeters into the cornea O.U. The patient told me the name of the previous supplier and said: "They never did this at the other place. After the first visit they never looked at them on my eye at all." This deeply disturbed me as the competitor is my friend and has a fine reputation.
I don't know how things are where you are, but here the doctors that send me work assume that I am doing all of the above (although they also send work to the competitor) and they also assume that I will:
Look at the patient when difficulty is encountered, refer this patient to the doctor if the problem is not a mechanical one that I can fix, or if the source of the problem is not evident to me.
Refer the patient for annual exams to the doctor.
Examine the patient on a bi-annual basis if no problems are evident to the patient.
Keep notes on my observations and improve fitting whenever indicated.
Examine each and every rigid lens for all specifications before dispensing or replacing to the patient.
Question: If we do not provide these minimal services, what are we getting paid for?
Chip
Jo:
I am sorry that I did not notice this post directed to me, earlier. Here I have the defense that: "State law require that I have a 'contact lens precription" before I can dispense them or sell them." This man not be the case in all locations. But for me, I am CYA when it comes to giving the board of optometry (although I work almost entirely by M.D. Rx's) a reason to hang me.
I also explain that when the doctor writes this Rx he is saying that eye eye is healthy enough to wear contact lenses. Many conditons that are not giving trouble can become very severe if aggravated with a contact lens.
Chip:)
Chip,
1) I agree with you, we should perform all of these functions before dispensing contact lenses to a patient. Even if the patient has seen someone else who is a great fitter for years and wants a duplication, I still do the required steps. My name is going on the fit from this time forward, so I will ensure it is correct.
2) The Rx issue. I also refuse to dispense without an Rx and also a current one (2yrs old or newer where I'm from). I always tell the patient that the doctor will ensure their eye is healthy and that they are still candidates for contacts. I will then resort to #1 and do my own research and proceed if I find no problems.
Mullo
Sabbir:
One could if so inclined fit all eyes with a 7.0mm (rigid) lens or any eye with an 11.5 mm lens without changing anything but the base curve. Like I said this all depends on the sagittal depth. I know (knew) fitters who fit all thier lens quite small and many who fit all thier lenses quite large. Now when one adds peripheral curve customizing (an almost lost art) the posiblilities are almost infinite and the diameter need to be the least of the conciderations.
In the words of Frank Sanning: If you have an 8.5 trial set, you find yourself fitting a lot of 8.5's , if you have an 8.0 trial set you find yourself fitting a lot of 8.0's.
Another cool axiom to live by: Quote at the Las Vegas Contact Lens Society meeting: "If there were any real fitters here, they would be ordering uncuts." Jim Tannehill of Hawaii who taught us how to fit torics.
Chip
Last edited by chip anderson; 08-26-2001 at 04:33 PM.
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