Fitting Guide for Rigid and Soft Contact Lenses by Stein and Slatt
This book is considered the 'bible' for contact lenses here in Canada:cheers:
Printable View
I just bought a copy of the second edition for $0.40, I figure if Ted's cocky self likes the book it's got to be good :D try this link:
http://books.onlineopticianry.com
SOMETIMES SPIT WORKS PRETTY WELL:rolleyes:
Loratz:
No spit on Contact Lenses. I have made enough artificial eyes for one lifetime. No need to increase my market.
Chip
I know chip likes to fit using nomograms and intuition but for us novices I have put online a favorite nomogram for GP lens fitting, enjoy. The soft lens version will be posted up there soon.
http://www.technicalopticians.org
Soft lens nomogram is posted at:
http://www.technicalopticians.org
A few pages back some one asked a question about cell mitosis and the explanation was posted, but my wife is in that part of her lesson and was taking pictures through a microscope of cells. So I thought wouldn't it be fun to put them up for people to guess what's happening.
From the images below match the phase of mitosis with the image
No 1 - ?
No 2 - ?
No 3 - ?
No 4 - ?
No 5 - ?
No 6 - ?
No 7 - Can you tell if this is an animal cell or a plant cell?
No 8 - What characteristic lead you to believe your conclusion to answer No 7?
[spoiler=For Answers Click Here]No 1 - Anaphase \nNo 2 - Telophase\nNo 3 - Prophase\nNo 4 - Between Prometaphase and Metaphase\nNo 5 - Metaphase\nNo 6 - Between Telophase and Cytokenisis\nNo 7 - Plant Cell\nNo 8 - Only plant cells have cell walls, animal cells have cell membranes. This would account for a square shape rather than an oval or round shape.\n\nThanks for Playing[/spoiler]
Here are some more contact related questions. Try them out before you check your answers.
1. The most refractive power comes from which component of the eye?
2. In the reduced Gullstrand Schematic Eye the index for the eye is?
- Crystalline Lens
- Posterior Corneal Surface
- Anterior Corneal Surface
- Aqueous and Vitreous
3. A patient presents with K's of 40.00@180 / 40.50@090 the patient wants soft lenses. What base curve would you fit the patient in?
- 1.33
- 1.337
- 1.336
- 1.37
4. A patient with HVID of 11mm wants soft lenses what would be the intitial choice for diameter?
- Steep
- Median
- Flat
5. If the radius of a lens is made larger, would the lens get?
- 12mm
- 1.4cm
- 12cm
- 11mm
- 15mm
[spoiler=Answers]1 - C\n2 - A\n3 - C\n4 - B\n5 - D (although B itself is acceptable)\n\nThanks for trying[/spoiler]
- Steeper
- Flatter
- Depends on diameter
- B and C
- A and C
Harry: What is HVID? What is alger?
I thought I knowed this stuff pretty well but I don't know what either is.
Chip
Just a little known fact to add to mixture. The actual corneal diameter (verified by a lot of moulds taken many years ago) is usuall abot 1.4 mm larger than the visible iris diamter. With 13.7 being average.
Chip
Harry, I think I'll fuss over the suggested answers to #5 being (d. or b.)
5. If the radius of a lens is made larger, would the lens get?
You did say (b) alone is OK, which I think is th only answer. I say regardless of the diameter, as the radius increases, the lens is flatter. The question does not say anything about changing the diameter when the the radius changes. The answer C hints at the fact that the fit is a function of diameter and curvature, which is true. But the answer C, realy does not aply to the question.
- Steeper
- Flatter
- Depends on diameter
- B and C
- A and C
Now to put out another idea, had the question read, "What happens when the radius is made smaller?". It is possible to order a base curve that is so tight that it can not be made in the requested diameter because the radius would describe a sphere smaller that the requested diameter, but this is getting pretty far out there. ( dia= 9.4, bc = 4.85 , would have to be a REAL THICK lens to reach 9.4 )
That's my 2 cents for the day
Jim Rumbaugh
Thanks Jim,
Originally I though the same as you did but was anticipating someone argueing that it would depend on if the diameter stayed the same or not, so I thought I would put it both ways to try and cover my bases.
Good to see that you took it. I will put more up.
Rigid lenses rule:
1: Either the lens is too damn flat or it's too damn big.
Softlens rules:
1: If the lens hurts it's too flat, has trash under it, is wrong side out or is damaged.
2: If the lens doesn't center or moves excessively it's too flat or too small.
3: If vision fluctuates, particularly improving after squeezing lids tight or rubbing and deteriorated before blink, lens is too steep.
Are there other factors, like edge design, modum (hoop strength) allergy, etc. Sure but if you just get and keep the above straight in your mind you will be way ahead of most in this business.
Chip
I was trying to pull you out of the fire there.
But, Oh well.:cry: Have it your way.
Respectfully,
dbracer
Someone came in today to get her contacts polished. Somebody did the polishing but did not finish with a peroxide cleaning -nor a boston conditioner rubbing/cleaning to remove the polish.She used the rinse with water which does not work. Result ? Superficial abrasions on both eyes.I can't believe that the opticians who still actually polish contacts do not use peroxide to remove polish and to immediately disinfect their contacts. Again,you rub the peroxide into the len as you are rinsing it with tap water. It will feel squeeky clean. It will be clean. When doing an enzyme cleaning on a gas perm, use peroxide instead of saline and the enzyme softened protein comes right off. To those of you who scoff about this -I've used this successfully 28 years with never a reaction. And my pts do not get reactions after I polish their contacts.
I feel bad that I haven't been posting any questions... instead I'm runnin' my mouth off in other threads like a yahoo instead of learning something, which is why I come here... so... I have a question for those that are far more learned than I.
with respect to RGP materials: I have been researching RGP materials a little bit, just to see what's available to me and so I can be more familiar with them... it got me thinking about the hyper-Dk materials on the market and I came down to Menicon's Z material, which surprisingly to me, is approved for up to 30 nights of continuous wear (I didn't realize that wearing RGPs continuously for days was safe).
My question: What are your feelings on continuous wear modality for rigid contacts? Is it something you would say should be avoided entirely, or under a very strict set of circumstances would it be acceptable to you?
as a side note: I can see where the benefit could instantly be appreciated in an orthokeratology application, but that's usually where patients are sleeping in their lenses anyhow and leaving them out during waking hours, and possibly the increased lens flexure may not be acceptable for maximum effectivity, however, I digress... I'll ask about orthokeratology stuff at a later time.