optical technician course

[Agnieszka]

Hi,I am doing the optical technician course and I have problems with my course question.Could anybody help me?Thank You very much.
1. A patient wears a spectacle frame whose BCD is 68. The Rx is +3.00 each eye and his Pd is 64. If the largest available blank was not large enough to optain the required decentration, what prism must be worked and in what direction, to obtain the centres in the correct position from a standard blank size?

2. A prismatic Rx has been ordered of 2.5 prism dioptres Base IN each eye on an Rx, BE -5.00D.
What would be the minimum blank size possible to produce this prism for an eyesize of 45mm by decentration?

3. A patient looks through a point 5mm above the lens optical centres of Rx BE +4.00D. How much prism (including the base direction) does the patient encounter?

4. If the Rx in question 3 was: R +4.00D and L -4.00D, how much total prismatic imbalance would there be between the two eyes?

[MakeOptics]

Hi, My name is Agnieszka.I am doing the optical technician course and I have problems with my course question.Could anybody help me?Thank You very much.
1. A patient wears a spectacle frame whose BCD is 68. The Rx is +3.00 each eye and his Pd is 64. If the largest available blank was not large enough to optain the required decentration, what prism must be worked and in what direction, to obtain the centres in the correct position from a standard blank size?

Base in prism, and if it's just to obtain the decentration then 1.25PD

2. A prismatic Rx has been ordered of 2.5 prism dioptres Base IN each eye on an Rx, BE -5.00D.
What would be the minimum blank size possible to produce this prism for an eyesize of 45mm by decentration?

55mm

3. A patient looks through a point 5mm above the lens optical centres of Rx BE +4.00D. How much prism (including the base direction) does the patient encounter?

2 BD

4. If the Rx in question 3 was: R +4.00D and L -4.00D, how much total prismatic imbalance would there be between the two eyes?

4 PD

that was interesting.

[Agnieszka]

that was interesting.[/COLOR]

Hi,thank you very much for answer, but I still don't know how to do it. Could you explain for me please?

[IaninIOM]

Given that you are probably doing the SMCTech course, you should have a supervisor, both at the place you work and also on the other end of the distance learning. Plus the text books for the course are very clear as are the course notes. Can I, therefore, suggest you read and use them rather than the internet.

[Agnieszka]

Hi, Thank you for yours advice. Maybe text books for the course ale very clear but not for me. I was reading the books but I still do not understand. Probably because of language barrier.

[MakeOptics]

1. A patient wears a spectacle frame whose BCD is 68. The Rx is +3.00 each eye and his Pd is 64. If the largest available blank was not large enough to optain the required decentration, what prism must be worked and in what direction, to obtain the centres in the correct position from a standard blank size?

The frame PD is 68 and the patient PD is 64 assuming that the largest blank would cut out if not decentered, then we would need to determine the decentration first.


Frame PD - Patient PD / 2 = decentration in each eye, in this case that is 2mm

Since the question asks for the prism that would need to be ground to obtain a 2mm decentration, we would plug our known values into prentices rule to obtain the prism.

Prism = Power * Decentration (cm), which is +3.00 * 0.2cm = 0.6 PD each eye or 1.2PD total, we know it's base in because that's the direction we are moving the optical center.

2. A prismatic Rx has been ordered of 2.5 prism dioptres Base IN each eye on an Rx, BE -5.00D.
What would be the minimum blank size possible to produce this prism for an eyesize of 45mm by decentration?

We would again work the problem in our prentices rule to obtain the decentration this time.

Prism= Power * Decentration (cm), which is Decentration(cm) = 2.5PD / -5.00 or 0.5cm which is 5mm of decentration since decentration is added to the radius of the blank we would need to double it to come up with the diameter or 10mm to add to the blank size which is 45mm + 10mm = 55mm.

3. A patient looks through a point 5mm above the lens optical centres of Rx BE +4.00D. How much prism (including the base direction) does the patient encounter?

Prentices rule is again employed in this problem, Prism = Power * Decentration (cm), which is Prism = +4.00 * 0.5cm = 2PD and since the patient is looking thorugh a point above the center and since the center is thicker than the edge then the base is below the point so we have 2PD Base Down.

4. If the Rx in question 3 was: R +4.00D and L -4.00D, how much total prismatic imbalance would there be between the two eyes?

This question is a gimme, we did all the work in the previous question we are just using a different sign on the left lens so if the right lens is 2PD BD and the left is 2PD BU then the total imbalance is the addition of the two prism powers or 4PD.

I was impressed that you were not just interested in the answers but the why, that was the only reason why I took the time to type this response. Good luck on your course, if it is the SMC Tech does that mean you are a member of the worshipful spectacle makers? If so that is a very prestigiuos group welcome and I look forward to more of your comments and responses.

I am sorry to hear that no one has time to mentor you, if you send me your questions I will do my best to not only provide answers but explanations in the future. I would be honored to mentor you in your studies as it will help keep my mind sharp as well and provide the world a better optical professional. Use the PM system and I will provide you an e-mail address if you are interested, I have e-mail on my phone so the responses will be a lot quicker.

[Agnieszka]

I am very grateful for your help.

[gmc]

Edited because I posted after the above response which explained the same thing.

[IaninIOM]

Agnieszka, I am glad that Phitrace explanined that well for you can I suggest that you also try theOptom.com as it is a UK based forum http://www.theoptom.com/ and I am sure that people will be quite happy to help once you have explained your position. I am there under another username.
I find it disturbing that no one at your work place has, after placing you on the course, not got the time to act as supervisor. Which level are you doing level 2 or level 4?
I ask this because quoted from the SMC website:
"The correspondence course is designed to fit easily into even the busiest job schedule and lifestyle. Your personal WCSM Education Trust tutor will take you through a series of papers covering the syllabus and you can work at your own pace."

I hadn't realised that you were having problems with mentoring, otherwise my answer would have been different. It is just that one or two students have posted on other websites wanting other people to do their homework for them. You now have several people to ask so please do so. Just remember the question you do not ask is the silly one.

[Agnieszka]

Hi,
Thank you for internet webside to theoptom in UK. I have to register.
And I don't want , that somebody do my homework. What is the point if, any way, I have to go and pass my exams (nobody do it for me). I have to do it myself , so I need help to understand lecture.

[MakeOptics]

Hi,
I am doing Level 4 Certificate for Optical Technicians SMC(Tech) Part I at the moment. Thank you for internet webside to theoptom in UK. I have to register.
And I don't want , that somebody do my homework. What is the point if, any way, I have to go and pass my exams (nobody do it for me). I have to do it myself , so I need help to understand lecture.

Like I said if your drive and motivation puts you in the top 5% then it makes it difficult to get the proper instruction just know i'm here if you need help. Who knows you may have to fit my mother in a pair of specs one day.