Podcast
Questions and Answers
What angle measurement is represented in this context?
What angle measurement is represented in this context?
- 130.5°
- 150.0°
- 143.13° (correct)
- 125.25°
The value of y represents the vertical meridian component.
The value of y represents the vertical meridian component.
False (B)
What does CAH likely symbolize in this context?
What does CAH likely symbolize in this context?
Cosine of angle A over Hypotenuse
The value y represents the _____ Meridian component.
The value y represents the _____ Meridian component.
Match the components with their meanings:
Match the components with their meanings:
What is the prescription strength of the spectacle lenses in Example 3?
What is the prescription strength of the spectacle lenses in Example 3?
The spectacles became aligned after the patient dropped them.
The spectacles became aligned after the patient dropped them.
What sport was the patient playing when the spectacles fell?
What sport was the patient playing when the spectacles fell?
The prescription of the lenses can be represented as _______ x 90.
The prescription of the lenses can be represented as _______ x 90.
Match the following terms related to resolving prisms:
Match the following terms related to resolving prisms:
What does the abbreviation PE stand for in the context of eye treatment?
What does the abbreviation PE stand for in the context of eye treatment?
Both methods aim to eliminate or standardize the prismatic effect.
Both methods aim to eliminate or standardize the prismatic effect.
Which method is considered more appropriate for eye treatment and why?
Which method is considered more appropriate for eye treatment and why?
To improve vision, one method aims to make the two eyes the same _____ effect.
To improve vision, one method aims to make the two eyes the same _____ effect.
Match the methods of addressing prismatic effects with their main focus:
Match the methods of addressing prismatic effects with their main focus:
What does the term 'bi-centric' mean in the context of lenses?
What does the term 'bi-centric' mean in the context of lenses?
A bi-centric lens has only one point of no prismatic effect.
A bi-centric lens has only one point of no prismatic effect.
What is the name given to a point where there is no prismatic effect?
What is the name given to a point where there is no prismatic effect?
Compounding of prisms refers to putting together two prisms to form one prism that is the equivalent of both, and this process is known as __________.
Compounding of prisms refers to putting together two prisms to form one prism that is the equivalent of both, and this process is known as __________.
Match the following definitions with their terms:
Match the following definitions with their terms:
What formula is used to get 'c' when resolving prisms?
What formula is used to get 'c' when resolving prisms?
The eye is looking towards the horizontal meridian in the example provided.
The eye is looking towards the horizontal meridian in the example provided.
In the example provided, what is the value of the resultant PE?
In the example provided, what is the value of the resultant PE?
To resolve prisms, the formula used is P = cF on _____ and on _____.
To resolve prisms, the formula used is P = cF on _____ and on _____.
Match the following terms with their appropriate descriptions:
Match the following terms with their appropriate descriptions:
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Study Notes
Resolving Prisms
- Example 1:
- Prescription: +5.00/-3.00 x 90
- Resultant Prism: 5∆ BU and BO @ 143.13°
- Question: Patient is looking towards the vertical and horizontal meridians.
- Solution: Decenter the lens or place a prism into the spectacle lens.
- Example 2:
- Scenario: Patient uses spectacles while playing volleyball, they fall and misalign.
- Problem: The spectacles are misaligned and need to be corrected.
- Goal: Eliminate all prismatic effects in both eyes and make their prismatic effect the same.
- Solution: Two methods are available, the most appropriate one is not specified.
- Calculations:
- To determine the horizontal meridian component (y) of the prismatic effect, use the formula P = cF for both horizontal and vertical components.
Bi-Centric Lenses
- Definition: Bi-centric lenses have two optical centers.
- Explanation:
- Bi means two, Centric means centers.
- At the optical center of a lens, there is no prismatic effect.
- Therefore, a bi-centric lens will have two points with no prismatic effect.
- Example:
- Scenario: Before placing a prism, a patient is looking at a point 1 cm above the optical center.
- Action: A 4∆ BU prism is placed to eliminate the 4∆ BD (caused by the eye looking at a different point).
- Result: The patient's eye is looking at a point that has both 4∆ BD and 4∆ BU, resulting in zero prismatic effect.
- Conclusion: The point with zero prismatic effect is called the optical center. Since the lens already has its own optical center, and the prism creates another point with no prismatic effect, a bi-centric lens is created.
Compounding and Resolving of Prisms
- Compounding: Combining two prisms with different powers and base orientations to create one equivalent prism.
- This process involves adding the vertical and horizontal components to find the resultant in an oblique meridian.
- Resolving: Converting an oblique prism into two prisms perpendicular to each other.
- This involves breaking down the oblique prism into its vertical and horizontal components.
- Methods: Two primary methods for resolving and compounding prisms are not detailed in the text.
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