4. Optical Prism 2.pdf

OPHD 2604 Optical Prism Part 2 Chapter 16 13 March 2024 2. GRAPHICALLY Compounding Prisms: Steps involved: R² = H² + V² 1. Draw the eye on a cross to scale SOH CAH TOA 2. Show the scale 3. Sho...

OPHD 2604 Optical Prism Part 2 Chapter 16 13 March 2024 2. GRAPHICALLY Compounding Prisms: Steps involved: R² = H² + V² 1. Draw the eye on a cross to scale SOH CAH TOA 2. Show the scale 3. Show the nose 4. Show the bases 5. Plot the V meridian 6. Plot the H meridian 7. Determine the R (literally by measuring) 8. Measure the angle with a protractor Compounding Prisms: Example 1: Px has a 2BU and 4BI deviation RE. Graphically determine the resultant deviation Compounding Prisms: OD 1. Draw the eye on a cross to scale 2. Show the scale 3. Show the nose 4. Show the bases 1cm = 1 ∆D Compounding Prisms: OD Example 1: Px has a 2BU and 4BI deviation RE 5. Plot the V meridian = 2BU 6. Plot the H meridian = 4BI Draw in the line R Draw in the angle alpha Compounding Prisms: Example 1: Px has a 2BU and 4BI deviation RE 7. Determine the r by measuring the line drawn in with a ruler = 4.5cm (on diagram) 1cm : 1 ∆D 4.5cm : r r = 4.5 ∆D What’s the base?? Compounding Prisms: Example 1: Px has a 2BU and 4BI deviation RE 7. Determine the r by measuring the line drawn in with a ruler r = 4.5 ∆D What’s the base?? BU and BI Compounding Prisms: Example 1: Px has a 2BU and 4BI deviation RE 8. Measure the angle with a protractor = 26° 26° or 154°?? Think of your trial frame Compounding Prisms: Example 1: Px has a 2BU and 4BI deviation RE Resultant prism = 4.5 ∆D BU AND BI @ 26° EXAM: 1mm difference marked correct Compounding Prisms: Redo Example 5 using the graphical method to determine the resultant prismatic effect if: The patient experiences a decentration 3mm in and 3mm down. RE: +2.00/-4.00 x 180 3mm in and 3mm down RE: +2.00/-4.00 x 180 Resolving Prisms: Steps involved: 1. Draw the eye on a cross to scale 2. Show the scale 3. Show the nose 4. Show the bases 5. Plot the resultant Use protractor to get the angle Along the angle line draw the length of the R 6. Determine the value on the horizontal meridian (literally by measuring) 7. Determine the value on the vertical meridian (literally by measuring) Resolving Prisms: Example 1: What are the vertical and horizontal components of 4.5 ∆D BU AND BI @ 26 ° RE? Resolving Prisms: OD 1. Draw the eye on a cross to scale 2. Show the scale 3. Show the nose 4. Show the bases 1cm = 1 ∆D Resolving Prisms: Example 1: 4.5 ∆D BU AND BI @ 26 ° RE 5. Plot the resultant - use protractor to get the angle Resolving Prisms: Example 1: 4.5 ∆D BU AND BI @ 26 ° RE 5. Plot the resultant - use protractor to get the angle Along the angle line draw the length of the r Resolving Prisms: Example 1: 4.5 ∆D BU AND BI @ 26 ° RE Draw in the perpendicular lines and label them x (horizontal) and y (vertical) Resolving Prisms: Example 1: 4.5 ∆D BU AND BI @ 26 ° RE 6. Determine the value on the vertical line = 2∆ BU 7. Determine the value on the horizontal line = 4∆ BI Resolving Prisms: Example 1: 4.5 ∆D BU AND BI @ 26 ° RE What are the horizontal and vertical components? Answer = 2∆ BU and 4∆ BI Resolving Prisms: Redo Example 2 using the graphical method to determine what the decentration along the vertical and horizontal meridians are to produce a resultant prismatic effect of 8.50Δ BI and BD @ 15° if: OS: -3.75/+5.00 x 90 Resultant prismatic effect of 8.50Δ BI and BD @ 15° OS: -3.75/+5.00 x 90 END!