Scientific measurement protocols 1

1. Churawan Lal sahu
M Optom
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2. Measurements
 Single vision
 Bifocals
 Progressive lenses
Scientific Measurement Protocols
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3. Single Vision
 IPD
 Centration
Scientific Measurement Protocols
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4. Scientific Measurement Protocols
Effect of decentration
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5. Bifocals
 IPD
 Distance & Near
 Segment insertion
 Segment height
Scientific Measurement Protocols
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6. Scientific Measurement Protocols
Near PD & Segment insertion
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7. Segment height
Scientific Measurement Protocols
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8. Progressive lenses
 Training
 Communication and counselling
 Convincing power
 Designs knowledge
Scientific Measurement Protocols
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9. Progressive lenses
 Possible causes of problems with PAL’s
 Indications
 Contraindications
Scientific Measurement Protocols
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10. Scientific Measurement Protocols
Fields of view Direction of Gaze
Contraindications
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11.  Mobility / Head Movement
Scientific Measurement Protocols
Contraindications
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12. Contraindications
 Anisometropia
 High Cylinders
 Prisms
 High ADD
Scientific Measurement Protocols
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13. Contraindications
 Bifocal users
 Reading glasses users
Scientific Measurement Protocols
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14. Scientific Measurement Protocols
Measurements step by steps
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15. Step 1
Patients selection
Scientific Measurement Protocols
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16. Patients selection
 Identification
 Requirements
 Expectations
Scientific Measurement Protocols
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17. Step 2
Frame selection
Scientific Measurement Protocols
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18. Scientific Measurement Protocols
Frame shape
Good Shape
Bad Shape
Good Depth Good Size
Too Large
Frame sizeFrame depth
Small frame 18Churawan Lal Sahu M Optom

19. Ideal frames
 Prefer metal frames
 Adjustable nose pads
 Min depth of 25-30 mm
 Min fitting height should be 18mm / 14mm
Scientific Measurement Protocols
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20. Step 3
Frame Adjustment
Scientific Measurement Protocols
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21. Scientific Measurement Protocols
Frame Adjustment
 Vertex distance
 Pantoscopic tilt
 Facial wrap
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22. Back vertex distance
 Shorter
 Reduce BVD – wider fields of view
Scientific Measurement Protocols
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23. Scientific Measurement Protocols
Effect of vertex distance
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24. Pantoscopic tilt
 10 to 12 degree
 Pantoscopic tilt – increases near field of view
Scientific Measurement Protocols
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25. Scientific Measurement Protocols
Effect of Pantoscopic tilt
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26. Facial wrap – must not be too flat
Scientific Measurement Protocols
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27. Scientific Measurement Protocols
Effect of facial wrap
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28. Step 4
Interpupillary distance (IPD)
Scientific Measurement Protocols
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29. IPD
 Monocular PD
 Binocular PD
 Scale or Pupillometer
Scientific Measurement Protocols
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30. IPD
 Use a corneal reflex for accuracy
 In case of strabismus – occlude one eye
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31. Pupillometer centration
Scientific Measurement Protocols
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32. Effect of inexact IPD marking
Scientific Measurement Protocols
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33. Scientific Measurement Protocols
Step 5
Monocular PD marking in the lens
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34. Step 6
Fitting Height/ Vertical Height
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35. Fitting Height
 Ensure that you are at eye level of patients
 Take monocular fitting height
 Measure directly to pupil centre
 Ensure that patient is looking strait ahead
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36. Scientific Measurement Protocols
Fitting height
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37. Effect of wearer posture
Scientific Measurement Protocols
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38. Scientific Measurement Protocols
Effect of parallax error
 Parallax error can significantly affect fitting
height
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39. Effect of Fudging Fitting Height
Scientific Measurement Protocols
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40. Scientific Measurement Protocols
Step7
Check the lens cut out
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41. Scientific Measurement Protocols
Delivery ..
Quality check up
 Markings
 Frame alignments
 Power
 Fitting cross heights & PDs
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42. Scientific Measurement Protocols
Delivery ..
On eye assessment
Frame fit Fitting crosses 42Churawan Lal Sahu M Optom

43. Delivery
Scientific Measurement Protocols
Delivery Instructions
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44. Thank you
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