Scientific measurement protocols 1

Churawan Lal Sahu M Optom 1

Scientific Measurement ProtocolsChurawan Lal sahu

M Optom

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Measurements

Single vision

Bifocals

Progressive lenses

Scientific Measurement Protocols

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Single Vision

IPD

Centration

Scientific Measurement Protocols

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Scientific Measurement Protocols

Effect of decentration

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Bifocals IPD

Distance & Near

Segment insertion

Segment height

Scientific Measurement Protocols

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Scientific Measurement Protocols

Near PD & Segment insertion

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Segment height

Scientific Measurement Protocols

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Progressive lenses

Training

Communication and counselling

Convincing power

Designs knowledge

Scientific Measurement Protocols

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Progressive lenses

Possible causes of problems with PAL’s

Indications

Contraindications

Scientific Measurement Protocols

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Scientific Measurement Protocols

Fields of view Direction of Gaze

Contraindications

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Mobility / Head Movement

Scientific Measurement Protocols

Contraindications

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Contraindications

Anisometropia High Cylinders Prisms High ADD

Scientific Measurement Protocols

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Contraindications

Bifocal users

Reading glasses users

Scientific Measurement Protocols

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Scientific Measurement Protocols

Measurements step by steps

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Step 1

Patients selection

Scientific Measurement Protocols

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Patients selection

Identification

Requirements

Expectations

Scientific Measurement Protocols

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Step 2

Frame selection

Scientific Measurement Protocols

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Scientific Measurement Protocols

Frame shape

Good Shape

Bad Shape

Good Depth Good Size

Too Large

Frame sizeFrame depth

Small frame

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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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Step 3

Frame Adjustment

Scientific Measurement Protocols

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Scientific Measurement Protocols

Frame Adjustment

Vertex distance

Pantoscopic tilt

Facial wrap

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Back vertex distance Shorter

Reduce BVD – wider fields of view

Scientific Measurement Protocols

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Scientific Measurement Protocols

Effect of vertex distance

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Pantoscopic tilt

10 to 12 degree

Pantoscopic tilt – increases near field of view

Scientific Measurement Protocols

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Scientific Measurement Protocols

Effect of Pantoscopic tilt

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Facial wrap – must not be too flat

Scientific Measurement Protocols

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Scientific Measurement Protocols

Effect of facial wrap

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Step 4

Interpupillary distance (IPD)

Scientific Measurement Protocols

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IPD

Monocular PD

Binocular PD

Scale or Pupillometer

Scientific Measurement Protocols

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IPD Use a corneal reflex for accuracy In case of strabismus – occlude one eye

Scientific Measurement Protocols

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Pupillometer centration

Scientific Measurement Protocols

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Effect of inexact IPD marking

Scientific Measurement Protocols

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Scientific Measurement Protocols

Step 5

Monocular PD marking in the lens

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Step 6

Fitting Height/ Vertical Height

Scientific Measurement Protocols

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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

Scientific Measurement Protocols

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Scientific Measurement Protocols

Fitting height

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Effect of wearer posture

Scientific Measurement Protocols

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Scientific Measurement Protocols

Effect of parallax error Parallax error can significantly affect fitting

height

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Effect of Fudging Fitting Height

Scientific Measurement Protocols

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Scientific Measurement Protocols

Step7

Check the lens cut out

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Scientific Measurement Protocols

Delivery ..

Quality check up

Markings

Frame alignments

Power

Fitting cross heights & PDs

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Scientific Measurement Protocols

Delivery ..

On eye assessment

Frame fit Fitting crosses

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Delivery

Scientific Measurement Protocols

Delivery Instructions

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Thank you