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PAL Fitting, facial measurement and markingGS Shrestha, B.OptM.OptomGS Shrestha, B.OptM.Optom
Gauri S. Shrestha, M.Optom, FIACLE
Gauri S. Shrestha, M.Optom, FIACLE
Fitting PALs is an art..
It requires adequate
training & skill
It involves
communication &
counselling skills and
convincing power
Gauri S. Shrestha, M.Optom, FIACLE
And a science..
It requires :
• A systematic approach
• Understanding of potential problems
• In-depth study of designs
Gauri S. Shrestha, M.Optom, FIACLE
What should be systematic approach..1) Identify the problem
--questing the presbyope
--remark the lenses
--check the frame fit
1.frame level 4.facial wrap
2.temple level 5.vertex distance
3.pantoscopic tilt
Gauri S. Shrestha, M.Optom, FIACLE
-- verify the lens fitting
-- observation of use
--confirm refraction and lens power
2) Possible signs and symptoms with PAL’s
3) Possible causes of problems with PAL’s
What should be systematic approach..
Gauri S. Shrestha, M.Optom, FIACLE
Whom to fit ?
ALL PRESBYOPES !
BUT..
Gauri S. Shrestha, M.Optom, FIACLE
Contraindications
Field of View
Gauri S. Shrestha, M.Optom, FIACLE
Contraindications
Direction of Gaze
Gauri S. Shrestha, M.Optom, FIACLE
Contraindications
Mobility / Head Movement
Gauri S. Shrestha, M.Optom, FIACLE
Prescriptions
Contraindications
• Anisometropia / Antimetropia• High Cylinders• Prisms
Gauri S. Shrestha, M.Optom, FIACLE
Patient selection Patient requiring vision for occasional intermediate distances and for those who request an invisible bifocal
Patients who resist convention bifocal or trifocals because of the “lines” are strongly motivated and are excellent candidates for PAL
Emerging presbyopes are also good candidates
Gauri S. Shrestha, M.Optom, FIACLE
Previous bifocal wearer who demonstrate need for a trifocal lens for occasional use may enjoy the flexibility of PALs
PALs should not be recommended for all presbyopes however discretion should be exercised, especially with the following patients
1) currently bifocal or trifocal wearer who are completely satisfied with their lenses
2) Patients with large oculomotor imbalances who require prism
Patient selection
Gauri S. Shrestha, M.Optom, FIACLE
3) patients who are accustomed to wearing and are satisfied with single vision lenses for near vision only
4) Patients with a significant amount of anisometropia(3D or >)
5) Patient who need adds of high power and who have large pupils
6) Patients who are nervous, tense, impatient, and generally intolerant of health-care devices
Patient selection
Gauri S. Shrestha, M.Optom, FIACLE
Fitting ...
Gauri S. Shrestha, M.Optom, FIACLE
Step 1
Identification of Patient’s
Requirements & Expectations
Gauri S. Shrestha, M.Optom, FIACLE
Useful tip
Judge the motivation
Highlight the advantages, but mention
the limitations as well
Gauri S. Shrestha, M.Optom, FIACLE
Step 2. Frame Selection
Frame shape
Good Shape
Bad Shape
Good Depth Good Size
Too LargeInsufficient Depth
Frame sizeFrame depth
Gauri S. Shrestha, M.Optom, FIACLE
Frame Selection
Back vertex distance
Pantoscopic tilt Facial wrap
Gauri S. Shrestha, M.Optom, FIACLE
Useful tip
Prefer metal frames with adjustable
nose pads
Gauri S. Shrestha, M.Optom, FIACLE
Step 3
Adjust before taking facial measurements
Adjust when delivering spectacles
Frame Adjustment
Gauri S. Shrestha, M.Optom, FIACLE
• When to Adjust Before taking the facial
measurements When delivering the
spectacles
Gauri S. Shrestha, M.Optom, FIACLE
Step 3
Back vertex Distance - shorter
Frame Adjustment
Reduced BVD giveswider field of view
Gauri S. Shrestha, M.Optom, FIACLE
Step 3
Pantoscopic Tilt - 10 to 12 degrees
Frame Adjustment
Increase Pantoscopic Tiltincreases near field of view
Gauri S. Shrestha, M.Optom, FIACLE
Step 3
Facial wrap - must not be too flat
Frame Adjustment
Gauri S. Shrestha, M.Optom, FIACLE
Step 4
Monocular PD
Gauri S. Shrestha, M.Optom, FIACLE
Step 4
Monocular PD
Monocular PDMonocular PDMonocular PDMonocular PD
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Gauri S. Shrestha, M.Optom, FIACLE
Step 5
Monocular PD
Gauri S. Shrestha, M.Optom, FIACLE
Step 6
Marking the lens insert
Gauri S. Shrestha, M.Optom, FIACLE
Step 7
Fitting height
Gauri S. Shrestha, M.Optom, FIACLE
Useful tip
Natural head posture
Sit at the same level as the patient
Check binocularly from a dist. of 1 meter
Use a fine marker
Gauri S. Shrestha, M.Optom, FIACLE
Step 8
Checking the cut out
Gauri S. Shrestha, M.Optom, FIACLE
Delivery ..
Markings
Distance power & prism
Addition
Fitting cross heights & PDs
Gauri S. Shrestha, M.Optom, FIACLE
Delivery ..
On eye assessment
Frame fit Fitting crosses
Gauri S. Shrestha, M.Optom, FIACLE
Delivery ..
On eye assessment
Distance Vision Near Vision
Gauri S. Shrestha, M.Optom, FIACLE
Delivery ..
Delivery Instructions
Gauri S. Shrestha, M.Optom, FIACLE
Useful tip
Use positive language
Remove the markings at the end
Maintain a record of the order forms
Gauri S. Shrestha, M.Optom, FIACLE
Useful tip
TAKE A BREAK !!!
Gauri S. Shrestha, M.Optom, FIACLE
3. Facial Measurements
•MethodsDistance method 1Distance method 2Near method 1 (the mirror method)
Near method 2
Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Distance Method 1 Step 1: Adjust the frame Step 2: Measure the monocular
PDs with the pupillometer
Monocular Monocular PDPD
Monocular Monocular PDPD
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Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Distance Method 1Step 3: Mark the HCL & PD on the dummy lenses
Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Distance Method 1 Step 4: Check the pupil height Step 5: Check the height while talking to the
patient
Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Distance Method 1 Step 6: Order the PD as per the
pupillometer reading & height as per step 5
Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Distance Method 2 Step 1: Adjust the
frame Step 2: Measure
the monocular PDs with the pupillometer
Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Distance Method 2 Step 3: Place the frame on the patient and dot the
pupil centre Step 4: Check the height while taking to the patient
Dotting the pupil centre
Gauri S. Shrestha, M.Optom, FIACLE
3. Facial Measurements
• Distance Method 2 Step 5: Order the PD as per the pupillometer
reading & height as per step 4
Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Near Method 1 Steps 1 - 5: as per Distance Method 1 Step 6: Mark the distance and near visual point
circles
Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Near Method 1 Step 7: Place a mirror between the patient and
you and observe through the mirror the patient’s eyes when looking at the mirror
Step 8: Adjust the near visual circles if necessary to correspond with the patient’s lines of sight
Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Near Method 1 Step 9: Place the adjusted near visual circles on
the layout chart to determine the final position of the fitting crosses.
Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Near Method 2 Step 1: Adjust the frame Step 2: Measure the monocular near CDs with
the pupillometer
Monocular Monocular PDPD
Monocular Monocular PDPD
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Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Near Method 2 Step 3: Mark the HCL & PD on the dummy lenses
Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Near Method 2 Step 4: Check the pupil height Step 5: Check the height while talking to
the patient
Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Near Method 2Step 6: Order the PD as per the pupillometer near PD
reading plus 2.5 mm each eye & height as per step 5
Gauri S. Shrestha, M.Optom, FIACLE
Facial Measurements
• Comparing the Methods Pre-marking the dummy lenses Vs dotting the lenses Pupillometer vs PD rule or dots
Gauri S. Shrestha, M.Optom, FIACLE
Lens Ordering
• PDs• Heights
From the horizontal centre line (Datum) From the frame bottom
Gauri S. Shrestha, M.Optom, FIACLE
Lens Ordering
• Checking the cut-out
Gauri S. Shrestha, M.Optom, FIACLE
Delivery1. Pre-delivery Verification
Checking the markings Checking the frame details Checking the distance power and prism
Gauri S. Shrestha, M.Optom, FIACLE
Re-locating ProgressiveLens Markings
1. Find micro-engraved permanent markings 2. Mark the position of the horizontal locators 3. Select manufacturer’s layout chart for the
correct lens type
Gauri S. Shrestha, M.Optom, FIACLE
Re-locating ProgressiveLens Markings
4. Lay the lens on the chart with the marked locators in the correct position
5. Trace the distance and near reference circles, the fitting cross and the prism reference point
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