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REFRACTOMETRY

TROUBLE-SHOOTINGAMY JOST, BS, COMT, CCRC, OSC

CINCINNATI EYE INSTITUTE

NO FINANCIAL INTERESTS

•Amy Jost has no conflicts of interest to report… financial or otherwise.

OBJECTIVES

• Review steps of refractometry and allowable variations

• Identify various starting points

• List reasons for using the Jackson Cross Cylinder

• Discuss how to refract with more than 6.00 D of cylinder.

• Identify ways to manage patients with various eye conditions, challenging responses, and various mental/literacy levels.

TROUBLESHOOTING REFRACTOMETRY

Where do I begin?

IDENTIFY STARTING POINT

• Lensometry

• Previous Refraction

• Auto-Refraction

• Retinoscopy

• Current written prescription

• Referral letters

LENSOMETRY PEARLS

• Avoid tilt• Check for prism (perform EOM

testing to confirm)• Age of glasses• Surgery since Rx?• Hx of LASIK or PRK? LRI?• Hx of Keratoconus, Post-laser

ectasia, DR, Cataracts, etc.

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VISUAL ACUITY HINTS

• Corrected DVA

• Uncorrected DVA

• Pinhole DVA

• Pinhole magic revealed

TRANSPOSITION

Step 1)

Take the cylinder of the Rx and add it algebraically to

the sphere.

Step 2)

Change the sign of the cylinder (+ to –) and (– to +).

Step 3)

Change the axis by 90 degrees

TRANSPOSITION

• EXAMPLE:

• -1.25 -0.75 X09

• Convert to PLUS Cylinder:

• -2.00 +0.75 x99

IDENTIFYING CORNEAL ASTIGMATISM

• Previous Rx/MR

•Use Keratometric readings as a starting point

•Check all 4 quadrants- search for it with JCC or without JCC

1. Prepare for refinement

2. Occlude the fellow eye

3. Refine the sphere power

4. Put the Jackson Cross Cylinder in place

5. Adjust the Jackson Cross Cylinder to assess the axis.

6. Refine the cylinder axis.

7. Adjust the Jackson Cross Cylinder to measure power.

8. Refine the cylinder power.

9. Remove the Jackson Cross Cylinder

10. Refine the sphere power

• Step 10: Refine the sphere power

STEPS IN PERFORMING REFRACTOMETRYREVIEW STEPS OF REFRACTOMETRY

• Step 1: Preparing for Refinement

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PREPARING FOR REFRACTOMETRY

• Align the patient

• Check for Level

LEVEL PHOROPTER

• Important for identifying correct axis

REVIEW STEPS OF REFRACTOMETRY

• Step 2: Occlude the patient’s fellow eye

• Step 3: Refine the sphere power.

WHAT’S WRONG HERE?

• Checking DVA

• Convergence knobs are pushed in

• Great for near vision,

• Not so good for distance

• JCC is down, check sphere power without it

DO NOT OVER-MINUS!

• Always go “Plus” first

• Be slow to give more minus

• Must “earn” it, able to read more letters

• Stop… take some away, see if they can still see that row of letters

IMPORTANCE OF JACKSON CROSS CYLINDER

• Find and refine cylinder AXIS and POWER

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CYLINDER AXIS

• WHERE (on what axis) it the astigmatism located?

90°

180°

45°

REVIEW STEPS OF REFRACTOMETRY

• Step 4: Put the Jackson Cross Cylinder in place.

REVIEW STEPS OF REFRACTOMETRY

• Step 5: Adjust the Jackson cross Cylinder to assess the axis.

• Step 6: Refine the cylinder axis.

AXIS:DIALS aligned with white arrows

(on axis).

USING JACKSON CROSS TO REFINE AXIS

• Chase the white dot (in Plus Cylinder power)

Dial to dot, turn clockwise, Dial to dot, turn counter-clockwise

Better one? Or two?

CORNEAL ASTIGMATISM POWER

Spherical Mild- Moderate Amount Severe Amount

• HOW MUCH astigmatism is present?

REVIEW STEPS OF REFRACTOMETRY

• Step 7: Adjust the Jackson Cross Cylinder to measure power.

• Step 8: Refine the cylinder power.

“P” (for Power) aligned with white arrows (on axis).

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REVIEW STEPS OF REFRACTOMETRY

• Better one or two?

• Do you want more cylinder power (White dot) ? Or…

White dot on Power= Add Cylinder Power

REVIEW STEPS OF REFRACTOMETRY

• Do you want less cylinder power (Red dot)?

Red dot on Power= Subtract Cylinder Power

REVIEW STEPS OF REFRACTOMETRY

• Step 9: Remove the Jackson Cross Cylinder

• Step 10: Refine the sphere power

DETERMINING IF

CYLINDER PRESENT

ALLOWABLE VARIATIONS OF REFRACTOMETRY

• Start with a something

• Start with nothing (plano sphere)

• Refine sphere first

• Determine IF cylinder present

DETERMINE IF CYLINDER PRESENT

• Use the Jackson Cross Cylinder

• Or check all 4 quadrants without using the Jackson Cross Cylinder

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FINDING CYLINDER AXIS• Using the Jackson Cross Cylinder:

• No cylinder power dialed in, but flip the white and red dot at 90°, 180°, 45°, and 135° axis.

• If none seem better with “white dot”, then no cylinder is present.

• If better on a particular axis, dial in 0.50 D cylinder power at that axis, (adjust the sphere power), and refine the cylinder axis as you normally would

DETERMINING PRESENCE AND LOCATION OF CYLINDER USING THE JCC

At 0°, better one or two? Some or none?

At 45°, better one or two? Some or none?

At 90°, better one or two? Some or none?

At 135°, better one or two? Some or none?

WITHOUT USING THE JCC TO DETERMINE CYLINDER

• Dial in 0.50 D of cylinder power in and then back out, at 0°, 45°, 90°, 135°, and back at 180°

At 0°, better one or two? Some or none?

At 45°, better one or two? Some or none?

At 135°, better one or two? Some or none?

At 90°, better one or two?Some or none?

DETERMINING PRESENCE OF CYLINDER POWER

If likes 0.00 better, continue to rotate at all quadrants. If does not want any at any axis= spherical

If likes 0.50 better, or the seems the same, drop down JCC and refine axis and cylinder power

REFRACT WITH MORE THAN 6.00D OF CYLINDER

• Use the auxiliary cylinder lenses

AUXILIARY LENSES

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INSTALLING THE AUXILIARY LENSES ADD AUXILIARY POWER TO CYLINDER POWER

For example:

5.50 +2.00

= +7.50 D of cylinder

6.00 +2.00

= +8.00 D of cylinder

BALANCING THE LENSES

• Using Prism… separate two images

• Using Red-Green Balance

USING PRISM, SEPARATE THE TWO IMAGES

With 5PD Base Up OS, the OS image will be the LOWER image of the two.

RED GREEN DUOCHROME TEST

• Based on chromatic aberration

• If the Green letters are clearer, Add +0.25 D

• If the Red letters are clearer, Add -0.25 D

• End-point obtained with the letters on the Red-Green chart appear equally dark or when a reversal occurs

MEASURING ADD POWER

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NEAR AND INTERMEDIATE VISION

• Near Vision, 14-16 inches

• Intermediate Vision, ~20 inchesMANAGING OTHER OBSTACLES

GET THE NERVOUS “TEST TAKER” TO RELAX

• Assure them the eye exam is not a “test” they will pass or fail

• Explain why you are asking “Which is better? One or Two?”

• Explain there are no right/wrong answers. It is up to the patient to decide which seems clearer.

• Explain some options may both be blurry (especially with the JCC), and that’s ok. We are trying to find the one that is most clear, but sometimes, they will be equally blurry.

DEAF PATIENTS

• Sign Language interpreter can help

• Placement of the interpreter is key

• Explain what will happen during the test BEFORE you occlude the eye(s)

• Prepare the patient with what they are expected to do or how to respond

• Address the patient, NOT the interpreter

TESTING VA IN CHILDREN & NON-VERBAL ADULTS:• Infant:

• Fixation behavior: CSM, F&F

• Preferential looking

• Toddler (As soon as child can talk)• Pictures

• Pre-School:• Matching: HOTV, Lea

• Tumbling E

• Landolt rings

• As soon as possible:• Snellen letters

• Numbers

REFRACTIONS IN BABIES, TODDLERS, NON-VERBAL IS NEARLY IMPOSSIBLE…

• Retinoscopy is the key!

• Purely objective

Dr. Tim Root gives great advice

• Retinoscopy is the key!

• Purely objective

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ILLITERATE, PRELITERATE, OR DYSLEXIC PATIENTS

• Use Allen Cards or Tumbling E’s

• Point in the direction of the legs of the E

• Name the pictures

NON-ENGLISH SPEAKING

• Get a professional interpreter

• Use Tumbling E’s, LandoltRings, etc.

BEFORE DROP INSTILLATION OR CONTACT WITH THE EYE

• To maximize vision and minimize fatigue and blur, perform vision related tests BEFORE instilling eye drops, performing tonometry, contact biometry, pachymetry, or any other test requiring contact with the ocular surface.

EXCEPT DRY EYE PATIENTS… ADD LUBRICANTS

• Dry Eye Patients may benefit from the instillation of artificial tears to clear the corneal surface and increase visual potential

• Avoid thick viscous drops

NYSTAGMUS

• Worsens when you occlude one eye

• Best to keep both eyes open, fog fellow eye

https://youtu.be/5vPCL7MaSDk

BINOCULAR DIPLOPIA

• Performing binocular balancing

• Use Prism to further separate the images to check for clarity

• Use Prisms to bring images together, if working towards a workable Rx.

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PATIENT’S ANSWER IS ALWAYS, “ONE IS BETTER”

• Reinstruct the Patient on what they are doing

• Reverse how you have labeled the options, to test your theory

• Reinstruct the patient again

• Use letters instead of numbers, or “This one or That one?”

THE “OLD” PHOROPTER

•Do you have a room with the “old” Green’s Phoropter?

• It is similar, and yet different

BIBLIOGRAPHY

• Subjective Refraction and Prescribing Glasses, The Number One (or Number Two) Guide to Practical Techniques and Principles, Kolker, R. J., 2015

• JCAHPO Learning Systems CD-Rom/ Refinement Module

ANY QUESTIONS?