CL 2-6: GP Troubleshooting Flashcards Preview

Contact Lens II: Part I > CL 2-6: GP Troubleshooting > Flashcards

Flashcards in CL 2-6: GP Troubleshooting Deck (34):

Poor Initial Vision

1. Stable
a. Could be 3 things?

2. Stable or Fluctuating
a. Could be 4 things?

1. a. Wrong lens
b. Power Change
c. Residual Astigmatism

2. a. Tearing
b. Poor Wetting
c. Poor Fit
d. Lens Flexure


Wrong Lens

1. Make sure what about the CL?

2. What should you do to see if VA improves?

3. Then you should do what?

4. Verify Diagnostic Lenses used to do what?

1. that right lens is in OD and left lens in OS (Colors, Dot)

2. Over-Refract (SOR and SCOR) to see if VA improves

3. Remove and Verify Lens Parameters

4. Verify Diagnostic Lenses used to fit patient


Vertex Distance

1. Any lens that does not sit directly on the eye has what?

2. Vertex distance must be considered for any refraction or Over-refraction that contains Meridian Powers of what?

1. has an Associated Vertex Distance

2. OVER +/-4.00


Power Change

1. What should you do?

1. Either Re-ORDER, or Re-Power


Residual Astigmatism

1. Empirically, it can be predicted by Calculating what?

2. Diagnostically, can be uncovered with what?

1. CRA




1. May affect what?

2. Tear lens induces what?

1. Tear Lens

2. Power

*Anesthetic vs. No Anesthetic


Anesthetic Use Study

1. What did they find?

1. Pt Satisfaction and Perception of Adaptation was Significantly better with Anesthetic

Conclusion: Topical Anesthetic Recommended for all new GP Patients, ESPECIALLY CHILDREN, Keratoconics, SCL Refits, and any Apprehensive Patients


Poor Wetting

1. Identify
a. How do you know?

2. Solve
a. Clean CL with what?
b. Counsel patient on use of what?
c. Or you could do what?

1. a. Tears Beading up on Surface

2. a. with Alcohol-Based Cleaner

b. of Cosmetics

c. Change Materials (Dk and Wettability)


Poor Fit

1. Vision Clearest:
a. Just after Blink...
b. Just Before Blink...

1. a. Indicates FLAT FIT

b. Indicates STEEP FIT


Clinically Significant BC Changes

1. How much is considered to be a Clinically Significant BC CHANGE?

a. What does this roughly equal?

b. This estimation becomes inaccurate outside of what?

c. Use what conversion to be Accurate?

1. 0.50 D


b. outside of Mid-range base curves

c. 337.5/mm to be accurate


Adjusting Power to Compensate for BC Changes

1. Flattening BC by a certain amt in Diopters induces what?

2. Steepening BC by a certain amt in Diopters induces what?

3. SAM FAP is what kind of relationship?

1. (-) tear lens of that magnitude

2. + tear lens of that magnitude

3. 1:1 Relationship


Addressing haloes and Glare

1. What 2 things can you increase?

a. What will this affect?


a. Affects the SAG


Clinically Significant OZD Changes

1. How much change is Considered to be a Clinically Significant OZD CHANGE?

1. 0.3 mm


Lens Flexure

1. Lens Bending is Diagnosed using what?

1. a. Over-Keratometry (Toric vs. Spherical)

b. Sphero-Cyl Over-Refraction
(Residual Astigmatism that doesn't match up with calculated)


Causes of Flexure

1. 5 things

1. Extended Wear

2. High Dk Material

3. Highly Toric Cornea

4. Thin Lens

5. Tight Lid


Lens Flexure

1. Increase CT
a. What mm/Diopter of Flexure

2. Flatten BC
a. More than how much as long as it doesn't compromise fit?

3. Change Material

4. What schedule?

1. a. 0.02 mm/Diopter of Flexure

2. a. Greater than or Equal to 0.50 D

3. Dk and Flexure

4. DW Schedule


Poor Acquired Vision

1. What five things?

1. Corneal Warpage

2. Decentration

3. Deposition

4. Lens Warpage

5. Scratched Lens



1. What three things?

1. Counsel Patient on Lens Care

2. Polish

3. Progent


Lens Warpage

1. PERMANENTLY Induced what?

a. BC will READ as what?

b. Power will READ as what?

2. This is CAUSED by what?

1. Change in Lens Shape

a. as TORIC on the RADIUSCOPE (Magnitude)

b. SPHERICAL on the Lensometer

2. Persistent flexure, excessive Pressure during rubbing, or use of an Abrasive Cleaner


Decentration: Inferior

1. What can you Flatten?

2. What can you Reduce?

3. What can you Increase?

4. Switch to a Material with what?

5. Use what design?

6. Clinically Significant CT Changes?

7. Clinically Significant OAD Changes?

1. BC

2. CT

3. OAD

4. with a Lower Specific Gravity

5. Lenticular Design

6. 0.02 mm is Considered to be a clinically significant CT CHANGE

7. 0.4 mm is considered to be this.



1. Lenticular Design: Central optical Portion is Placed in what?

2. Plus Lenticular does what to thickness?

3. Minus Lenticular does what to thickness?

1. in a Peripheral Carrier


3. Increases Edge Thickness


Lenticulation Guidelines: Power

1. -5.00 D

1. Minus Lenticular

2. Plus Lenticular, or CN Bevel


CN Bevel

1. Alternative to what?

2. What do you thin?

1. Plus Lenticular

2. Thinning of Anterior Edge


Decentration: Superior

1. Steepen what?

2. Increase what?

3. Decrease What?

4. Switch to a Material with what?

5. Use what Design?

1. BC

2. CT

3. OAD

4. with a Higher Specific Gravity

5. a Lenticular Design


Superior vs. Inferior Decentration

1. In INFERIOR Decentration, Changing to a LOWER SPECIFIC GRAVITY MATERIAL is what?

2. In SUPERIOR Decentration, INCREASING CT is MORE EFFECTIVE than what?

1. MORE Effective than Decreasing CT

2. than Changing to a Higher Specific Gravity Material


Center of Gravity

1. What is it?

1. An imaginary point in a body of matter where, for convenience in certain calculations, the total weight of the body may be thought to be concentrated


Decentration: Lateral

1. Increase what?

2. Steepen what?

3. Use what when indicated?

4. Use what design?

1. OAD

2. BC

3. use a TORIC BC




1. To Improve Centration with an ATR Astigmatic Cornea, Consider what 3 designs?

1. Aspheric Designs

2. Bitoric Designs

3. Steep Spherical BC Designs


Poor Initial Comfort

1. What three things should you do?

1. Inspect Edge for Defects

2. Address Decentration

3. Increase OAD


Poor Acquired Comfort

1. Primarily Related to what?

2. Inspect what?

3. Upper Eyelid what?

1. to Corneal Desiccation

2. Inspection of Edge for Defects

3. Eversion


Causes of Corneal Dessication

1. What eye issue?

2. Lens Material, what do you do?

3. What should you assess?

1. Pre-Existing Dry Eye

2. In general, Lower Dk Material have SUPERIOR WETTABILITY

3. Edge-Cornea Relationship


Patient Symptoms with Various Levels of Edge Clearance

1. Excessive (3)

2. Insufficient (3)

1. Edge Sensation, Lens Awareness, Overall Discomfort

2. Needing to take out lenses frequently, Visual Fluctuations, Vision Clearest after the blink


Changing Peripheral Curves

1. Excessive Peripheral Clearance
a. Steepen what?
b. Narrow what?

2. Insufficient Peripheral Clearance
a. Flatten what?
b. Widen what?

1. a. PCR
b. PCW

2. a. PCR
b. PCW


Clinically Significant PC Changes

1. How much PCR change is Considered to be Clinically SIGNIFICANT?

2. How much PCW change is considered to be Clinically Significant?

1. 0.5 mm

2. 0.05 mm (?? maybe a typo)