CL 2-6: GP Troubleshooting Flashcards
Poor Initial Vision
- Stable
a. Could be 3 things? - Stable or Fluctuating
a. Could be 4 things?
- a. Wrong lens
b. Power Change
c. Residual Astigmatism - a. Tearing
b. Poor Wetting
c. Poor Fit
d. Lens Flexure
Wrong Lens
- Make sure what about the CL?
- What should you do to see if VA improves?
- Then you should do what?
- Verify Diagnostic Lenses used to do what?
- that right lens is in OD and left lens in OS (Colors, Dot)
- Over-Refract (SOR and SCOR) to see if VA improves
- Remove and Verify Lens Parameters
- Verify Diagnostic Lenses used to fit patient
Vertex Distance
- Any lens that does not sit directly on the eye has what?
- Vertex distance must be considered for any refraction or Over-refraction that contains Meridian Powers of what?
- has an Associated Vertex Distance
2. OVER +/-4.00
Power Change
- What should you do?
- Either Re-ORDER, or Re-Power
Residual Astigmatism
- Empirically, it can be predicted by Calculating what?
- Diagnostically, can be uncovered with what?
- CRA
2. SCOR
Tearing
- May affect what?
- Tear lens induces what?
- Tear Lens
- Power
* Anesthetic vs. No Anesthetic
Anesthetic Use Study
- What did they find?
- 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
- Identify
a. How do you know? - Solve
a. Clean CL with what?
b. Counsel patient on use of what?
c. Or you could do what?
- a. Tears Beading up on Surface
- a. with Alcohol-Based Cleaner
b. of Cosmetics
c. Change Materials (Dk and Wettability)
Poor Fit
- Vision Clearest:
a. Just after Blink…
b. Just Before Blink…
- a. Indicates FLAT FIT
b. Indicates STEEP FIT
Clinically Significant BC Changes
- 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?
- 0.50 D
a. 0.1 mm in MID-RANGE BASE CURVES ONLY
b. outside of Mid-range base curves
c. 337.5/mm to be accurate
Adjusting Power to Compensate for BC Changes
- Flattening BC by a certain amt in Diopters induces what?
- Steepening BC by a certain amt in Diopters induces what?
- SAM FAP is what kind of relationship?
- (-) tear lens of that magnitude
- tear lens of that magnitude
- 1:1 Relationship
Addressing haloes and Glare
- What 2 things can you increase?
a. What will this affect?
- OZD/OAD
a. Affects the SAG
Clinically Significant OZD Changes
- How much change is Considered to be a Clinically Significant OZD CHANGE?
- 0.3 mm
Lens Flexure
- Lens Bending is Diagnosed using what?
- a. Over-Keratometry (Toric vs. Spherical)
b. Sphero-Cyl Over-Refraction
Residual Astigmatism that doesn’t match up with calculated
Causes of Flexure
- 5 things
- Extended Wear
- High Dk Material
- Highly Toric Cornea
- Thin Lens
- Tight Lid
Lens Flexure
- Increase CT
a. What mm/Diopter of Flexure - Flatten BC
a. More than how much as long as it doesn’t compromise fit? - Change Material
- What schedule?
- a. 0.02 mm/Diopter of Flexure
- a. Greater than or Equal to 0.50 D
- Dk and Flexure
- DW Schedule
Poor Acquired Vision
- What five things?
- Corneal Warpage
- Decentration
- Deposition
- Lens Warpage
- Scratched Lens
Deposition
- What three things?
- Counsel Patient on Lens Care
- Polish
- Progent
Lens Warpage
- PERMANENTLY Induced what?
a. BC will READ as what?
b. Power will READ as what? - This is CAUSED by what?
- Change in Lens Shape
a. as TORIC on the RADIUSCOPE (Magnitude)
b. SPHERICAL on the Lensometer - Persistent flexure, excessive Pressure during rubbing, or use of an Abrasive Cleaner
Decentration: Inferior
- What can you Flatten?
- What can you Reduce?
- What can you Increase?
- Switch to a Material with what?
- Use what design?
- Clinically Significant CT Changes?
- Clinically Significant OAD Changes?
- BC
- CT
- OAD
- with a Lower Specific Gravity
- Lenticular Design
- 0.02 mm is Considered to be a clinically significant CT CHANGE
- 0.4 mm is considered to be this.
Lenticulation
- Lenticular Design: Central optical Portion is Placed in what?
- Plus Lenticular does what to thickness?
- Minus Lenticular does what to thickness?
- in a Peripheral Carrier
- Reduces EDGE THICKNESS
- Increases Edge Thickness
Lenticulation Guidelines: Power
- -5.00 D
- Minus Lenticular
2. Plus Lenticular, or CN Bevel
CN Bevel
- Alternative to what?
- What do you thin?
- Plus Lenticular
2. Thinning of Anterior Edge
Decentration: Superior
- Steepen what?
- Increase what?
- Decrease What?
- Switch to a Material with what?
- Use what Design?
- BC
- CT
- OAD
- with a Higher Specific Gravity
- a Lenticular Design
Superior vs. Inferior Decentration
- In INFERIOR Decentration, Changing to a LOWER SPECIFIC GRAVITY MATERIAL is what?
- In SUPERIOR Decentration, INCREASING CT is MORE EFFECTIVE than what?
- MORE Effective than Decreasing CT
2. than Changing to a Higher Specific Gravity Material
Center of Gravity
- What is it?
- 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
- Increase what?
- Steepen what?
- Use what when indicated?
- Use what design?
- OAD
- BC
- use a TORIC BC
- an ASPHERIC DESIGN
Decentration
- To Improve Centration with an ATR Astigmatic Cornea, Consider what 3 designs?
- Aspheric Designs
- Bitoric Designs
- Steep Spherical BC Designs
Poor Initial Comfort
- What three things should you do?
- Inspect Edge for Defects
- Address Decentration
- Increase OAD
Poor Acquired Comfort
- Primarily Related to what?
- Inspect what?
- Upper Eyelid what?
- to Corneal Desiccation
- Inspection of Edge for Defects
- Eversion
Causes of Corneal Dessication
- What eye issue?
- Lens Material, what do you do?
- What should you assess?
- Pre-Existing Dry Eye
- In general, Lower Dk Material have SUPERIOR WETTABILITY
- Edge-Cornea Relationship
Patient Symptoms with Various Levels of Edge Clearance
- Excessive (3)
- Insufficient (3)
- Edge Sensation, Lens Awareness, Overall Discomfort
2. Needing to take out lenses frequently, Visual Fluctuations, Vision Clearest after the blink
Changing Peripheral Curves
- Excessive Peripheral Clearance
a. Steepen what?
b. Narrow what? - Insufficient Peripheral Clearance
a. Flatten what?
b. Widen what?
- a. PCR
b. PCW - a. PCR
b. PCW
Clinically Significant PC Changes
- How much PCR change is Considered to be Clinically SIGNIFICANT?
- How much PCW change is considered to be Clinically Significant?
- 0.5 mm
2. 0.05 mm (?? maybe a typo)