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GP LENS DESIGN & FITTING PowerPoint Presentation
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GP LENS DESIGN & FITTING

GP LENS DESIGN & FITTING

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GP LENS DESIGN & FITTING

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Presentation Transcript

  1. GP LENS DESIGN & FITTING

  2. Plasma Treatment: Is it Worth It? Results of a Recent Survey • GP Lens Institute Advisory Committee surveyed (25 responses) • What % of lenses Plasma Treated: 84% PT > 10% of lenses; 20% PT > 50% • 56% indicate initial wettability better; 28% same; 8% worse • 65% indicate better initial comfort; 31% the same; 4% worse

  3. How long does the treatment last? • 1 - 7 days: 13% • 1 - 2 weeks: 8% • 2 - 4 weeks: 4% • 1 - 3 months: 26% • 3 - 6 months: 31% • > 6 months: 18%

  4. GP LENS COMFORT • Presentation • Topical Anesthetic • Good Initial Vision • Lens Design

  5. GP LENS DESIGN & FITTING • GP Comfort • Lens Design • Fitting • Ordering

  6. GP LENS DESIGN & FITTING • GP Lens Comfort

  7. GP LENS COMFORT • Presentation • Topical Anesthetic • Lens Design

  8. GP LENS COMFORT • Presentation

  9. PRESENTATION • Perceptions about Adaptation • Concerns • Patient Apprehension • Practitioner Apprehension The New Practitioner • Inadequate Education • Takes too much time • Too uncomfortable

  10. PRESENTATION METHODS • Gauge patient’s reactions to ocular tests • High reactors = gradual adaptation • Offer realistic expectations • Don’t be tentative in GP description • Don’t use negative phrases: discomfort, pain, intolerance, failure; use “lens awareness,” “lid sensation” • “GP” (not “RGP”)

  11. PRESENTATION STUDY • “The Effect of Patient Personality Profile and Verbal Presentation on Initial Comfort and Adaptation to Rigid Gas Permeable Contact Lenses” • Edward S. Bennett • Cristina M. Schnider • Bruce W. Morgan • Ruth Davies (et al)

  12. STUDY METHODS • 49 subjects, non-CL Wearers, age and sex matched, randomly assigned to 3 groups • Fear-arousing: observed a video of Dr. talking to Pt about GP adaptation using fear-arousing terms • Neutral Non-Enthused: Dr. talking to Pt using neutral terms but is non-enthused • Neutral Enthused: Same as previous but Dr. has positive attitude

  13. STUDY RESULTS • 6/19 dropped out (in one month) from fear-arousing; 2/17 in neutral NE; 0/13 in neutral enthused • Fear-arousing submitted only 50% of daily questionaires; neutral NE = 55%; neutral enthused = 87%

  14. UNSUCCESSFUL SUBJECTS

  15. QUESTIONAIRE RETURN

  16. STUDY CONCLUSIONS • Method of presentation of GP lenses can affect success. If presented negatively, there was a significantly greater risk of discontinuation of lens wear during the first month of wear. • Subjects provided with a positive approach towards GPs were most likely to be compliant with daily questionaire return.

  17. GP LENS COMFORT • Presentation • Topical Anesthetic Use

  18. TOPICAL ANESTHETIC USE: CONTROVERSIAL • Concerns: • Staining • Effect of Eye Rubbing • Potentially Mislead Patient

  19. TOPICAL ANESTHETIC USE: CONTROVERSIAL • Potential Benefits: • Improved Initial Comfort • Less Reflex Tearing • Less Initial Chair Time • Greater Patient Satisfaction

  20. ANESTHETIC USE STUDY • “The Effect of Topical Anesthetic Use on Initial Patient Satisfaction and Overall Success with Rigid Gas Permeable Contact Lenses” Edward S. Bennett Jennifer Smythe Vinita Allee Henry (et al)

  21. ANESTHETIC STUDY METHODS • One Month Study • 80 subjects at four institutions (UMSL, SCO, Pacific & OSU) • All new GP wearers • 40 given Ophthaine, 40 placebo at fitting visit

  22. ANESTHETIC STUDY RESULTS • 10 dropouts, 8 in the placebo group • Patient satisfaction, perception of adaptation significantly better with anesthetic • Bottom Line: Topical Anesthetic recommended for all new GP patients but especially beneficial with children, keratoconics, soft lens refits & any apprehensive patients; remember, you have to compete with soft (efficiency/comfort)

  23. OVERALL ADAPTATION

  24. OVERALL SATISFACTION

  25. CONCLUSIONS • Use of topical anesthetic at fitting visit resulted in fewer dropouts, improved initial comfort, enhanced perception of adaptation process and greater overall satisfaction • Use of topical anesthetic in combination with effective presentation and optimum lens design should result in a positive adaptation process and successful wear

  26. CONCLUSION “Topical anesthetic use is more for the practitioner than it is for the patient”

  27. LENS DESIGN & FITTING • GP Lens Comfort • Lens Design

  28. LENS DESIGN • Overall/Optical Zone Diameter • Base Curve Radius • Peripheral Curve Design • Center Thickness • Edge Design

  29. LENS DESIGN • Overall/Optical Zone Diameter

  30. OVERALL/OPTICAL ZONE DIAMETER • Pupil Size • Refractive Power • Corneal Curvature: steep curvatures = go smaller (8.6 - 9.0mm); flat curvatures = go larger (9.6 - 10.0mm) • Lid Tension

  31. OVERALL DIAMETER

  32. Design a GP Lens Diameter

  33. OVERALL/OPTICAL ZONE DIAMETER • Optical Zone Diameter (OZD) often approximately 1.4mm less than Overall Diameter (OAD) • Average OAD/OZD = 9.4/8.0mm

  34. LENS DESIGN • Overall/Optical Zone Diameter • Base Curve Radius

  35. BASE CURVE RADIUS • Selected to optimize the lens-to-cornea fitting relationship • Often fitted close to the flatter keratometry value (i.e., “On K”)

  36. BASE CURVE RADIUS SELECTION (Minus Lenses) Corneal Cylinder Fit PL - 0.50D 0.50 - 0.75D Flat 0.75 - 1.00D 0.25 - 0.50D Flat 1.25 - 1.50D “On K” - 0.25D Flat 1.75 - 2.00D 0.25D Steep 2.25 - 2.50D 0.50D Steep 2.50 - 3.00D 0.50 - 0.75D Steep

  37. BASE CURVE SELECTION (Plus Lenses) • As a result of the more anterior center of gravity of plus lenses, hyperopes should be fit 0.25 - 0.50D STEEPER than the BCR’s recommended for myopic patients.

  38. BASE CURVE SELECTION • Lens Movement Important to: • Remove debris/wastes • Prevent adhesion phenomenon

  39. LENS DESIGN • Overall/Optical Zone Diameter • Base Curve Radius • Peripheral Curve Design

  40. PERIPHERAL CURVE FUNCTIONS • Ensure adequate tear pump • Debris removal • Adequate Fit • Eliminate bearing

  41. EDGE LIFT/CLEARANCE • Edge Clearance = actual distance from lens edge to cornea and is dependent upon edge lift and peripheral corneal shape • Edge Lift = geometrical calculated values from lens edge to cornea; more easily determined; it approximates edge clearance but is often greater

  42. EDGE LIFT/CLEARANCE • Axial Edge Lift = vertical distance from lens edge to extension of BCR • Radial Edge Lift (rarely used) = distance from lens edge perpendicular to an extension of the BCR