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Soft Toric Contact Lenses

Soft Toric Contact Lenses. Courtesy Pat Caroline. Vinita Allee Henry, OD, FAAO UMSL College of Optometry. Astigmatism Education. Cross on the front of the eye Football Have the patient take their spectacles off, so that they can rotate the specs in front of their eye

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Soft Toric Contact Lenses

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  1. Soft Toric Contact Lenses Courtesy Pat Caroline Vinita Allee Henry, OD, FAAO UMSL College of Optometry

  2. Astigmatism Education • Cross on the front of the eye • Football • Have the patient take their spectacles off, so that they can rotate the specs in front of their eye • Spectacle correction versus CL (Stable versus rotation) • Spherical CL versus Toric CL (Fees, rotation, expense due to manufacturing & fit time)

  3. Who Needs Soft Toric CL’s? How much astigmatism?

  4. How much Astigmatism? • Spherical GP’s for? • <2D corneal astigmatism • Toric GP’s for? • >2D corneal astigmatism • Front toric for lenticular astigmatism • Spherical Soft for ? • <1D of astigmatism • Aspheric Soft for? • 0.50-0.75D astigmatism • Toric Soft for? • >0.75D astigmatism

  5. If the patient does not need much correction for astigmatism, should it be corrected?

  6. DISTRIBUTION OF ASTIGMATISM > 0.25D = 76.5% > 1.50D = 19.2% > 0.50D = 61.5% > 1.75D = 15.8% > 0.75D = 45.5% > 2.25D = 10.0% > 1.00D = 34.8% > 2.50D = 6.0% > 1.25D = 24.8% > 3.00D = 3.4% Courtesy of D. Becherer

  7. How does the patient’s refraction affect correction? • Demonstrate with phoropter-may give an idea if toric lens will help • As cylinder goes up, rotational stability is more critical

  8. Patient Selection • Low amounts of astigmatism • More astigmatism error than spherical error • More spherical error than astigmatism error • Presbyopes • Need to be good soft lens candidate

  9. Becherer Twist • Subjective refraction in phoropter • Twist cylinder knob until patient notices blur • 20 degrees or > = 90% success first lens • 10 degrees = 70% success with 3 lenses • 5 degrees = <5% chance of success

  10. Remba Rule of Thumb • Sphere > 2(minus cylinder) • Becherer Rule of Thumb • Sphere > 3(minus cylinder if oblique)

  11. Aspheric Lenses • Do not optically correct astigmatism • May improve spherical aberration of CL & eye • Enhance focus by minimizing aberration, improve contrast sensitivity, enhance optics • May report better vision even if not measurably so

  12. Spherical Aberration Becherer and CLS Snyder

  13. Spherical Aberration Becherer & CLS Snyder

  14. Aspheric Lenses • Frequency Aspherics, Biomedics XC, Biomedics 55 Premier • PureVision • Focus N&D, O2 Optix, Air Optix • Biofinity, Avaira

  15. Lens Design • Prism Ballast • Double Slab Off/Thin Zones • Eccentric Lenticulation • Accelerated Stabilization Design • Back Surface Toric • Front Surface Toric

  16. Watermelon Seed Principle • Upper lid tends to push away the thickest portion, like squeezing a watermelon seed between your fingers, the thickest portion will be forced out. • Works with prism ballast and double thin zones-more so double thin zones

  17. Prism Ballast(1-1.5PD) • Vertex Toric, Proclear Toric & Frequency Toric – Back surface • Focus Toric – Back surface • Extreme H2O Toric – Back surface • Optima Toric – Front surface • SF 66 & PureVision Toric – Back surface • Air Optix for Astig. – Thin at 6, thick at 4&8

  18. Eccentric Lenticulation • Hydrasoft Toric –Back surface

  19. Binocular problems Use non-prism lens

  20. Double Slab-Off/Thin Zones • Freshlook Toric – Back surface • AV Toric – Back surface • Torisoft – Front surface • Focus Dailies Toric – Back Surface • Accelerated Stabilization Design • AV Advance for Astigmatism (4 active zones, mid-periphery)

  21. Initial Lens Selection • Realistic expectations • Use up-to-date Refraction, not previous Toric CL Rx • Cyl and axis match Rx (Less is better) • Figure nasal rotation?

  22. Initial Lens Selection • Vertex both meridians >+ 4D • Check Parameter Availability • Can insert with laser markings in correct location

  23. Initial Lens Selection • If the Rx you need is not available, then order correct lens • Go lower than expected cyl, works well (e.g. Focus Dailies Toric)

  24. Vertex Rx -4.00-1.75 X 180 Converts to -4.00 @ 180 to -3.75 -5.75 @090 to -5.25 -3.75 -1.50 X180, try on -3.75-1.25 X 180

  25. Fitting • Allow 15-20 minutes to settle • Lag up & down, rotate little • Large & Steep to stabilize • Be familiar with markings and separation • Poor fit, ditch the lens prior to VA and OR

  26. Fitting • Oblique and ATR astigmatism harder to fit than WTR- more effects from blink • OR sphere first, then sphere/cyl • Try to OR on axis • Use cross cyl calculator • 1.4-1.6 lenses /eye for successful result

  27. Fitting-Rotation • Quick rotational return • Try forced lid closure and see how lens rotates • >30degree rotation-get new lens • Inconsistent rotation-get new lens

  28. Rotation • Tends toward nasal due to temporal-nasal motion of upper lid • Higher outer canthus tends toward temporal rotation • Higher nasal canthus tends toward nasal rotation • Dial axis to proper location and see if VA improves

  29. Rotation • Large axis shifts cause minimal change, then insufficient cyl correction • Steep fit-Locks in at incorrect location, slow return when dialed off • Flat fit- Variable vision due to blink, unstable rotation

  30. High Astigmatism • Check Tyler’s Quarterly for cyl power & axis • (-1.75 and off 180 & 90 more than 20 degrees) • Consult with company • Available lenses: • CooperVision (Vertex XR, Proclear XR, Frequency XR, Preference XR, Hydrasoft Torics) • Bausch & Lomb (Optima Toric) • Ciba (Durasoft Optifit Toric)

  31. LARS • Left • Add • Right • Subtract • Add to Spectacle Rx, Dr’s perspective

  32. Ways to determine rotation: • Trial frame and low power cyl lens • Narrow slit and SL protractor scale • Measuring reticule in ocular • Clock dial-guesstimate

  33. Spec Rx -3.00 -1.00 X 180OR -0.50-1.00 X 40 Final Rx?

  34. Cross Cylinder Calculation • AOA CLS EZ fitter-Dr. Paul Whitten • www.eyedock.com • Check company websites for calculators • (Vistakon, CooperVision & Ciba) • Cylinder 90 degrees away means too much cyl, cyl at same axis add, cyl at oblique axis means change axis

  35. Common Mistakes

  36. LARS • Based on practitioner viewpoint • Based on base of lens • Scribe mark indicates base not axis • Make change from spectacle axis • After compensation, want new lens to rotate the same way • Vertex back both meridians

  37. Dispense lenses for 1 week trial

  38. Dispense when good vision and no rotation or good vision and some rotation

  39. Trouble-shooting • Blurry vision • Incorrect Rx, rotation, poor fit • Fluctuating vision • Poor stabilization, poor fit, rotation • Variable vision • Check fit, change design

  40. Trouble-shooting-Becherer • Consistent blur – adjust power/axis • Intermittent blur – adjust fitting

  41. Patient Education Nuggets • Use rewetting drop before lens removal • Twist lens one way to remove and the other the following night – alternating the spot that is pinched off

  42. Look for neo, dehydration, edema under inferior portion of lens

  43. Si Hy Torics

  44. Acuvue Advance & Oasys for Astigmatism • 2 week replacement • Laser markings at 6 & 12 • Accelerated Stabilization Design • UV inhibitor

  45. PureVision Toric • Anterior Aspheric Optics to reduce spherical aberration • Prism ballast with 360° comfort chamfer for enhanced rotational stability • Laser markings at 5,6,7 • Monthly replacement • DW or 30 day CW

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