Vinita Allee Henry, OD, FAAO UMSL College of Optometry Courtesy Pat Caroline
Courtesy Pat Caroline Vinita Allee Henry, OD, FAAO UMSL College of Optometry 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) How much astigmatism? Spherical GP’s for? <2D corneal astigmatism Toric GP’s for? <1D of astigmatism Aspheric Soft for? >2D corneal astigmatism Front toric for lenticular astigmatism Spherical Soft for ? 0.50-0.75D astigmatism Toric Soft for? >0.75D astigmatism > 0.25D = 76.5% > 0.50D = 61.5% > 0.75D = 45.5% > 1.00D = 34.8% > 1.25D = 24.8% > 1.50D = 19.2% > 1.75D = 15.8% > 2.25D = 10.0% > 2.50D = 6.0% > 3.00D = 3.4% Courtesy of D. Becherer Demonstrate with phoropter-may give an idea if toric lens will help As cylinder goes up, rotational stability is more critical Low amounts of astigmatism More astigmatism error than spherical error More spherical error than astigmatism error Presbyopes Need to be good soft lens candidate 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 Sphere > 2(minus cylinder) Becherer Rule of Thumb Sphere > 3(minus cylinder if oblique) 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 Spherical Aberration Becherer and CLS Snyder Spherical Aberration Becherer & CLS Snyder Frequency Aspherics, Biomedics XC, Biomedics 55 Premier PureVision Focus N&D, O2 Optix, Air Optix Biofinity, Avaira Prism Ballast Double Slab Off/Thin Zones Eccentric Lenticulation Accelerated Stabilization Design Back Surface Toric Front Surface Toric 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 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 Hydrasoft Toric –Back surface Use non-prism lens 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, midperiphery) Realistic expectations Use up-to-date Refraction, not previous Toric CL Rx Cyl and axis match Rx (Less is better) Figure nasal rotation? Vertex both meridians > + 4D Check Parameter Availability Can insert with laser markings in correct location If the Rx you need is not available, then order correct lens Go lower than expected cyl, works well (e.g. Focus Dailies Toric) 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 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 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 Quick rotational return Try forced lid closure and see how lens rotates >30degree rotationget new lens Inconsistent rotationget new lens 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 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 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) Left Add Right Subtract Add to Spectacle Rx, Dr’s perspective Trial frame and low power cyl lens Narrow slit and SL protractor scale Measuring reticule in ocular Clock dial-guesstimate Final Rx? 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 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 Blurry vision Fluctuating vision Incorrect Rx, rotation, poor fit Poor stabilization, poor fit, rotation Variable vision Check fit, change design Consistent blur – adjust power/axis Intermittent blur – adjust fitting 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 AV Advance for Astigmatism AV Oasys for Astigmatism PureVision Toric Air Optix for Astigmatism Material Galyfilcon A Senofilcon A Balafilcon A Lotrafilcon B Dk 60 103 91 103 Water content 47% 38% 36% 33% Powers +6 to -9 +6 to -9 +6 to -9 +6 to -9 Cylinder -0.75 to -2.25 -0.75 to -2.25 -0.75 to 2.25 -0.75 to 2.25 BCR 8.6 8.6 8.7 8.7 Avail axis steps Restrictions in steps Restrictions in steps 0-180 in 10° Restrictions in steps 2 week replacement Laser markings at 6 & 12 Accelerated Stabilization Design UV inhibitor 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 Bausch & Lomb Ciba Vision Monthly replacement Laser marks 3,6,9 DW or 6 nights EW Lenses may rotate when the eyes converge for near tasks No backup lens if one lens rotates off-axis Consistent rotation important Patient has the following Spec Rx: OD – 5.00-2.50 X170 OS -5.00-2.00 X 5 Trial lenses selected: Patient has the following correction: Spec Rx OD -3.00 OS -2.00-1.25 X180 Trial lens design? Patient has the following Spec Rx: OD -5.00-0.75 X180 OS -5.50-0.75 X180 Trials lenses? Patient has the following Spec Rx: OD -2.50-0.75 X90 OS -2.75-0.75 X90 Trial lenses match Rx. OD rotates 10 degrees nasal & OS rotates 5 degrees nasal. If you correct for rotation, the final lenses would be? Which of the following patients makes the best candidate for toric lenses? a. -0.75-3.00 X 180 b. -2.00-1.25 X 45 c. -4.00-1.00 X 180 d. -3.00-0.75 X 90 Patient is fit with the following lenses: Frequency 55 Toric, 8.7 BCR OD -3.00-1.75 X10 OS -2.75-1.25 X 170 The lenses center and cover well, but the laser mark rotates from 10 degrees nasal to right on and sometimes 10 degrees temporal. Suggestion? College student wears Biomedic Torics. He sometimes studies late and works some evenings until 2 am. His eyes are mildly injected and have some neovascularization. Suggestions? Patient is long-time wearer of spherical soft lenses. Her Spec Rx is OD -2.00-1.00 X 20, OS 2.50 -0.75 X 180. Her CL Rx is OD -2.50 and OS -2.75. She has started a job that requires a lot of reading. She feels her vision is a little blurry. Solution: Patient is a new patient to you. He comes in wearing soft torics. He brings the box and shows you that they are PureVision Torics, 8.6 OD -3.00 -1.25 X10 and OS -3.75 -1.75 X 170. The lenses fit well and the vision is 20/20 OD & OS. The OD lens is rotated 10° temporal and the OS is 10° temporal. Anything you want to know? What lenses will you order?
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