End of Lecture, You Will Be Able To…

• Determine good candidates for toric • Determine most appropriate toric Hard and Soft Contact Lenses • Differentiate soft toric stabilization techniques for • Assess soft toric fits: power, rotation • Know GP toric options Jeffrey J. Walline, OD PhD The Ohio State University College of • Empirically fit GP toric lenses

Toric Market When Soft Versus GP Toric?

• Soft toric • Can’t tolerate GP lens • Corneal toricity ≠ refracve asgmasm • Example • K Readings: 43.00 / 44.00 @ 090 MC • : ‐2.00 ‐3.00 X 180 20/15 • Example • K Readings: 42.00 / 44.00 @ 090 MC • Refraction: ‐3.50 ‐1.50 X 045 20/15

• Nichols, et al. Spectrum Jan 2014

When Soft Versus GP Toric? Who Are Better Candidates?

• GP • Both: Poor VA with spherical lens • Corneal toricity = refractive astigmatism • Soft: GPs difficult to fit or not tolerated • Poor vision with soft toric • ATR astigmatism, discomfort, 3‐9 staining • Poor fit with spherical GP • 3‐9 staining • Excessive bearing • Spectacle blur • Reduce flexure

1 Who Are Worse Candidates? What Affects Fit of Soft Toric Lens?

• Cylinder greater than sphere • Gravity • Example • Surface tension / tear film quality • ‐4.00 ‐6.00 X 090 • Lid / lens interaction • +0.25 ‐3.50 X 180 • Watermelon seed effect OS • Oblique cylinders • Powers in each meridian -4.25 -2.00 • Example Lens interact w/ thick • ‐3.00 ‐2.00 X 045 meridian and rotate lens temporally

Watermelon Effect Stabilization Techniques

Prism Truncation Thin Zones Peri-ballast Picture courtesy of Jason Nichols

Prism Ballast Prism Ballast

100 • 0.75∆ to 2∆ • Oxygen Transmissibility Map

• Stabilized by 80 • Thickness difference • Weight (very minimal) 60 • Disadvantage 40 • ↓ O2 transmissibility • Discomfort lid‐lens interact 20 • Visual problems with unilateral • Vertical prism 0

2 Truncation Thin Zones

• Truncated lens lines up with lower lid • Thinning at top and bottom of lens

Peri‐Ballast Stabilization Techniques

• Minus carrier over entire lens then thin • Affect lens design superiorly • Physiological considerations • No prism in optic zone

Fitting Soft Torics Fitting Soft Torics • Diameter • Lens should settle ~15 mins • Typically slightly larger • Assume first trial will have no rotation • Base curve • Typically no choice; may consider steeper first • Power • Trials rarely have exactly what you need • Use power cross and vertex each meridian • If limited cylinder power, adjust sphere • If cylinder power not available, lower power

3 Fit Assessment Assessing Rotation

• Centration (coverage) • Bottom of lens Same as spherical lenses • Movement • As you look at lens OD • Orientation • Nasal (must indicate eye) • Rotation must be consistent • Right • Wait until lens settles • Counter‐clockwise • Assess re‐orientation • Assess rotation • Don’t guess!

Assessing Rotation Measuring Rotation

• Bottom of lens • Nasal (must indicate eye) OD • Right • Counter‐clockwise

Measuring Rotation Measuring Rotation

4 Measuring Rotation Measuring Rotation

Measuring Rotation Measuring Rotation

Toric Markings Toric Markings

• Tyler’s Quarterly

5 LARS Adjust for Consistent Rotation

• Try to align rotated contact lens axis with • CL: ‐2.50 ‐2.25 X 090 refractive astigmatism • Rotation: 10° right (counterclockwise) • Look at… • Bottom of lens • Order: ‐2.50 ‐2.25 X 080 • As you look at lens Lens Rotation Axis Compensation Left (clockwise) Add Right (counterclockwise) Subtract

Adjust for Consistent Rotation Adjust for Consistent Rotation

• CL: ‐2.50 ‐2.25 X 180 • Rotation: 10° ?

• Order: ?

10° Left Rotation 10° Left Rotation

Axis adjusted: lens marking still in same place

Assessment of Soft Toric Poor Visual Acuity

• Visual acuity • Confirm rotational stability • SOR • Tighter base curve or different lens • Slit lamp • Compensate for stable rotation • Contact lens fit • Spherical over‐refraction • Movement • Spherocylindrical over‐refraction? • Centration (coverage) • • Rotation SCOR, CL power, and cross cylinder effect • Ocular health • Recheck baseline data • New lens

6 Example Example

• MR: ‐4.00 ‐3.50 X 180 -7.50 -7.00

• Proclear Toric vertex -4.00 -4.00

• What is your first contact lens order? • ‐4.00 ‐3.00 X 180 • Only comes up to ‐2.25 DC • Spherical equivalent • ‐4.25 –2.25 X 180

Example Example: Final Rx

• Base curve = 8.4 • Diameter = 14.4 • Power = ‐4.25 ‐2.25 X 165

15 degree rotation

How GP Corrects Astigmatism Fitting Philosophies –All Back Torics

• Lacrimal lens • Full alignment (saddle fit) • Typically 2.00 to 2.50 D K toricity • On K for each meridian • Tighter fit, more centered • Smaller diameter, interpalpebral fit

• Toric front and / or back surface

7 Fitting Philosophies –All Back Torics All Back Surface Torics ‐ Base Curve

• Low toric simulation • Ks: 42.50 / 45.50 @ 090 • Typically when K toricity >2.50 D • Base curve undercorrects corneal toricity • Saddle fit • BC aligns (± 0.25 D) with flat meridian and • undercorrects steep meridian BCflat: 42.50 • Typically 75% of corneal toricity • BCsteep: 45.50 • Small amount of “rock” over flat meridian • Low toric simulation

• Diameters can be bigger • BCflat: 42.50

• BCsteep: 44.75

GP Toric Options Bitoric

• Back surface toric (spherical front surface) • Specify BC/Power for each meridian • Front surface toric (spherical back surface) • It is as though you are fitting a spherical lens on • Consider spectacle cylinder, corneal cylinder, each meridian independently residual astigmatism • Use optical cross • Bitoric • Power for toric CL not written in • ≈ 98% of toric GP lenses spherocylindrical notation • Two curvatures on back surface and two curvatures on front surface

Calculating Bitoric Lenses Empirically Order Bitoric

• Empirical • Manifest Rx: ‐1.00 ‐3.00 X 180 • Optical crosses • Ks: 43.00 / 46.00 @ 090 • Mandell‐Moore Bitoric Worksheet • http://www.gpli.info/mandell‐moore/ • Diagnostic • Spherical trial lens • SPE trial lens

8 Empirically Order Bitoric Order a GP Lens • Secondary Curve • Example: Low Toric 46.00 45.25 -0.75 • BC + 1.0 mm; 0.4 mm wide • Peripheral Curve 43.00 42.75 -0.25 • BC + 3.0 mm; 0.2 mm wide Cornea BC LL • OZD -4.00 (-3.87) -0.75 45.25 / -3.12 • OAD = (2 * SCW) + (2 * PCW) + OZD -1.00 -0.25 42.75 / -0.75 • CT

Spec LL CL • Use power that yields greatest CT (most +)

• CTminus lens = 0.18 + 0.01 (power)

• CTplus lens = 0.18 + 0.02 (power)

Empirically Order Bitoric Mandell‐Moore Bitoric Guide

• Saddle fit • Manifest Rx: ‐1.00 ‐3.00 X 180 • Ks: 43.00 / 46.00 @ 090

7.90/7.46 8.90/8.460.3 10.90/10.46 0.2 9.5 8.5

-0.75/-3.25 0.17

Mandell‐Moore Bitoric Guide Mandell‐Moore Bitoric Guide

43.00 180 46.00 090

-1.00 -3.00 180

43.00 46.00

-1.00 -4.00

-1.00 -3.87

0.25 0.25 0.75 0.75

42.75 -0.75 45.25 -3.25

9 Mandell‐Moore Bitoric Guide Assessing GP Torics

• SOR • ScOR if not 20/20ish • Contact lens fit • Movement • Centration • Rotation (front surface toric only) • Fluorescein

Back Surface Toric Back Surface Toric Summary

• Fitting is exactly the same as bitoric • Example • When refractive astig = 1.5 * corneal toricity, • then front surface is spherical Manifest Rx: +1.00 ‐3.00 X 180 • Ks: 42.00 / 44.00 @ 090 • If you know, you could save $10 when you order

Back Surface Toric Order a Back Surface Toric

44.00 44.00 0.00 • Manifest Rx: +1.00 ‐3.00 X 180 • Ks: 44.00 / 46.00 @ 090 42.00 42.00 0.00

K BC LL

-2.00 0.00 -2.00 7.67/7.42 8.67/8.42 0.3 10.67/10.42 0.2 8.7 7.7

+1.00 0.00 +1.00

+1.00/-1.50 0.20 RE LL CL

10 Front Surface Toric Front Surface Toric Example

• ≥ 1 D residual astigmatism • Ks: 41.00 / 41.50 @ 090 and • MR: ‐1.00 ‐2.00 X 180 • ≤ 2.00 corneal toricity • CL: BC = 40.75; Power = ‐3.00 • Typically soft toric, but patient may not like vision Toricity Initial BC Spherical 0.50 D flatter than flat K 0.12 D - 0.75 D 0.25 D flatter than flat K 0.87 D - 1.37 D flat K ≥ 1.50 D (0.33 X diff b/t K’s) steeper than flat K

Front Surface Toric Example Summary

• Toric contact lenses are often necessary for 8.28 9.28 0.411.28 0.2 9.2 8.0 clear vision • Soft toric are most common -0.75 -1.50 X180 • GP bitoric provide excellent vision • Front and back surface GP torics rarely used

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