Article Date: 5/1/2004

SOFT TORIC LENSES
Soft Toric Lenses: What's Available Today
A look at the tried-and-true lenses of old as well as those recently entering the market.
By P. Douglas Becherer, OD, FAAO

Soft toric contact lenses have come a long way since their introduction more than 20 years ago. Gone are the unpredictable manufacturing processes that left prescribers guessing about the true power and design of each lens. We now expect consistent optical and physical quality.

More soft toric designs are also available today, and knowing what's out there can help you choose the right lens for each patient. Ready-made lenses are available in higher astigmatic components than ever before, and custom lenses are available in an even wider range of powers.

We're limited only by how many available base curves and overall diameters each design offers. A persistent prescriber will jump from one design to another to obtain the lens parameters needed for success.

Evaluating Lens Fit

Success with soft toric lenses has many definitions. Some practitioners are satisfied if the patient isn't complaining. Such "good enough" patient care is a disservice considering that straightforward techniques are available to help you refine prescribed lenses. Always strive to offer patients the best available prescription.

After choosing what you believe is the best design, perform a physical evaluation of the lens fit. Is the overall diameter acceptable? Is the coverage of the cornea optimal? Is the alignment to the cornea acceptable?

Next, evaluate proper axis alignment to determine if the design suits the patient. If you achieve proper axis alignment, then check that lens movement is acceptable and consistent. Assess the quality of vision only after you determine that the physical fit of the lens is adequate. In most cases, the closer the trial lens is to the theoretical lens needed, the easier it is to determine whether you'll succeed.

Perform a sphero-cylinder over-refraction to evaluate the resultant power of the lens. No shortcuts exist in determining the proper final prescription. Computer programs and calculators are available to help you combine the over-refraction result with powers of the lens on the eye. Many contact lens companies, as well as the American Optometric Association Contact Lens and Cornea Section, offer free software for this purpose.

Soft toric lens quality, consistency and availability has improved almost yearly over the last 25 years. As technology improves, we can increasingly prescribe lenses that meet our patients' exact needs.

What's Available Now?

As I said before, knowing what soft toric lens choices are available today will help you choose the best lens for each patient. Following is a list, by manufacturer, of some currently available soft toric lenses.

CIBA Vision's most recent addition is the single-use Focus Dailies Toric. It's available in a limited power range from ­0.50D to ­6.00D sphere, with cylinder power of only ­0.75D at two axis locations (180 degrees and 90 degrees). Despite the limited parameters, many patients report improved clarity with this lens compared to the vision they achieve through a spherical lens. CIBA manufacturers its Focus Dailies Toric in nefilcon A, which is comfortable on the first day, but less comfortable with over-use, according to CIBA.

Fit the Dailies Toric lens for patients who have either with-the-rule or against-the-rule astigmatism located within 20 degrees of the 90-degree or 180-degree axis. The lenses don't feature axis location marks -- vision is either acceptable to the patient or it's not. If it's unacceptable, then you can make only spherical changes.

Christopher Snyder, OD, MS, FAAO's Induced Astigmatism graph (International Contact Lens Clinic, 1989) (see figure below) shows why this lens is so successful: As long as a lens with ­0.75D cylinder rotates less than 30 degrees, it will improve vision over a spherical lens.

CIBA also offers the FreshLook Toric, which was the first disposable toric lens to receive FDA approval six years ago. It's now available in four colors as well as a handling tint. If you want more colors, CIBA's Optifit line of toric lenses has 11 to choose from. They're available in both a 38.6 percent and a 55 percent water content phemfilcon material.

The CSI Toric is still available in crofilcon A, a stiff material that helps stabilize the lens on the eye.

The Torisoft Toric, which CIBA introduced more than 20 years ago, is the first lens that incorporated double slab-off thin zones for stability. CIBA's Hydrocurve Toric lens, the first soft toric to receive FDA approval in the Unites States, is made to order.

Bausch & Lomb added higher cylinder powers to its SofLens 66 Toric lens. Made of alphafilcon A 66, this cast-molded lens has sphere powers ranging from +6.00D to ­9.00D, five cylinder powers (­0.75D, ­1.25D, ­1.75D, ­2.25D, ­2.75D) and around-the-clock axes in 10-degree steps. It has a median base curve of 8.5mm and a 14.5mm diameter. The lens features three laser marks at 5 o'clock, 6 o'clock and 7 o'clock, each line representing a 30-degree difference.

The Optima Toric is a front-surface design that features three base curves and eight cylinder powers.

Vistakon The Acuvue Toric's 600-lens fitting set makes judging its success often immediate during the initial examination. A double-thin-zone toric lens with ultraviolet (UV) protection, it boasts minimal rotation independent of the power combination and has cylinder powers up to ­1.75D.

Ocular Sciences, Inc. The Sunsoft line of lenses is available from OSI. Made of methafilcon A, all but the Eclipse feature a 15mm diameter. The conventional Sunsoft toric is available in two base curves (8.3mm, 8.9mm), sphere powers from +10.00D to ­20.00D and up to a ­7.00D cylinder in any axis.

OSI released its Biomedics Toric, which incorporates a UV blocker, two and a half years ago. Both the Biomedics Toric and the Sunsoft Eclipse Toric have a 14.5mm diameter. The Eclipse Toric's material is methafilcon A and the Biomedics Toric is made of ocufilcon.

CooperVision, Inc. released its Encore Toric more than four years ago. It complements Cooper's workhorse lens, the Frequency 55 Toric. Both lenses are monthly and made of methafilcon in a 14.4mm diameter. The Encore Toric features a single base curve (8.6mm) and the Frequency has two base curves (8.4mm, 8.7mm).

CooperVision manufactures its Preference Toric in tetrafilcon, with a 14.4mm diameter and two base curves (8.4mm, 8.7mm). The Preference Toric and the XR version offer a wide range of powers for both sphere and cylinder correction. Tetrafilcon is a stable material that you should use for challenging prescriptions.

Consider CooperVision's Proclear Compatibles Toric, made of omafilcon A, for patients who have drier eyes. This monthly replacement lens is available in 8.8mm base curve, 14.4mm diameter and cylinder options of ­0.75D, ­1.25D and ­1.75D. Also available in omafilcon A, the Proclear Tailor Made Toric is a conventional lens available in 14 base curves from 8.0mm to 9.3mm and seven diameters from 13.6mm to 15.2mm.

If these CooperVision lenses don't meet the patient's needs, you could try the Hydrasoft Toric DW and EW, made of methafilcon A and available in sphere powers from ±20.00D and cylinder powers up to ­10.00D.

Acuity One offers the Ultragel Toric, a 49 percent water content lens made of hioxifilcon B. Its sphere powers range from ±20.00D, with a cylinder component of up to ­10.00D at any axis. It features two diameters (14.5mm, 15mm) and four base curves (8.0mm, 8.3mm, 8.6mm, 8.9mm).

You can also combine this lens with the Ultravue presbyopic design. For the Ultravue Toric Multifocal, prescribe the "D" lens for the patient's dominant eye and the "N" lens for the nondominant eye. The D lens features a distance central zone of either 2.3mm or 2.6mm, surrounded by an aspheric annular near zone. The N lens has a near central zone of either 1.7mm or 2mm, surrounded by an aspheric annular distance zone.

Alden Optical offers a series of soft torics in hioxifilcon B as well as polymacon in an extensive range of sizes, powers and base curves. The Alden Classic Toric is notable in that it's available in three diameters (13mm, 13.5mm, 14mm). A 13mm lens is less cumbersome for children and is available in steep base curves (7.7mm to 8.9mm). This lens also comes in nine colors.

Biocurve has two lines of toric lenses: the Biocurve Gold Toric in hioxifilcon A material (59 percent water) and the Biocurve Toric in methafilcon A. Both lenses are available in a combination of three diameters (14.4mm, 14.5mm, 15mm) and six base curves (8.4mm to 9.0mm).

Blanchard Contact Lens Company manufactures the Essential Soft Toric Multifocal in hioxifilcon B. Cylinder correction is available within 30 degrees of axis 180 or 90.

California Optics offers a range of both planned replacement and conventional designs in methafilcon and polymacon. Its CO Soft 55 custom toric bifocal features a double slab-off, center-near design.

Contact Lens Laboratories of Greater Cincinnati offers conventional toric lenses, available in four diameters and a wide power range.

Innovations in Sight, Inc. has a standard toric design (Super Nova Toric) available in five base curves (8.0mm, 8.3mm, 8.6mm, 8.9mm, 9.2mm) and five diameters (13.5mm, 14mm, 14.5mm, 15mm, 15.5mm). If that's not adequate, you can order a custom Super Nova HydroKone toric lens in any base curve from 4.1mm to 9.3mm and any diameter from 12mm to 17mm. Sphere powers range from +50.00D to ­75.00D and cylinders range from ­0.25D to ­50.00D. The material is hioxifilcon A (59 percent water), and you can order the lenses custom tinted to desired intensity, with a clear or tinted pupil.

Kontur Kontact Lens David Ewell, OD, president of Kontur, designed the Kontur 55 Toric lens, which many other companies have mimicked. This methafilcon lens features eccentric lenticulation, prism of 1.5 to 1.8 base down and back-surface design. It's available in four base curves (8.0mm, 8.3mm, 8.6mm, 8.9mm), four diameters (14mm, 14.5mm, 15mm, 16mm) and a large sphere and cylinder power range.

The LifeStyle Company combined its MV2 Multifocal lens with a double slab off toric design. Prescribe this lens as you would monovision, fitting the dominant eye with the MV2 distance lens and the nondominant eye with the MV2 near lens. The distance lens features a central, concentric area of +0.50D, and the near lens has a central annular area of ­1.25D. This enhances the mid-vision range. This polymacon lens is available in base curves of 8.5mm and 8.8mm.

Metro Optics makes the Satureyes Toric in hioxifilcon A (59 percent water). It's a lathe-cut, prism-ballasted, back-surface lens with cylinder correction of ­0.75D to ­4.00D in any axis. The Metrosoft Toric is a polymacon lens that's available in the same design and as a front-aspheric, center-distance multifocal.

Ocu-Ease Optical Ocuflex lenses are available in both hioxifilcon B (49 percent water) and in ocufilcon B (53 percent water) in conventional, tinted and combined toric-multifocal designs. The toric features a back-surface design with two base-down prisms and cylinder correction up to ­6.00D in any axis. The aspheric multifocal features either a low add or high add and has a center concentric zone of either 1.9mm or 2.18mm.

Optech, Inc. offers both a toric and a multifocal toric design. The toric design in focofilcon offers custom base curves, diameters and powers. The standard Freflex toric as well as the Polyvue multifocal toric are available in ocufilcon. The Polyvue features an aspheric, center-near add of 1.5mm, 1.7mm or 1.9mm.

Optical Connection, Inc. manufactures its Definition-AC toric lens in methafilcon in minus powers up to ­6.00D and two cylinder choices (­1.00D and ­1.75D) in around-the-clock axes (10-degree steps).

Unilens Corporation offers its Sof-form 55 conventional toric in methafilcon in two base curves (8.6mm, 8.9mm) and one diameter (15mm). It features cylinders from ­0.50D to ­5.00D in any axis.

United Contact Lens uses ocufilcon A for its UCL Torics, which are available in colors and can correct up to ­10.00D cylinder in any axis. You can order its Tresoft Toric with either front surface or back surface design to correct up to ­7.00D of cylinder.

Westcon Contact Lens makes its Westhin Toric in either methafilcon or polymacon in spheres from ±20.00D, 14.2mm diameter and three base curves (8.3mm, 8.6mm, 8.9mm). The prism-ballasted Horizon Soft Toric features an additional base curve of 9.2mm, three diameters (14mm, 14.5mm, 15mm) and cylinder correction from ­0.75D to ­10.00D in any axis. Custom torics are also available.

You Can Find What You Need

We have no excuse today if we improperly care for our astigmatic patients. You can obtain today's soft toric lens designs in either trial or warranted lenses, decreasing the risk of material costs. Cylinder powers start as low as ­0.75D and range as high as needed. You can choose from standard and custom designs, with either prismatic or dynamic stabilization. Colors or clear, large or small, you can usually find what you need for each patient.

Dr. Becherer is in private practice in Belleville, IL. He is a past chair of the AOA Contact Lens & Cornea Section, past president and OD of the Year for the Heart of America Contact Lens Society. He's also an adjunct professor for the University of Missouri-St. Louis College of Optometry and for Southern College of Optometry.

 


Contact Lens Spectrum, Issue: May 2004