Recently, soft bifocal and multifocal contact lenses have made great strides in their development and ability to provide binocular vision correction for distance, near and intermediate performance. Eyecare professionals are looking for an easy-to-fit, comfortable lens with sufficient add correction for near vision and minimal compromise to distance vision, all without sacrificing intermediate vision performance. They seek a product that delivers a high first fit success rate and a fitting regimen that reduces chair time.

Hope for Astigmatic Presbyopes

In the past, astigmatic presbyopic patients had little choice when it came to correcting their vision. But with today's advancements in soft contact lens manufacturing technology, multifocal and bifocal soft contact lenses have become an attractive and viable alternative to spectacle correction for their presbyopic needs. However, such lenses may prove difficult to fit, require large amounts of chair time and result in a loss of binocular vision correction and intermediate visual performance.

Patients who have an astigmatic error in addition to their presbyopia present special challenges. Fortunately, eyecare professionals now have another option for contact lens correction in this hard-to-fit demographic with the introduction of the Essential Soft Toric Multifocal (Blanchard Contact Lens, Inc.) contact lens (Figure 1). Table 1 lists its parameter availability.

Testing a Screening Method

Three private practice eyecare offices as well as my own participated in a study to evaluate a five-step screening guideline (see sidebar on p. 43) designed to assist the fitting of the Essential Soft Toric Multifocal using the Quattro Aspheric Soft Multifocal lens (Blanchard) as the initial trial (screening) lens. The study authors chose 28 patients from a population of current successful soft toric contact lens patients who now require presbyopic vision correction, excluding monovision patients. The study evaluated the ability to provide astigmatic presbyopic patients with acceptable distance, near and intermediate vision using the Quattro trial (screening) lens in concert with a sphero-cylindrical over-refraction. If the "Quattro Screening Method" is a viable alternative to empirical fitting, then we could assume that the additional cylinder correction available with the Essential Soft Toric Multifocal would allow practitioners to successfully fit astigmatic presbyopic patients with a significant reduction in chair time and would provide patients with vision performance comparable to their current toric soft lenses and near vision performance with minimal compromise of intermediate vision.

	Figure 2. Anterior surface aspheric power profile for both lens designs.

A Look at Lens Design

Both study lenses are simultaneous vision lenses featuring an identical aspheric multifocal optic on their respective anterior surfaces. Blanchard uses its patented proprietary "S-Form" lathing manufacturing process to create a true aspheric optic or an "S-Curve" anterior surface aspheric power gradient (Figure 2). S-Form Lathing technology compresses more effective add correction (up to +2.50D) within a usable optical area, beginning at the axial center of the anterior lens surface. The Essential Soft Toric Multifocal incorporates a posterior toric base curve, double slab-off anterior design with axis markings at three o'clock and six o'clock (Figure 3).

Performing the Screening Fit

We began the fitting process by selecting the appropriate lens power of a Quattro lens according to the suggested manufacturing guidelines using only the spherical component of the refraction. Following lens equilibration (20 minutes), we performed a sphero-cylindrical over-refraction for distance and near vision. If the patient could achieve acceptable visual acuity at distance, near and intermediate, then we ordered the new lens with the resulting combination of the trial lens and the over-refraction. If the patient couldn't achieve acceptable vision at either distance or near, then we discontinued the fitting.

Figure 3. Optics of the Essential Soft Toric Multifocal.

Study Results

We screened 28 patients into the study, and 89 percent of them completed the study. Overall, we ordered 86 lenses and achieved a first-fit success rate of 32 percent. We had only a 35 percent warranty exchange rate for the study and we replaced 30 lenses mainly because of incorrect axis orientation.

We also discovered that some study patients who had low amounts of cylinder didn't need the Essential Soft Toric Multifocal because they performed well with the Quattro. The aspheric multifocal optic present on the Quattro lens effectively masked small amounts of cylinder correction for seven percent of the eyes fit.

The binocular visual performance of the study group was outstanding with 85 percent achieving 20/25 or better for distance, 75 percent achieving 20/30 or better for intermediate and 83 percent achieving 20/30 or better for near.

Screening patients to predict success may eliminate excessive lens orders (unnecessary warranty exchanges) and significantly reduce chair time. Our study shows that the Quattro trial (screening) method is effective and more proficient than empirical fitting in successfully fitting Essential Soft Toric Multifocal lenses for astigmatic presbyopes.

Additional Study Participants:

• Jon Franklin, OD, Mount Juliet, TN
• Bruce Gaddie, OD, Louisville, KY
• Thomas Scannell, OD, FAAO, Boerne, TX.

Blanchard Contact Lens, Inc. funded this study.