MULTIFOCAL RGPs

An RGP Multifocal for Moderate to High Presbyopes

Urs Businger, OD, FAAO; Steve Byrnes, OD, FAAO; & Richard Baker, OD, FAAO
OCTOBER 2000

Evaluating the Blanchard Essential RGP Aspheric Multifocal contact lens for patients requiring greater than +1.75D adds.

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Attaining clear near vision as well as crisp distance vision in multifocal RGPs for the moderate to high presbyope can be challenging. We evaluated the one-month clinical performance of the Blanchard Essential RGP Aspheric Multifocal for patients requiring greater than a +1.75D spectacle reading addition.

Study Overview

Thirty subjects were enrolled in the study. While the Essential design comes in three series offering varying degrees of presbyopic add correction, we evaluated only two of the lens types. Some 14 of the subjects (47 percent) received Series II lenses, and 16 of the subjects (53 percent) received the Series III design. Of the 30 subjects that entered the study, 26 (87 percent) completed the study, wearing the lenses for the one-month time period. Ninety-two percent of the subjects attained a distance visual acuity of 20/20 or better and a near visual acuity of 20/25 or better. At the completion of the study, subjects were given the option of receiving either Essential lenses or financial compensation similar in value.

Study Methods

Subjects. Thirty adapted subjects, all habitual RGP lens wearers, joined the study. The mean age of the seven males and 23 females enrolled was 53 years, ranging from 45 to 63. The mean spherical equivalent was ­3.14D, ranging from +2.50D to ­6.94D. Eighteen of the 30 subjects enrolled (60 percent) required a moderate spectacle addition of +1.75D to +2.00D, and 12 (40 percent) required a high spectacle addition of +2.25D to +2.50D. Four patients dropped out of the study: two with a moderate spectacle addition and two with a high spectacle addition.

Lenses. The Series II lens fits patients with adds from +1.50D to +2.25D (Figure 1). The Series III lens fits patients with adds of +2.50D or greater (Figure 2). All lenses were evaluated to the higher add powers in the subject group. The lenses were dispensed in a power range of +3.00D to ­7.75D, with base curves ranging from 7.20 to 8.30mm.

 

Figure1

Figure 2

Design. Each subject wore the contact lenses for a period of one month on a daily wear basis. We evaluated the lenses for visual acuity (both distance and near), lens positioning and movement, ocular response and patient acceptance.

Procedure. We determined patient eligibility using the criteria defined in the referenced study protocol. At the initial examination, a fitting set determined the initial lens parameters. At the dispensing visit, the subjects received instructions on contact lens wear, care and handling, and were advised to wear the lenses on a daily wear basis. Subjects used Boston Advance Cleaner and Boston Advance Comfort Formula Conditioning Solution to care for their contact lenses. Follow-up examinations occurred at one week and one month from the date of dispense. The study took approximately five months with final results compiled in the spring of 2000.

Lens Fit. Of the 30 study subjects, 17 (57 percent) were successfully fit with the initial lens order requiring no subsequent changes to enhance comfort, fit or visual performance. Thirteen subjects (43 percent) required a lens reorder (Figure 3). Reasons for lens reorder included base curve/diameter change (50 percent), power (44 percent) and comfort enhancement (6 percent). An average of 2.6 lenses was required for the entire study population to receive two lenses illustrating proper lens fit and acceptable visual acuity. All four of the subjects that chose to discontinue from the study needed at least one lens reordered.

Success of Lens Wear

One measure of success is the percentage of subjects that completed one month of wear. Twenty-six of the 30 subjects enrolled (87 percent) completed one month of lens wear (Figure 4). Of those completing one month of wear, 22 subjects (85 percent) chose to receive the lenses over financial compensation of similar value.

Distance Visual Acuity. At the one-month visit, two subjects (8 percent) achieved a distance visual acuity of 20/15. Twenty-two (84 percent) achieved 20/20, one (4 percent) achieved 20/25 and one (4 percent) achieved 20/30 (Figure 5). For purposes of analysis, distance visual acuity was converted to Snellen VA from LogMAR notation. There was no significant difference in the mean distance visual acuity over time. Mean LogMAR distance visual acuity was 0.01 at dispense, 0.01 at one week and 0.00 at one month (approximately 20/20).

Near Visual Acuity. At the one-month visit, two subjects (8 percent) achieved a near visual acuity of 20/15. Seventeen (65 percent) achieved 20/20, five (19 percent) achieved 20/25, one (4 percent) achieved 20/40 and one (4 percent) achieved 20/50 (Figure 6). There was no significant difference in the mean near visual acuity over time. Mean LogMAR near visual acuity was 0.05 at dispense, 0.05 at one week and 0.04 at one month (approximately 20/20⁺²).

Slit Lamp Findings. Compared to baseline, we saw no significant differences in the mean findings over time for corneal staining, limbal injection, tarsal conjunctival abnormalities and anterior segment abnormalities. Bulbar injection showed a statistically significant decrease (p=0.032, ANOVA) over the duration of the study. No positive findings were noted on the slit lamp examinations for epithelial edema, epithelial microcysts, corneal neovascularization, corneal infiltrates, corneal striae, conjunctivitis or the external adnexa.

Comparison of Series II and Series III. The Series II and III contact lenses performed very similarly in most categories at the one-month visit. The performance in distance visual acuity and near visual acuity was very similar, as were the patient assessments of the quality of distance and near vision. The success rate with the Series II lens was 93 percent versus 81 percent for the Series III lens. Of those patients that completed one month of contact lens wear, 92 percent of those wearing the Series II design chose the lenses over financial compensation, while 77 percent of those wearing the Series III design chose the lenses.

Discussion

The Blanchard Essential RGP Aspheric Multifocal contact lens performed well in most categories. This lens provided excellent distance and near visual acuity for most patients in both the Series II and Series III designs. There was an excellent success rate with 26 of 30 subjects enrolled (87 percent) completing one month of contact lens wear. Patient assessment scores generally rated the lens to be excellent or good in most categories. There was a trend towards corneal flattening and refractive changes in some patients, a finding that has been previously noted in the literature with many RGP aspheric multifocal contact lenses.

Dr. Businger is in private practice in Luzern, Switzerland, and provides technical evaluation and analysis of contact lenses and related products for numerous corporations.

Dr. Byrnes is in private practice in Londonderry, New Hampshire, and is a faculty member of the New England College of Optometry/Contact Lens Department.

Dr. Baker is in private practice in Lafayette, Calif., with an emphasis on contact lenses. He is a member of the clinical faculty at the University of California at Berkeley.