Crystalens/Trulign Intraocular Lenses

45   Crystalens/Trulign Intraocular Lenses

Mitchell A. Jackson

We are fortunate to have several options in presbyopia-correcting intraocular lenses (IOLs) to offer our cataract patients. These fundamentally different lens designs give us an opportunity to tailor the implant to each patient’s needs and lifestyle, especially as we pursue the ideal of an emmetropic outcome. But being able to recommend the best choice for each patient also requires a thorough knowledge of the strengths and weaknesses of these lens technologies so that we can manage patients’ expectations appropriately. Having had extensive experience with both multifocal and accommodating lens designs, I have found that the latter design provides the range and quality of vision that more of my patients hope to achieve following surgery, with fewer of the complaints commonly associated with multifocal IOLs. Since the United States Food and Drug Administration’s (FDA) approval of the Crystalens (Bausch and Lomb, Rochester, NY) in 2003, many changes have occurred to the original model AT-45 platform including the introduction of the toric version known as Trulign (Bausch and Lomb). This chapter reviews the FDA approvals for both Crystalens and Trulign, the Centers for Medicare and Medicaid Services (CMS) ruling on presbyopia-correcting IOLs, the design evolution of the Crystalens, patients’ preoperative expectations with this technology, intraoperative and postoperative tips to optimize visual outcomes, and management of adverse events or complications, including yttrium-aluminum-garnet (YAG) laser approaches to treat and prevent Z syndrome/capsular contraction syndrome.

Food and Drug Administration Approval of Crystalens/Trulign

There is only one FDA-approved accommodating IOL available to U.S. surgeons (as of September 2015)—the Crystalens family of IOLs including the most current Crystalens Advanced Optics (AO) and the Trulign Toric (Figs. 45.1 and 45.2). The Crystalens models AT50AO and AT52AO were approved in the United States in 2009, whereas the Trulign Toric was FDA-approved in 2013. Unlike multifocal IOL designs, the Crystalens lens platform is aspheric and aberration-free and has uniform center-to-edge power,1,2 producing a more natural range of vision through physical accommodation in the eye (forward movement),3 and typically requires less neuroadaptation than multifocals. The optic design also enables the lens to use 100% of available light regardless of pupil size or lens centration for enhanced contrast sensitivity.4 Robert Ang’s4 prospective randomized subject-masked 6-month study, as presented at the European Society of Cataract and Refractive Surgeons (ESCRS) 2011 meeting compared the contrast sensitivity among three FDA-approved lenses: the Crystalens AT50AO, the Acrysof ReStor 3.0 (Alco, Fort Worth, TX), and the Tecnis ZMB00 (Abbott Medical Optics, Abbott Park, IL). The Crystalens AT50AO demonstrated statistically significant improved binocular mesopic contrast sensitivity without glare compared with the two multifocal IOLs at both 1.5 cycles/degree and 3.0 cycles/degree spatial frequencies. In binocular low-contrast uncorrected distance visual acuity (UDVA),4 Crystalens was statistically better than Tecnis ZMB00 (+4.00 add); in binocular cumulative low- and high-contrast uncorrected intermediate visual acuity (UIVA), Crystalens statistically outperformed both multifocals. As for binocular cumulative low- and high-contrast uncorrected near visual acuity (UNVA), Crystalens was statistically similar to both multifocal designs. Because the Crystalens is an aspheric aberration-free optic design, it avoids any of the light-splitting disturbances seen with multifocal designs described above. The newer FDA-approved low add Acrysof Restor 2.5 and Tecnis ZKB00 and ZLB00 (+2.75 and +3.25, respectively) multifocal designs have improved contrast and glare complaints in low light conditions such as night driving compared with its predecessor designs but still have not reached mesopic contrast sensitivity levels seen with the Crystalens AO and Trulign platforms (Fig. 45.3).

One of the key clinical advantages of the Crystalens AO (AT50 and AT52) platform is its long-term refractive stability as published in 20115 and continues to date in 2015. Colvard5 found that binocular UDVA was sustained over 7 years such that 96% of the 24 patients seen this far out retained 20/40 or better UDVA and 75% retained 20/20 or better. Binocular UIVA was also sustained and even improved from year 1 out to 7 years, such that 100% of the 24 patients saw 20/40 or better and 83% saw 20/20 or better.

Both the Crystalens AT50AO and Crystalens AT52AO IOLs have a central prolate anterior and posterior aspheric aberration-free 5.0-mm BioSil silicone elastomer optic body with index of refraction of 1.43 (35°C), an equiconvex shape, a 360-degree square edge to reduce posterior capsular opacification (PCO), rectangular hinged haptics to increase forward translation, a plate haptic diameter of 10.5 mm, and round-to-the-right asymmetric polyimide loops (“knobs”), the latter designed to prevent inadvertent upside down implantation intraoperatively (Figs. 45.1 and 45.4). The overall diameter of the Crystalens AT50 AO and Trulign Toric BL1UT is 11.5 mm, and the Crystalens AT52AO is 12.0 mm in length, the latter designed to be placed in eyes with axial lengths > 25 mm and maintain improved effective lens position (ELP) per FDA labeling. The FDA-approved IOL powers for the Crystalens AT50 AO range from +17 to +33 D (in 0.5-D increments) and +18 to +22 D (in 0.25-D increments) and for the Crystalens AT52AO range from +4 to +9 D (in 1.0-D increments) and +10 to +24 D (in 0.5-D increments) (Fig. 45.2). Table 45.1 summarizes the Crystalens platforms approved since 2003; the Crystalens models AT50AO and AT52AO are the most commonly used designs as of 2015.6

The FDA-approved model BL1UT Trulign Toric IOL has a central anterior aspheric axis mark just inside the haptic junction and a posterior aspheric toric aberration-free 5.0-mm BioSil optic body, with index of refraction of 1.43 (35°C), an equiconvex shape, a 360-degree square edge, rectangular hinged haptics with a plate haptic diameter of 10.5 mm, and round-to-the-right polyimide loops similar to those in the Crystalens AO designs (Figs. 45.2 and 45.4). The BL1UT comes in three FDA-approved IOL labeled cylindrical powers of 1.25, 2.00, and 2.75 D that correlate to a corneal cylindrical correction of 0.83, 1.33, and 1.83 D, respectively. The FDA-approved powers for all three cylindrical designs are +4 to +10 D spherical equivalent (SE) (in 1.0-D increments) and +10.5 to +33 D SE (in 0.5-D increments).

The original FDA labeling for each of the two platforms (Crystalens and Trulign) enables near, intermediate, and distance vision without spectacles. The Crystalens is intended for primary implantation in the capsular bag of the eye for the visual correction of aphakia secondary to the removal of a cataractous lens in adult patients with and without presbyopia. The Crystalens provides approximately 1 D of monocular accommodation, which enables near, intermediate, and distance vision without spectacles.7 The Trulign Toric posterior chamber IOL is intended for primary implantation in the capsular bag of the eye for the visual correction of aphakia and postoperative refractive astigmatism secondary to removal of a cataractous lens in adult patients with or without presbyopia who desire reduction of residual refractive cylinder with increased spectacle independence and improved uncorrected near, intermediate, and distance vision. The original FDA pivotal clinical trial based on the Crystalens model AT-45 paved the way for all future platforms. In this trial prior to 2003 approval, 497 eyes of 324 patients had the AT-45 platform implanted, with a range of axial lengths of 21.0 to 26.6 mm and dioptric power range between 16.5 and 27.5 D. The clinical results were obtained using an A constant of 119.0, the SRK/T formula, and immersion biometry or interferometry and manual keratometry. In 124 bilaterally implanted patients, the proportion of patients achieving uncorrected visual acuities of 20/32 (J2) or better at 1 year was 97.6% at distance, 100% at intermediate (80 cm), and 93.5% at near (40 cm). In 74 bilaterally implanted patients who were within ±0.5 D of plano in each eye, the proportion of patients achieving uncorrected visual acuities of 20/32 (J2) or better at 1 year was 100% at distance, 100% at intermediate (80 cm), and 97.3% at near (40 cm).

The pivotal clinical trial in the United States of the Trulign Toric IOL was conducted on 229 eyes of 229 patients, of which 227 eyes had it implanted. The dioptic power range was 16.0 to 27.0 D with cylindrical powers at the lens plane of 1.25, 2.00, and 2.75 D for the AT50T/AT52T. The Crystalens Accommodating IOL models AT50SE/AT52SE (nontoric optic) were used as the control IOLs. To facilitate toric IOL selection and axis placement, a proprietary Toric Calculator was used to determine the appropriate Trulign Toric IOL model and axis of placement for each eye (Fig. 45.5). The Trulign Toric IOL Calculator was used to calculate the predicted postoperative corneal astigmatism using preoperative keratometry, phaco/insertion incision location, and predicted magnitude of surgically induced astigmatism (SIA) inputs entered by the physician. The calculator accounted for SIA, incision location, and the patient’s preoperative corneal astigmatism, and determined the toric IOL cylinder power needed and placement orientation to best correct the patient’s predicted postoperative corneal astigmatism. In the trial, all cataract incisions were placed on the preoperative keratometric steep axis and a fixed SIA value of 0.50 D was used in the Trulign Toric IOL Calculator for all study subjects. The results achieved by 227 patients followed postoperatively for 6 months provide data to support the conclusion that eyes implanted with a Trulign Toric IOL following cataract extraction achieved visual correction of aphakia and astigmatism. The data also support a percent reduction in absolute cylinder, cylinder correction accuracy, rotational stability of the lens, and improvement of UDVA following implantation of Trulign Toric IOL (Figs. 45.6, 45.7, 45.8, 45.9). All three toric powers implanted cumulatively had a 78.4% cylinder correction accuracy within 0.5 D of intended target compared with 45.1% in the control group, and 95.5% were within 1.00 D of the intended target compared with 72.1% in the control group (Fig. 45.6).

The data in Fig. 45.8 show quantitatively that the Trulign Toric IOL provides a range of vision from distance to intermediate, and at 6 months 97.8% of patients achieved at least 20/40 in both UDVA and UIVA, the latter measured at 32 inches. Rotational stability is vital in terms of final visual outcome with a toric IOL and even as little as a 4-degree misalignment or a cyclotorsion effect can cause a loss of 14% of the cylindrical correction effect, correlating to an approximate 3.3% decrease in cylinder correction per degree of rotation (Fig. 45.10). Looking at all toric cohorts at 4 to 6 months postoperatively, the mean rotation was less than 2 degrees, and 96.1% of all eyes had 5 degrees or less of rotation (Fig. 45.10). When comparing the pivotal trial data for Trulign Toric compared with the other two FDA-approved toric IOLs, Trulign achieved 96.1% rotational stability less than 5 degrees, whereas the Acrysof IQ monofocal toric achieved only 81.1% rotational stability less than 5 degrees, and the Tecnis monofocal toric achieved only 94.0% less than 5 degrees (Fig. 45.11). By far, the Trulign Toric definitely did not any show any noninferiority compared with its two toric IOL predecessors on the U.S. market.

May 13, 2018 | Posted by in OPHTHALMOLOGY | Comments Off on Crystalens/Trulign Intraocular Lenses
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