Toric posterior chamber IOL reduces residual astigmatism after phaco

Issue: May 2015

ByHoo Yeun Kim

ByGregg Feinerman, MD, FACS

BySheila Nardelli

Corneal astigmatism is one of the most common ophthalmic conditions, both in the general population and patients undergoing cataract surgery. According to one study, 64.4% of cataract patients had corneal astigmatism between 0.25 D and 1.25 D and 22.2% had astigmatism greater than 1.5 D. Another recent study of 23,239 eyes reported corneal astigmatism of more than 1 D in 36% of eyes.

As a result, greater emphasis is being placed on treating corneal astigmatism at the time of cataract surgery, most often with either limbal relaxing incisions (LRIs) or placement of a toric IOL. The Trulign toric IOL (Bausch + Lomb) is one method of managing astigmatism.

My special guest in this column is Dr. Gregg Feinerman, who would like to share his experience with the Trulign toric IOL.

Amar Agarwal, MS, FRCS, FRCOphth
OSN Complications Consult Editor

Historically, both LRIs and toric IOLs have limitations in managing corneal astigmatism. LRIs are often associated with denervation of the cornea, which may result in a decreased blink reflex, reduced tear production and a reduced rate of epithelial cell mitosis, while early versions of toric IOLs have been shown to have poor rotational stability and frequently needed to be repositioned. Since its approval in 2003, more than 315,000 eyes have been implanted worldwide with the Crystalens accommodating IOL (Bausch + Lomb). The lens is designed to reduce spectacle dependence after cataract surgery by correcting defocus and presbyopia and has a proven record of efficacy and safety. However, patients with preoperative corneal astigmatism who opt to receive any of the premium IOLs are frequently left with significant residual astigmatism, which may potentially lead to decreased uncorrected visual acuity and decreased patient satisfaction.

Trulign toric IOL

The Trulign toric IOL incorporates a toric posterior optic surface and axis marks on the anterior surface. It has been approved by the U.S. Food and Drug Administration for a mean spherical dioptric power range of 4 D to 33 D in 0.5 D increments and is available in three cylinder powers to address varying degrees of astigmatism: 1.25 D, 2 D and 2.75 D.

A recent prospective, randomized, monocular FDA trial of 229 eyes demonstrated the safety and efficacy of the Trulign toric IOL (models AT50T and AT52T) in providing near, intermediate and distance vision, as well as decreasing the effects of preoperative corneal astigmatism in subjects undergoing cataract extraction and IOL placement. Postoperatively, subjects received a complete ophthalmic examination at regular intervals as per the study visit schedule (up to 330 to 420 days or until rotational stability was achieved). Rotational stability, using photographic assessment, was performed by an independent reading center at day 0 (operative day) and at postoperative days 30 to 60, 120 to 180, 245 to 301, and 330 to 420. The lens was considered stable when 90% of the eyes showed axial rotational stability of 5° or less between consecutive scheduled visits at least 3 months apart, with stability being achieved at the latter of the two consecutive visits.

In the study, the Trulign toric IOL provided a mean reduction in absolute cylinder of 85.8%. Further, the mean percent reduction in absolute cylinder was significantly greater in eyes implanted with the Trulign toric 1.25 D IOL compared with eyes implanted with the Crystalens AT (81.1% vs. 46.3%, respectively; P < .001). Ninety-five percent of all Trulign eyes had reached, within 1 D, the intended reduction in cylinder at the final study evaluation.

The Trulign toric IOL also provided a high degree of stability (Figure 1), with little rotation. Overall, 95.7% of toric lenses were within 10° of the target at the day 120 to 180 evaluation, and 96.1% of toric eyes had 5° or less of rotation between two consecutive visits (Figure 2). Both best corrected distance visual acuity and best corrected near visual acuity were 20/40 or better in the majority of all toric IOL eyes at the postoperative visits, including unscheduled visits.

Figure 1. Clinical picture of immediate postoperative (a) and 1 year (b) after Trulign toric IOL implantation. Note the good IOL stability.

Image: Agarwal A, Feinerman G

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In my experience, the Trulign toric IOL provides an excellent array of patient outcomes, including reduction in cylinder (Figure 3) and improved visual acuity. Our Trulign patients are less likely to need LASIK correction after IOL implant surgery compared with patients who receive the spherical Crystalens or multifocal IOLs. This is due to the fact that their refractive cylinder is significantly reduced or eliminated with the Trulign IOL. Our patients also maintain excellent UCVA with the Trulign throughout the postoperative period. The lens is easy to insert and rotate into the proper axis. Trulign has excellent rotational stability, which is due to the four points of fixation provided by its polyamide haptics.

Surgical pearls

1. Compare your corneal astigmatism measurements, ie, manual keratometry, IOLMaster (Carl Zeiss Meditec) and autorefractor, to help determine the correct Trulign toric IOL power.

2. Avoid patients with asymmetric astigmatism on corneal topography, ie, keratoconus or pellucid marginal degeneration.

3. Mark the axis of astigmatism with the patient in the upright position before commencing surgery. Alternatively, you can mark the 180° axis with the patient upright and then mark the axis of astigmatism using a Mendez astigmatic marker intraoperatively.

4. Make sure the Trulign is posteriorly vaulted, but avoid overinflating the eye at the conclusion of surgery.

Advantages

The Trulign toric posterior chamber IOL is the only toric IOL that provides an extended range of vision approved by the FDA. It is based on the Crystalens IOL platform and was developed to reduce residual astigmatism. Trulign may reduce the need for secondary surgical procedures frequently used to reduce residual astigmatism, including LRIs, wedge resections, manually created arcuate keratotomy, PRK and LASIK, thereby significantly increasing patient satisfaction and UCVA.

References:

Chen W, et al. J Cataract Refract Surg. 2013;doi:10.1016/j.jcrs.2012.08.060.
Ferrer-Blasco T, et al. J Cataract Refract Surg. 2009;doi:10.1016/j.jcrs.2008.09.027.
Hoffer KJ. Am J Ophthalmol. 1980;90(3):360-368.
Hoffman PC, et al. J Cataract Refract Surg. 2010;doi:10.1016/j.jcrs.2010.02.025.
Khan MI, et al. J Cataract Refract Surg. 2011;doi:10.1016/j.jcrs.2011.04.026.
Lekhanont K, et al. J Cataract Refract Surg. 2011;doi:10.1016/j.jcrs.2010.12.038.
Riley AF, et al. Clin Experiment Ophthalmol. 2001;doi:10.1046/j.1442-9071.2001.d01-27.x.
Stern ME, et al. Cornea. 1998;17(6):584-589.
Till JS, et al. J Cataract Refract Surg. 2002;28(2):295-301.

For more information:

Amar Agarwal, MS, FRCS, FRCOphth, is director of Dr. Agarwal’s Eye Hospital and Eye Research Centre. Agarwal is the author of several books published by SLACK Incorporated, publisher of Ocular Surgery News, including Phaco Nightmares: Conquering Cataract Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders and Stem Cell Surgery and Presbyopia: A Surgical Textbook. He can be reached at 19 Cathedral Road, Chennai 600 086, India; email: dragarwal@vsnl.com; website: www.dragarwal.com.
Gregg Feinerman, MD, FACS, can be reached at Feinerman Vision Center, 320 Superior Ave., Suite 390, Newport Beach, CA 92663; email: lasiksurgeon@mac.com.
Disclosures: Agarwal and Feinerman are consultants for Bausch + Lomb.