All About Cataracts

A multifocal IOL recently approved for use in the United States produces a wide range of clear vision and a high degree of independence from eyeglasses after cataract surgery, according to a multi-center European study published this month in Journal of Cataract and Refractive Surgery.

The study evaluated the performance of the AcrySof IQ ReSTOR IOL with +3.0 D add power implanted in both eyes of 93 patients. The procedures took place at five European sites and were performed by five surgeons.

At 6 months after surgery, mean binocular uncorrected visual acuity was better than 20/20 at distance (4 meters), approximate 20/30 at arm’s length and slightly better than 20/20 vision at the patient-preferred reading distance (approximately 16 inches).

In a postoperative survey, the mean patient satisfaction with their vision was 8.3 out of 10, and 88 percent of the patients did not need eyeglasses after surgery.

The use of premium intraocular lenses (IOLs) in cataract surgery performed in the United States is increasing, according to recent surveys.

Premium IOLs include multifocal lens implants and accommodating IOLs. Both types of presbyopia-correcting intraocular lenses give patients a broader range of vision, reducing or eliminating the need for reading glasses after cataract surgery.

According to a recent survey of cataract and refractive surgeons reported by the eyecare industry research firm Market Scope, 71 percent of U.S. eye surgeons offered their patients the option of premium IOLs in 2008, up from approximately 59 percent in 2007. The company also estimates that 210,000 presbyopia-correcting IOLs were implanted during cataract surgery or other vision correction procedures in the U.S. in 2008, up from 153,000 in 2007.

Eye surgeons also say they prefer premium IOLs for the correction of high myopia. In a 2008 member survey of the American Society of Cataract and Refractive Surgery (ASCRS) more eye surgeons responding to the survey reported preferring premium IOLs (40 percent) to LASIK (23 percent) for the correction of large amounts of nearsightedness in patients desiring elective refractive surgery.

Among ASCRS surgeons using presbyopia-correcting premium IOLs, their top three lens choices in 2008 were the AcrySof ReSTOR multifocal IOL (Alcon), the Crystalens accommodating IOL (Bausch & Lomb) and the ReZoom Multifocal IOL (Abbott Medical Optics).

Other premium intraocular lenses include toric IOLs that correct astigmatism and aspheric IOLs designed to reduce glare and improve night vision.

Premium IOLs cost more than standard IOLs, and the added expense of these lenses typically is not covered by vision insurance and must be paid out-of-pocket, increasing your cataract surgery cost. However, most people who choose premium IOLs are very pleased with the added visual benefits the lenses provide, according to eye surgeons who offer them.

Posterior capsule opacification (PCO) is one of the most common cataract surgery complications. It can occur relatively quickly after cataract surgery or months later.

The natural lens inside the eye is surrounded by a clear, membrane-like capsule. The front portion of this capsule is removed during cataract surgery to gain access to the cloudy natural lens and remove it. The posterior portion of the lens capsule is left intact to prevent loss of the gel-like fluid behind it, which would increase the risk of a detached retina from cataract surgery.

Posterior capsule opacification is thought to be caused by lens epithelial cells remaining in the eye after the cloudy lens is removed during cataract surgery. These cells can migrate onto the surface of the posterior capsule, where they undergo cellular changes and form an opaque membrane that decreases vision.

PCO can be successfully treated with a non-invasive outpatient procedure called a neodymium:YAG (Nd:YAG) laser capsulotomy. The procedure uses laser energy to obliterate the opacity, restoring vision.

Researchers at Storm Eye Institute, Medical University of South Carolina (Charleston, SC) recently conducted a retrospective study of 225 eyes that underwent cataract surgery with intraocular lens (IOL) implantation to investigate whether the type of IOL used in the surgery has an effect on the rate of PCO occurrence.

The eyes in the study received one of three IOLs: AcrySof ReSTOR SN60D3 (a spherical multifocal IOL), AcrySof Natural SN60AT (a spherical monofocal IOL), or AcrySof IQ SN60WF (an aspheric monofocal IOL).

All three IOLs are manufactured and marketed by the same company (Alcon, Inc.). Each lens was implanted in 75 study eyes, and mean follow-up time after surgery was 15.9 months.

The researchers found the rate of posterior capsule opacification after surgery was:

• 42.7 percent among eyes receiving the spherical multifocal IOL (ReSTOR)
• 28.0 percent among eyes receiving the spherical monofocal IOL (Natural)
• 14.7 percent among eyes receiving the aspheric monofocal IOL (IQ)

The Nd:YAG laser capsulotomy rate for eyes receiving the IOLs was 25.3 percent, 17.3 percent and 4.0 percent, respectively.

The researchers concluded that IOL design affects the rate of posterior capsule opacification occurring after cataract surgery.

Also, based on the rates of laser capsulotomy procedures performed, PCO appears to be less visually significant in eyes receiving the AcrySof IQ aspheric monofocal IOL, compared with eyes receiving the spherical multifocal IOL (AcrySof ReSTOR) and the spherical monofocal IOL (AcrySof Natural). 

The study was supported in part by Research to Prevent Blindness and the National Institutes of Health.

Source: Comparison of the incidence and visual significance of posterior capsule opacification between multifocal spherical, monofocal spherical, and monofocal aspheric intraocular lenses. Journal of Cataract & Refractive Surgery. July 2009.

Researchers at Emory Eye Center and Emory Vision (Emory University, Atlanta) recently investigated the outcomes of cataract surgery performed with multifocal intraocular lenses (IOLs). The purpose of the study was to determine reasons for patient dissatisfaction with the procedure and the outcomes after remedial actions are taken.

The researchers reviewed the cases of 32 patients who were dissatisfied with the outcomes of their cataract surgery with multifocal IOL implantation. 

Most eyes (65 percent) had received an AcrySof ReSTOR IOL (Alcon) and the others (35 percent) received a ReZoom Multifocal IOL (Abbott Medical Optics). 

Outcomes analyzed included type of visual complaint, the remedial treatment applied to address the complaint, and the degree of improvement after intervention.

Findings of the study included:

1. Thirty patients (94 percent) reported blurred vision.
2. Fifteen patients (47 percent) reported photic phenomena (visual disturbances caused by optical aberrations; also called “negative dysphotopsia”).
3. Thirteen patients (41 percent) reported both blurred vision and photic phenomena. 

Causes of blurred vision included:

• Posterior capsule opacification, or “PCO” (22 eyes, 54 percent)
• Residual nearsightedness, farsightedness or astigmatism (12 eyes, 29 percent)
• Dry eye syndrome (6 eyes, 15 percent)

Causes of photic phenomena included:

• PCO (12 eyes, 66 percent)
• IOL decentration (2 eyes, 12 percent)
• Retained lens fragment from the removed cataractous lens (1 eye, 6 percent)
• Dry eye syndrome (1 eye, 6 percent)

Remedial treatments applied to relieve patient symptoms included artificial tears and other dry eye therapy, laser surgery for PCO and surgery for IOL exchange.

Thirty-five eyes (81 percent) had improvement with conservative treatment. Five eyes (12 percent) did not have improvement despite treatment combinations. Three eyes (7 percent) required IOL exchange.

The researchers concluded complaints of blurred vision and photic phenomena after multifocal IOL implantation can be effectively managed with appropriate treatment, though a few eyes may require IOL exchange.

The study was supported in part by Research to Prevent Blindness and the National Institutes of Health.

Source: Dissatisfaction after multifocal intraocular lens implantation. Journal of Cataract and Refractive Surgery. June 2009.