All About Cataracts

Cataract surgery does not cause a progression of early age-related macular degeneration (AMD) to a more sight-threatening stage of the disease, according to a new study.

Researchers in Australia performed cataract surgery on 27 eyes of 27 patients with early macular degeneration to see if removal of their cataracts would improve the patients’ vision and quality of life without increasing their risk of AMD progression and vision loss from choroidal neovascularization (CNV).

CNV is the growth of fragile new blood vessels in the choroid layer of the eye underlying the retina. In macular degeneration, these blood vessels can leak into the retina, causing “wet” macular degeneration and severe vision loss.

Prior to the phacoemulsification cataract surgery performed in the study, all patients underwent a test called fundus fluorescein angiography (FFA) to make sure no eyes had pre-existing CNV.

Data gathered 6 months after surgery revealed a 2.8-line mean improvement in visual acuity (measured with a standard eye chart) and a 2.1-fold average gain in quality of life scores (measured by a patient survey) after cataract removal. One eye (3.7 percent) developed CNV within 6 months of surgery.

The researchers concluded that there was no significant increase in short-term risk of progression from dry AMD to CNV following uncomplicated phacoemulsification cataract surgery, and that there are distinct benefits of cataract surgery in people with early macular degeneration.

Source: Cataract surgery in high-risk age-related macular degeneration: A randomized controlled trial. Clinical & Experimental Ophthalmology. Published online June 22, 2009.

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.