All About Cataracts

Results of a new study show that implantation of a light-filtering intraocular lens (IOL) during cataract surgery increases the amount of important nutrients in the eye and may reduce the risk of age-related macular degeneration.

The special IOL blocks high energy visible light (also called HEV light or blue light) that has been associated with damage to the retina. This damage occurs in the most sensitive part of the retina called the macula, which is responsible for central vision and color vision.

Prolonged exposure to blue light depletes macular pigments that protect important visual cells in the retina called photoreceptors. The blue light-filtering IOL helps preserve or increase these pigments, thereby reducing the risk of macular degeneration, according to the researchers.

Macular pigments include lutein and zeaxanthin.

In the study, 42 patients scheduled for cataract surgery were randomly assigned to have either the blue light-filtering acrylic IOL or a standard acrylic IOL implanted during their procedure.

Macular pigment optical density and blood serum levels of lutein and zeaxanthin were measured prior to surgery and at one week and three, six and 12 months after surgery.

The researchers found that there was an increase in protective macular pigments over time (as measured by optical density) in eyes with the light-filtering IOL implant, but no such increase in eyes with the standard IOL.

They concluded that this suggests the light-filtering IOL may reduce the risk of macular degeneration after cataract surgery, but they cautioned that further and long-term study is needed to determine if this is true.

Macular pigments are obtained entirely from the diet and are transported to the retina through the blood. Because of growing evidence that macular pigments play a role in reducing the risk or progression of macular degeneration, many commercially-available eye vitamins contain lutein and zeaxanthin.

A full report of the study appears in the October issue of Investigative Ophthalmology & Visual Science, the journal of The Association for Research in Vision and Ophthalmology (ARVO).

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.