All About Cataracts

Crystalens HD, an accommodating intraocular lens (IOL), is producing excellent visual outcomes and a high degree of independence from eyeglasses after cataract surgery, according to three European eye surgeons.

The surgeons presented their findings at the 2010 winter meeting of the European Society of Cataract and Refractive Surgeons, held in Budapest, Hungary, February 12-14.

Mark Tomalla, MD, of Duisburg, Germany, said he has implanted the Crystalens HD accommodating IOL in a series of 48 patients. At the time of his presentation, 17 of these patients had been been evaluated at a 6-month follow-up visit.

Six months after surgery:

• All patients could see clearly in the distance and at arm’s length without glasses.
• 71 percent reported they did not need reading glasses.
• The remaining 29 percent said they needed reading glasses only occasionally.

Angel Lopez-Castro, MD, reported similar results in his surgical implantation of the Crystalens HD after cataract removal in the eyes of 42 patients in Madrid, Spain. He said 80 percent of these patients achieved uncorrected reading vision of 20/25 or better, and all patients had distance vision of 20/20 or better without glasses.

Kristien Vanhoucke, MD, of Mol, Belgium, reported that 6 months after implanting the Crystalens HD in 26 eyes, 90 percent of these patients reported good vision at all distances and freedom from glasses after cataract surgery.

Crystalens HD is the fourth-generation accommodating IOL produced by Bausch & Lomb (Rochester, NY). The company received approval from the U.S. Food and Drug Administration (FDA) in June 2008 to market Crystalens HD in the United States.

In January 2010, Bausch & Lomb announced the introduction of Crystalens AO, its latest accommodating IOL that is designed to reduce higher-order aberrations for even sharper vision after cataract removal.

All Crystalens accommodating IOLs are premium intraocular lenses and therefore increase cataract surgery cost. Ask your cataract surgeon for details.

SOURCE: Multiple European clinics report promising accommodating IOL visual outcomes. Ocular Surgery News. Published online February 15, 2010.

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).

Certain age-related cataracts may be due to problems with a specific gene, according to researchers at Case Western Reserve University School of Medicine (Cleveland, Ohio).

A gene called EPHA2 appears to be involved in maintaining the health and normal structure of proteins in the lens of the human eye. When this gene is absent or damaged, lens proteins begin to clump together and form lens opacities, or cataracts, say investigators Bing-Cheng Wang, PhD, and Sudha K. Iyengar, PhD.

Drs. Wang and Iyengar are collaborating in research with several other investigators in laboratories across the U.S. and in Australia and the U.K.

So far, the researchers have identified several mutations of the human EPHA2 gene that appear to be associated with age-related cataracts, and they continue to look for more.

By better understanding the processes by which the EphA2 gene helps maintain clarity of the human lens, they researchers may be able to find ways to prevent cataracts and possibly reverse them, perhaps reducing the need for cataract surgery.

The researchers also say other studies suggest common genes and pathways may be involved in both age-related cataracts and neurodegenerative diseases (e.g. Alzheimer’s disease) that affect the elderly.

Their report, “EPHA2 is associated with age-related cortical cataract in mice and humans,” appears in the July 2009 issue of PLoS Genetics.

Carnosine, a dietary supplement available without a prescription, may be able to prevent or treat cataracts, according to a study published in the July 14 issue of the American Chemical Society journal Biochemistry.

If true, taking daily supplements of carnosine may reduce the risk of developing cataracts, decreasing the need for cataract surgery.

Carnosine is a small molecule composed of two amino acids. It is found in relatively high concentrations in several body tissues, including muscles, nerves and the brain. The exact role of carnosine in the body is not fully understood but it appears to have an antioxidant effect.

The researchers exposed tissue cultures of lenses taken from healthy rat eyes to either guanidine — a substance known to form cataracts — or a combination of guanidine and carnosine. The lens tissue exposed to guanidine became completely cloudy, while the lens tissue exposed to guanidine and carnosine developed 50 to 60 percent less cloudiness. Carnosine also restored clarity to clouded lens tissue.

Cataracts occur when the primary structural protein in the eye’s lens, alpha-crystallin, forms abnormal clumps. These clumps make the lens cloudy and impair vision. Carnosine appears to play a role in blocking the formation of these clumps and/or reversing them.

Though further research is needed, the findings of the study prompted the researchers to suggest that carnosine could potentially prevent and treat cataracts in humans.

Source: Protective effects of l- and d-carnosine on a-crystallin amyloid fbril formation: Implications for cataract disease. Biochemistry. Published online July 14, 2009.