All About Cataracts

Subjects undergoing cataract surgery with implantation of the AcrySof Natural IOL (Alcon Laboratories, Inc., Fort Worth, Tex.) achieved better contrast sensitivity under conditions of veiling glare than subjects receiving a clear IOL, according to a new study.

Researchers at the University of Georgia (Athens, GA) assessed the vision of a total of 58 subjects: 17 with yellow AcrySof Natural IOLs implanted after cataract surgery, 20 with clear IOLs implanted after cataract surgery and 21 control subjects who did not have cataracts.

The yellow-colored AcrySof Natural IOL filters ultraviolet (UV) and high-energy visible light (also called “blue light”), which has been associated with glare.

Two tests were performed:

1. Visual acuity under veiling glare conditions. Subjects watched a contrast sensitivity (CS) target while a circular xenon lamp was directed toward their eyes and the intensity of the light was adjusted until the target was no longer visible.
2. Photostress recovery. The time required to detect a CS target after a 5-second exposure to an intense circular disk of broad-band xenon light.

In the test of visual acuity under veiling glare, eyes with the AcrySof Natural IOL could withstand significantly more light than eyes with a clear intraocular lens and eyes with a natural lens (no cataracts).

In the photostress test, visual recovery was faster in eyes with natural lenses (no cataracts) than eyes with either type of IOL. Photostress recovery times in eyes with the two types of IOLs were similar.

The researchers concluded the blue-filtering AcrySof Natural IOL is associated with reduced glare disability compared with clear IOLs and control eyes without cataracts.

The AcrySof Natural IOL may be considered a premium intraocular lens and may increase your cataract surgery cost if you choose this lens implant.

The full report of the comparison test (”The effect of the AcrySof Natural lens on glare disability and photostress”) is published in the August 2009 issue of the American Journal of Ophthalmology.

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.

Bausch & Lomb (Rochester, N.Y.) recently announced the U.S. launch of its new Akreos MICS lens, a foldable intraocular lens (IOL) designed for implantation through a 1.8 mm incision during phacoemulsification cataract surgery.

The ability to insert the new acrylic lens through such a small incision offers several potential advantages, including faster healing and less surgically-induced astigmatism, according to the company.

The lens also features aspheric optics designed to reduce spherical aberration and produce excellent post-operative vision. (Spherical aberration is a common higher-order aberration that can degrade vision and cause glare and halos around lights.)

The new Akreos IOL represents a new level of micro-incision cataract surgery (MICS). With most other IOLs used in MICS, an incision of 2.2 mm to 2.75 mm is required.

Prior to phacoemulsification technology, incision sizes of 10 mm or greater were common in cataract surgery, with greater risks of eye infection, delayed healing and other cataract surgery complications.

Because the Akreos MICS lens is a premium IOL, it may increase your cataract surgery cost if you choose this implantable lens for your surgery.

The Akreos MICS is the latest addition to Bausch & Lomb’s Akreos line of IOLs. First introduced in Europe over 10 years ago, more than 3 million Akreos IOLs have been implanted worldwide, according to the company.

People with diabetes who undergo cataract surgery have twice the risk of progression of their diabetic retinopathy, according to a new study.

Researchers at the University of Sydney (New South Wales, Australia) and the University of Melbourne (Victoria, Australia) followed 190 diabetic patients age 65 and older who underwent phacoemulsification cataract surgery between 2004 and 2006. Of the 190 patients, 169 were followed for at least 12 months after surgery.

During the 12-month follow-up period, diabetic retinopathy (DR) developed in 28.2 percent of eyes that underwent cataract surgery with intraocular lens (IOL) implantation and did not have DR prior to surgery. During the same 12-month period, diabetic retinopathy developed in 13.8 percent of eyes that did not undergo cataract surgery and did not have DR at the beginning of the study period.

In a paired-eye comparison of 45 patients with pre-existing diabetic retinopathy who had cataract surgery in one eye but not the other and were at risk of DR progression, 35.6 percent of the post-surgical eyes exhibited progression of diabetic retinopathy, compared with 20 percent of the fellow eyes that did not undergo surgery.

The researchers concluded that people with diabetes who undergo modern phacoemulsification cataract surgery appear to have twice the risk of developing diabetic retinopathy or experiencing a progression of their DR  12 months after surgery.

This added risk, however, is lower that the risk of diabetes-related cataract surgery complications that has been previously documented in diabetic patients who have undergone less advanced cataract surgery (”intracapsular” and “extracapsular” cataract surgery without phacoemulsification).

Source: Development and progression of diabetic retinopathy 12 months after phacoemulsification cataract surgery. Ophthalmology. August 2009.