All About Cataracts

August is Cataract Awareness Month, and to mark the occasion the American Academy of Ophthalmology (AAO) recently issued the following tips to help consumers maintain healthy vision and make the right choices when cataracts develop:

When cataracts interfere with daily activities, it's time to consider surgery.

• Have an eye exam if you are over age 40. Advancing age is a risk factor for cataracts and other eye problems. Based on the findings of your exam, your eye doctor will advise you how often you should have your eyes examined in the future.

• Know the risk factors for cataracts. In addition to advancing age, risk factors for cataracts include smoking, extensive exposure to the sun’s harmful UV rays, a history of a serious eye injury or inflammation, having diabetes, prolonged used of steroid medications and a family history of cataracts.

• Know how to reduce your cataract risk. A healthy diet, exercise, maintaining control of your blood sugar if you have diabetes, avoiding smoking and protecting your eyes from the sun’s harmful rays with UV-blocking sunglasses and a wide-brimmed hat may help reduce your risk of cataracts.

• Evaluate how cataracts affect your life. If you have cataracts, the decision when to have cataract surgery should be based on your daily activities and how much interference your cataracts are causing. If you are noticing blurred vision, glare, halos, reduced color perception or other cataract-related problems when driving or performing other daily activities, it’s time to consider surgery.

The AAO offers additional information about cataracts and cataract surgery at its EyeSmart consumer website.

Though people who are highly nearsighted have a greater risk of a developing a detached retina than the general population, cataract surgery doesn’t add to that risk.

That’s the finding of a large-scale study presented at the World Ophthalmology Congress held last month in Berlin.

Irmingard Neuhann, MD, who practices at Tuebingen University Eye Hospital in Germany, reported the results of a retrospective study of 1,519 consecutive patients with high myopia that underwent modern phacoemulsification cataract surgery. The surgery was performed on a total of 2,356 eyes that had an axial length greater than 27 millimeters.

Axial length is the distance between the front surface of the eye (cornea) and the back of the eye (retina), usually measured in millimeters (mm).

A normal adult eye typically has an axial length of approximately 24 mm. Eyes with axial length greater than 24 mm usually are nearsighted, and each additional millimeter corresponds to approximately -2.50 diopter (D) of myopia. Therefore, an axial length greater than 27 mm typically corresponds to myopia of -7.50 D or more.

The incidence of retinal detachment following cataract surgery among the eyes in the study was approximately 2 percent, according to Dr. Neuhann. The patients were followed for a period of 2 years.

Though this rate is higher than the rate of detached retina among the general population, no large study has ever demonstrated that this rate is different than that of spontaneous retinal detachment in nearsighted individuals with eyes of comparable axial length, she said.

High myopia associated with increased axial length of the eye is believed to be a risk factor for retinal detachment because, as the eye elongates during development, the peripheral retina becomes thinner and more fragile in these longer-than-normal eyes.

[Resource: Cataract surgery not a risk factor for retinal detachment in highly myopic eyes, study says. Published online June 8, 2010 on Ocular Surgery News website.]

Thankfully, congenital cataracts are relatively rare. But when a baby is born with cataracts, prompt treatment is essential to insure normal infant vision development and prevent permanent vision loss from amblyopia.

Performing cataract surgery on an infant poses special challenges to cataract surgeons. Also, an often-debated question is whether the best treatment for the young, developing eyes of an infant after cataract removal is implantation of an intraocular lens (IOL) or the use of contact lenses.

To answer this question, Scott R. Lambert, MD, at Emory University (Atlanta, Ga.) and other members of the multi-center Infant Aphakia Treatment Study Group conducted a study of the two treatment options.

The researchers compared the visual outcomes and adverse events among 114 infants with congenital cataracts who underwent cataract surgery at an average age of 1.8 months. The infants were randomly assigned to either be treated with an IOL (57 infants) or with contact lenses (57 infants).

Results of the study revealed that surgical complications occurred in 28 percent of infants in the IOL group and 11 percent of those in the contact lens group.

At 1 year of age, visual acuity results were equal in the two groups, but more infants in the IOL group (77 percent) experienced adverse events after surgery, compared with 25 percent in the contact lens group.

Infants in the IOL group also were five times more likely to undergo additional eye surgery (63 percent compared with 12 percent in the contact lens group).

“There appears to be no short-term visual benefit and some increased risk to implanting intraocular lenses in infants,” the researchers concluded. But they also said it is “premature to recommend that intraocular lenses not be implanted in infants” and that a longer a follow-up period is needed to clarify the role of IOLs in the treatment of congenital cataracts.

A full report of the study will appear in the July 2010 print issue of Archives of Ophthalmology.

Modern cataract surgery may have long-term benefits for people with glaucoma and ocular hypertension, according to a new study.

Researchers in Arkansas, Washington and Utah reviewed the medical charts of 266 non-glaucoma patients who underwent phacoemulsification (or “phaco”) cataract surgery to evaluate both short-term and long-term changes in IOP after cataract removal with intraocular lens (IOL) implantation.

Elevated IOP is a risk factor for glaucoma. Lowering IOP may reduce a person’s risk of developing the disease.

All cataract extractions were performed using a technique called “temporal clear corneal phacoemulsification,” in which a small incision is created in the peripheral cornea and an ultrasonic probe is inserted through the opening. This probe breaks the cataract into small pieces so it can be removed more easily.

IOP measurements were taken with a Zeiss Humphrey IOLMaster (Carl Zeiss Meditech), a non-contact automated device, prior to surgery and 1 day, 1 week, 3 months, 6 months, 1 year and 2 years after surgery.

The researcher found that phaco cataract surgery produced both short-term and long-term reductions of IOP, compared with pre-operative measurements. Mean reduction of IOP was:

• 8.2 percent at 3 months
• 4.6 percent at 6 months
• 6.7 percent at 1 year
• 7.8 percent at 2 years

The authors of the study concluded that temporal clear corneal phacoemulsification cataract surgery results in a decrease in intraocular pressure that persists for at least two years following surgery.

SOURCE: Intraocular pressure change after temporal clear corneal phacoemulsification in normal eyes. Acta Ophthalmologica. February 2010.