All About Cataracts

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.

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.