All About Cataracts

If you have had cataract surgery, should you worry about your intraocular lenses eventually dislocating?

To answer this question, researchers at the Mayo Clinic checked the records of all residents of Olmsted County, Minn., who had undergone cataract extraction from Jan. 1, 1980 through May 31, 2009. In the 14,471 cataract cases studied, 16 cases of late posterior chamber IOL dislocation were identified.

The researchers calculated that at five, 10, 15, 20, and 25 years after cataract surgery, the cumulative risk of IOL dislocation was low, at 0.1%, 0.1%, 0.2%, 0.7%, and 1.7%, respectively. And the risk did not change much over the three-decade study period.

They also found that pseudoexfoliation and zonular laxity at surgery were significantly correlated with late IOL dislocation. (Pseudoexfoliation involves fluffy material appearing on the lens capsule; it can weaken the zonules, which are fibers that hold in place the chamber containing the cataract and later the intraocular lens. This weakness is called zonular laxity.)

The study report was published online in the American Journal of Ophthalmology on June 17.

Taking a daily aspirin and/or prescription medicine to prevent blood clotting does not appear to cause a significant risk of bleeding during and after cataract surgery.

That’s the finding of a new study in Japan that assessed the risk for bleeding during and after phacoemulsification cataract removal among patients taking anti-platelet and/or anti-coagulant medicines (blood thinners) to reduce the risk of heart attack and stroke.

In the study, a total of 355 patients taking aspirin, the prescription anti-clotting drug warfarin (brand name: Coumadin) or both underwent modern phacoemulsification cataract surgery.

Patients were randomly assigned to two groups: 182 patients discontinued their anti-clotting medicine at least one week prior to cataract surgery (discontinuation group) and 173 patients continued taking aspirin and/or warfarin up to the day of their cataract surgery (maintenance group).

All patients were followed for a period of one month after surgery to monitor visual outcomes and any cataract surgery complications.

Results of the study included:

• No eyes in either group had significant bleeding during cataract surgery.

• Minor post-surgical bleeding occurred in seven eyes (2.5 percent) in the discontinuation group and in 11 eyes (4.0 percent) in the maintenance group.

• A total of 31 eyes (10.8 percent) in the discontinuation group and 47 eyes (16.5 percent) in the maintenance group experienced a subconjunctival hemorrhage after cataract surgery.

• Vision improvement following surgery was comparable in the two groups.

The researchers concluded that though patients taking blood thinners up to the time of cataract surgery were more likely to experience a subconjunctival hemorrhage following surgery than those who discontinued their medications one week prior to surgery, there was no significant difference between the two groups in the incidence of cataract surgery complications or in visual outcomes following surgery.

A full report of the study appears in the July 2010 issue of Journal of Cataract & Refractive Surgery.

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.]

People who have cataract surgery before age 65 appear to have a greater risk of clouding of the eye tissue directly behind the intraocular lens (IOL) that can lead to vision loss, according to a Swedish study.

The good news is that vision loss from this cataract surgery complication — called a posterior capsule opacity (PCO) — usually can be restored with a simple laser procedure called a ND:YAG laser capsulotomy.

Researchers at Norrlands University Hospital in Umea, Sweden, compared the vision of 116 patients who had cataract surgery prior to age 65 with the post-operative vision of patients age 65 and older at the time of surgery. Ten years after cataract surgery, 102 of the 116 people in the study group were given an eye exam and were asked to complete a questionnaire about their vision.

Analysis of the data revealed that within 10 years of cataract surgery, 37 percent of those younger than age 65 at the time of surgery experienced PCO and underwent a ND:YAG laser capsulotomy to restore their vision. In comparison, only 20 percent of those who were 65 or older at the time of cataract surgery required the laser procedure afterward.

The researchers concluded that more than one-third of patients in this study who were under age 65 at the time of cataract surgery subsequently developed a posterior capsule opacity that required a laser capsulotomy to restore vision.

Secondarily, the researchers said that 10 years after surgery, subjective visual function (measured with a questionnaire) and objective visual acuity (measured with an eye chart) remained stable in most patients who had cataract surgery when they are younger than age 65.

SOURCE: Ten-year longitudinal vision function and ND:YAG laser capsulotomy rates in patients less than 65 years at cataract surgery. American Journal of Ophthalmology. Published online November 18, 2009.