All About Cataracts

New research suggests it is safe to perform cataract surgery using topical anesthesia and intravenous sedation without requiring patients to fast prior to surgery.

Fasting before cataract surgery is a long-standing precautionary practice. Doing so allows the stomach to empty prior to surgery, reducing the risk of the patient aspirating contents of their stomach into their lungs when medications are given that may reduce the body’s normal protective mechanisms.

Aspiration of stomach contents during surgery can cause aspiration pneumonia, a potentially serious cataract surgery complication.

But there also are risks associated with fasting, particularly for people with diabetes.

Canadian researchers at the Department of Ophthalmology and Visual Sciences, University of British Columbia and the Department of Anesthesia, Providence Health Care (Vancouver, B.C.) performed a retrospective study of more than 5,000 cases of cataract surgery performed at Mount St. Joseph Hospital (Vancouver) between April 2007 and March 2008.

Nearly all of the cataract removal procedures (97 percent) were performed using only topical anesthesia. A small minority (3 percent) required additional anesthesia injected behind or around the eye to prevent eye movements during surgery.

Approximately 50 percent of patients received intravenous (IV) sedation for the cataract procedure, as deemed appropriate by the attending medical staff.

All patients in the study were allowed to eat and drink freely until they arrived at the hospital, approximately one hour prior to their cataract removal.

Results of the study, published in this month’s issue of Canadian Journal of Ophthalmology, indicate that there were no cases of aspiration pneumonia among the 5,125 non-fasting cataract surgery patients in the study.

The authors concluded that it is safe to perform cataract surgery under topical anesthesia and intravenous sedation without requiring patients to fast prior to surgery.

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.

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.

Aspheric intraocular lenses (IOLs) used in cataract surgery provide higher quality vision than spherical IOLs, according to a new study.

Researchers at Johann Wolfgang Goethe-University (Frankfurt, Germany) and Cullen Eye Institute, Baylor College of Medicine (Houston) performed bilateral cataract surgery on 26 patients. The patients received an aspheric IOL in one eye and a spherical IOL in the other. All lenses were produced by the same manufacturer (Alcon).

Aspheric IOLs feature a gradually changing curve from the center of the lens outward and are designed to control spherical aberration produced by spherical IOLs. Spherical aberration is one of many higher-order aberrations of the eye, and is believed to cause glare and halos around lights at night.

Six months after surgery, aberrometry and visual acuity measurements showed the eyes receiving the aspheric IOLs had significantly lower spherical aberration, better visual acuity (measured with an eye chart in medium/low lighting) and better contrast sensitivity than the eyes with spherical lens implants.

The researchers concluded that aspheric IOLs produce better retinal image quality and higher quality vision than spherical IOLs.

Note: Aspheric IOLs typically are considered premium lens implants, and choosing this type of intraocular lens may increase the your cataract surgery cost.

Source: Effect of intraocular lens asphericity on quality of vision after cataract removal: An intraindividual comparison. Ophthalmology. Published online July 29, 2009.