March 2008

 

OPHTHALMOLOGY NEWS

 

Risk for diabetic maculopathy


by Matt Young EyeWorld Contributing Editor

 

 

Macular thickening occurs after cataract surgery in diabetic eyes but often resolves

MICS as performed with the Infiniti system; cataract surgery may not always exacerbate diabetic maculopathy Source: Jorge L. Alio, M.D.

Research has shown that cataract surgery can exacerbate diabetic maculopathy, but a new study suggests there may be less risk of that than some believe. The study, recently published online in Eye, found that even though macular thickening does occur in most diabetic eyes after cataract surgery, it often resolves spontaneously.

“The change in macular edema in some diabetic patients is transient,” wrote lead study author Ken Hayashi, M.D., Hayashi Eye Hospital, Fukuoka, Japan. The study confirms previous reports that there appear to be two kinds of worsening of macular edema after surgery: transient pseudophakic edema that spontaneously resolves, and actual diabetic maculopathy progression. Most importantly, Dr. Hayashi’s study could help cataract surgeons better weigh the risks of operating on diabetic patients. “Because it is important to be able to predict long-term visual effects before cataract surgery is performed, surgeons need to have a better understanding of the natural course of diabetic macular edema in addition to diabetic retinopathy (DR) after cataract surgery,” Dr. Hayashi noted.

A study of progression

Dr. Hayashi analyzed 34 eyes with DR and 34 eyes without DR that underwent cataract surgery. Before surgery, no significant differences existed in foveal thickness and macular volume. But by three months post-op, foveal thickness increased 20.3% in the DR group and 6.0% in the non-DR group. In both groups, the thickness then gradually decreased. The grade of macular edema worsened in 8 eyes (23.5%) in eyes with DR, and just one (2.9%) in the no DR group. “It is thought that pseudophakic cystoid macular edema is caused by cytokines including prostaglandin or vascular endothelial growth factor, which are released from blood–ocular barrier after cataract extraction,” Dr. Hayashi reported. “Breakdown of the blood–ocular barrier in diabetic eyes, particularly in eyes with DR, is known to be greater than that in nondiabetic eyes. Indeed, the mean intensity of flare in the DR group was significantly greater than that in the no DR group throughout the follow-up.”

Furthermore, of the nine eyes that worsened, three (33.3%) resolved spontaneously. “These results suggest that the change in macular edema in some diabetic patients is transient, while in other diabetics, the macular edema is substantial, with marked progression of maculopathy,” Dr. Hayashi wrote. “Macular edema that occurs after cataract surgery resolves spontaneously in some patients for up to a year.”

It is particularly important to try to distinguish short-lived edema from maculopathy progression in order to determine treatment options, such as laser photocoagulation, vitrectomy, and triamcinolone injection, Dr. Hayashi noted. One way to predict macular edema progression is to look at hemoglobin A1C levels, the researchers found (which is in contrast to other studies). “The hemoglobin A1C level at the time of surgery in eyes with DR was significantly greater than that in eyes without DR, and was correlated significantly with the foveal thickness,” Dr. Hayashi reported. “Although previous studies did not find a significant correlation between hemoglobin A1C and progression of macular edema, our quantitative study suggests that the percentage of hemoglobin A1C present at the time of surgery may be a significant predictor for progression of macular edema.”

Overall, mean visual acuity improved in eyes both with and without DR. Both transient oedema and diabetic maculopathy progression occurred more frequently in the DR group. “Only two eyes ultimately lost more than two decimal lines of vision because of marked progression of maculopathy,” Dr. Hayashi wrote. “This indicates that worsening of the macular oedema after small incision cataract surgery decreases visual acuity only in some cases.”

Still, clinical experience suggests cataract surgery can impact diabetic retinopathy too frequently for comfort, said Mark Packer, M.D., clinical associate professor, Casey Eye Institute, Oregon Health & Science University, Portland. “There’s no doubt in my experience that cataract surgery can exacerbate diabetic retinopathy,” Dr. Packer said. “It’s probably due to inflammatory mediators of cataract surgery, in the same way cystoid macular edema occurs.”

Patients who already have diabetic retinopathy should have fluorescein angiography and optical coherence tomography examinations of the posterior pole and should be treated by a retinal specialist if there is any concerning findings, he said. In other words, they should be treated prophylactically. “Otherwise, it can be disappointing for patients to have an uncomplicated course of cataract surgery but no improvement in vision, or improvement of vision is delayed,” Dr. Packer said. These patients may also prompt an intravitreal or trans-zonular infusion of Avastin (bevacizumab, Genentech, San Francisco) at the time of cataract surgery, Dr. Packer said. “It reduces vascular permeability,” Dr. Packer said. “I know surgeons who are doing that, and it stands to reason it would be helpful. This needs to be addressed further.”

Editors’ note: Dr. Hayashi has no financial interests related to this study. Dr. Packer has no financial interests related to his comments.

Contact Information

Hayashi: +81-92-431-1680, hayashi-ken@hayashi.or.jp

Packer: 541-687-2110, mpacker@finemd.com

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