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Laser, surgery still viable options for treatment of diabetic patients
Combining drugs and laser procedures in the treatment of diabetic retinopathy and diabetic macular edema could be the most effective way of controlling damage, experts said.
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Even as pharmacologic options assume an increasingly important role in the treatment paradigm for diabetic eye disease, laser remains an essential component of any treatment regimen for diabetic retinopathy and diabetic macular edema, experts say.
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If patients advance to the later stages of the disease, laser and surgical intervention are typically indicated, according to physicians. However, the introduction of drugs such as intravitreal triamcinolone acetonide and anti-vascular endothelial growth factor compounds has altered the approach to diabetic retinopathy and diabetic macular edema.
A combination of different medical therapies or medical treatments combined with laser can help avert damage caused by more invasive procedures and reduce potential side effects from medications, they said.
During a panel discussion on diabetic eye disease at the World Ophthalmology Congress in Hong Kong, diabetic retinopathy expert Dennis S.C. Lam, MD, FRCS, FRCOphth, said that there are many treatment choices available for patients, especially if fluorescein angiography and optical coherence tomography reveal no macular ischemia and no structural abnormalities at the vitreomacular interface, respectively.
 OCT diagram (OS) showing significant structural abnormality (vitreo-macular traction) that requires surgical treatment (pars plana vitrectomy (OD) ± membrane peeling). Image: Lam DSC |
“With structural things, we go for surgery, but if not, then there is a choice, and laser is only one of the choices,” Dr. Lam said. “I would say less than 20% of our patients are receiving grid laser alone. The majority will get intravitreal triamcinolone acetonide or Avastin (bevacizumab, Genentech) or a combination treatment that includes intravitreal injection plus grid laser.
 OCT diagrams showing changes in foveal thickness in a patient with significant diabetic macular edema before (OS) and after (OD) intravitreal triamcinolone injection. Image: Lam DSC |
“I am in favor of the combination treatment with grid laser performed 2 to 4 weeks after intravitreal triamcinolone or Avastin injection that could reduce the macular edema substantially. The grid laser treatment at this time would be much more effective when compared with eyes that did not have prior intravitreal injection,” he said.
 Suggested treatment algorithm for diabetic macular edema. |
Early treatment
Some physicians view laser photocoagulation – as outlined in the Early Treatment Diabetic Retinopathy Study – as the standard of first-line care in non-traction diabetic retinopathy patients. The National Eye Institute-backed clinical trial found that scatter laser treatment should be reserved for patients with early proliferative stages or severe nonproliferative stages of the disease, especially those with non-insulin-dependent diabetes mellitus.
At the panel discussion, Peter E. Liggett, MD, said he agreed with Dr. Lam and that he prefers to use a combination of medical therapies before laser.
“I’m a little leery of the laser except when it’s very focal leakage,” he said. “I think you can do a lot more damage.”
Focal leakage is an important factor to consider when choosing initial therapy. Thomas J. Wolfensberger, MD, said clinicians must determine whether the leakage is focal or diffuse and use that knowledge to select either laser or medical therapy.
“I think the problem starts when you have diffuse leakage, either straightaway for the first time or after laser treatment,” he said. “I actually do a lot of sub-Tenon injections of triamcinolone, and I’ve been quite encouraged by the latest literature in Japan and Korea and other studies.”
Dr. Wolfensberger said up to 40 mg of triamcinolone can be injected, with the amount determined by the anatomy of the sub-Tenon’s space. Dr. Lam said that he and his colleagues have been using twice that amount for a more prolonged effect and minimal side effects.
Later treatment
Donald J. D’Amico, MD, who led the panel discussion, asked the experts what approach they would choose for a patient who had laser treatment but whose condition continued to deteriorate. He said the hypothetical patient exhibited no problems on OCT or vitreous exam.
He asked if physicians would perform a second laser procedure on such a patient. The majority of speakers on the panel said they would not automatically perform a second laser procedure, but would instead try a combination of medical options first.
Dr. Liggett said he would try intravitreal triamcinolone acetonide or bevacizumab. With bevacizumab, the dosage would have to be more frequent, at an estimated rate of every 4 weeks, while triamcinolone could be administered possibly every several months, he said. With triamcinolone, results can be hampered by serious side effects including ocular hypertension and cataract formation, especially after repeated use.
Dr. Liggett said the drug still serves an important role in initial treatment of the disease.
“You’re in a situation, you’re dealing with an injury-related phenotype from elevated glucose, and that’s going to be an ongoing problem. It’s not going to go away. So you buy time, or hopefully you reduce the amount of edema, allowing for lighter laser treatment,” he said.
After several interventions with both laser and medical therapies, a vitrectomy is sometimes indicated in advanced cases, Dr. D’Amico said.
Diabetic macular edema
For patients who have diabetic macular edema, a combination of laser and medical therapies also might prove to be the most effective treatment, according to the physicians. More large-scale prospective multicenter randomized controlled clinical trials are needed to examine the results of combined therapy in treating the condition, according to Dr. Lam.
In a recent commentary submitted to Ocular Surgery News, Dr. Lam said that despite findings by the ETDRS that grid or focal laser photocoagulation treatment to the macula is most effective in treating diabetic macular edema, long-term results have shown otherwise.
A study by Lee and Olk found that only 15% of patients had visual improvements at 3 years after grid laser photocoagulation, Dr. Lam said.
He said triamcinolone showed great promise in reducing macular thickness, but its potential was diminished by results showing recurrence of macular edema. Side effects from the drug were also an issue.
Anti-VEGF compounds show promise for inhibiting the production or action of VEGF, thereby reducing the extent of vascular hyperpermeability, Dr. Lam said. But results with those compounds are also not guaranteed to be as effective as needed.
“Despite the availability of triamcinolone and anti-VEGF agents as new treatment modalities for diabetic macular edema in recent years, the final verdict for the optimal treatment for diabetic macular edema is still very much open,” Dr. Lam said. “There are preliminary evidences that combination therapy to target different pathways in the pathogenesis of diabetic macular edema with anti-VEGF, corticosteroid and macular laser photocoagulation might have the ability to set a new benchmark for treating diabetic macular edema.”
For more information:
- Donald J. D’Amico, MD, can be reached at Weill Cornell Department of Ophthalmology, 1305 York Ave., 11th Floor, New York, NY 10021; 646-962-2020; fax: 212-746-4520; e-mail: djdamico@med.cornell.edu. Dr. D’Amico has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.
- Dennis S.C. Lam, MD, FRCS, FRCOphth, can be reached at Hong Kong Eye Hospital, The Chinese University of Hong Kong, 3/F, 147K Argyle St., Kowloon, Hong Kong SAR, China; 852-2762-3157; fax: 852-2715-9490; e-mail: dennislam8@cuhk.edu.hk. Dr. Lam has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.
- Peter E. Liggett, MD, can be reached at 162 Kings Highway North, Westport, CT 06880; 203-222-7474; fax: 203-288-2470; e-mail: neretina@msn.com. Ocular Surgery News was unable to determine whether Dr. Jones has a direct financial interest in the products discussed in this article or if he is a paid consultant for any companies mentioned.
- Thomas J. Wolfensberger, MD, can be reached at Hôpital Ophtalmique Jules Gonin, University of Lausanne, 15, Av. de France, CH-1004 Lausanne, Switzerland; e-mail: thomas.wolfensberger@ophtal.vd.ch. Dr. Wolfensberger has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.
References:
- The Early Treatment Diabetic Retinopathy Study Research Group. Photocoagulation for diabetic macular edema: Early Treatment Diabetic Retinopathy Study Report No. 4. Int Ophthalmol Clin. 1987;27(4):265-272.
- Lee CM, Olk RJ. Modified grid laser photocoagulation for diffuse diabetic macular edema. Long-term visual results. Ophthalmology. 1991;98(10):1594-1602.
- Erin L. Boyle is an OSN Staff Writer who covers all aspects of ophthalmology.
- Katrina Altersitz, Managing Editor, OSN India and Latin America Editions, contributed to this report.