During Friday’s Retina Subspecialty Day, Gaurav K. Shah, MD, answered key questions for surgeons considering vitrectomy in patients with diabetic macular edema (DME). Dr. Shah began with a look at the current literature.
Past findings. A review of previous findings shows that vitrectomy is effective at reducing retinal thickness in DME. However, vision fails to improve in many of these patients. According to Dr. Shah, the reason may be that only recalcitrant DME cases—such as those with permanent outer retinal damage—that have failed other therapies are undergoing vitrectomy. In many of these studies, investigators did not employ optical coherence tomography (OCT) when evaluating their DME patients.
Can OCT markers help? Are there OCT markers for predicting which patients will have the best outcomes? Yes, according to Dr. Shah, who explained that the integrity of the external limiting membrane and the inner segment/outer segment, disorganization of the retinal inner layers, size of the foveal avascular zone, and the presence of hyperreflective foci are all significant prognostic indicators.
In addition, parallelism—the measure of how straight and parallel the retinal layers are—is a quantifiable measure of retinal layer integrity and can be used to forecast which patients can benefit from surgery.
To peel or not to peel? A pars plana vitrectomy (PPV) can be performed with or without peeling of the internal limiting membrane (ILM). However, there is prospective evidence to suggest that ILM removal during PPV with posterior vitreous detachment (PVD) induction is more effective for stabilizing vision and improving cystoid macular edema than PPV and PVD alone.
In summary, Dr. Shah urged clinicians to have a realistic definition for recalcitrant DME and to set appropriate expectations with their patients. Preoperative OCT measurements can be useful in identifying those who can benefit from surgery. When performed before unfavorable OCT findings appear, said Dr. Shah, vitrectomy can be an appropriate and safe treatment option for patients with DME.—Keng Jin Lee
Financial disclosures. Allergan: S,C; Bausch+Lomb: L; Johnson & Johnson: L; QLT Phototherapeutics, Inc: C,L; Regeneron Pharmaceuticals, Inc.: C,L.
Disclosure key. C = Consultant/Advisor; E = Employee; L = Speakers bureau; O = Equity owner; P = Patents/Royalty; S = Grant support.
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