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Does vitrectomy still have a role in the treatment of diabetic macular edema?
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Vitrectomy may be efficacious, long-lasting treatment
Although anti-VEGFs are now the first-line treatment for DME, a significant proportion of eyes treated with anti-VEGFs are nonresponders, ranging from 35% to 60% in different series. This is not surprising because not only VEGF but multiple inflammatory pathways are at play in DME, and many cytokines are present in the vitreous. Intravitreal steroids help address the inflammatory pathways and can be a good adjunct for many eyes. Nevertheless, only 20% of eyes treated with a dexamethasone implant and 28% with a fluocinolone implant improve three or more lines of visual acuity. Not only are anti-VEGFs and steroids inconsistently efficacious for DME, but they also entail significant cost, treatment burden and potentially devastating complications such as endophthalmitis. Thus, there is no panacea for the treatment of DME.
Younger patients with diabetes can have vitreoretinal interface pathologies present, and in these eyes, vitrectomy has been shown to be beneficial. A thickened hyaloid, as well as cytokines in the vitreous, contribute to DME. Therefore, it makes sense that vitrectomy with hyaloid removal would be of benefit. DME untreated for more than 6 months causes permanent damage to photoreceptors and can limit visual acuity gains. In the past, vitrectomy has been used as a last-resort treatment after everything else had failed, so it is not surprising that visual acuity results may be limited. Nevertheless, published series of vitrectomy for DME show long-lasting improvement in visual acuity of two lines or more in 38% to 52% of eyes. These visual acuity gains are not only comparable to anti-VEGF treatment, but are long lasting and do not involve a treatment burden of monthly visits and injections, its costs and potential complications. The yearly cost of anti-VEGF treatment can be more than $20,000, whereas the cost of vitrectomy can be under $10,000. A prospective 3- to 5-year study of vitrectomy for DME as first-line treatment is necessary to assess the potential benefit of this more permanent treatment modality.
- References:
- Blinder KJ, et al. Clin Ophthalmol. 2017;doi:10.2147/OPTH.S128509.
- Boyer DS, et al. Ophthalmology. 2014;doi:10.1016/j.ophtha.2014.04.024.
- Brown DM, et al. Ophthalmology. 2013;doi:10.1016/j.ophtha.2013.02.034.
- Browning DJ, et al. Clin Ophthalmol. 2016;doi:10.2147/OPTH.S104906.
- Campochiaro PA, et al. Ophthalmology. 2012;doi:10.1016/j.ophtha.2012.04.030.
- Kumagai K, et al. Retina. 2015;doi:10.1097/IAE.0000000000000497.
- Wells JA, et al. Ophthalmology. 2016;doi:10.1016/j.ophtha.2016.02.022.
Maria H. Berrocal, MD, is from Berrocal and Associates, San Juan, Puerto Rico. Disclosure: Berrocal reports she is a consultant for Alcon.
With current therapies, vitrectomy rarely needed
Surgical intervention to treat DME is rarely necessary. We now have a plethora of intravitreal pharmacologic therapies, which include bevacizumab, ranibizumab, aflibercept, triamcinolone acetonide, dexamethasone implant and fluocinolone implant. These therapies either alone or in combination effectively treat DME in most patients. In my practice, first-line therapy for center-involving DME typically consists of intravitreal anti-VEGF therapy. In the DRCR.net Protocol T study, we learned about the comparative efficacy of bevacizumab, ranibizumab and aflibercept. At 2 years, all three agents had similar yet significant visual gains in patients who started with vision better than 20/50. In patients with 20/50 vision or worse, all three agents also yielded significant visual gains, but aflibercept resulted in a greater visual gain than bevacizumab. The visual gains between aflibercept and ranibizumab were not statistically different.
If patients either fail to respond or suboptimally respond to anti-VEGF therapy, my second-line treatment consists of either an intravitreal steroid or focal retinal laser. I usually use laser as combination therapy along with anti-VEGF, while steroids are more often replacement therapy but in some instances can be combined with ant-VEGF agents. If there are discrete, causative microaneurysms, or the risk of cataractogenesis or elevated IOP is sufficiently high, I prefer focal laser. When the edema is more diffuse, I treat with steroids.
It is extremely rare for me to recommend pars plana vitrectomy (PPV) for DME. Instances in which I might consider PPV include vitreomacular traction (VMT) or macular pucker, in which the traction or puckering is directly inhibiting macular edema resolution. Before PPV, I usually first treat with intravitreal therapies because in many cases the DME component will improve despite the VMT or macular puckering. Some downsides of surgical intervention include the risk of iatrogenic breaks, especially in cases of VMT, and the altered half-life of future intravitreal therapies. That is, when intravitreal anti-VEGF agents or triamcinolone are administered post-vitrectomy, they often have a shorter duration of action as compared with pre-PPV, although this seems to be less of a phenomenon with the dexamethasone and fluocinolone implants.
- References:
- Blinder KJ, et al. Clin Ophthalmol. 2017;doi:10.2147/OPTH.S128509.
- Boyer DS, et al. Ophthalmology. 2014;doi:10.1016/j.ophtha.2014.04.024.
- Brown DM, et al. Ophthalmology. 2013;doi:10.1016/j.ophtha.2013.02.034.
- Browning DJ, et al. Clin Ophthalmol. 2016;doi:10.2147/OPTH.S104906.
- Campochiaro PA, et al. Ophthalmology. 2012;doi:10.1016/j.ophtha.2012.04.030.
- Kumagai K, et al. Retina. 2015;doi:10.1097/IAE.0000000000000497.
- Wells JA, et al. Ophthalmology. 2016;doi:10.1016/j.ophtha.2016.02.022.
Marc J. Spirn, MD, is from Wills Eye Hospital, Philadelphia. Disclosure: Spirn reports no relevant financial disclosures.