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Injection frequency varies in treatment of vitreomacular interface disease
Improved BCVA and decreased central foveal thickness were shown, despite continued inner retinal traction.
Intravitreal anti-VEGF injections resulted in significant improvement in best corrected visual acuity and decreased central foveal thickness in patients with exudative age-related macular degeneration with and without vitreomacular interface disease, according to a study. However, eyes with vitreomacular interface disease required an average 14.7 injections during the 4-year study period compared with 9.5 injections in patients without inner retinal traction.
Co-author Sophie J. Bakri, MD, a professor of ophthalmology and director of the vitreoretinal surgery fellowship program at the Mayo Clinic, said that some of her patients with wet AMD have persistent fluid on optical coherence topography despite having frequent injections, and some patients require more injections than others.
When considering the factors that might cause these differences in response to treatment, Bakri noticed the presence of vitreomacular traction in certain patients.
“These patients appeared to need more injections, but visual acuity seemed to be good in many of them,” she said.
Bakri and colleagues evaluated the effect of vitreomacular traction on visual acuity and retinal thickness in those patients receiving anti-VEGF injections.
Sophie J. Bakri, MD, and colleagues investigated the relationship between traction on the macula, fluid beneath the retina and response to anti-VEGF injections.
“[Vitreomacular interface disease] causes traction on the macula, which may contribute to fluid under the retina and, in theory, make response to anti-VEGF injections less likely,” Bakri told Ocular Surgery News. “We wanted to test this hypothesis.”
Retrospective review
The study, which appeared in Retina, retrospectively reviewed the charts of consecutive patients treated for exudative AMD with anti-VEGF injection at the Mayo Clinic between January 2005 and December 2009. Inclusion criteria included being older than 50 years at the time of initial visit, a diagnosis of AMD, the availability of OCT results and data from at least 1 year of follow-up.
The study enrolled 32 eyes with vitreomacular interface disease and 146 eyes without traction.
Mean BCVA was statistically similar for both groups at baseline (20/94 in eyes with traction and 20/80 without traction) and at year 1 through year 4 (20/59 and 20/55, respectively).
Central foveal thickness was also statistically similar for both groups at baseline OCT examination — 364 µm in eyes with traction and 281 µm in eyes without inner retinal traction — and at years 1, 2 and 3: 262 µm, 204 µm and 179 µm, respectively, for eyes with traction, and 227 µm, 200 µm and 285 µm, respectively, for eyes without traction.
“Both the visual acuity and OCT results surprised me,” Bakri said. “I would have thought that patients with traction would have lower levels of vision at baseline and at follow-up. Perhaps we saw similar levels of vision because the relative contribution of visual decline due to traction is minimal compared with the visual morbidity of choroidal neovascularization.”
Eyes with vitreomacular interface disease required an average of five more anti-VEGF injections, according to Bakri.
“We know that inner retinal traction can cause fluid on OCT, as can choroidal neovascularization,” she said. “Patients were treated in an OCT-guided regimen, so it is likely they needed more injections due to the presence of fluid from traction.”
Follow-up
Bakri said clinicians should carefully consider the role of fluorescein angiography in the follow-up of these patients as a way to give useful information on the activity of the choroidal neovascular membrane. But, there is still much to learn.
“We need to find out if releasing the traction pharmacologically results in the requirement for fewer injections,” Bakri said. “Releasing the traction surgically via vitrectomy exposes the eye to the unique pharmacokinetics of a vitrectomized eye, with faster clearance of drug, which may result in the need for more injections.”
By releasing the traction pharmacologically, one might surmise the need for fewer injections.
“But on the other hand, the eye now has a vitreous detachment, with different pharmacokinetics yet again,” Bakri said. “This should be studied carefully as part of a clinical trial with PRN injection regimen.”
In addition, with the advent of drugs to treat vitreomacular interface disease, further studies might focus on whether or not treating the disease in this population affects outcomes. – by Bob Kronemyer
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Perspective
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Anterior-posterior and/or tangential macular traction that would normally be considered subclinical might significantly hinder successful anti-VEGF treatment of exudative age-related macular degeneration.
Previous studies have reported both the high rate of persistent vitreous attachment in AMD, particularly in exudative AMD, and the occurrence of choroidal neovascularization precisely at points of OCT-proven vitreomacular traction. Despite acknowledged limitations of being retrospective and employing old OCT technology, this study adds another brick in the wall, building a case for the need to consider even macular traction that would normally be regarded as subclinical when initiating treatment of exudative AMD, and throughout its treatment.
In a disease that desperately cries out for any small treatment advance, traction release by small-gauge (eg, 27-gauge) vitrectomy with or without internal limiting membrane removal, pharmaceutical vitreolysis or even injection of a small gas bubble is a reasonable consideration for certain cases, pending completion of clinical trials that will be many years in the making. Traction (release) is one more controllable variable to be considered in a disease process that currently offers too few.