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Mohammad Dahrouj, Jan A Kylstra, Bethany Wolf, Zsolt Ablonczy, Craig E Crosson; Association between IOP and retinal thickness following intravitreal triamcinolone injections in DME patients. Invest. Ophthalmol. Vis. Sci. 2017;58(8):243.
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© ARVO (1962-2015); The Authors (2016-present)
Intravitreal triamcinolone (IVT) can be effective in treating macular edema due to a variety of etiologies including diabetic retinopathy, retinal vein occlusion and recent intraocular surgery. Its mechanism of action is attributed to a decrease in the permeability of macular capillaries through anti-inflammatory and anti-VEGF effects. It is well known, however, that IVT is frequently associated with intraocular pressure (IOP) elevation and, according to Starling's law, elevation of IOP should decrease tissue edema. The goal of this study was to determine the association between IOP and retinal thickness (RT) following treatment with IVT in patients with DME.
Linear mixed regression models were utilized to analyze publicly available data from a randomized controlled clinical trial -DRCR network Protocol I- in which 180 subjects were treated every four months with 4 mg of IVT plus focal photocoagulation. Patients were grouped into quartiles based on mean IOP (IOP) or mean change in IOP from baseline (ΔIOP). The median RT and mean change in RT from baseline of the lowest quartile were compared to that of the highest quartile.
At 8 weeks, subjects whose IOP was in the lowest quartile (IOP<15mmHg) had a 13.6% higher median RT compared to subjects whose IOP remained in highest quartile (IOP>20 mmHg) (p=0.052). Subjects whose ΔIOP was in the lowest quartile (ΔIOP <0) had a 17.2% higher median RT compared to patients whose mean ΔIOP was in the highest quartile (ΔIOP >5mmHg) (p=0.008). At 52 weeks, subjects whose IOP was in the lowest quartile had a 17.5% higher median RT compared to patient whose IOP values were highest quartile (p=0.030). Subjects whose ΔIOP was in the lowest quartile had a 19.7% higher median retinal thickness compared to patients whose ΔIOP values were in the highest quartile (p=0.007).At 8 weeks, the mean decrease in retinal thickness for the lowest quartile of ΔIOP was 88.00 microns and 143.3 microns for the highest quartile (p>0.05). At 52 weeks, the mean decrease in RT for the lowest quartile of ΔIOP was 95.41 microns and 175.7 microns for the highest quartile (p = 0.024).
Increasing IOP following IVT was associated with larger decrease in retinal thickness in DME patients. These data support the idea that steroid induced elevation in IOP contributes to the efficacy of IVT in treating DME.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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