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V. B. Voleti, L.-S. B. Leung, R. Iranmanesh, L. V. Del Priore, G. R. Barile, W. M. Schiff, S. Chang, H. F. Fine; Comparison of Spectral Domain OCT Volumetric Analysis Before and After Intravitreal Bevacizumab Injection for Diabetic Macular Edema. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3252.
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© ARVO (1962-2015); The Authors (2016-present)
To measure response to intravitreal bevacizumab using spectral domain OCT (SD-OCT) volumetric and subfield thickness analysis in patients with diabetic macular edema (DME).
Retrospective review of patients with DME who underwent SD-OCT examination in conjunction with a complete ophthalmic exam at baseline and then again 3-5 weeks following intravitreal bevacizumab injection. Patients were excluded if they had received laser photocoagulation, injection of any pharmacologic agent, or intraocular surgery ≤ 3 months before injection. The primary outcome measures were change in macular volume, average retinal thickness, and the 9 subfield retinal thicknesses as measured by the Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA). A paired student t-test was used to compare patients before and after injection, as well as to non-diabetic controls.
Retinal thickness was significantly elevated among diabetic eyes (n = 14) prior to injection compared to control eyes (n = 18) [mean retinal volume 12.2 ± 2.4 mm3 vs. 9.5 ± 0.5 mm3 (p=0.00005), mean average retinal thickness 340 ± 65 µm vs. 265 ± 14 µm (p = 0.00004), and mean central macular thickness 480 ± 191 µm vs. 245 ± 23 µm (p = 0.00001)]. Following bevacizumab injection, there was a non-significant mean reduction in thickness for the central macular subfield (480 ± 191 to 455 ± 187, p = 0.40), the peripheral superior subfield (313 ± 49 to 299 ± 54, p = 0.19), the central superior subfield (407 ± 119 to 397 ± 99, p = 0.51), and the central temporal subfield (438 ± 129 to 426 ± 136, p = 0.40). There was also a non-significant improvement in mean visual acuity following injection (0.63 to 0.55 logMAR, p = 0.17). Change in macular volume following injection was not statistically different (pre-injection 12.2 ± 2.4 mm3 vs. post-injection 12.5 ± 2.9 mm3, p= 0.40). The mean change in average retinal thickness and the remaining subfield thicknesses were also not significant.
The study demonstrates that quantification of DME using SD-OCT yields statistically significant differences in volume and thickness parameters compared to controls. Following bevacizumab injection, there was a non-significant reduction in central macular thickness that correlated with a modest improvement in visual acuity. Overall, however, retinal volume and thickness parameters did not significantly change after a single injection of bevacizumab in patients with DME. Explanations for this observation include insufficient dosage or the involvement of non-VEGF factors in disease pathogenesis.
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