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K. Ishikawa, H. Nishihara, S. Ozawa, C.-H. Piao, Y. Ito, M. Kondo, H. Terasaki; Focal Macular Electroretinograms After Photodynamic Therapy Combined With Intravitreal Bevacizumab. Invest. Ophthalmol. Vis. Sci. 2009;50(13):235.
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Retinal function is commonly depressed transiently after photodynamic therapy (PDT). A study from our laboratory using focal macular electroretinograms (FMERGs) found that the transient reduction in the amplitude of the FMERGs after PDT may be related to a dysfunction of the outer retina due to a reduction of choroidal circulation caused by the PDT. Additional treatment may prevent this transient impairment of retinal function. The purpose of this study was to determine the changes in the FMERGs following PDT combined with intravitreal bevacizumab for choroidal neovascularization (CNV) associated with age-related macular degeneration.
Thirty-eight eyes that were successfully treated by PDT with intravitreal bevacizumab were studied. FMERGs, optical coherence tomography, and indocyanine green angiography (ICGA) were performed before and after the PDT. The intensity of the diffuse fluorescence within the region of the PDT spot and the normal retina peripheral to the disc were measured by densitometry (Topcon IMAGEnet computer system) of the indocyanine green angiograms obtained at 10 minutes 3 months after the PDT. The ratio of averaged brightness of the retina within the PDT area to that of the retina peripheral to the disc (irradiated/normal retina, brightness ratio=I/N brightness ratio) was calculated for each angiogram.
The mean amplitudes of the a-wave before and one week after PDT were 0.76 ± 0.05 µV, and 0.67 ± 0.05 µV (mean ± SEM, P>0.05), respectively. The mean amplitudes of the b-wave before and one week after PDT were 1.99 ± 0.12 µV, and 1.87 ± 0.11 µV, respectively (P>0.05). The mean macular thickness within a 3 mm diameter circle centered on the fovea was 311.7 ± 8.4 µm before PDT and 315.3 ± 8.5 µm one week after PDT(P>0.05). The mean ratio of the FMERGs b-wave 1 week after PDT to that before PDT was 0.95 in eyes with a mild hypofluorescence at the site of the PDT (I/N brightness ratio ≥0.9, 18 eyes), and the ratio was 1.00 in eyes with a severe hypofluorescence (I/N brightness ratio ≤0.9, 20 eyes, P <0.05).
The combined use of bevacizumab with PDT mitigated the depression of retinal function soon after PDT. Even if the choroidal hypoperfusion at the site of the laser spot was severe after PDT with bevacizumab, the macular function was well preserved.
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