Small dense particles in the retina observable by spectral-domain optical coherence tomography in age-related macular...

To observe detailed changes in neurosensory retinal structure after anti-VEGF upload in age-related macular degeneration (AMD), by using spectral domain optical coherence tomography (SD-OCT).

The retinal structure was observed by using SD-OCT in 61 patients, before and 1 month after the third ranibizumab injection (upload phase). The main focus of attention was a subjective determination of the amount and behavior of the numerous small, dense particles (SDPs) frequently observed within the outer and inner neurosensory layers in eyes with neovascular AMD. The Spearman rho correlation was used for statistical analysis.

In all eyes, various amounts of SDPs were seen within the neurosensory layer of the foveal and parafoveal area. In 54%, the amount of SDPs became significantly less after ranibizumab therapy (stable, 41%; higher, 5%). SDP reduction correlated positively with the reduction of retinal disease according to OCT (P = 0.000), with central foveal thickness (P = 0.040), and with the improvement in best corrected visual acuity (BCVA; P = 0.006). The baseline amount of SDPs also correlated positively with the increase in BCVA (P = 0.005).

The origin of the SDPs observable in SD-OCT is unknown, but they may represent migrating RPE cells or leukocytes, indicating a certain status of retinal inflammation. The amount of SDPs is substantially reduced after ranibizumab upload therapy and correlates positively with BCVA. Moreover, an initial large number of SDPs may indicate a higher grade of inflammation, but the presence of a high number enhances the effect of ranibizumab therapy. Thus, the amount of SDPs before treatment may be a predictive factor for the therapy's outcome.