Abstract
Purpose: :
Small dense Particles (SDP) or hyper-reflective dots visible on OCT in cases of retinal thickening, retinal oedema and sub-retinal exudation due to a variety of causes have been described but their correlation to clinical parameters have not been demonstrated. Our objective was to evaluate characteristics of SDP following ranibizumab therapy in cases of wet AMD.
Methods: :
Patients who have received at least three loading doses of ranibizumab were selected and data retrospectively collected at baseline visit and at month 4. Foveal thickness, visual acuity and number of SDP on one selected OCT cut were recorded. The OCT cut selected for SDP determination was the cut which showed the maximum number of SDP at baseline and the same cut location was used for evaluation at month 4 timepoint (Spectralis Tru Track®). Location of SDP at baseline was qualitatively graded in terms of distribution in outer or inner layers or both. Mean SDP number was compared between baseline and month 4 (unpaired t test) and also between those with good response, Group 1(absence of fluid) and those with poorer response, Group 2(persistent fluid), [paired t- test].
Results: :
36 patients were included. At baseline, mean acuity was 0.77±0.30 logMAR and mean foveal thickness was 449.61 ±146.59 µm. At baseline, the majority (80%) of all SDP were clustered in the outer retinal layers. At month 4, mean acuity improved to 0.60±0.29 logMAR (p=0.009) and mean foveal thickness improved to 322.86 ±98.06 (p=0.0003). Mean number of SDP reduced significantly from 12.16±11.02 to 5.30±7.90 (p= 0.0013). Subgroup analysis showed mean reduction in SDP of 6.33 in Group 1 (n= 18) and 7.33 in Group 2 (n= 18). The difference between Group 1 and 2 was not statistically significant (p= 0.78).
Conclusions: :
In most cases, reduction in SDP occurred quickly following treatment, indicating a link between lesion activity and presence of SDP. The clustering of SDP in the outer retinal layers at baseline suggests that SDP may represent a watershed or a tide mark effect of the exudation. However, the overall number of SDP is not a sensitive parameter upon which to judge lesion activity.
Keywords: age-related macular degeneration • vascular endothelial growth factor