Abstract
Purpose:
To asses, non invasively, early morphologic modifications, as signs of (anti)inflammatory response, in the retina and choroid, after intravitreal steroid treatment in centre-involving diabetic macular edema (DME).
Methods:
Retrospective analysis of images of 20 eyes (20 patients) who underwent intravitreal dexamethasone implant. All patients had good quality fundus color photo, spectral-domain (SD)-OCT and fundus autofluorescence (FAF) before and at 2 months after treatment. The following parameters were evaluated on SD-OCT: number of hyper-reflective spots (HRS) in the area between 500μm and 1500μm nasally and temporally to the fovea, on a linear 180° scan, in three specific layers: from inner limiting membrane-(ILM) to inner plexiform layer-(IPL), from inner nuclear layer-(INL) to outer plexiform layer-(OPL) and in the outer nuclear layer-(ONL); inner and outer retinal and choroidal thickness (RT, CT) in 5 specific sites (fovea, 500μm and 1500μm both nasally and temporally to the fovea); FAF images were evaluated for patterns of normal and increased FAF in the fovea and for the extent of increased FAF. All measurements were performed by 2 masked graders, independently. Signed Rank test was used for statistical analysis.
Results:
At baseline HRS were mainly located in the INL-OPL and ILM-IPL. After treatment: there was a significant decrease in HRS in the INL-OPL(-3.8+2.5, p=0.007) and ONL, (-1.8+2.3, p=0.04); mean RT decreased in the fovea (612.9μm+157.3 vs 337.9μm +118.5, p=0.003), and at almost all measurement sites, (p<0.03, et least for all). CT increased in the fovea (201.4μm+51.3 vs 229.8μm+39.6, p=0.03), temporally at 1500μm, (160.9 μm+43.3 vs 211.9 μm+46.1, p=0.01) and nasally at 500μm, (170.8μm+50.4 vs 220.0μm+24.5, p=0.01); FAF changed from increased to normal in 12 eyes (60%), and decreased in extent in all 20 eyes (100%).
Conclusions:
HRS and increased foveal FAF have been recently proposed as signs of microglial cells activation in DME. Activated microglia is considered responsible of retinal inflammation in diabetics. SD-OCT and FAF show, non invasively, the decrease in inflammatory signs and safety (increase in CT) after intravitreal dexamethasone implant treatment. These parameters could become new clinical biomarkers of inflammation in DME.