Abstract

Purpose: To evaluate, in vivo, the relationship between intraretinal hyperreflective spots and corneal dendritic cells in diabetic eyes.

Methods: The corneas of 20 diabetic subjects with confirmed intraretinal hyperreflective spots (Spectralis OCT, Heidelberg Engineering, Germany) were compared with 20 corneas of diabetic eyes without hyperreflective spots, and the corneas of 10 healthy controls. Each cornea was examined, in vivo, using corneal confocal microscopy (CCM: HRT with Rostock Corneal Module, Heidelberg Engineering, Germany). Subjects with previous corneal surgery, corneal disorders or wearing contact lenses were excluded. Full ophthalmic examination, including anterior and posterior segment biomicroscopy, was performed in all eyes. All retinal OCT and CCM grading were performed twice, by at least two independent masked graders, for each tecnique.

Results: The inter-grader agreement was at least substantial for all measurements, for both techniques. In all eyes with hyperreflective intraretinal spots, dendritic corneal cells were detected by CCM. Corneal dendritic cells were rarely present in eyes without intraretinal hyperreflective spots versus eyes with hyperreflective retinal spots (p<0.005), and fully absent in all healthy control eyes (p< 0.0001).

Conclusions: The presence of retinal discrete microaggregates, appearing on SD-OCT as hyperreflective spots, is a recently accepted biomarker of retinal microglia activation. Corneal dendritic cells share substantial biological characteristics with retinal microglial cells. The expression of in vivo inflammatory cells at both retinal and corneal level may represent a new approach to evaluate inflammation in the pathophysiology of eye involvement in diabetes.