Abstract
Purpose: :
To investigate if choroidal involvement (diabetic choroidopathy) may be observed in diabetic patients with and without diabetic retinopathy (DR), by spectral domain OCT.
Methods: :
Eighty seven subjects were enrolled:59 diabetic patients (102 eyes) and 28 normals. Exclusion criteria were: previously treated diabetic retinopathy (DR), refractive error higher than +/- 3D, treated or untreated glaucoma. All patients underwent: full ophthalmic examination, stereoscopic color fundus photography and spectral domain OCT(SD-OCT: RS-3000, Nidek, Japan). SD-OCT was performed in the macula and peripapillary region. SD-OCT examination consisted in linear scans, 6 mm in length, centered onto the fovea, and circle scan positioned around the optic disc (3.46mm in diameter). Choroidal thickness (CT) was measured manually at the fovea, and at 1, 2, 3mm distance along all scans in the macula. Peripapillary CT was measured at 8 points along the circle scan. All measurements were performed independently by two masked graders.
Results: :
Mean age was not significantly different between diabetics and controls. In the macular area, CT was significantly lower in the nasal quadrant vs all other quadrants (p<0.0001), in both groups. In the peripapillary area, CT was significantly lower in the inferior quadrant vs all other quadrants (p<0.05), in both groups. Mean macular and peripapillary CT progressively and significantly decreased with increasing level of DR (non proliferative and proliferative DR vs controls, p<0.05). No significant CT difference was found between controls and diabetic eyes without detectable DR. Diabetic macular edema did not influence CT. Choroidal thickness in the macula and peripapillary area was highly correlated in diabetics (r >0.7, p<0.0001). Intergrader agreement was almost perfect for all measurements, (k >0.9).
Conclusions: :
In diabetic patients, diabetic retinopathy precedes diabetic choroidopathy. Diabetic choroidopathy starts when DR is already present and parallels it afterwards. SD-OCT clearly confirms in vivo previously reported histopathologic choroidal observations. The role of choroid in the pathophysiology of DR needs to be further investigated.
Keywords: diabetic retinopathy • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • choroid