Abstract
Purpose: :
to compare optic nerve and macular thickness in patientes with Diabetes Mellitus (DM) type 1 without retinopathy, with healthy subjects; to determine if there is optic nerve neuropathy in absence of retinopathy; and to determine if there are changes in retinal thickness even if there is no sign of ophthalmoscopy retinopathy.
Methods: :
Comparative cross-sectional study. Fifty eyes of 50 healthy subjects and 50 eyes of 50 patients with type I DM without retinopathy with intensive glycemic control were studied. One eye per patient was randomly selected for the study. Patients were scanned using Cirrus HD-OCT (Carl Zeiss Meditec, Inc., Dublin, CA). The scan protocols were optic disc cube 200x200 and 512x128 volumen cube to assess the retinal nerve fiber layer and the macular thickness respectively.
Results: :
The control group was formed by 34 women, 16 men, aged 20-53 yr (mean ± SD 30.26 ± 8.90). DM were 25 women and 25 men, aged 30.08 yr (±10.38). Mean period from the onset of diabetes was 12.8 years (SD ±9.40). None of the diabetic group had changes at the fundus examination. In optic nerve study, statistically significant differences were found in temporal and nasal quadrants (temporal 5.45 microns higher in healthy subjects, nasal 9.09 microns higher in DM subjects). No differences were found in average, superior and inferior thickness measuremens between control and diabetic group. In macular thickness study we did found differences in all the studied parameters including macular volumen, average thickness, superior, nasal ant temporal of the 3 mm ETDRS ring, and superior, nasal, inferior and temporal thickness of the 6 mm ETDRS ring; excluding the central 1 mm ETDRS ring and inferior value of the 3 mm ETDRS ring (all the values were higher in DM patients).
Conclusions: :
Cirrus OCT is no able to detect retinal nerve fiber layer lost in type I diabetes mellitus patients before the development of diabetic retinopathy, only can detect differences in the way they are distributed. Cirrus showed an increase of retinal thickness in patients with DM, even when there is no sign of retinopathy or macular edema, and even when these patients are preserving the foveal shape. These data support the importance of increasing our knowledge of optic nerve study in diabetic patients and the follow up of macular thickness.
Keywords: diabetes • optic nerve • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)