Abstract
Purpose: :
To assess the thickness measurements of the macula and intraretinal layers in patients with type 1 diabetes mellitus and no retinopathy using optical coherence tomography (OCT); and to compare these findings with those of age-matched healthy volunteers.
Methods: :
Standard macular mapping by Stratus OCT was performed in 74 healthy eyes (34±16 yrs, 51 female, 23 male) and 39 eyes with type 1 diabetes mellitus (DM) with no retinopathy (36±10 yrs, 19 female, 20 male) on biomicroscopy. Automatic layer segmentation was performed using a custom-built software for OCT retinal image analysis (OCTRIMA). Mean values of thickness of the macula and RNFL, GCL+IPL, INL, OPL, ONL, IS/OS and OS/RPE junction in healthy volunteers and DM eyes were compared using Mann-Whitney U test. Because of the number of statistical comparisons made in the study, a modified p value of <0.001 was considered statistically significant. Missed significance (MS, 0.001<p<0.05) was also recorded.
Results: :
Stratus OCT-measured thickness of the total retina in the central subfield (R1) of DM eyes was higher than those from healthy volunteers (242±23 versus 232±24, p<0.001). Intraretinal thickness was significantly different between DM and healthy eyes for RNFL, which was thinner in the pericentral regions in DM eyes (R2, R3, R4 and R5, p<0.001 and MS); GCL+IPL complex in R4, R6, R7 and R8 , which was also thinner in DM eyes; INL in R2 and R3 (thicker in DM eyes); OPL only in R8 (thicker in DM eyes) and; OS/RPE junction in R1, R4, R5, R8 and R9(thicker in DM eyes). Our study also showed no significant differences in macular and intraretinal layer thickness measurements within regions between females and males in the DM group.
Conclusions: :
In contrast to previous results reported in the literature for subjects with diabetes but minimal or no retinopathy, our results suggest that macular and intraretinal layer thickness measurements in DM subjects are not similar to thickness measurements obtained from age-matched healthy subjects without diabetes. In addition, the differences of the macular and intraretinal layer thickness measurements between men and women in the DM group were not significant. These results are not consistent with past reports which could be due to analyzing data composed of mixed diabetic groups (i.e. type 1 and type 2; and minimal and no DR). Caution should be taken when preparing future studies involving diabetic subjects.
Keywords: image processing • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • diabetic retinopathy