Abstract
Purpose:
To evaluate the segmentational diurnal variations of total, inner, and outer retinal thickness (RT) and subfoveal choroidal thickness (CT) in diabetic macular edema (DME) and healthy subjects using spectral domain optical coherence tomography (SD-OCT).
Methods:
21 eyes of patients with diabetic macular edema (DME) and 21 healthy subjects (controls) underwent five SD-OCT measurements of RT and CT at 9 AM, 11 AM, 1 PM, 3 PM, and 5 PM. The inner and the outer RT in the parafoveal subfields were measured manually. Measurement of CT was performed in the same subfoveal area. Mean arterial pressure (MAP) was calculated from ambulatory arterial pressure measurement.
Results:
The inner RT did not exhibit significant diurnal variation at all of subfields. A positive correlation between MAP and RT was not found (p=0.610). In the subgroup analysis, 10 patients with a baseline foveal thickness of <300 µm showed a significant diurnal change of total and outer RT only in superior subfield. Meanwhile, 11 diabetic patients with a baseline foveal thickness of ≥300 µm demonstrated significant diurnal changes of total and outer RT in all subfields. Comparing controls, Total and outer RT decreased in superior subfield over the course of the day (p=0.016; p=0.04). Subfoveal choroidal thickness decreased over the course of the day (p<0.001). Subfoveal choroidal thickness decreased over the couse of the day (p<0.001). The circadian fluctuation of CT is higher in patients with a baseline foveal thickness of ≥300 µm.
Conclusions:
In the eyes with DME, total and outer RT decreased significantly due to gravitational shift in superior subfield while inner RT supplied by retinal vasculature did not show diurnal variation in any subfield. This means that circadian fluctuation of DME may be more influenced by postural change than hydrostatic pressure in retinal capillaries. Larger decreases in RT and CT occur mostly in patients with more severe DME. Presence of diabetic retinoapthy is associated with a significant decrease in the CT, and the significant diurnal change was found.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)