Abstract
Purpose: :
To examine physiological diurnal variations in choriodal thickness and axial length using the enhanced depth imaging spectralis optical coherence tomography (EDI-OCT) and the IOL-Master.
Methods: :
9 eyes of 9 patients were examined 6 times over a time period of 24 hours in 3 hours intervals, at 7:30am, 10:30am, 1:30pm, 4:30pm, 7:30pm and at 10:30pm. At each time of assessment a 7-lines scan of the choroid was performed (30x5 mm, averaging 100 frames) using the EDI-OCT. The choroidal thickness was measured underneath the fovea from the retinal pigment epithelium (RPE) to the chorioscleral interface. Also at each time of assessment the axial length was defined by averaging 7 measurements of the IOL-Master.
Results: :
Four right and five left eyes of near emmetropic patients were examined. The axial length (IOL-Master) showed significant diurnal variation (p < 0.05). The longest mean axial length (23.82 +/- 15,7mm) was measured at 10:30am, the shortest mean axial length (23.18 +/- 1.02mm) twelve hours later at 10:30pm. Mean choroidal thickness (EDI-OCT) revealed no significant diurnal variation, however was found to be thickest at 7:30am (340 +/- 112µm) and thinnest at 13:30pm (328 +/- 123 µm).
Conclusions: :
In this study, limited by the small number of 9 patients, significant diurnal variations in axial length, but not in choroidal thickness were found. There was a tendency for a reduction in choroidal thickness at noon and an increase in thickness during the evening and night reaching the maximum in the morning hours.
Keywords: choroid • circadian rhythms • imaging/image analysis: clinical