In Vivo Human Choroidal Thickness Measurements: Evidence for Diurnal Fluctuations

Abstract

Purpose The authors applied partial coherence interferometry (PCI) to estimate the thickness of the human choroid in vivo and to learn whether it fluctuates during the day. Methods By applying signal processing techniques to existing PCI tracings of human ocular axial length measurements, a signal modeling algorithm was developed and validated to determine the position and variability of a postretinal peak that, by analogy to animal studies, likely corresponds to the choroidal/scleral interface. The algorithm then was applied to diurnal axial eye length datasets. Results The postretinal peak was identified in 28% of subjects in the development and validation datasets, with mean subfoveal choroidal thicknesses of 307 and 293 μm, respectively. Twenty-eight of 40 diurnal PCI datasets had at least two time points with identifiable postretinal peaks, yielding a mean choroidal thickness of 426 μm and a mean high-low difference in choroidal thickness of 59.5 ± 24.2 μm (range, 25.9–103 μm). The diurnal choroidal thickness fluctuation was larger than twice the SE of measurement (24.5 μm) in 16 of these 28 datasets. Axial length and choroidal thickness tended to fluctuate in antiphase. Conclusions Signal processing techniques provide choroidal thickness estimates in many, but not all, PCI datasets of axial eye measurements. Based on eyes with identifiable postretinal peaks at more than one time in a day, choroidal thickness varied over the day. Because of the established role of the choroid in retinal function and its possible role in regulating eye growth, further development and refinement of clinical methods to measure its thickness are warranted.

Change in subfoveal choroidal thickness in central serous chorioretinopathy following spontaneous resolution and low-fluence photodynamic therapy

“…24 However, authors thought that averaging the choroidal thickness in two different sections-vertical and horizontal sectionswould decrease the measuring error. Previous studies also showed that the measurements of choroidal thickness, using EDI-OCT, have good reproducibility and repeatability.…”

Optical Coherence Tomography–based Correlation Between Choroidal Thickness and Drusen Load in Dry Age-Related Macular Degeneration

“…However, the moderate interrater agreement that we observed in the measurement of choroid thickness suggests that other methods for measuring choroid thickness, such as automated algorithms, 38 may be more reproducible than manual measurements. Furthermore, diurnal fluctuations in choroidal thickness 39,40 would need to be accounted for in the clinical use of these measurements.…”

The Influence of Light Exposure and Seasonal Changes on Short-Term and Longer-Term Changes in Axial Length of the Human Eye

“…The choroid typically exhibits an approximate anti-phase relationship with axial length, with a peak in thickness around mid-night and a trough around mid-day (Nickla et al, 1998b;Nickla et al, 1998a;Papastergiou et al, 1998;Chakraborty et al, 2011;Lee et al, 2014;Kinoshita et al, 2016) and several studies have established an association between diurnal changes in axial length and choroidal thickness (Weiss & Schaeffel, 1993;Nickla et al, 1998b;Papastergiou et al, 1998;Nickla et al, 2001Nickla et al, , 2002Stone et al, 2004;Wilson et al, 2006;Brown et al, 2009;Chakraborty et al, 2011Chakraborty et al, , 2012Chakraborty et al, , 2013Nickla, 2013). These associations suggest that choroidal variations may have contributed towards the axial length changes observed in our study.…”

“…The human choroid also exhibits a significant diurnal variation in its thickness, with the choroid typically thicker at night and thinner during the day (Brown et al, 2009;Chakraborty et al, 2011). In a 24-hour diurnal study, Usui et al (2012) reported that the 32 Chapter 1: Literature review choroid is thinnest in the evening at 6 pm and thickest during the night at 3 am.…”

“…(Brown et al, 2009;Chakraborty et al, 2011;Seidel et al, 2015) and the phase relationship between axial length and choroidal thickness is found to be associated with longitudinal eye growth in animals (Nickla, 2006(Nickla, , 2013. Therefore, future studies examining diurnal variations in choroidal thickness may help to further explain the association between the amplitude of diurnal changes and longitudinal eye growth more clearly.…”