Subfoveal, peripapillary choroidal thicknesses decrease with acute increase in IOP
A 2-hour dark room test shows that choroidal thickness in the subfoveal region and in the peripapillary region decreases parallel to an acute intraocular pressure (IOP) elevation in individuals. Furthermore, choroidal thickness depends on the actual IOP, which may be noted when choroidal thickness is measured.
A prospective cohort study was conducted to evaluate changes in subfoveal choroidal thickness (SFCT) and peripapillary choroidal thickness (PPCT) after acute increase in IOP provoked by a dark room prone provocative test (DRPPT).
A total of 65 individuals (114 eyes) who had an IOP elevation ≥2 mm Hg during the DRPPT were included in the study. The participants stayed in a dark room for 2 hours with the forehead placed on a desk. Researchers performed tonometry and enhanced depth imaging by spectral-domain optical coherence tomography at baseline and within 5 minutes after the end of the DRPPT.
IOP rose by 10.1 mm Hg, SFCT significantly decreased (p<0.001) from 280 to 267 µm, and PPCT significantly decreased (p<0.001) from 177 to 169 µm during the DRPPT.
Multivariate analysis showed that a more marked SFCT thinning was correlated with higher IOP elevation (p<0.001) and shallower anterior chamber depth at baseline (p=0.01). Likewise, a higher PPCT change was associated with a higher IOP elevation (p<0.001) and a thicker choroidal thickness at baseline (p<0.001).