Abstract
Purpose: :
Valsalva manoeuvre has been associated with increases in intra-ocular pressure and increase in ciliary body thickness. These changes in uveal thickness were recorded using ultrasound. We investigated the influence of the Valsalva manoeuvre in the posterior choroidal thickness using enhanced depth imaging OCT (EDI - Spectralis) to evaluate acute changes caused by the sudden increase in intra-thoracic pressure.
Methods: :
Nine healthy volunteers performed vertical and horizontal EDI of the choroid both at rest and during Valsalva. From the choroidal images, best fit curves were produced to better evaluate choroidal anatomy. Subfoveal choroidal thickness were compared using the generated curves and using the callipers provided in the Spectralis software. Average choroidal thickness under the central 3mm was also compared.
Results: :
Subfoveally, the mean change in choroidal thickness was 4.1µm on horizontal scans (p=0.28) and 1.4µm on vertical scans (p=0.75). The mean choroidal thickness difference in the central 3000 µm was 8.5µm on horizontal scans (p=0.73) and 5.3µm on vertical scans (p=0.41).
Conclusions: :
Valsalva does not change the choroidal volume at the posterior pole. Acute increases in ocular pressure caused by this gesture cannot be explained by significant changes of the macular choroidal volume. Changes of the uveal thickness outside the posterior pole cannot me monitored using EDI and could eventually influence intra-ocular pressure.
Keywords: choroid • intraocular pressure • imaging/image analysis: clinical