![]() However, as high myopia has been shown to influence choroidal thickness, no one with myopia greater than 6.0 diopters was accepted as a volunteer. The volunteers had no history of systemic or ocular diseases (except for refractive error). Eighteen eyes of 9 young, healthy volunteers were included in this study. This was a prospective interventional case series performed in an institutional setting. Using this method, the authors studied the effect of the Valsalva maneuver on choroidal thickness at the posterior pole in order to better understand the mechanisms of IOP rise associated with the maneuver. The choroidal thickness is increased in diseases such as Vogt-Koyanagi-Harada disease and central serous chorioretinopathy and after the intake of sildenafil. With this technique it is possible to investigate choroidal thickness changes that occur at the posterior pole in various physiologic and pathologic conditions. By pushing the OCT closer to the eye, one is able to obtain an inverted image that penetrates deeper into the choroidal tissue, allowing a cross-sectional image of the full choroidal thickness at the posterior pole. Spaide and associates described a technique called “enhanced depth imaging” using the Heidelberg Spectralis spectral-domain OCT imaging system (Heidelberg Engineering, Heidelberg, Germany). Recently, with the advent of spectral-domain optical coherence tomography (OCT), the ability to image the choroid at the posterior pole of the eye has increased. This increase in the uveal thickness would lead to an increase in the IOP. The authors hypothesized that this increase in the uveal tract would occur throughout the whole globe. Measurements were performed with ultrasonic biomicroscopy at the posterior part of the ciliary body before and during wind instrument blowing. Shuman and associates demonstrated that, in patients performing Valsalva maneuver while playing high-resistance wind instruments, there was an increase in thickness of the choroid that is situated right posterior to the pars plana of the ciliary body. Others have related this IOP increase with an increase in episcleral venous pressure. One hypothesis is that the increase in systemic venous pressure may lead to a decrease of the ocular venous flow through the vortical veins and a consequent increase in choroidal volume and intraocular pressure. The mechanism for IOP rise has not been completely explained. In people who repeatedly perform Valsalva maneuvers, such as musicians who play wind instruments, visual field loss has been reported and attributed to this repeated phenomenon. Valsalva maneuver has been shown to transiently increase IOP in special circumstances such as weight lifting and isometric exercises. This has been postulated to cause choroidal vascular engorgement and an increased choroidal volume that ultimately leads to an increase in intraocular pressure (IOP). The increase in intrathoracic venous pressure is transmitted through the jugular, orbital, and vortex veins to the choroid. This causes an increase in intrathoracic venous pressure and a sustained decrease of the venous flow into the thoracic cavity, leading to an increase in the venous pressure in the head and neck. The Valsalva maneuver occurs when a forced exhalation is performed against a closed glottis. The increase in ocular pressure caused by this maneuver cannot be explained by an increase in choroidal thickness in this portion of the uveal tract. ![]() Valsalva maneuver does not change choroidal thickness at the posterior pole. The mean choroidal thickness difference in the central 3000 μm was 8.5 μm on horizontal scans ( P =. The subfoveal thickness difference was −4.1 μm on horizontal scans ( P =. There was no statistically significant difference in choroidal thickness at rest or during Valsalva maneuver in any of the compared groups. Changes in choroidal thickness were evaluated. Subfoveal and average choroidal thickness in the central 3 mm were compared in the resting position and during the Valsalva maneuver using manual and semiautomatic measuring tools. Horizontal and vertical B-scans centered on the fovea were acquired. Nine healthy volunteers performed macular spectral-domain optical coherence tomography using enhanced-depth imaging at rest and during a Valsalva maneuver. To evaluate the influence of Valsalva maneuver on the morphology and thickness of the choroid at the macular area. ![]()
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