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Editors Selection IGR 9-4

Clinical Examination Methods: Swimming goggles and IOP

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69845 Effects of Swimming Goggles Wearing on Intraocular Pressure, Ocular Perfusion Pressure, and Ocular Pulse Amplitude, Paula AP; Paula JS; Silva MJ et al., Journal of Glaucoma, 2016; 25: 860-864

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Paula, Rodrigues, and coworkers performed a study to determine the effects of swimming goggle wear on IOP, ocular perfusion pressure (OPP), and ocular pulse amplitude (OPA). The study was done on 35 eyes of 35 healthy volunteers, and was well designed and adequately powered. Variables were measured at baseline, two minutes after putting on the swimming goggles, and immediately after goggle removal. Unsurprisingly, the results showed that IOP significantly increased from a mean of 13 mmHg to 23 mmHg after swimming goggles were put on the eyes, presumably from compression of the orbital tissues, and decreased to ~3 mmHg below baseline IOP after removal. This indicates that outflow facility increased as IOP increased, which lowered ocular volume and resulted in a lower IOP after goggle removal. Also unsurprisingly, OPP decreased from 52 to 47 mmHg after the goggles were put on, and increased to ~3 mmHg above baseline OPP after removal. Most interestingly, OPA increased from 1.8 mmHg to 2.6 mmHg after applying goggles (an acute IOP elevation), and decreased to 0.3 mmHg below baseline after goggle removal. Results confirm that transient IOP fluctuations are larger at higher baseline IOPs in humans in response to vascular filling (ocular volume change) that is tightly autoregulated within the range of IOPs at which this result is reported. This has important implications, as it shows that transient IOP fluctuations are larger at higher baseline IOPs in the same eye, and confirms that ocular rigidity is nonlinear in nature (i.e., the ocular coats are stiffer at higher IOPs). We have hypothesized that transient IOP fluctuations are higher in the elderly, in persons of African heritage, and in ocular hypertensive eyes in which the ocular coats are stiffer, and that larger IOP fluctuations contribute to the higher prevalence of glaucoma in these at-risk populations. The study also demonstrates that applying swimming goggle frames with the central plastic lens removed is a robust method to raise IOP ~10 mmHg acutely in humans noninvasively, while still allowing access to the cornea for IOP measurement and unimpeded imaging of the posterior pole. Hence, this method could easily be applied in the clinic to measure the acute biomechanical compliance of the optic nerve head (ONH) or assess the robustness of retinal or ONH blood flow in response to an applied acute IOP insult using current imaging techniques.

Applying swimming goggle frames with the central plastic lens removed is a robust method to raise IOP ~10 mmHg acutely in humans noninvasively, while still allowing access to the cornea for IOP measurement and unimpeded imaging of the posterior pole.

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