@article{Siaudvytyte_Daveckaite_Januleviciene_Ragauskas_Siesky_Harris_2016, title={Intracranial, intraocular and ocular perfusion pressures: differences between morning and afternoon measurements}, volume={1}, url={https://www.maio-journal.com/index.php/MAIO/article/view/9}, DOI={10.35119/maio.v1i1.9}, abstractNote={<p><em>Purpose:</em> To assess how intracranial pressure (ICP), intraocular pressure (IOP) and ocular perfusion pressure (OPP) differ between the morning and the afternoon in healthy subjects.</p><p><em>Design:</em> Prospective pilot study.</p><p><em>Methods:</em> Ten healthy subjects age 26.5 (1.2) years were included in the prospective pilot study. For each participant, blood pressure, heart rate, IOP, ICP and calculated OPP, translaminar pressure difference (TPD) were assessed two times per day, in the morning (9 ± 1 a.m.) and afternoon (2 ± 1 p.m.) by the same experienced operator. Best-corrected visual acuity and body mass index were also evaluated. TPD was calculated as IOP minus ICP. ICP was measured using a non-invasive two-depth transcranial Doppler device. P < 0.05 was considered significant.</p><p><em>Results:</em> Mean ICP was higher during afternoon (10.09 (1.8) mmHg) compared to morning ICP (9.80 (2.2) mmHg), but the difference was not statistically significant (p = 0.14). By analyzing ICP according to different refractive errors categories, we found that emmetropic patients had higher ICP (morning 11.94 (3.0), afternoon 11.5 (2.6) mmHg), compared to myopic (accordingly, 9.14 (1.2) and 9.72 (1.3) mmHg) or hypermetropic (accordingly, 8.85 (0.7) and 9.17 (0.8) mmHg) patients, but the difference was not statistically significant (p > 0.05). We also found that higher OPP in the morning was correlated to lower TPD (r = -0.65; p = 0.04).</p><p><em>Conclusion:</em> We found no significant variations in ICP, IOP or OPP during morning and afternoon in young healthy subjects. Higher OPP was related to lower TPD in the morning. Further prospective studies are warranted to investigate diurnal ICP variations in glaucoma patients to understand if fluctuations in ICP and TPD may contribute to the disease process.</p>}, number={1}, journal={Modeling and Artificial Intelligence in Ophthalmology}, author={Siaudvytyte, Lina and Daveckaite, Akvile and Januleviciene, Ingrida and Ragauskas, Arminas and Siesky, Brent and Harris, Alon}, year={2016}, month={Feb.}, pages={37–50} }