{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T01:13:08Z","timestamp":1779325988775,"version":"3.51.4"},"reference-count":37,"publisher":"Public Library of Science (PLoS)","issue":"3","license":[{"start":{"date-parts":[[2023,3,23]],"date-time":"2023-03-23T00:00:00Z","timestamp":1679529600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:p>The purpose of this study was to develop a method of estimating pulsatile ocular blood volume (POBV) from measurements taken during an ophthalmic exam, including axial length and using a tonometer capable of measuring intraocular pressure (IOP) and ocular pulse amplitude (OPA). Unpublished OPA data from a previous invasive study was used in the derivation, along with central corneal thickness (CCT) and axial length (AL), as well as IOP from the PASCAL dynamic contour tonometer (DCT) and intracameral (ICM) measurements of IOP for 60 cataract patients. Intracameral mean pressure was set to 15, 20, and 35 mmHg (randomized sequence) in the supine position, using a fluid-filled manometer. IOP and OPA measurements were acquired at each manometric setpoint (DCT and ICM simultaneously). In the current study, ocular rigidity (OR) was estimated using a published significant relationship of OR to the natural log of AL in which OR was invasively measured through fluid injection. Friedenwald\u2019s original pressure volume relationship was then used to derive the estimated POBV, delivered to the choroid with each heartbeat as a function of OR, systolic IOP (IOP<jats:sub>sys<\/jats:sub>), diastolic IOP (IOP<jats:sub>dia<\/jats:sub>), and OPA, according to the derived equation POBV = log (IOP<jats:sub>sys<\/jats:sub>\/IOP<jats:sub>dia<\/jats:sub>) \/ OR. Linear regression analyses were performed comparing OPA to OR and calculated POBV at each of the three manometric setpoints. POBV was also compared to OPA\/IOP<jats:sub>dia<\/jats:sub>with all data points combined. Significance threshold was p &lt; 0.05. OR estimated from AL showed a significant positive relationship to OPA for both DCT (p &lt; 0.011) and ICM (p &lt; 0.006) at all three manometric pressure setpoints, with a greater slope for lower IOP. Calculated POBV also showed a significant positive relationship to OPA (p &lt; 0.001) at all three setpoints with greater slope at lower IOP, and a significant negative relationship with IOP<jats:sub>dia<\/jats:sub>. In the combined analysis, POBV showed a significant positive relationship to OPA\/ IOP<jats:sub>dia<\/jats:sub>(p &lt; 0.001) in both ICM and DCT measurements with R<jats:sup>2<\/jats:sup>= 0.9685, and R<jats:sup>2<\/jats:sup>= 0.9589, respectively. POBV provides a straight-forward, clinically applicable method to estimate ocular blood supply noninvasively. Higher IOP in combination with lower OPA results in the lowest values of POBV. The simplified ratio, OPA\/ IOP<jats:sub>dia<\/jats:sub>, may also provide a useful clinical tool for evaluating changes in ocular blood supply in diseases with a vascular component, such as diabetic retinopathy and normal tension glaucoma. Future studies are warranted.<\/jats:p>","DOI":"10.1371\/journal.pone.0283387","type":"journal-article","created":{"date-parts":[[2023,3,23]],"date-time":"2023-03-23T18:03:46Z","timestamp":1679594626000},"page":"e0283387","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":5,"title":["Estimating pulsatile ocular blood volume from intraocular pressure, ocular pulse amplitude, and axial length"],"prefix":"10.1371","volume":"18","author":[{"given":"Ryan H.","family":"Somogye","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0483-4163","authenticated-orcid":true,"given":"Cynthia J.","family":"Roberts","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Eberhard","family":"Spoerl","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Karin R.","family":"Pillunat","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lutz E.","family":"Pillunat","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6362-9437","authenticated-orcid":true,"given":"Robert H.","family":"Small","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"340","published-online":{"date-parts":[[2023,3,23]]},"reference":[{"issue":"5","key":"pone.0283387.ref001","doi-asserted-by":"crossref","first-page":"669","DOI":"10.1016\/S1350-9462(98)00037-8","article-title":"Progress in measurement of ocular blood flow and relevance to our understanding of glaucoma and age-related macular degeneration","volume":"18","author":"A Harris","year":"1999","journal-title":"Prog Retin Eye Res"},{"issue":"2","key":"pone.0283387.ref002","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1016\/j.exer.2010.09.002","article-title":"The complex interaction between ocular perfusion pressure and ocular blood flow\u2014relevance for glaucoma","volume":"93","author":"D Schmidl","year":"2011","journal-title":"Exp Eye Res"},{"issue":"3","key":"pone.0283387.ref003","doi-asserted-by":"crossref","first-page":"295","DOI":"10.3129\/i08-049","article-title":"Ocular blood flow in diabetes and age-related macular degeneration","volume":"43","author":"B Pemp","year":"2008","journal-title":"Can J Ophthalmol J Can Ophtalmol"},{"issue":"1","key":"pone.0283387.ref004","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1016\/j.survophthal.2009.02.024","article-title":"Ocular ischemic syndrome","volume":"55","author":"E Mendrinos","year":"2010","journal-title":"Surv Ophthalmol"},{"issue":"8","key":"pone.0283387.ref005","article-title":"Ocular ischemic syndrome\u2014a systematic review","volume":"18","author":"B Terelak-Borys","year":"2012","journal-title":"Med Sci Monit Int Med J Exp Clin Res"},{"issue":"Suppl","key":"pone.0283387.ref006","doi-asserted-by":"crossref","first-page":"S72","DOI":"10.1016\/0039-6257(94)90049-3","article-title":"Validity of pulsatile ocular blood flow measurements","volume":"38","author":"DM Silver","year":"1994","journal-title":"Surv Ophthalmol"},{"key":"pone.0283387.ref007","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1111\/j.1755-3768.1989.tb07083.x","article-title":"Estimation of pulsatile ocular blood flow from intraocular pressure","volume":"191","author":"DM Silver","year":"1989","journal-title":"Acta Ophthalmol Suppl"},{"issue":"12","key":"pone.0283387.ref008","doi-asserted-by":"crossref","first-page":"5718","DOI":"10.1167\/iovs.09-3760","article-title":"Ocular rigidity, ocular pulse amplitude, and pulsatile ocular blood flow: the effect of intraocular pressure","volume":"50","author":"AI Dastiridou","year":"2009","journal-title":"Invest Ophthalmol Vis Sci"},{"issue":"3","key":"pone.0283387.ref009","doi-asserted-by":"crossref","first-page":"2087","DOI":"10.1167\/iovs.12-11576","article-title":"Ocular rigidity, ocular pulse amplitude, and pulsatile ocular blood flow: the effect of axial length","volume":"54","author":"AI Dastiridou","year":"2013","journal-title":"Invest Ophthalmol Vis Sci"},{"issue":"2","key":"pone.0283387.ref010","doi-asserted-by":"crossref","first-page":"409","DOI":"10.1167\/iovs.04-0162","article-title":"Ocular rigidity in living human eyes","volume":"46","author":"IG Pallikaris","year":"2005","journal-title":"Invest Ophthalmol Vis Sci"},{"issue":"2","key":"pone.0283387.ref011","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1076\/0271-3683(200002)2021-DFT115","article-title":"Pressure-volume relation for the living human eye","volume":"20","author":"DM Silver","year":"2000","journal-title":"Curr Eye Res"},{"issue":"6","key":"pone.0283387.ref012","doi-asserted-by":"crossref","first-page":"2472","DOI":"10.1167\/iovs.07-1366","article-title":"Dynamic contour tonometry in comparison to intracameral IOP measurements","volume":"49","author":"AG Boehm","year":"2008","journal-title":"Invest Ophthalmol Vis Sci"},{"issue":"10","key":"pone.0283387.ref013","doi-asserted-by":"crossref","first-page":"985","DOI":"10.1016\/S0002-9394(37)90425-2","article-title":"Contribution to the Theory and Practice of Tonometry*","volume":"20","author":"JS Friedenwald","year":"1937","journal-title":"Am J Ophthalmol"},{"key":"pone.0283387.ref014","unstructured":"PASCAL DCT User Manual. Published online September 2012."},{"issue":"7","key":"pone.0283387.ref015","doi-asserted-by":"crossref","first-page":"731","DOI":"10.1136\/bjo.82.7.731","article-title":"Pulsatile ocular blood flow investigation in asymmetric normal tension glaucoma and normal subjects","volume":"82","author":"L Fontana","year":"1998","journal-title":"Br J Ophthalmol"},{"issue":"Suppl","key":"pone.0283387.ref016","doi-asserted-by":"crossref","first-page":"S177","DOI":"10.1016\/0039-6257(94)90064-7","article-title":"The effect of increased intraocular pressure on pulsatile ocular blood flow in low tension glaucoma","volume":"38","author":"L Quaranta","year":"1994","journal-title":"Surv Ophthalmol"},{"issue":"2","key":"pone.0283387.ref017","doi-asserted-by":"crossref","first-page":"66","DOI":"10.1136\/bjo.75.2.66","article-title":"Postural studies in pulsatile ocular blood flow: I. Ocular hypertension and normotension","volume":"75","author":"DR Trew","year":"1991","journal-title":"Br J Ophthalmol"},{"issue":"2","key":"pone.0283387.ref018","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1016\/S0014-4835(81)80062-0","article-title":"Ocular volume and ocular rigidity","volume":"33","author":"ES Perkins","year":"1981","journal-title":"Exp Eye Res"},{"issue":"12","key":"pone.0283387.ref019","doi-asserted-by":"crossref","first-page":"1697","DOI":"10.1136\/bjophthalmol-2013-304652","article-title":"Estimation of ocular volume from axial length","volume":"98","author":"M Nagra","year":"2014","journal-title":"Br J Ophthalmol"},{"issue":"1","key":"pone.0283387.ref020","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1111\/j.1442-9071.2012.02809.x","article-title":"Ocular rigidity: biomechanical role, in vivo measurements and clinical significance","volume":"41","author":"ET Detorakis","year":"2013","journal-title":"Clin Experiment Ophthalmol"},{"issue":"12","key":"pone.0283387.ref021","doi-asserted-by":"crossref","first-page":"1994","DOI":"10.1016\/S0161-6420(97)30066-9","article-title":"Clinical findings and hemodynamic changes associated with severe occlusive carotid artery disease","volume":"104","author":"VP Costa","year":"1997","journal-title":"Ophthalmology"},{"issue":"4","key":"pone.0283387.ref022","doi-asserted-by":"crossref","first-page":"689","DOI":"10.1016\/S0161-6420(98)94025-8","article-title":"Collateral blood supply through the ophthalmic artery: a steal phenomenon analyzed by color Doppler imaging","volume":"105","author":"VP Costa","year":"1998","journal-title":"Ophthalmology"},{"issue":"5","key":"pone.0283387.ref023","doi-asserted-by":"crossref","first-page":"670","DOI":"10.1016\/S0002-9394(00)00588-2","article-title":"Normal-tension glaucoma with reversed ophthalmic artery flow","volume":"130","author":"M Hashimoto","year":"2000","journal-title":"Am J Ophthalmol"},{"issue":"6","key":"pone.0283387.ref024","doi-asserted-by":"crossref","first-page":"919","DOI":"10.1007\/s00540-013-1648-y","article-title":"Perioperative visual loss after nonocular surgery","volume":"27","author":"A Kitaba","year":"2013","journal-title":"J Anesth"},{"issue":"Suppl","key":"pone.0283387.ref025","doi-asserted-by":"crossref","first-page":"S161","DOI":"10.1016\/0039-6257(94)90061-2","article-title":"Ocular blood flow and vision in healthy and glaucomatous eyes","volume":"38","author":"ME Langham","year":"1994","journal-title":"Surv Ophthalmol"},{"key":"pone.0283387.ref026","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1007\/978-3-642-76084-6_24","volume-title":"Glaucoma Update IV.","author":"ME Langham","year":"1991"},{"issue":"2","key":"pone.0283387.ref027","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1136\/bjo.75.2.71","article-title":"Postural studies in pulsatile ocular blood flow: II. Chronic open angle glaucoma","volume":"75","author":"DR Trew","year":"1991","journal-title":"Br J Ophthalmol"},{"issue":"7","key":"pone.0283387.ref028","first-page":"1604","article-title":"Parapapillary retinal vessel diameter in normal and glaucoma eyes. II. Correlations","volume":"30","author":"JB Jonas","year":"1989","journal-title":"Invest Ophthalmol Vis Sci"},{"issue":"7","key":"pone.0283387.ref029","first-page":"1599","article-title":"Parapapillary retinal vessel diameter in normal and glaucoma eyes. I. Morphometric data","volume":"30","author":"JB Jonas","year":"1989","journal-title":"Invest Ophthalmol Vis Sci"},{"issue":"4","key":"pone.0283387.ref030","doi-asserted-by":"crossref","first-page":"466","DOI":"10.1136\/bjo.83.4.466","article-title":"Peripapillary retinal blood flow in normal tension glaucoma","volume":"83","author":"HS Chung","year":"1999","journal-title":"Br J Ophthalmol"},{"issue":"2","key":"pone.0283387.ref031","first-page":"385","article-title":"Foveolar choroidal blood flow in age-related macular degeneration","volume":"39","author":"JE Grunwald","year":"1998","journal-title":"Invest Ophthalmol Vis Sci"},{"issue":"2","key":"pone.0283387.ref032","doi-asserted-by":"crossref","first-page":"211","DOI":"10.1016\/S0002-9394(14)75989-6","article-title":"Choroidal perfusion abnormality with age-related Bruch\u2019s membrane change","volume":"109","author":"D Pauleikhoff","year":"1990","journal-title":"Am J Ophthalmol"},{"issue":"6","key":"pone.0283387.ref033","doi-asserted-by":"crossref","first-page":"558","DOI":"10.1136\/bjo.79.6.558","article-title":"Foveal electroretinograms and choroidal perfusion characteristics in fellow eyes of patients with unilateral neovascular age-related macular degeneration","volume":"79","author":"JF Remulla","year":"1995","journal-title":"Br J Ophthalmol"},{"key":"pone.0283387.ref034","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1155\/2015\/864871","article-title":"Ocular Blood Flow Autoregulation Mechanisms and Methods.","volume":"2015","author":"X Luo","year":"2015","journal-title":"J Ophthalmol"},{"issue":"1","key":"pone.0283387.ref035","doi-asserted-by":"crossref","first-page":"38","DOI":"10.1097\/APO.0000000000000183","article-title":"Ocular Blood Flow and Influencing Factors for Glaucoma","volume":"5","author":"T. Nakazawa","year":"2016","journal-title":"Asia-Pac J Ophthalmol"},{"key":"pone.0283387.ref036","doi-asserted-by":"crossref","first-page":"96","DOI":"10.1016\/j.preteyeres.2017.12.001","article-title":"Neural control of choroidal blood flow","volume":"64","author":"A Reiner","year":"2018","journal-title":"Prog Retin Eye Res"},{"issue":"5","key":"pone.0283387.ref037","doi-asserted-by":"crossref","first-page":"563","DOI":"10.1016\/S1350-9462(01)00004-0","article-title":"The blood supply of the optic nerve head and the evaluation of it\u2014myth and reality","volume":"20","author":"SS Hayreh","year":"2001","journal-title":"Prog Retin Eye Res"}],"container-title":["PLOS ONE"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0283387","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,12,9]],"date-time":"2023-12-09T13:59:08Z","timestamp":1702130348000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0283387"}},"subtitle":[],"editor":[{"given":"Sanjoy","family":"Bhattacharya","sequence":"first","affiliation":[],"role":[{"role":"editor","vocabulary":"crossref"}]}],"short-title":[],"issued":{"date-parts":[[2023,3,23]]},"references-count":37,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2023,3,23]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0283387","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,3,23]]}}}