{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,26]],"date-time":"2026-06-26T04:48:22Z","timestamp":1782449302561,"version":"3.54.5"},"reference-count":45,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2025,10,6]],"date-time":"2025-10-06T00:00:00Z","timestamp":1759708800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.mdpi.com"],"crossmark-restriction":true},"short-container-title":["Medicina"],"abstract":"<jats:p>Background and Objectives: Circadian fluctuations in blood pressure, particularly the non-dipping pattern characterized by the absence of a nocturnal decline, are associated with an increased risk of microvascular complications. The retina, as a highly sensitive microvascular tissue, offers a valuable window into systemic hemodynamic alterations. However, the literature lacks detailed structural analyses that evaluate all retinal regions by segmenting nighttime into specific time intervals. Notably, the early morning period (04:00\u201308:00), during which stress hormones such as cortisol and catecholamines rise physiologically, leads to increased blood pressure that may significantly affect retinal microcirculation. This prospective study aims to assess retinal microvascular structures in dipper and non-dipper individuals using structural optical coherence tomography and to investigate their relationship with blood pressure parameters by dividing nighttime into distinct time segments. Materials and Methods: A total of 60 participants were classified as dipper (n = 26) or non-dipper (n = 34) based on 24 h ambulatory blood pressure monitoring results. Structural optical coherence tomography was used to evaluate superficial and deep capillary plexus densities in the foveal, parafoveal, and perifoveal regions, along with the area and perimeter of the foveal avascular zone (FAZ) and flow density (FD). Blood pressure values, including systolic, diastolic, mean arterial, and pulse pressure, were recorded during two nighttime intervals (00:00\u201304:00 and 04:00\u201308:00), and correlations with retinal parameters were analyzed. Results: No significant differences were observed in retinal microvascular parameters between the dipper and non-dipper groups. Deep capillary densities, particularly in the parafoveal and perifoveal regions, showed significant positive correlations with serum total protein, albumin, and very low-density lipoprotein (VLDL) levels. Furthermore, systolic and mean arterial pressures measured during the 04:00\u201308:00 interval demonstrated significant positive correlations with deep retinal vascular densities. The FAZ perimeter was negatively correlated with pulse pressure variability, while FD showed a negative correlation with mean arterial pressure variability. Conclusions: This prospective study is among the first to investigate the effects of circadian blood pressure patterns on retinal microvascular structures by segmenting nighttime into specific intervals and employing comprehensive structural optical coherence tomography across the entire retina. The findings suggest that retinal microvascular structure may be associated with fluctuations in blood pressure. Analyses of blood pressure measurements between 04:00 and 08:00 may offer supplementary insights into the evaluation of retinal microvascular structure.<\/jats:p>","DOI":"10.3390\/medicina61101801","type":"journal-article","created":{"date-parts":[[2025,10,6]],"date-time":"2025-10-06T15:05:06Z","timestamp":1759763106000},"page":"1801","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Effect of Circadian Blood Pressure Variations on Retinal Microvascular Structures: Optical Coherence Tomography Angiography Analysis with the Nighttime Divided into Subintervals (Retinal Dawn Pattern)"],"prefix":"10.3390","volume":"61","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6575-4450","authenticated-orcid":false,"given":"O\u011fuzhan","family":"Zengin","sequence":"first","affiliation":[{"name":"Department of Internal Medicine, University of Health Sciences, Ankara Bilkent City Hospital, Ankara 06800, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u015eule Nur","family":"Polat","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, University of Health Sciences, Ankara Bilkent City Hospital, Ankara 06800, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-8688-9501","authenticated-orcid":false,"given":"Canan","family":"Sat\u0131lm\u0131\u015f","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, University of Health Sciences, Ankara Bilkent City Hospital, Ankara 06800, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6082-8323","authenticated-orcid":false,"given":"Burak","family":"G\u00f6re","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, \u00c7erke\u015f State Hospital, \u00c7ank\u0131r\u0131 18600, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8198-8588","authenticated-orcid":false,"given":"Melike","family":"Yakut","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, \u00c7ifteler State Hospital, Eski\u015fehir 26700, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u0130rem","family":"Aydo\u011fmu\u015f","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, University of Health Sciences, Ankara Bilkent City Hospital, Ankara 06800, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7252-1292","authenticated-orcid":false,"given":"Merve","family":"\u00c7elik","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, G\u00f6lba\u015f\u0131 \u015eehit Ahmet \u00d6zsoy State Hospital, Ankara 06830, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8797-9634","authenticated-orcid":false,"given":"Mehmet","family":"\u00d6nen","sequence":"additional","affiliation":[{"name":"Department of Ophthalmology, Ankara Bilkent City Hospital, Ankara 06800, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u0130hsan","family":"Ate\u015f","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, University of Health Sciences, Ankara Bilkent City Hospital, Ankara 06800, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,10,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1094","DOI":"10.1002\/clc.23938","article-title":"Management of arterial hypertension: Challenges and opportunities","volume":"45","author":"Silva","year":"2022","journal-title":"Clin. Cardiol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"S61","DOI":"10.1038\/sj.jhh.1001345","article-title":"Hypertension and coronary heart disease","volume":"16","author":"Escobar","year":"2002","journal-title":"J. Hum. Hypertens."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1186\/s40885-023-00241-w","article-title":"Clinical and life style factors related to the nighttime blood pressure, nighttime dipping and their phenotypes in Korean hypertensive patients","volume":"29","author":"Kim","year":"2023","journal-title":"Clin. Hypertens."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1093\/ehjcvp\/pvae084","article-title":"2024 ESC Guidelines for the management of elevated blood pressure and hypertension: What is new in pharmacotherapy?","volume":"11","author":"McCarthy","year":"2025","journal-title":"Eur. Heart J. Cardiovasc. Pharmacother."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"719","DOI":"10.1161\/HYPERTENSIONAHA.122.19996","article-title":"Pathophysiology of the Nondipping Blood Pressure Pattern","volume":"80","author":"Huart","year":"2023","journal-title":"Hypertension"},{"key":"ref_6","first-page":"e86751","article-title":"Evaluation of Cardiovascular Disease Risk According to the Morningness-Eveningness Status in Adult Individuals","volume":"17","author":"Elibol","year":"2025","journal-title":"Cureus"},{"key":"ref_7","first-page":"31","article-title":"Assessment of Circadian Variations in Blood Pressure and Their Correlation with Sleep Patterns in Medical Students","volume":"30","author":"Arora","year":"2025","journal-title":"J. Heart Valve Dis."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3323","DOI":"10.2147\/IJGM.S521364","article-title":"Association Between the Circadian Rhythm of Arterial Blood Pressure and White Matter Lesions in Hospitalized Hypertensive Patients: A Cross-Sectional Study","volume":"18","author":"Shen","year":"2025","journal-title":"Int. J. Gen. Med."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"181","DOI":"10.1016\/S1566-0702(01)00238-7","article-title":"Non-dipper phenomenon in essential hypertension is related to blunted nocturnal rise and fall of sympatho-vagal nervous activity and progress in retinopathy","volume":"88","author":"Nakano","year":"2001","journal-title":"Auton. Neurosci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"632","DOI":"10.3109\/10641963.2013.776572","article-title":"The effect of non-dipper and dipper blood pressure patterns on aortic elasticity in patients with metabolic syndrome","volume":"35","author":"Kuzeytemiz","year":"2013","journal-title":"Clin. Exp. Hypertens."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Carollo, C., Vadal\u00e0, M., Sorce, A., Sinatra, N., Orlando, E., and Cirafici, E. (2025). Relationship Between Renal Resistive Index and Retinal Vascular Density in Individuals with Hypertension. Biomedicines, 13.","DOI":"10.20944\/preprints202501.0200.v1"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Cirillo, A., Huart, J., Taminiau, B., Descy, J., Saint-Remy, A., and Daube, G. (2021). Human Stool Metabolome Differs upon 24 h Blood Pressure Levels and Blood Pressure Dipping Status: A Prospective Longitudinal Study. Metabolites, 11.","DOI":"10.3390\/metabo11050282"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1795","DOI":"10.1016\/j.lfs.2004.08.034","article-title":"Plasma melatonin concentrations in hypertensive patients with the dipping and non-dipping blood pressure profile","volume":"76","author":"Zeman","year":"2005","journal-title":"Life Sci."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"425","DOI":"10.1016\/S0140-6736(07)60198-6","article-title":"The eye in hypertension","volume":"369","author":"Wong","year":"2007","journal-title":"Lancet"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"678","DOI":"10.1161\/HYPERTENSIONAHA.113.01519","article-title":"Retinal vasculature: A window on the brain","volume":"62","author":"Spence","year":"2013","journal-title":"Hypertension"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"356","DOI":"10.1093\/ajh\/hpab172","article-title":"Application of Optical Coherence Tomography Angiography Macular Analysis for Systemic Hypertension. A Systematic Review and Meta-analysis","volume":"35","author":"Anjos","year":"2022","journal-title":"Am. J. Hypertens."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1111\/ceo.12905","article-title":"Hypertensive eye disease: A review","volume":"45","author":"Symes","year":"2017","journal-title":"Clin. Exp. Ophthalmol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"188","DOI":"10.1016\/j.atherosclerosis.2017.11.001","article-title":"Retinal vascular imaging in cardiovascular medicine: New tools for an old examination","volume":"268","author":"Geraci","year":"2018","journal-title":"Atherosclerosis"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1094","DOI":"10.1161\/HYPERTENSIONAHA.111.189142","article-title":"Retinal microvasculature as a model to study the manifestations of hypertension","volume":"60","author":"Cheung","year":"2012","journal-title":"Hypertension"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1016\/j.pcad.2024.10.011","article-title":"Optical coherence tomography angiography in cardiovascular disease","volume":"87","author":"Runsewe","year":"2024","journal-title":"Prog. Cardiovasc. Dis."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"158","DOI":"10.1177\/1120672119880390","article-title":"Optical coherence tomography angiography and arterial hypertension: A role in identifying subclinical microvascular damage?","volume":"31","author":"Donati","year":"2021","journal-title":"Eur. J. Ophthalmol."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Niro, A., Sborgia, G., Lampignano, L., Giuliani, G., Castellana, F., and Zupo, R. (2022). Association of Neuroretinal Thinning and Microvascular Changes with Hypertension in an Older Population in Southern Italy. J. Clin. Med., 11.","DOI":"10.3390\/jcm11041098"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Lee, W.H., Park, J.H., Won, Y., Lee, M.W., Shin, Y.I., Jo, Y.J., and Kim, J.Y. (2019). Retinal Microvascular Change in Hypertension as measured by Optical Coherence Tomography Angiography. Sci. Rep., 9.","DOI":"10.1038\/s41598-018-36474-1"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"3505","DOI":"10.1007\/s00417-022-05706-6","article-title":"Retinal microvasculature and vasoreactivity changes in hypertension using optical coherence tomography-angiography","volume":"260","author":"Zeng","year":"2022","journal-title":"Graefes Arch. Clin. Exp. Ophthalmol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"6541","DOI":"10.1038\/s41598-020-63603-6","article-title":"Peripapillary microvascular changes in patients with systemic hypertension: An optical coherence tomography angiography study","volume":"10","author":"Shin","year":"2020","journal-title":"Sci. Rep."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"425","DOI":"10.1038\/s41371-025-01017-5","article-title":"The hidden role of left atrial strain: Insights into end-organ damage in dipper and nondipper hypertension","volume":"39","year":"2025","journal-title":"J. Hum. Hypertens."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"438","DOI":"10.1177\/00033197211050446","article-title":"Can Serum Endocan Levels be Used as an Early Prognostic Marker for Endothelial Dysfunction in COVID-19?","volume":"73","author":"Guzel","year":"2022","journal-title":"Angiology"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"8835","DOI":"10.2174\/0109298673349473250410132823","article-title":"Endothelial Function Biomarkers in Hypertension","volume":"32","author":"Vlachakis","year":"2025","journal-title":"Curr. Med. Chem."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1826","DOI":"10.1097\/HJH.0000000000002863","article-title":"Capillary vascular density in the retina of hypertensive patients is associated with a non-dipping pattern independent of mean ambulatory blood pressure","volume":"39","author":"Nolde","year":"2021","journal-title":"J. Hypertens."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Park, J., Song, W.K., Baek, M.S., Yoon, J., Lee, A., Kim, K.E., and Kook, M.S. (2025). Relationship between nocturnal blood pressure dip and \u03b2-parapapillary atrophy zone choroidal vessel density in normal-tension glaucoma patients. PLoS ONE, 20.","DOI":"10.1371\/journal.pone.0317468"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1177\/00369330211011175","article-title":"Optical coherence tomography measurements in patients with systemic hypertension","volume":"66","author":"Bursali","year":"2021","journal-title":"Scott. Med. J."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"765","DOI":"10.1161\/HYPERTENSIONAHA.110.157149","article-title":"Morning surge in blood pressure and cardiovascular risk: Evidence and perspectives","volume":"56","author":"Kario","year":"2010","journal-title":"Hypertension"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"2205050","DOI":"10.1080\/10641963.2023.2205050","article-title":"Effect of blood pressure variability on hypertensive retinopathy","volume":"45","author":"Jiao","year":"2023","journal-title":"Clin. Exp. Hypertens."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"149","DOI":"10.1097\/APO.0000000000000509","article-title":"The New Era of Retinal Imaging in Hypertensive Patients","volume":"11","author":"Tan","year":"2022","journal-title":"Asia Pac. J. Ophthalmol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"301","DOI":"10.1186\/s12944-024-02287-7","article-title":"Assessment of the impact of low-density lipoprotein cholesterol on retinal vessels using optical coherence tomography angiography","volume":"23","author":"He","year":"2024","journal-title":"Lipids Health Dis."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Wang-Evers, M., Casper, M.J., Glahn, J., Luo, T., Doyle, A.E., and Karasik, D. (2021). Assessing the impact of aging and blood pressure on dermal microvasculature by reactive hyperemia optical coherence tomography angiography. Sci. Rep., 11.","DOI":"10.1038\/s41598-021-92712-z"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"103969","DOI":"10.1016\/j.mvr.2019.103969","article-title":"Use of optical coherence tomography angiography for assessment of microvascular changes in the macula and optic nerve head in hypertensive patients without hypertensive retinopathy","volume":"129","author":"Hua","year":"2020","journal-title":"Microvasc. Res."},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Choi, J., and Kook, M.S. (2015). Systemic and Ocular Hemodynamic Risk Factors in Glaucoma. Biomed. Res. Int., 2015.","DOI":"10.1155\/2015\/141905"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"918","DOI":"10.1097\/IJG.0000000000001580","article-title":"Diurnal Measurements of Macular Thickness and Vessel Density on OCT Angiography in Healthy Eyes and Those with Ocular Hypertension and Glaucoma","volume":"29","author":"Milani","year":"2020","journal-title":"J. Glaucoma"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"603","DOI":"10.1016\/S0002-9394(14)70067-4","article-title":"Nocturnal arterial hypotension and its role in optic nerve head and ocular ischemic disorders","volume":"117","author":"Hayreh","year":"1994","journal-title":"Am. J. Ophthalmol."},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Liu, K., Xu, H., Jiang, H., Wang, H., Wang, P., and Xu, Y. (2020). Macular vessel density and foveal avascular zone parameters in patients after acute primary angle closure determined by OCT angiography. Sci. Rep., 10.","DOI":"10.1038\/s41598-020-73223-9"},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"van Koeverden, A.K., He, Z., Nguyen, C.T.O., Vingrys, A.J., and Bui, B.V. (2018). Systemic hypertension is not protective against chronic intraocular pressure elevation in a rodent model. Sci. Rep., 8.","DOI":"10.1038\/s41598-018-25264-4"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"101095","DOI":"10.1016\/j.preteyeres.2022.101095","article-title":"Retinal vessel diameters and function in cardiovascular risk and disease","volume":"91","author":"Hanssen","year":"2022","journal-title":"Prog. Retin. Eye Res."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"345","DOI":"10.1016\/j.ohc.2005.04.001","article-title":"The role of optic nerve blood flow in the pathogenesis of glaucoma","volume":"18","author":"Harris","year":"2005","journal-title":"Ophthalmol. Clin. N. Am."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"328","DOI":"10.3129\/i08-051","article-title":"Measuring and interpreting ocular blood flow and metabolism in glaucoma","volume":"43","author":"Harris","year":"2008","journal-title":"Can. J. Ophthalmol."}],"container-title":["Medicina"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1648-9144\/61\/10\/1801\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T04:27:51Z","timestamp":1760156871000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1648-9144\/61\/10\/1801"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,10,6]]},"references-count":45,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2025,10]]}},"alternative-id":["medicina61101801"],"URL":"https:\/\/doi.org\/10.3390\/medicina61101801","relation":{},"ISSN":["1648-9144"],"issn-type":[{"value":"1648-9144","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,10,6]]}}}