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Böhm EW, Pfeiffer N, Wagner FM, Gericke A. Methods to measure blood flow and vascular reactivity in the retina. Front Med (Lausanne) 2023; 9:1069449. [PMID: 36714119 PMCID: PMC9877427 DOI: 10.3389/fmed.2022.1069449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/23/2022] [Indexed: 01/14/2023] Open
Abstract
Disturbances of retinal perfusion are involved in the onset and maintenance of several ocular diseases, including diabetic retinopathy, glaucoma, and retinal vascular occlusion. Hence, knowledge on ocular vascular anatomy and function is highly relevant for basic research studies and for clinical judgment and treatment. The retinal vasculature is composed of the superficial, intermediate, and deep vascular layer. Detection of changes in blood flow and vascular diameter especially in smaller vessels is essential to understand and to analyze vascular diseases. Several methods to evaluate blood flow regulation in the retina have been described so far, but no gold standard has been established. For highly reliable assessment of retinal blood flow, exact determination of vessel diameter is necessary. Several measurement methods have already been reported in humans. But for further analysis of retinal vascular diseases, studies in laboratory animals, including genetically modified mice, are important. As for mice, the small vessel size is challenging requiring devices with high optic resolution. In this review, we recapitulate different methods for retinal blood flow and vessel diameter measurement. Moreover, studies in humans and in experimental animals are described.
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Král M, Svrčinová T, Hok P, Dorňák T, Rybáriková M, Mareš J, Kaňovský P, Šín M. Correlation between retinal oxygen saturation and the haemodynamic parameters of the ophthalmic artery in healthy subjects. Acta Ophthalmol 2022; 100:e1489-e1495. [PMID: 35599335 PMCID: PMC9790634 DOI: 10.1111/aos.15189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 05/11/2022] [Indexed: 12/30/2022]
Abstract
PURPOSE The aim of the study was to obtain the values of oxygen saturation in retinal vessels and ophthalmic blood flow parameters in a healthy Caucasian population and assess whether the oximetry parameters are affected by the flow rate or the vascular resistance. METHODS The spectrophotometric retinal oximetry and colour Doppler imaging (CDI) of retinal vessels were successfully performed with 52 healthy subjects (average age 29.7 ± 5.6 years). The retinal oximeter simultaneously measures the wavelength difference of haemoglobin oxygen saturation in retinal arterioles and venules. The arteriolar and venular saturation in both eyes was measured. The peak systolic (PSV) end diastolic (EDV) velocities, resistive (RI) and pulsatility (PI) indices were obtained for both eyes using CDI in the ophthalmic artery. A paired t-test and two sample t-tests were used for statistical analyses. The correlation was assessed using the Pearson coefficient correlation. RESULTS The mean oxygen saturation level was 96.9 ± 3.0% for the retinal arterioles and 65.0 ± 5.1% for the retinal venules. The A-V difference was 31.8 ± 4.6%. The mean of the measured haemodynamic parameters was PSV 46.6 ± 9.4 cm/s, EDV 12.0 ± 3.5 cm/s, PI 1.68 ± 0.38 and RI 0.74 ± 0.05. No significant difference in oxygen saturation and haemodynamic parameters was found between the left and the right eyes or the dominant and non-dominant eye. The oximetry and ultrasound values were sex independent. The Pearson correlation coefficient demonstrated a significant yet weak negative correlation between A-V difference and RI (r = -0.321, p = 0.020). CONCLUSIONS A negative correlation between A-V difference and resistance index was observed, suggesting that reduced oxygen consumption may reflect the increased vascular tone of the ophthalmic vessels, which is likely determined by autoregulatory mechanisms.
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Affiliation(s)
- Michal Král
- Department of NeurologyUniversity Hospital and Faculty of Medicine and Dentistry, Palacky University OlomoucOlomoucCzech Republic
| | - Tereza Svrčinová
- Department of NeurologyUniversity Hospital and Faculty of Medicine and Dentistry, Palacky University OlomoucOlomoucCzech Republic
| | - Pavel Hok
- Department of NeurologyUniversity Hospital and Faculty of Medicine and Dentistry, Palacky University OlomoucOlomoucCzech Republic
| | - Tomáš Dorňák
- Department of NeurologyUniversity Hospital and Faculty of Medicine and Dentistry, Palacky University OlomoucOlomoucCzech Republic
| | - Martina Rybáriková
- Department of OphthalmologyUniversity Hospital and Faculty of Medicine and Dentistry, Palacky University OlomoucOlomoucCzech Republic
| | - Jan Mareš
- Department of NeurologyUniversity Hospital and Faculty of Medicine and Dentistry, Palacky University OlomoucOlomoucCzech Republic
| | - Petr Kaňovský
- Department of NeurologyUniversity Hospital and Faculty of Medicine and Dentistry, Palacky University OlomoucOlomoucCzech Republic
| | - Martin Šín
- Department of OphthalmologyUniversity Hospital and Faculty of Medicine and Dentistry, Palacky University OlomoucOlomoucCzech Republic
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Abstract
Similar to other organs, the retina relies on tightly regulated perfusion and oxygenation. Previous studies have demonstrated that retinal blood flow is affected in a variety of eye and systemic diseases, including diabetic retinopathy, age-related macular degeneration, and glaucoma. Although measurement of peripheral oxygen saturation has become a standard clinical measurement through the development of pulse oximetry, developing a noninvasive technique to measure retinal oxygen saturation has proven challenging, and retinal oximetry technology currently remains inadequate for reliable clinical use. Here, we review current strategies and approaches, as well as several newer technologies in development, and discuss the future of retinal oximetry.
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Affiliation(s)
- Anupam K Garg
- Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA.,School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Darren Knight
- Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Leonardo Lando
- Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Daniel L Chao
- Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA.,School of Medicine, University of California San Diego, La Jolla, CA, USA.,Janssen Research and Development, Raritan, NJ, USA
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della Volpe Waizel M, Scholl HPN, Valmaggia C, Todorova MG. Retinal vessel oximetry in children with inherited retinal diseases. Acta Ophthalmol 2021; 99:52-60. [PMID: 32573052 DOI: 10.1111/aos.14466] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 04/21/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND Retinal vessel oximetry (RO) has been used to show altered metabolic function in patients with inherited retinal diseases (IRDs). The aim of this study was to investigate RO parameters of children with IRDs and presumed IRD carriers (pIRDc) and to compare them to controls. METHODS In this cross-sectional cohort study, 142 eyes from 71 Caucasian subjects were included: 40 eyes with IRDs, 26 eyes with pIRDc and 76 control eyes. The oxygen saturation was measured with the Retinal Vessel Analyser (IMEDOS Systems UG, Jena, Germany). Mean oxygen saturations in the peripapillary retinal arterioles (A-SO2 ; %) and venules (V-SO2 ; %) were estimated, and their difference (A-V SO2 ; %) was calculated. In addition, we evaluated the mean diameter in all major retinal arterioles (D-A; μm) and venules (D-V; μm). anova-based linear mixed-effects models were calculated with SPSS® . RESULTS In general, children suffering from IRDs differed from controls when the A-SO2 and A-V SO2 were taken into account: both the A-SO2 and the A-V SO2 were significantly increased (p = 0.012). In subgroup analyses, children suffering from rod-cone dystrophy (RCD) presented an A-SO2 increase (99.12 ± 8.24%) when compared to controls (91.33 ± 10.34%, p = 0.014) and pIRDc (92.37 ± 6.57%, p = 0.065). For V-SO2 significant changes in RCD (67.42 ± 9.19%) were found in comparison with controls (58.24 ± 11.74%, p < 0.041), pIRDc (56.67 ± 7.16%, p = 0.007), cone-rod dystrophies (CRD, 52.17 ± 5.32%, p < 0.001) and inherited macular dystrophies (IMD, 55.74 ± 6.96%, p = 0.004), In addition, A-V SO2 was decreased in RCD (31.69 ± 3.92%) when measured against CRD (41.9 ± 8.87%, p = 0.017) or IMD (39.52 ± 8.95%, p = 0.059). CONCLUSION In general, we found that children with IRDs presented early metabolic changes. Within IRDs, children with RCD showed more affected metabolic changes. Thus, RO may support early screening to rule out IRDs in children, and more precisely may help to differentiate those suffering from RCD.
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Affiliation(s)
- Maria della Volpe Waizel
- Department of Ophthalmology University of Basel Basel Switzerland
- Institute of Molecular and Clinical Ophthalmology Basel (IOB) Basel Switzerland
| | - Hendrik P. N. Scholl
- Department of Ophthalmology University of Basel Basel Switzerland
- Institute of Molecular and Clinical Ophthalmology Basel (IOB) Basel Switzerland
| | - Christophe Valmaggia
- Department of Ophthalmology University of Basel Basel Switzerland
- Department of Ophthalmology Cantonal Hospital St. Gallen St. Gallen Switzerland
| | - Margarita G. Todorova
- Department of Ophthalmology University of Basel Basel Switzerland
- Department of Ophthalmology Cantonal Hospital St. Gallen St. Gallen Switzerland
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Mohan A, Kemmanu V, Baliga S, Patil M, Madhavrao B, Webers CAB, Yadav NK, Shetty R, Berendschot TTJM. Retinal oximetry in normal and amblyopic children: a pilot study. Acta Ophthalmol 2019; 97:684-687. [PMID: 30843376 DOI: 10.1111/aos.14075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 02/02/2019] [Indexed: 11/28/2022]
Abstract
PURPOSE To study the retinal vascular oxygen saturation in amblyopic eyes and compare them to unaffected fellow eyes and eyes of normal subjects. METHODS A total of 32 amblyopic, 24 normal and 13 fellow eyes of patients below age of 18 were enrolled in this prospective observation study. Retinal oximetry was performed using the Oxymap T1 retinal oximeter. Retinal vascular oxygen saturations and diameters were compared between amblyopic eyes, normal eyes and unaffected fellow eyes. RESULTS The average age was 8.6 years in the amblyopia group (M:F 16:16) and 10.9 years in the normal group (M:F 7:5; p = 0.024). Median corrected distance visual acuity in the amblyopia group was 20/50; it was 20/20 in the other groups (p < 0.001). The average arteriolar and venous saturation in the amblyopia, normal and fellow group was 84.5% (95% CI: 82.6-86.4), 83.2% (95% CI: 80.7-85.6) and 80.8% (95% CI: 78.6-82.9) and 51.9% (95% CI: 50.4-53.4), 50.8% (95% CI: 48.2-53.4) and 49.3% (95% CI: 45.7-52.9). There was no statistically significant difference between the saturation values of the amblyopia group and the controls, however, significantly higher values were found in the amblyopia group compared to the fellow group for arteriolar and venous saturations (p = 0.013; p = 0.005). Arteriolar and venous diameters showed no significant difference between groups. CONCLUSION Amblyopic eyes showed higher mean oxygen saturations than the fellow eyes. This observation could be due to altered neuronal activity or could be due to a measurement artefact due to alterations in retinal reflectivity.
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Lim LS, Lim XH, Tan L. Retinal Vascular Oxygen Saturation and Its Variation With Refractive Error and Axial Length. Transl Vis Sci Technol 2019; 8:22. [PMID: 31403000 PMCID: PMC6685695 DOI: 10.1167/tvst.8.4.22] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 06/18/2019] [Indexed: 11/24/2022] Open
Abstract
Purpose To evaluate the relationships between refractive error, axial length (AL), and retinal vascular oxygen saturation in an adult population. Methods This was a hospital-based, prospective observational study. The left eyes of phakic adult subjects without media opacity were analyzed. Subjective undilated manifest refraction was performed, and refractive errors were defined as myopia (spherical equivalent [SE], <−1 D), emmetropia (SE between −1 D and +1 D) and hyperopia (SE >+1 D). Retinal oximetry was performed using the Oxymap system (Oxymap Inc., Reykjavik, Iceland). Multivariate linear regression models were constructed to assess the relationship between retinal vascular oxygen saturation, SE, and AL obtained with optical biometry, with adjustments for age, sex, race, blood pressure, hyperlipidemia, and diabetes mellitus. Results There were 85 subjects, with mean age of 66.1 ± 11.3 years. The majority were female (60%) and Chinese (84%). A total of 60% were myopic, 28% emmetropic, and 12% hyperopic. Mean SE was −5.29 ± 6.51 D and mean AL was 25.30 ± 2.99 mm. In multivariate analyses, more myopic SE and longer AL were associated with lower retinal arteriolar oxygen saturation (regression coefficient B = 0.61 [95% confidence interval, 0.28, 0.95], P = 0.001; and B = −1.13 [95% confidence interval, −1.71, −0.56], P < 0.001, respectively). Subjects with myopic SE and AL also had lower retinal arteriolar oxygen saturation than emmetropes and hyperopes (P = 0.03 and P = 0.02, respectively). Conclusions Eyes with more myopic SE and longer AL have lower retinal arteriolar oxygen saturation. Translational Relevance This study provides direct evidence of a link between retinal oxygenation and hypoxia and myopia by using a novel device that quantifies retinal vascular oxygenation in vivo.
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Affiliation(s)
- Laurence Shen Lim
- Singapore National Eye Centre, 11 Third Hospital Ave, Singapore 168751, Singapore.,Singapore Eye Research Institute, 11 Third Hospital Ave, Singapore 168751, Singapore
| | - Xian Hui Lim
- Singapore National Eye Centre, 11 Third Hospital Ave, Singapore 168751, Singapore
| | - Licia Tan
- Singapore National Eye Centre, 11 Third Hospital Ave, Singapore 168751, Singapore
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Retinal oximetry: Metabolic imaging for diseases of the retina and brain. Prog Retin Eye Res 2019; 70:1-22. [DOI: 10.1016/j.preteyeres.2019.04.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/27/2019] [Accepted: 04/10/2019] [Indexed: 12/20/2022]
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Yang Y, Yang D, Sun Y, Xie Y, Zhang Z, Li S, Wu S, Wang N. Retinal vessel oxygen saturation and vessel diameter in healthy individuals during high-altitude exposure. Acta Ophthalmol 2019; 97:279-286. [PMID: 30259682 DOI: 10.1111/aos.13897] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Accepted: 07/20/2018] [Indexed: 12/29/2022]
Abstract
PURPOSE To assess changes of retinal vessel oxygen saturation and vessel diameter in healthy individuals during high-altitude exposure. METHODS Retinal oxygen saturation and vessel diameter were obtained at sea level (SL, 40 m) and high altitude (HA, 3681 m) on 17 healthy individuals from Beijing (six males, 28.06 ± 8.06 years) using Oxymap T1 and then compared with 21 residents from Yushu (10 males, 28.63 ± 6.00 years). Systemic and ocular parameters were also measured before and after high-altitude exposure. Data were presented as mean ± SD and analysed using paired and independent Student t-test with significance accepted at p < 0.05. RESULTS Short-term high-altitude exposure of Beijing Group significantly affected all the systemic and ocular parameters, as well as retinal oxygen saturation and vessel diameter ranging from overall quadrant to different quadrants, other than retinal venous oxygen saturation and retinal arterial diameter. However, these changes were not evident in those permanently living at HA. Pearson's correlation analysis revealed correlations between retinal oxygen saturation and systemic and ocular parameters (all p < 0.05). The multivariate linear regression analysis indicated that retinal arterial oxygen saturation was significantly associated with arterial peripheral arterial oxygen saturation (SpO2 ) and subfoveal choroidal thickness. CONCLUSION Short-term exposure to HA induces retinal microcirculation disturbance and auto-regulatory response in healthy individuals, which is probably attributed to arterial SpO2 and endothelial dysfunction under hypoxic conditions.
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Affiliation(s)
- Yiquan Yang
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
- Beijing Institute of Ophthalmology Beijing Tongren Hospital Capital Medical University Beijing China
| | - Diya Yang
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
| | - Yunxiao Sun
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
- Beijing Institute of Ophthalmology Beijing Tongren Hospital Capital Medical University Beijing China
| | - Yuan Xie
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
- Beijing Institute of Ophthalmology Beijing Tongren Hospital Capital Medical University Beijing China
| | - Zheng Zhang
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
| | - Shuning Li
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
| | - Shizheng Wu
- Departments of Neurology The Qinghai Provincial People's Hospital Xining Qinghai China
| | - Ningli Wang
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
- Beijing Institute of Ophthalmology Beijing Tongren Hospital Capital Medical University Beijing China
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Liu X, He X, Yin Y, Zhang B, Sun S, Zhu J, Zou H, Wang L, Xu X. Retinal oxygen saturation in 1461 healthy children aged 7-19 and its associated factors. Acta Ophthalmol 2019; 97:287-295. [PMID: 30714353 PMCID: PMC6590240 DOI: 10.1111/aos.14043] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 01/09/2019] [Indexed: 11/30/2022]
Abstract
Purpose The aim of the present study was to investigate age‐specific normative retinal oxygen saturation values and explore the associated factors in healthy Chinese school‐aged children with different refractive statuses. Design Population‐based observational cross‐sectional study. Methods Children aged 7–19 years were enrolled. Each participant underwent a series of comprehensive ocular examinations, including axial length (AL), cycloplegic refraction and Oxymap T1 imagery following cycloplegia. The acquired oximetry images were measured, and the values of the retinal oxygen saturation parameters were calculated. The independent factors of the retinal oxygen saturation were analysed using multiple linear regression. The oxygen saturation of retinal arteries (SaO2) and veins (SvO2) as well as the differences between the arteries and veins (AVD) were measured as the main outcomes. Results In total, 1461 participants were included in the study. The mean age of the participants was 12.1 ± 3.2 years, and 53.0% were boys. The mean SaO2, SvO2 and AVD values were 83.7 ± 6.4%, 50.1 ± 5.4% and 33.6 ± 5.4%, respectively, and the values increased with age. Girls had higher SvO2 and lower AVD than boys (p < 0.05). The Pearson correlation coefficients among spherical equivalent (SE) and SaO2, SvO2 and AVD were −0.372, −0.203 and −0.240, respectively (all p < 0.001), while the correlations between AL and SaO2, SvO2 and AVD were 0.276, 0.106 and 0.221, respectively (all p < 0.001). The myopia group had significantly higher SaO2, SvO2 and AVD than the emmetropia and hyperopia groups (p < 0.001), but the high myopia group had lower SaO2 and SvO2 than the moderate myopia group. When age, gender, body mass index (BMI), intraocular pressure (IOP) and axial length (AL) were included as factors in the multiple regression, older age was associated with higher SaO2, SvO2 and AVD, while longer AL was associated with higher SaO2 and AVD. Gender was an independent factor predicting SvO2, while gender and BMI were the independent factors predicting AVD. Age explained more variance than AL in SaO2, SvO2 and AVD. Conclusions Our population‐based study provides age‐specific profiles of retinal oxygen saturation in Chinese children and adolescents. Older age and longer AL were important independent factors of increased retinal oxygen saturation.
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Affiliation(s)
- Xiaoxiao Liu
- Department of Preventative Ophthalmology Shanghai Eye Disease Prevention and Treatment Center Shanghai Eye Hospital Shanghai China
- Department of Ophthalmology Shanghai General Hospital Shanghai Jiao Tong University School of Medicine Shanghai Key Laboratory of Ocular Fundus Diseases Shanghai Engineering Center for Visual Science and Photomedicine Shanghai China
| | - Xiangui He
- Department of Preventative Ophthalmology Shanghai Eye Disease Prevention and Treatment Center Shanghai Eye Hospital Shanghai China
- Department of Maternal and Child Health School of Public Health Key Laboratory of Public Health Safety Ministry of Education Fudan University Shanghai China
| | - Yao Yin
- Department of Preventative Ophthalmology Shanghai Eye Disease Prevention and Treatment Center Shanghai Eye Hospital Shanghai China
| | - Bo Zhang
- Department of Preventative Ophthalmology Shanghai Eye Disease Prevention and Treatment Center Shanghai Eye Hospital Shanghai China
| | - Sifei Sun
- Jiading Center for Disease Prevention and Control Shanghai China
| | - Jianfeng Zhu
- Department of Preventative Ophthalmology Shanghai Eye Disease Prevention and Treatment Center Shanghai Eye Hospital Shanghai China
| | - Haidong Zou
- Department of Preventative Ophthalmology Shanghai Eye Disease Prevention and Treatment Center Shanghai Eye Hospital Shanghai China
- Department of Ophthalmology Shanghai General Hospital Shanghai Jiao Tong University School of Medicine Shanghai Key Laboratory of Ocular Fundus Diseases Shanghai Engineering Center for Visual Science and Photomedicine Shanghai China
| | - Ling Wang
- Department of Maternal and Child Health School of Public Health Key Laboratory of Public Health Safety Ministry of Education Fudan University Shanghai China
| | - Xun Xu
- Department of Preventative Ophthalmology Shanghai Eye Disease Prevention and Treatment Center Shanghai Eye Hospital Shanghai China
- Department of Ophthalmology Shanghai General Hospital Shanghai Jiao Tong University School of Medicine Shanghai Key Laboratory of Ocular Fundus Diseases Shanghai Engineering Center for Visual Science and Photomedicine Shanghai China
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Van Keer K, Van Keer J, Barbosa Breda J, Nassiri V, Van Cleemput J, Abegão Pinto L, Stalmans I, Vandewalle E. Retinal oxygen saturation as a non-invasive estimate for mixed venous oxygen saturation and cardiac output. Acta Ophthalmol 2019; 97:e308-e312. [PMID: 30280510 DOI: 10.1111/aos.13890] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 07/18/2018] [Indexed: 01/15/2023]
Abstract
PURPOSE To investigate the correlation between retinal vessel oxygen saturation and mixed venous oxygen saturation (SvO2-mixed ) and cardiac output (CO). METHODS Retinal arterial (SaO2-retinal ) and venous (SvO2-retinal ) oxygen saturation were measured non-invasively with dual-wavelength retinal oximetry in subjects receiving invasive measurements of SvO2-mixed and CO through right heart catheterization. Correlations were analysed using Spearman's rank correlation coefficients and linear regression models. RESULTS Fourteen patients (median age 62.7 years, range: 21-77) were included in the analysis. When adjusted for age, SvO2-retinal showed a positive correlation with SvO2-mixed (β = 0.80, p = 0.003). Retinal arteriovenous oxygen saturation difference was significantly correlated with the inverse of CO (Spearman's ρ = 0.59, p = 0.026). CONCLUSION This pilot study provides proof of concept for the use of retinal oximetry as a non-invasive tool to assess systemic cardiovascular function.
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Affiliation(s)
- Karel Van Keer
- Department of Ophthalmology University Hospitals Leuven Leuven Belgium
- Research Group Ophthalmology Department of Neurosciences KU Leuven Leuven Belgium
| | - Jan Van Keer
- Department of Cardiology University Hospitals Leuven Leuven Belgium
| | - João Barbosa Breda
- Department of Ophthalmology University Hospitals Leuven Leuven Belgium
- Research Group Ophthalmology Department of Neurosciences KU Leuven Leuven Belgium
- Department of Ophthalmology Centro Hospitalar São João Porto Portugal
| | | | | | - Luìs Abegão Pinto
- Department of Ophthalmology Lisbon North Hospital Centre Lisbon Portugal
| | - Ingeborg Stalmans
- Department of Ophthalmology University Hospitals Leuven Leuven Belgium
- Research Group Ophthalmology Department of Neurosciences KU Leuven Leuven Belgium
| | - Evelien Vandewalle
- Department of Ophthalmology University Hospitals Leuven Leuven Belgium
- Research Group Ophthalmology Department of Neurosciences KU Leuven Leuven Belgium
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Waizel M, Türksever C, Todorova MG. Normative values of retinal vessel oximetry in healthy children against adults. Acta Ophthalmol 2018; 96:e828-e834. [PMID: 30187646 DOI: 10.1111/aos.13726] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 01/21/2018] [Indexed: 01/15/2023]
Abstract
BACKGROUND Retinal oximetry (RO) has been established as a non-invasive method to analyse oxygen saturation in retinal vessels. The aim of our study was to compare the RO parameters of healthy children to those in adults. METHODS A total of 200 eyes of 104 healthy subjects were examined: 20 eyes of children aged <10 years and 62 eyes of children aged 10-19 years were compared to the eyes of adult controls from five different age groups (20-29 years:n = 24; 30-39 years:n = 32; 40-49 years:n = 15; 50-59 years:n = 20, 60-80 years:n = 27; n indicates the number of analysed eyes). The oxygen saturation was estimated with the oxygen saturation measurement tool of the Retinal Vessel Analyser (RVA; IMEDOS Systems UG, Jena, Germany). The global oxygen saturations, within 1.0-1.5 optic disc diameters from the disc margin, in the peripapillary retinal arterioles (A-SO2 ; %) and venules (V-SO2 ; %) were estimated and their difference (A-V SO2 ; %) was calculated. In addition, we evaluated the mean diameter in all four major retinal arterioles (D-A; μm) and venules (D-V; μm). The ratio between venular and arterial vessel diameter (D-V/A; μm) was calculated thereafter. For statistical evaluation, anova-based linear mixed-effects models were calculated with spss® . RESULTS Based on our results, younger children (<10 years) present a statistically significant lower A-SO2 and A-V SO2 when compared to adult subgroups. The D-A values revealed to be significantly lower in 10 + children when compared to the other groups, while the D-V values did not show significant differences. CONCLUSION These data indicate that the retinal oxygen metabolism changes throughout lifetime. Therefore, normative data for different age groups are mandatory.
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Affiliation(s)
- Maria Waizel
- Department of Ophthalmology; University of Basel; Basel Switzerland
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12
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Abstract
PURPOSE Continuous peripheral pulse oximetry for monitoring adequacy of oxygenation is probably the most important technological advance for patients' monitoring and safety in the last decades. Pulse oximetry has the disadvantage of measuring the peripheral circulation, and the only mean to measure oxygen content of the central circulation is by invasive technology. Determination of blood oxyhaemoglobin saturation in the retinal vessels of the eye can be achieved noninvasively through spectrophotometric retinal oximetry which provides access to the central nervous system circulation. The aim of the thesis was to determine whether retinal oximetry technique can be applied for estimation of the central nervous system circulation which until now has only been possible invasively. This was achieved by measuring oxyhaemoglobin saturation in three adult subject study groups: in people with central retinal vein occlusion (CRVO) to observe local tissue hypoxia, in patients with severe chronic obstructive pulmonary disease (COPD) on long-term oxygen therapy to observe systemic hypoxaemia and in healthy subjects during hyperoxic breathing to observe systemic hyperoxemia. In addition, the fourth study that is mentioned was performed to test whether retinal oximetry is feasible for neonates. METHODS Retinal oximetry in central retinal vein occlusion: Sixteen subjects with central retinal vein occlusion participated in the study. The oxyhaemoglobin saturation of the central retinal vein occlusion affected eye was compared with the fellow unaffected eye. Retinal oximetry in healthy people under hyperoxia: Thirty healthy subjects participated in the study, and the oxyhaemoglobin saturation of retinal arterioles and venules was compared between normoxic and hyperoxic breathing. Retinal oximetry in severe chronic obstructive pulmonary disease: Eleven patients with severe chronic obstructive pulmonary disease participated in the study. Retinal oximetry measurements were made with and without their daily supplemental oxygen therapy. Retinal arteriolar oxyhaemoglobin saturation when inspiring ambient air was compared with blood samples from the radial artery and finger pulse oximetry and healthy controls. The healthy control group was assembled from our database for comparison of oxyhaemoglobin saturation of retinal arterioles and venules during the ambient air breathing. The retinal oximeter is based on a conventional fundus camera and a specialized software. A beam splitter coupled with two high-resolution digital cameras allows for simultaneous acquisition of retinal images at separative wavelengths for calculation of oxyhaemoglobin saturation. In addition, retinal images of 28 full-term healthy neonates were obtained with scanning laser ophthalmoscope combined with modified Oxymap analysis software for calculation of the optical density ratio and vessel diameter RESULTS: Retinal oximetry in central retinal vein occlusion: Mean retinal venous oxyhaemoglobin saturation was 31 ± 12% in CRVO eyes and 52 ± 11% in unaffected fellow eyes (mean ± SD, n = 14, p < 0.0001). The arteriovenous oxygen difference (AV-difference) was 63 ± 11% in CRVO eyes and 43 ± 7% in fellow eyes (p < 0.0001). The variability of retinal venous oxyhaemoglobin saturation was considerable within and between eyes affected by CRVO. There was no difference in oxyhaemoglobin saturation of retinal arterioles between the CRVO eyes and the unaffected eyes (p = 0.49). Retinal oximetry in healthy people under hyperoxia: During hyperoxic breathing, the oxyhaemoglobin saturation in retinal arterioles increased to 94.5 ± 3.8% as compared with 92.0 ± 3.7% at baseline (n = 30, p < 0.0001). In venules, the mean oxyhaemoglobin saturation increased to 76.2 ± 8.0% from 51.3 ± 5.6% (p < 0.0001) at baseline. The AV-difference was markedly lower during hyperoxic breathing as compared with the normoxic breathing (18.3 ± 9.0% versus 40.7 ± 5.7%, p < 0.0001). Retinal oximetry in severe chronic obstructive pulmonary disease: During ambient air breathing, chronic obstructive pulmonary disease subjects had significantly lower oxyhaemoglobin saturation than healthy controls in both retinal arterioles (87.2 ± 4.9% versus 93.4 ± 4.3%, p = 0.02, n = 11) and venules (45.0 ± 10.3% versus 55.2 ± 5.5%, p = 0.01) but the AV-difference was not markedly different (p = 0.17). Administration of their prescribed oxygen therapy significantly increased the oxyhaemoglobin saturation in retinal arterioles (87.2 ± 4.9% to 89.5 ± 6.0%, p = 0.02) but not in venules (45.0 ± 10.3% to 46.7 ± 12.8%, p = 0.3). Retinal oximetry values were slightly lower than finger pulse oximetry (mean percentage points difference = -3.1 ± 5.5) and radial artery blood values (-5.0 ± 5.4). Retinal oximetry study in neonates: The modified version of the retinal oximetry instrument estimated the optical density ratio in retinal arterioles to be 0.256 ± 0.041 that was significantly different from the 0.421 ± 0.089 in venules (n = 28, p < 0.001, paired t-test). The vascular diameter of retinal arterioles was markedly narrower than of venules (14.1 ± 2.7 and 19.7 ± 3.7 pixels, p < 0.001). CONCLUSION The results of this thesis indicate that spectrophotometric retinal oximetry is sensitive to both local and systemic changes in oxyhaemoglobin saturation. Retinal oxyhaemoglobin saturation values are slightly lower than radial artery blood sample and finger pulse oximetry values. The discrepancies between the different modalities are expected to derive from countercurrent exchange between central retinal artery and vein within the optic nerve but calibration issues cannot be excluded as contributing to this difference. Despite these differences, the findings indicate the potential of retinal oximetry for noninvasive real-time measurements of oxyhaemoglobin saturation in central nervous system vessels. Following calibration upgrade and technological improvement, verification retinal oximetry may potentially be applied to critically ill and anaesthesia care patients. The study on combined scanning laser ophthalmoscope and retinal oximetry supports the feasibility of the technique for oximetry analysis in newly born babies.
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Told R, Boltz A, Schmetterer L, Garhöfer G, Sacu S, Schmidt-Erfurth U, Pollreisz A. Method comparison of two non-invasive dual-wavelength spectrophotometric retinal oximeters in healthy young subjects during normoxia. Acta Ophthalmol 2018; 96:e614-e618. [PMID: 29488329 DOI: 10.1111/aos.13719] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 01/10/2018] [Indexed: 01/14/2023]
Abstract
PURPOSE Spectrophotometric retinal oximetry is a non-invasive technology for measuring oxygen saturation in arterioles and venules (SaO2 , SvO2 ). We compared two commercially available systems: the Oxymap T1 (Oxymap ehf., Reykjavik, Iceland) and the Dynamic Vessel Analyzer (DVA, Imedos, Jena, Germany). METHODS Twenty healthy adults were included after giving informed consent. Two measurement cycles 30 min apart, including Oxymap T1, DVA, arterialized capillary blood draw of the earlobe (ScO2 ) and peripheral oxygen saturation using finger pulse oximetry (SpO2 ) were scheduled. RESULTS SaO2 (p > 0.0004) but not SvO2 (p < 0.05) was statistically significantly different between the retinal oximeters used. Agreement between devices using repeated SO2 measurements resulted in a standard deviation (SD) of differences of 3.5% in retinal arterioles and 4.8% in venules. Bland-Altman plot using the mean of a participant's two measurements from each device showed an average mean difference of 4.4% (95% confidence limits of agreement: -8.6 to 17.4) and -3.3% (95% confidence limits of agreement: -28.8 to 22.2) for SaO2 and SvO2 , respectively. Comparison of mean SaO2 and SvO2 with mean ScO2 and SpO2 indicated that SO2 measurements were generally higher in ScO2 and SpO2 . CONCLUSION This study shows very good repeatability for both devices, which is consistent with the literature. However, it does not show sufficient concordance between SaO2 measurements from both devices, indicating that patients should be followed by one device only. Differences in absorbance wavelengths used and image post-processing may explain the differences.
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Affiliation(s)
- Reinhard Told
- Department of Ophthalmology and Optometry; Vienna Clinical Trial Center (VTC); Medical University of Vienna; Vienna Austria
| | - Agnes Boltz
- Department of Ophthalmology and Optometry; Vienna Clinical Trial Center (VTC); Medical University of Vienna; Vienna Austria
| | - Leopold Schmetterer
- Department of Clinical Pharmacology; Medical University of Vienna; Vienna Austria
- Center for Medical Physics and Biomedical Engineering; Medical University of Vienna; Vienna Austria
- Singapore Eye Research Institute; Singapore National Eye Centre; Singapore Singapore
- Department of Ophthalmology; Lee Kong Chian School of Medicine; Nanyang Technological University; Singapore Singapore
- Ophthalmology and Visual Sciences Academic Clinical Program; Duke-NUS Medical School; Singapore Singapore
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology; Medical University of Vienna; Vienna Austria
| | - Stefan Sacu
- Department of Ophthalmology and Optometry; Vienna Clinical Trial Center (VTC); Medical University of Vienna; Vienna Austria
| | - Ursula Schmidt-Erfurth
- Department of Ophthalmology and Optometry; Vienna Clinical Trial Center (VTC); Medical University of Vienna; Vienna Austria
| | - Andreas Pollreisz
- Department of Ophthalmology and Optometry; Vienna Clinical Trial Center (VTC); Medical University of Vienna; Vienna Austria
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