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Nakazawa K, Higashide T, Tsuchiya S, Shioya S, Okayama M, Sugiyama K. Association of Ambulatory Blood Pressure and Other Factors With Intraocular Pressure-Related 24-Hour Contact Lens Sensor Profile in Untreated Glaucoma. Transl Vis Sci Technol 2022; 11:18. [PMID: 36223126 PMCID: PMC9583745 DOI: 10.1167/tvst.11.10.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To investigate the association of diurnal blood pressure (BP) and other factors with the intraocular pressure (IOP)–related 24-hour contact lens sensor (CLS) profile of patients with untreated glaucoma. Methods The prospective study included 82 patients with untreated normal-tension glaucoma. CLS measurements and ambulatory BP monitoring were performed simultaneously for 24 hours. The association between the mean arterial pressure (MAP) and CLS profile was examined for the daytime and nocturnal periods using linear regression analysis. The associations between other factors and the CLS profile were also examined. Results Multivariate analysis of data from 63 eligible patients showed that higher average MAPs were significantly associated with larger average nocturnal CLS values (β coefficient = 0.273; P = 0.023); a larger increase in the last CLS value (β coefficient = 0.366; P = 0.003); larger standard deviations (SDs) of CLS values for the daytime, nocturnal, and 24-hour periods (β coefficient = 0.407, 0.293, and 0.375; P < 0.001, P = 0.032 and 0.002, respectively); and higher average ocular pulse frequencies for the daytime, nocturnal, and 24-hour periods (β coefficient = 0.268, 0.380, and 0.403; P = 0.029, 0.002, and 0.001, respectively). Thicker subfoveal choroids and shorter axial length were significantly associated with larger SDs and larger average CLS values, respectively. Smaller anterior chamber volume and lower corneal hysteresis were associated with larger SDs or larger average ocular pulse amplitude. Conclusions Ambulatory BP and several ocular parameters were significantly associated with various parameters of the 24-hour CLS profile. Translational Relevance Ambulatory BP and ocular parameters may be modifiers of the 24-hour IOP-related profile of CLS.
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Affiliation(s)
- Kazuki Nakazawa
- Department of Ophthalmology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan.,Department of Ophthalmology, Hakui General Hospital, Ishikawa, Japan
| | - Tomomi Higashide
- Department of Ophthalmology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Shunsuke Tsuchiya
- Department of Ophthalmology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Satomi Shioya
- Department of Ophthalmology, Noto General Hospital, Ishikawa, Japan
| | - Masahiko Okayama
- Department of Ophthalmology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan.,Department of Ophthalmology, Nanto Municipal Hospital, Toyama, Japan
| | - Kazuhisa Sugiyama
- Department of Ophthalmology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
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Zhao M, Lam AK, Cheong AM. Structural and haemodynamic properties of ocular vasculature in axial myopia. Clin Exp Optom 2021; 105:247-262. [PMID: 34343434 DOI: 10.1080/08164622.2021.1943320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
The high prevalence of myopia has become a global concern, especially in East and Southeast Asia. Alarmingly, the prevalence of high myopia is increasing. Mechanical stretching caused by excessive eyeball elongation leads to various anatomical changes in the fundus. This stretching force may also lead to the development of vascular abnormalities, which tend to be subtle and easily overlooked. A healthy ocular vasculature is a prerequisite of adequate oxygen supply for normal retinal functions. This review summarises previous findings on structural and haemodynamic aspects of myopia-related vascular changes.
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Affiliation(s)
- Mei Zhao
- Centre for Myopia Research, School of Optometry, Faculty of Health and Social Science, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Andrew Kc Lam
- Centre for Myopia Research, School of Optometry, Faculty of Health and Social Science, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Allen My Cheong
- Centre for Myopia Research, School of Optometry, Faculty of Health and Social Science, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
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Intraocular Temperature at Different Sites in Eye Measured at the Beginning of Vitreous Surgery. J Clin Med 2021; 10:jcm10153412. [PMID: 34362195 PMCID: PMC8348370 DOI: 10.3390/jcm10153412] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 07/25/2021] [Accepted: 07/28/2021] [Indexed: 11/17/2022] Open
Abstract
The temperature of the vitreous has been reported to vary during cataract and vitreous surgery. We measured intraocular temperature at four intraocular sites; the anterior chamber (AC), just behind the crystalline lens, mid-vitreous, and just anterior to the optic disc (OD) at the beginning of vitrectomy with a thermoprobe in 48 eyes. The temperatures were compared in three groups; eyes that underwent vitrectomy for the first time (Group V, n = 30), eyes that had previous vitrectomy and the vitreous cavity had been filled with balanced salt solution (BSS; Group A, n = 12), and eyes that had previous vitrectomy and the vitreous cavity was filled with silicone oil (Group S, n = 6). There was a gradient in the temperature in all groups, i.e., it was lowest in the AC, and it increased at points closer to the retina. The intraocular temperature was significantly correlated with the type of fluid in the vitreous cavity. The mean intraocular temperatures were not significantly different in Groups V and A, but they were significantly higher in Group S. Clinicians should be aware of the differences in the temperature at the different intraocular sites because the temperatures may affect the physiology of the retina and the recovery process.
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Kuroda Y, Uji A, Yoshimura N. Factors associated with optic nerve head blood flow and color tone: a retrospective observational study. Graefes Arch Clin Exp Ophthalmol 2016; 254:963-70. [PMID: 26728756 DOI: 10.1007/s00417-015-3247-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 12/09/2015] [Accepted: 12/16/2015] [Indexed: 10/22/2022] Open
Abstract
PURPOSE To investigate the relationship between optic nerve head (ONH) blood flow and color tone. METHODS Retrospective observational study conducted between February 2014 and August 2014. We examined 29 eyes of 17 young healthy subjects and 37 eyes of 26 cataract patients undergoing cataract surgery. Blood flow was measured using laser speckle flowgraphy, and color tone was quantified using the public domain ImageJ software. Blood flow and color tone of the ONH before and after cataract surgery were compared. The influence of age, axial length, and color tone on ONH blood flow were also investigated. RESULTS Mean blur rate (MBR) in the ONH decreased with increasing age (R = -0.437, P < 0.001) and axial length (R = -0.306, P = 0.012). In young subjects, ONH redness had a moderate positive correlation with MBR (R = 0.376, P = 0.044); however, this correlation was not observed in the study population as a whole (R = 0.066, P = 0.601). MBR in the ONH was higher after cataract surgery (P < 0.001). Moreover, the ONH redness reduced postoperatively from that preoperatively (P < 0.001). An increase in MBR after cataract surgery correlated with improved visual acuity (R = -0.399, P = 0.014) and decreased redness the of ONH (R = -0.433, P < 0.01). CONCLUSIONS Ocular blood flow decreased in older people and in myopic eyes. The reddish appearance of the ONH was not an indicator of a circulatory condition, particularly in older people. Lens opacity appeared to underestimate hemodynamic quantification using laser speckle flowgraphy.
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Affiliation(s)
- Yoshimasa Kuroda
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Akihito Uji
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, 606-8507, Japan.
| | - Nagahisa Yoshimura
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, 606-8507, Japan
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Yang YS, Koh JW. Choroidal Blood Flow Change in Eyes with High Myopia. KOREAN JOURNAL OF OPHTHALMOLOGY 2015; 29:309-14. [PMID: 26457036 PMCID: PMC4595256 DOI: 10.3341/kjo.2015.29.5.309] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 03/31/2015] [Indexed: 12/04/2022] Open
Abstract
Purpose To evaluate choroidal blood flow changes in eyes with high myopia according to the pulsatile components of ocular blood flow analysis. Methods A total of 104 subjects (52 males and 52 females) were included in this study. One eye of each participant was randomly selected and assigned to one of four refractive groups, designated as, hyperopes (n = 20; refractive error, ≥+1.00 diopter [D]), emmetropes (n = 28; refractive error, ±0.75 D), lower myopes (n = 33; refractive error, -1.00 to -4.75 D), and high myopes (n = 23; refractive error, ≤-5.00 D). Components of pulse amplitude (OBFa), pulse volume (OBFv), pulse rate (OBFr), and pulsatile ocular blood flow (POBF) were analyzed using a blood flow analyzer. Intraocular pressure and axial length were measured. Results Pulsatile components of OBFa, OBFv, and POBF showed positive correlations with refractive error and showed negative correlations with axial length (r = 0.729, r = 0.772, r = 0.781, respectively, all p < 0.001; r = -0.727, r = -0.762, r = -0.771, respectively, all p < 0.001). The correlations of refractive error and axial length with OBFr were irrelevant (r = -0.157, p = 0.113; r = 0.123, p = 0.213). High myopes showed significantly lower OBFa, OBFv, and POBF than the other groups (all p < 0.001). Conclusions Axial length changes in high myopes potentially influence choroidal blood flow, assuming the changes are caused by narrowing of the choroidal vessel diameter and increasing rigidity of the choroidal vessel wall. These finding explains the influence of axial length on OBFa, OBFv, and POBF, but not on OBFr. Thus, changes in axial length and the possible influence of these changes on the physical properties of choroidal vessels is the mechanism believed to be responsible for putting high myopes at risk for ocular vascular diseases.
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Affiliation(s)
- Young Seong Yang
- Department of Ophthalmology, Chosun University School of Medicine, Gwangju, Korea
| | - Jae Woong Koh
- Department of Ophthalmology, Chosun University School of Medicine, Gwangju, Korea
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Mamikonyan VR, Galoyan NS, Kazaryan EE, Kharlap SI, Shmeleva-Demir OA, Andzhelova DV, Rafaelyan AA, Kakunina TA. [Effects of blood flow properties on ocular hemodynamics]. Vestn Oftalmol 2015; 131:17-21. [PMID: 26310002 DOI: 10.17116/oftalma2015131317-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
AIM to study the effects of blood rheology on ocular blood flow (OBF) parameters and estimated individual normal range of intraocular pressure (IOP). MATERIAL AND METHODS A total of 15 patients (15 eyes) taking warfarin were enrolled. Volumetric parameters and linear velocity of OBF under warfarin treatment and after its cessation were obtained by means of flowmetry (Paradigm's Blood Flow Analyzer) and color Doppler flow mapping (Voluson 730), respectively. On the basis of flowmetry results an individual normal range of IOP was calculated in all patients. RESULTS Pulsatile OBF does not appear to correlate with warfarin-induced changes in blood rheology (p = 0.09), however, depends on IOP fluctuations (p = 0.02). Resistance index of retinal vessels is found to rise significantly with increasing blood viscosity (p < 0.05). CONCLUSION The use of warfarin, an indirect thrombin inhibitor, has no effect on estimated individual normal range of IOP, which is crucial for glaucoma diagnosis and monitoring.
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Affiliation(s)
- V R Mamikonyan
- Research Institute of Eye Diseases, 11 A, B Rossolimo St., Moscow, Russian Federation, 119021
| | - N S Galoyan
- Research Institute of Eye Diseases, 11 A, B Rossolimo St., Moscow, Russian Federation, 119021
| | - E E Kazaryan
- Research Institute of Eye Diseases, 11 A, B Rossolimo St., Moscow, Russian Federation, 119021
| | - S I Kharlap
- Research Institute of Eye Diseases, 11 A, B Rossolimo St., Moscow, Russian Federation, 119021
| | - O A Shmeleva-Demir
- Research Institute of Eye Diseases, 11 A, B Rossolimo St., Moscow, Russian Federation, 119021
| | - D V Andzhelova
- Research Institute of Eye Diseases, 11 A, B Rossolimo St., Moscow, Russian Federation, 119021
| | - A A Rafaelyan
- Research Institute of Eye Diseases, 11 A, B Rossolimo St., Moscow, Russian Federation, 119021
| | - T A Kakunina
- Research Institute of Eye Diseases, 11 A, B Rossolimo St., Moscow, Russian Federation, 119021
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Pallikaris IG, Dastiridou AI, Tsilimbaris MK, Karyotakis NG, Ginis HS. Ocular rigidity. EXPERT REVIEW OF OPHTHALMOLOGY 2014. [DOI: 10.1586/eop.10.30] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Turk A, Mollamehmetoglu S, Imamoglu HI, Kola M, Erdol H, Akyol N. Effects of phacoemulsification surgery on ocular hemodynamics. Int J Ophthalmol 2013; 6:537-41. [PMID: 23991393 DOI: 10.3980/j.issn.2222-3959.2013.04.24] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 07/09/2013] [Indexed: 11/02/2022] Open
Abstract
AIM To evaluate the possible effects of phacoemulsification cataract surgery on ocular hemodynamics. METHODS In this prospective study, intraocular pressure (IOP), pulsatile ocular blood flow (POBF), and ocular pulse amplitude (OPA) were measured pre-operatively (baseline) and at 1 week and 3 weeks postoperation in 52 eyes of 26 patients (mean age 63.15±10.25 years) scheduled for unilateral phacoemulsification cataract surgery with intraocular lens implantation. In all of the eyes, a blood flow analyzer (Paradigm DICON; Paradigm Medical Industries Inc.; USA) was used to obtain measurements of IOP, POBF, and OPA. The data obtained from operated eyes were compared statistically to untreated fellow phakic eyes of the patients. RESULTS For operated eyes, the mean baseline IOP, POBF, and OPA values were 15.9±4.64mmHg, 17.41±4.84µL/s, and 2.91±1.12mmHg, respectively. The IOP, POBF, and OPA values were 17.19±4.34mmHg, 17.56±6.46µL/s, and 3.12±1.1mmHg, respectively, in the nonoperated control eyes. Statistically significant differences from baseline measurements were not observed 1 week and 3 weeks postoperation for the operated or nonoperated eyes. There were also no statistically significant differences in any measurements between the operated and nonoperated eyes in all the examination periods (P>0.05 for all). CONCLUSION Uncomplicated phacoemulsification surgery does not affect ocular hemodynamics in normotensive eyes with cataracts.
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Affiliation(s)
- Adem Turk
- Department of Ophthalmology, School of Medicine, Karadeniz Technical University, Trabzon 61080, Turkey
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Yılmaz T, Güler M, Turkcuoglu P, Artas H, Ulku G, Arslanhan O, Yiğit M. The effect of anisometropic amblyopia on retrobulbar blood flow parameters. Anisometropic amblyopia and retrobulbar blood flow. Int Ophthalmol 2012; 32:357-60. [PMID: 22552580 DOI: 10.1007/s10792-012-9572-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Accepted: 04/15/2012] [Indexed: 11/28/2022]
Abstract
To look for a correlation between or the effect of anisometropia amblyopia on retrobulbar blood flow parameters. Peak systolic velocity (PSV) and end-diastolic velocity (EDV) of the ophthalmic artery (OA), central retinal artery (CRA), and temporal posterior ciliary artery (tPCA) were measured with color Doppler imaging, and systolic/diastolic ratio, resistivity index (RI), and pulsatility index (PI) were computed in 42 patients with anisometropic amblyopia. The mean PSV of OA, CRA, and tPCA in amblyopic and fellow eyes were 62.69 ± 24.04, 62.64 ± 20.18; 9.28 ± 3.71, 10.27 ± 4.18; 10.81 ± 4.59, 11.28 ± 4.91, respectively. The mean EDV of OA, CRA, and tPCA in amblyopic and fellow eyes were 15.87 ± 11.31, 14.52 ± 6.54; 2.48 ± 1.17, 2.62 ± 2.06; 3.04 ± 2.34, 3.14 ± 2.18, respectively. The mean RI of OA, CRA, and tPCA in amblyopic and fellow eyes were 0.76 ± 0.08, 0.76 ± 0.08; 0.72 ± 0.08, 0.74 ± 0.95; 0.72 ± 0.09, 0.72 ± 0.08, respectively. The mean PI of OA, CRA, and tPCA in amblyopic and fellow eyes were 1.77 ± 0.42, 1.81 ± 0.46; 01.58 ± 0.42, 1.59 ± 0.43; 1.54 ± 0.43, 1.58 ± 0.49, respectively. There was no statistically significant difference in any of the measured parameters between the amblyopic and fellow eyes. Anisometropic amblyopia did not cause any change in retrobulbar blood flow in amblyopic eyes.
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Affiliation(s)
- Turgut Yılmaz
- Department of Ophthalmology, Elazığ Training and Research Hospital, Elazig, Turkey
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Plange N, Rennings C, Herr A, Weber A, Roessler GF, Mazinani BE, Kaup M, Remky A. Ocular pulse amplitude before and after cataract surgery. Curr Eye Res 2011; 37:115-9. [PMID: 22007729 DOI: 10.3109/02713683.2011.626910] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To investigate the impact of cataract surgery on the association of the ocular pulse amplitude (OPA) and intraocular pressure (IOP) with respect to the interpretation of OPA as an estimate of ocular blood flow. METHODS Twenty-four patients with cataract were included in a clinical study. OPA was measured using dynamic contour tonometry (DCT, Pascal(®), SMT Swiss Microtechnology AG, Switzerland). IOP was measured by means of Goldmann applanation tonometry (IOP GAT) and DCT (IOP DCT). All measurements were performed before and one day after cataract surgery. RESULTS At baseline, OPA was correlated to IOP GAT (r = 0.67, P = 0.0002) and IOP DCT (r = 0.82, P < 0.0001), but not to age or axial length. Postoperative OPA was correlated to IOP GAT (r = 0.67, P = 0.0002) and IOP DCT (r = 0.65, P = 0.0004). In 17 patients, IOP GAT decreased after surgery (IOP DCT n = 14), whereas an increase was apparent in seven patients (IOP DCT n = 10). The mean absolute deviation of IOP GAT pre- to post-surgery was 4.54 mmHg ± 2.47 (range 1-10 mmHg) and 5.4 mmHg ± 3.2 (range 1.1-13.1 mmHg) for IOP DCT. The changes of OPA were significantly correlated to changes in IOP GAT (r = 0.48, P = 0.017) and IOP DCT (r = 0.60, P = 0.001). IOP GAT and IOP DCT changes were not correlated to changes in corneal thickness. CONCLUSIONS The OPA measured with the Pascal(®) device seems to be dependent on IOP changes. Particular caution should be taken in the interpretation of OPA in estimating pulsatile ocular blood flow.
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Affiliation(s)
- Niklas Plange
- Department of Ophthalmology, RWTH Aachen University, Aachen, Germany.
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Govêia CS, Magalhães E. Ropivacaine in peribulbar anesthesia - vasoconstrictive properties. Rev Bras Anestesiol 2011; 60:495-512. [PMID: 20863930 DOI: 10.1016/s0034-7094(10)70061-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 05/03/2010] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND AND OBJECTIVES Peribulbar anesthesia can reduce ocular blood flow (OBF) by increasing intraocular pressure (IOP) or due to the action of drugs. Ropivacaine has low toxicity and intrinsic vasoconstrictive properties, yet to be proven on the ocular vasculature. Measurements of ocular pulse amplitude (OPA) allow the indirect evaluation of the OBF. The objective of the present study was to evaluate through the OBF the vasoconstrictive properties of ropivacaine in peribulbar anesthesia. METHODS Forty eyes undergoing peribulbar anesthesia with 7 mL of anesthetic solution without vasoconstrictor were randomly divided into two groups: ropivacaine (n = 20) and bupivacaine (n = 20). The IOP, ocular perfusion pressure (OPP), OPA, hemodynamic parameters, and the degree of akinesia before and 5 and 10 minutes after the blockade were evaluated. A dynamic contour tonometer was used to evaluate ocular parameters. Sedation was similar in both groups. RESULTS A significant variation in hemodynamic parameters and intensity of the motor blockade was not observed between groups. Differences in IOP, OPP, and OPA (p < 0.05) were observed between both groups at 5 and 10 minutes. The variation of IOP at 5 and 10 minutes was -0.88% and -4.54%, respectively with ropivacaine, and 17.61% and 16.56% with bupivacaine. The change in OPP after 5 and 10 minutes was 1.5% and 4.2% with ropivacaine, and -7% and -6% with bupivacaine. Ocular pulse amplitude varied -55.59% and -59.67% with ropivacaine at 5 and 10 minutes, and -34.71% and -28.82% with bupivacaine. CONCLUSIONS Ropivacaine reduced more intensely the ocular pulse amplitude despite little changes in IOP and OPP. The reduction in ocular blood flow caused by ropivacaine can be attributed to its vasoconstrictive effect.
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Maleki N, Dai W, Alsop DC. Blood flow quantification of the human retina with MRI. NMR IN BIOMEDICINE 2011; 24:104-111. [PMID: 20862658 DOI: 10.1002/nbm.1564] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 04/21/2010] [Indexed: 05/29/2023]
Abstract
The purpose of this study was to investigate the feasibility of measuring blood flow to the retina using arterial spin labeling MRI, a quantitative, noninvasive tomographic technique. Blood flow imaging was performed in a single axial slice through both eyes of five healthy volunteers with no history of retinal diseases. The imaging was optimized to minimize the errors from motion and nonuniform magnetic fields caused by proximity to the sinuses. Key hemodynamic factors for flow quantification, including arterial transit delay and the apparent decay time of the signal, were estimated by repeated measurements with different arterial spin labeling timing. A clearly elevated signal, consistent with the anatomical location of the retina, was observed in all subjects. The measured blood flow to a 1 cm × 1.47 cm section of the retina, centered on the fovea, was 1.75 ± 0.54 µL/mm(2) /min (total blood flow of 261 ± 87 µL/min). The arterial transit delay from a labeling plane 5 cm below the slice was 1137 ± 288 ms. These results establish the feasibility of measuring blood flow to the retina with MRI, and support the future characterization of the healthy and diseased ocular circulation with this method.
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Affiliation(s)
- Nasim Maleki
- Department of Psychiatry, McLean Hospital, Harvard Medical School, Boston, MA, USA.
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Berisha F, Findl O, Lasta M, Kiss B, Schmetterer L. A study comparing ocular pressure pulse and ocular fundus pulse in dependence of axial eye length and ocular volume. Acta Ophthalmol 2010; 88:766-72. [PMID: 20337602 DOI: 10.1111/j.1755-3768.2009.01577.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE There is a long-standing discussion about whether myopia is associated with decreased choroidal blood flow, as suggested by pneumotonometric measurements of pulsatile ocular blood flow (POBF). However, it has been noted previously that calculations of POBF depend on intraocular volume. METHODS In the present study we investigated this volume dependence through the comparison of ocular pressure pulse and ocular fundus pulse. Fifty-one healthy participants with different refractive errors participated in the study. Pulse amplitude (PA) and POBF were measured using pneumotonometry. Fundus pulsation amplitude (FPA) was measured with laser interferometry. Axial eye length (AEL) was measured with partial coherence interferometry. A mathematical model was used to calculate choroidal volume changes based on FPA. The ocular pressure pulse was converted into pulse volume (PV) according to the standard procedure used for pneumotonometry. RESULTS PA and POBF were found to decrease with increasing axial length (r = -0.55, p < 0.001 and r = -0.57, p < 0.001, respectively). A similar relationship existed for PV (r = -0.57, p < 0.001) and FPA (r = -0.46, p = 0.001). In addition, there was a significant association between PV and choroidal volume change during the cardiac cycle (r = 0.61, p < 0.001). CONCLUSION The present study confirms experimentally that PA, FPA and POBF are dependent on ocular volume and indicates that the pulsatile component of ocular blood flow is not reduced in myopic patients. Accordingly, the relationship between AEL and POBF described previously appears to be a consequence of different ocular volumes. Our findings have important implications for studies using PA or POBF.
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Affiliation(s)
- Fatmire Berisha
- Department of Clinical Pharmacology, Medical University of Vienna, Austria
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Kowalska MA, Kasprzak HT, Iskander DR. Comparison of high-speed videokeratoscopy and ultrasound distance sensing for measuring the longitudinal corneal apex movements. Ophthalmic Physiol Opt 2010; 29:227-34. [PMID: 19422553 DOI: 10.1111/j.1475-1313.2009.00648.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two different methods to measure binocular longitudinal corneal apex movements were synchronously applied. High-speed videokeratoscopy at a sampling frequency of 15 Hz and a custom-designed ultrasound distance sensor at 100 Hz were used for the left and the right eye, respectively. Four healthy subjects participated in the study. Simultaneously, cardiac electric cycle (ECG) was registered for each subject at 100 Hz. Each measurement took 20 s. Subjects were asked to suppress blinking during the measurements. A rigid headrest and a bite-bar were used to minimize undesirable head movements. Time, frequency and time-frequency representations of the acquired signals were obtained to establish their temporal and spectral contents. Coherence analysis was used to estimate the correlation between the measured signals. The results showed close correlation between both corneal apex movements and the cardiopulmonary system. Unraveling these relationships could lead to better understanding of interactions between ocular biomechanics and vision. The advantages and disadvantages of the two methods in the context of measuring longitudinal movements of the corneal apex are outlined.
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Affiliation(s)
- Malgorzata A Kowalska
- Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wrocław, Poland.
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Abstract
BACKGROUND High myopia is associated with a decreased ocular blood flow. In some cases this ocular ischemia may be the cause of severe visual loss. METHODS Three patients with high myopia and progressive loss of visual acuity had a diagnosis of ocular ischemia by color Doppler. Intravenous prostaglandin E1, a powerful vasodilator of the microcirculation, was used to treat the ocular ischemia in all 3 patients. RESULTS The visual acuity improved in all three cases with one patient improving from 20/100 to 20/30. The mean deficit of the visual fields in this patient improved from -19.08 to -9.52 after treatment. The treatment was repeated every 6 weeks to 8 weeks. CONCLUSION Patients with high myopia and progressive visual acuity loss should be evaluated for ocular ischemia. Intravenous prostaglandin E1 should be considered in those cases of ocular ischemia with visual loss. Unfortunately the effect does not last for more than 6 weeks to 8 weeks and needs to be repeated at this interval for extended periods.
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Comparisons of intraocular pressure measurements: Goldmann applanation tonometry, noncontact tonometry, Tono-Pen tonometry, and dynamic contour tonometry. Eye (Lond) 2009; 23:1582-8. [PMID: 19407845 DOI: 10.1038/eye.2009.77] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Affiliation(s)
- Christoph Kniestedt
- Department of Ophthalmology, University Hospital Zurich (USZ), Zurich, Switzerland
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Kim SK, Cho BJ, Hong S, Kang SY, Kim JS, Kim CY, Seong GJ. Pulsatile ocular blood flow in healthy Koreans. KOREAN JOURNAL OF OPHTHALMOLOGY 2008; 22:6-9. [PMID: 18323699 PMCID: PMC2629955 DOI: 10.3341/kjo.2008.22.1.6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
PURPOSE To determine the normal reference range of pulsatile ocular blood flow (POBF) values in healthy Korean subjects and to find out the factors that may affect them. METHODS A total of 280 eyes of 280 normal subjects were included in this study. Best corrected visual acuity (BCVA), intraocular pressure (IOP), axial length, POBF, systemic blood pressure, and pulse rate were measured. The mean, standard deviation, range, and the 5th and 95th percentiles of POBF were calculated, and the influences of various parameters to POBF were determined by multiple regression analyses. RESULTS The mean POBF value was 766.0+/-221.6 microl/min in men and 1021.1+/-249.5 microl/min in women. The 5th and 95th percentiles for POBF values were 486.0 microl/min and 1140.0 microl/min in men and 672.0 microl/min and 1458.0 microl/min in women. The POBF values were significantly influenced by gender, mean blood pressure, pulse rate, and axial length. CONCLUSIONS Even though the POBF values were influenced by gender, BP, and axial length, we could define the normal reference range of POBF in healthy Koreans.
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Affiliation(s)
- Seung Kab Kim
- Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea
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Riva CE, Schmetterer L. Microcirculation of the Ocular Fundus. Microcirculation 2008. [DOI: 10.1016/b978-0-12-374530-9.00018-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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Yu BSY, Lam AKC. Technical note: How many readings are required for an acceptable accuracy in pulsatile ocular blood flow assessment? Ophthalmic Physiol Opt 2007; 27:213-9. [PMID: 17324213 DOI: 10.1111/j.1475-1313.2006.00463.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE Pulsatile ocular blood flow (POBF) assessment aids the diagnosis of ocular diseases with defective ocular haemodynamics, such as glaucoma. Although each successful POBF measure given by the instrument represents five 'repeatable' pulses, there has been no study verifying how repeatable they are. There is also no report on the minimal number of measurements for an acceptable accuracy. METHODS Forty-three healthy young subjects were recruited and each subject had five consecutive POBF measurements obtained from one randomly selected eye. The coefficient of variation was calculated from the raw data of the five 'repeatable' pulses. The average from five consecutive measurements was considered as the standard for comparison with the first, average of the first two, the first three and the first four measurements. The 95% limits of agreement were determined using the Bland and Altman approach. RESULTS The coefficient of variation was greater than the manufacturer's claim of within 10%. The mean (+/-S.D.) POBF calculated from five consecutive measures was 732.5 +/- 243.2 microL min(-1). The mean (+/-S.D.) difference between the standard POBF and the first, average of the first two, the first three and the first four measurements was (in microL min(-1)): 12.5 +/- 59.8, 7.8 +/- 42.1, 9.6 +/- 32.5 and 3.7 +/- 19.6 respectively. The corresponding 95% limits of agreement were (in microL min(-1)): +/-117.2, +/-82.6, +/-63.8 and +/-38.4 respectively. CONCLUSIONS As the five 'repeatable' pulses were not as repeatable as the manufacturer claims, practitioners should not rely on one single POBF measure. An average of three consecutive measurements will be adequate to detect the minimum reported difference in POBF between glaucoma and normal patients.
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Affiliation(s)
- Bibianna S Y Yu
- School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
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Januleviciene I, Kuzmiene L, Sliesoraityte I. Comparison of intraocular pressure fluctuations measured by goldmann applanation tonometer and pulsatile ocular blood flow analyser. INTERNATIONAL JOURNAL OF BIOMEDICAL SCIENCE : IJBS 2006; 2:428-33. [PMID: 23675012 PMCID: PMC3614641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Intraocular pressure (IOP) is the major known risk factor in glaucoma and the primer mover of the functional damage in glaucomatous patients but it is not a unique determinant of glaucomatous damage. Clinical assessment of glaucoma patients may not be a true reflection of overall IOP control. Evaluation of the effect of glaucoma medication is restricted by measurement of IOP as a dynamic physiological parameter. PURPOSE To compare IOP fluctuations over time using Goldmann applanation tonometry (IOPGAT) and pulsatile ocular blood flow analyzer (IOP-POBFA) under the Dorzolamide/timolol or latanoprost treatment regimes. DESIGN Prospective 1 year follow-up study. PARTICIPANTS 30 randomly chosen controlled open angle glaucoma patients (60 eyes): 16 patients (32 eyes) receiving Dorzolamide/timolol fixed combination (D/T) and 14 (28 eyes) latanoprost 0.005% treatment. MAIN OUTCOME MEASURES Changes in IOP and perfusion pressure dynamics. RESULTS THERE WAS NO STATISTICALLY SIGNIFICANT DIFFERENCE IN BASELINE IOP PARAMETERS BETWEEN STUDY GROUPS: 15.69 ± 2.02 mmHg with D/T and 16.71 ± 2.84 mmHg with latanoprost (p=0.314). Both treatment regimes were tolerated and patients were adherent to treatment. Determined a strong positive correlation between IOP-GAT and IOP-POBFA; verified over time period under particular treatment regime. After 1 year follow-up D/T and latanoprost results referred to statistically significant tachyphylaxis effect, i.e. IOP-GAT increased in 2.31mmHg with D/T (p=0.007) and 2.72 mmHg (p=0.004) with latanoprost and IOP-POBFA increased in 1.74 mmHg (p=0.026) and 3.13 mmHg (p=0.007) respectively. Multiple regression analysis revealed no important blood flow factors as predictors in the increase of IOP. CONCLUSIONS Strong positive correlation was revealed between IOP-POBFA and IOP-GAT over a time period. Observed tachyphylaxis effects after 1 year under both treatment regimes should be assessed with respect to patient compliance and persistence to treatment.
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Sandhu R, Sivaprasad S, Shah SP, Adewoyin T, Chong NV. Pulsatile ocular blood flow in asymmetric age-related macular degeneration. Eye (Lond) 2006; 21:506-11. [PMID: 16456596 DOI: 10.1038/sj.eye.6702242] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PURPOSE Ocular perfusion abnormalities have been proposed in the pathogenesis of age-related macular degeneration (AMD) with differences in pulsatile ocular blood flow (POBF) in eyes with asymmetric AMD in Japanese and Taiwanese patients. The purpose of our study was to observe POBF difference in the fellow eyes of Caucasians with asymmetric AMD. METHODS This was a cross-sectional study comparing POBF in three groups of patients with asymmetric AMD in the fellow eyes: Group 1 (n=21) with drusen and active choroidal neovascularisation (CNV); Group 2 (n=18) with drusen and disciform scar; Group 3 (n=8) with CNV and disciform scar. The POBF was adjusted for intraocular pressure (IOP), pulse rate (PR), and axial length using multiple regression analysis. Generalised estimation equation model was used to include both eyes in each group. RESULTS The geometric mean (95% confidence interval) POBF values were as follows: Group 1 with drusen 1097.9 microl/min (957.0, 1259.7) in one eye and the fellow eye with CNV 1090.1 microl/min (932.3, 1274.7); Group 2 with drusen 946.0 microl/min (794.2, 1126.7) and disciform scar 966.2 microll/min (780.3, 1196.4); Group 3 with CNV 877.1 microl/min (628.3, 1224.6) and disciform scar 767.2 microl/min (530.5, 1109.7). Adjusting for differences in axial length, pulse rate and intraocular pressure, no statistically significant difference in POBF was found between fellow eyes in the same subject. CONCLUSIONS POBF is not different between fellow eyes of Caucasian patients with asymmetric AMD.
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Affiliation(s)
- R Sandhu
- Retinal Research Unit, Department of Ophthalmology, King's College Hospital, Denmark Hill, London, UK
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Lam AKC, Lam CH, Ng PW, Tsoi TH, Chan ST. Pulsatile ocular blood flow in patients with asymmetric internal carotid artery stenosis. Clin Exp Optom 2006; 88:382-6. [PMID: 16329746 DOI: 10.1111/j.1444-0938.2005.tb05104.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2005] [Revised: 04/28/2005] [Accepted: 05/16/2005] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND The pulsatile ocular blood flow (POBF) of patients with asymmetric internal carotid artery (ICA) stenosis was measured bilaterally. The purpose of this study was to investigate the sensitivity of POBF assessments in screening for ICA stenosis. METHODS Seventeen subjects with asymmetric ICA stenosis confirmed with carotid duplex ultrasound were recruited. The diagnoses of ICA stenosis were categorised into less than 50 per cent, 50 to 69 per cent and 70 per cent or greater. Their POBF and ocular dimensions were measured after local anaesthesia. Twenty-three normal healthy subjects were recruited as the control. All of the subjects had an inter-ocular axial length difference of less than one millimetre. RESULTS There were 14 males and three females in the patient group with a median age of 74 years. Fourteen patients had reduced POBF to the eye ipsilateral on the side with greater ICA stenosis. The reduction in POBF ranged from 3.1 to 49.2 per cent. Two patients had reduced POBF contralateral to the side with greater ICA stenosis. One patient had similar POBF between the eyes. The control group included six males and 17 females with a median age of 65 years. The difference in their POBF between the eyes ranged from 0.3 to 13.0 per cent. CONCLUSIONS Stenosis of the internal carotid artery was found to reduce the POBF ipsilateral to the side with greater stenosis. The overlap in the difference in inter-ocular POBF between the patient and control groups led to a low sensitivity (calculated as 41.2 per cent) for screening ICA stenosis from an assessment of POBF. Therefore, POBF assessment is not a good diagnostic tool for screening for ICA stenosis.
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Affiliation(s)
- Andrew K C Lam
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong SAR, China.
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Lam AKC, Lam CH. Effect of breath-holding on pulsatile ocular blood flow measurement in normal subjects. Optom Vis Sci 2004; 81:597-600. [PMID: 15300118 DOI: 10.1097/01.opx.0000141795.95597.98] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND The Valsalva maneuver is known to affect intraocular pressure (IOP). Simple breath-holding may cause IOP elevation. A recent study demonstrated a decrease in pulsatile ocular blood flow (POBF) during forcible exhalation. This study investigated whether breath-holding could affect POBF measurement. METHODS Thirty-eight healthy young adults were recruited. Their POBF's were measured with an ocular blood flow pneumatonometer. The first set of measurements was made using normal measurement protocol. Three consecutive readings were obtained, and the mean was used for analysis. The second set of measurements was taken after 5-min rest, and the subjects were required to hold their breath during the acquisition period. RESULTS As previously reported, POBF reduced with increasing myopia. There was no significant change in IOP, pulse rate, POBF, and pulse amplitude between normal protocol and breath-holding condition. POBF and pulse amplitude demonstrated a greater variation, shown by coefficient of variation, when subjects held their breath. CONCLUSIONS This study found a greater variation in consecutive POBF measurements during breath-holding condition. There was no significant difference in either POBF or pulse amplitude during breath-holding session, probably because of the use of three consecutive measurements, and averaged results were generated from them. It is advised to measure the POBF by taking consecutive readings, and subjects should not hold their breath.
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Affiliation(s)
- Andrew K C Lam
- Department of Optometry & Radiography, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China.
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Barkana Y, Harris A, Hefez L, Zaritski M, Chen D, Avni I. Unrecordable pulsatile ocular blood flow may signify severe stenosis of the ipsilateral internal carotid artery. Br J Ophthalmol 2004; 87:1478-80. [PMID: 14660457 PMCID: PMC1920575 DOI: 10.1136/bjo.87.12.1478] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AIM To examine the relation between stenosis of the internal carotid artery (ICA) and pulsatile ocular blood flow (POBF). METHODS In 57 eyes of 30 patients who were referred for Doppler ultrasound examination of the ICA we measured POBF and analysed the correlation with degree of ipsilateral ICA stenosis. RESULTS There was a significant negative correlation between POBF and ipsilateral ICA stenosis (Pearson correlation coefficient, r=-0.516, p<0.0001). In 14 eyes POBF could not be measured by the OBF tonometer, and in 11 of these cases (79%) severe stenosis (>75%) of the ipsilateral ICA was present. When these eyes were excluded from analysis, there was no correlation between POBF and ICA stenosis (r=-0.02, p=0.91). Among these 43 eyes in which POBF could be measured it ranged 667-2095 microl/min with a mean of 970.72 microl/min. CONCLUSION Low or unrecordable POBF may signify severe stenosis of the internal carotid artery. POBF is not a direct reflection of ipsilateral ICA blood flow.
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Affiliation(s)
- Y Barkana
- Department of Ophthalmology, Assaf Harofe Medical Center, Beer Yaacov, Zerifin, Israel.
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Aydin A, Wollstein G, Price LL, Schuman JS. Evaluating pulsatile ocular blood flow analysis in normal and treated glaucomatous eyes. Am J Ophthalmol 2003; 136:448-53. [PMID: 12967797 DOI: 10.1016/s0002-9394(03)00237-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To evaluate pulsatile ocular blood flow (POBF) analysis in normal subjects and glaucoma patients by comparison of POBF measurements with functional (as determined by visual field [VF]) and structural (as determined by optical coherence tomography [OCT]) measures. DESIGN Prospective, cross-sectional study. METHODS Forty-one eyes of 24 consecutive glaucoma patients and 20 eyes of 10 healthy subjects were studied; POBF analysis was performed on all subjects at the same visit as VF testing and OCT retinal nerve fiber layer (NFL) thickness measurement. The mean results of normal and glaucomatous eyes were compared for each method. Correlation between measurements obtained with each modality and the discriminating power using receiver operator characteristic curves was tested. RESULTS The mean POBF (standard deviation [SD]) in the normal group was 1,010.4 (292.8) microl/min and 989.3 (305.5) microl/min in the glaucoma group (P =.90). Significant differences between groups were found for VF mean deviation and pattern standard deviation (P =.02, P =.004, respectively) and OCT mean NFL thickness (P <.0001). No correlation was found between POBF parameters and intraocular pressure, VF, or OCT variables except for intraocular pressure in glaucoma group (r = -.43, P =.003). The area under the receiver operator characteristic curves was higher for VF indexes and OCT mean NFL thickness than POBF parameters for distinguishing between normal and glaucomatous eyes. CONCLUSIONS The wide range of normal values and the low discriminating power of POBF between normal and glaucomatous eyes limits the clinical use of the device for glaucoma patients.
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Affiliation(s)
- Ali Aydin
- New England Eye Center, Tufts-New England Medical Center, Tufts School of Medicine, Boston, Massachusetts 02111, USA
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Lam AKC, Chan ST, Chan B, Chan H. The effect of axial length on ocular blood flow assessment in anisometropes. Ophthalmic Physiol Opt 2003; 23:315-20. [PMID: 12828621 DOI: 10.1046/j.1475-1313.2003.00122.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Pulsatile ocular blood flow (POBF) assessment measures the choroidal circulation and therefore provides data with diagnostic value in certain ocular diseases, such as glaucoma. The technique assumes a constant pressure-volume relationship. The current study investigated the effect of axial length on POBF from subjects with axial anisometropia. Ocular blood supply in the ophthalmic artery was also determined using colour Doppler ultrasonography. METHODS Thirty-one normal, anisometropic subjects were recruited, whose ages ranged from 20 to 34 years. They had axial anisometropia (expressed by spherical equivalent) of at least 2 D. After Goldmann tonometry, the POBF of each eye was measured in a supine posture by one examiner, followed by a measurement of the blood flow velocity in the ophthalmic artery using colour Doppler ultrasonography in the same posture by another examiner. There was a 10 min rest between the two techniques. All the measurements were made at around the same time to eliminate any effect from diurnal variation. RESULTS The mean anisometropia (expressed by spherical equivalent) was 3.89 +/- 1.96 D and the mean inter-ocular axial length difference was 1.49 +/- 1.00 mm. The anisometropia and axial length were significantly different between the two eyes (paired t-tests: p < 0.001). However, the intra-ocular pressure was similar between the two eyes (paired t-test: p = 0.41). The POBF was significantly lower in the eye with the longer axial length (459.3 microL min-1) than the fellow eye (590.8 microL min-1), paired t-test: p < 0.001. The pulse amplitude was also significantly lower in the eye with the longer axial length (1.61 mmHg) than the fellow eye (1.89 mmHg), paired t-test: p < 0.001. However, the blood flow velocity from colour Doppler ultrasonography did not demonstrate any significant difference between the two eyes (paired t-test: p > 0.05). CONCLUSIONS The POBF and pulse amplitude were found to be reduced in the eye with the longer axial length but colour Doppler ultrasonography did not show any significant difference. This suggests that a new pressure-volume relation should be considered in deriving POBF. Practitioners should measure the axial length in POBF assessment.
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Affiliation(s)
- Andrew K C Lam
- Department of Optometry and Radiography, The Hong Kong Polytechnic University, Hong Kong SAR, China.
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Lam AKC, Chan ST, Chan H, Chan B. The effect of age on ocular blood supply determined by pulsatile ocular blood flow and color Doppler ultrasonography. Optom Vis Sci 2003; 80:305-11. [PMID: 12692487 DOI: 10.1097/00006324-200304000-00008] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Pulsatile ocular blood flow (POBF) assessment measures the choroidal circulation and provides diagnostic value to certain ocular diseases such as glaucoma. This technique assumes a constant ocular rigidity and is influenced by axial length, diurnal variation, and age. This study investigated the effect of age on POBF, with consideration of the above factors. Ocular blood supply in the ophthalmic artery was also determined using color Doppler ultrasonography. METHODS A total of 118 healthy subjects aged 19 to 75 years were recruited. They were divided into five groups (below age 30, 30 to 39, 40 to 49, 50 to 59, and 60 or above) of at least 20 subjects each. Only one eye of each subject, with axial length <24.5 mm, was considered. The subject's supine POBF was determined followed by a measurement of the blood flow velocity in the ophthalmic artery using color Doppler ultrasonography. All the measurements were at around the same time of day to eliminate any effect from diurnal variation. The scleral rigidity was measured using a Schiotz tonometer with 5.5- and 7.5-g weights. RESULTS Linear regression analysis demonstrated a significant increase of scleral rigidity with age (Pearson correlation coefficient r = 0.26, p < 0.01) and a significant decrease of POBF with age (r = -0.35, p < 0.01). The reduction in peak systolic velocity in the ophthalmic artery with age was significant (r = -0.28, p < 0.01). Both the systolic and diastolic brachial pressure showed significant increase with age (r = 0.55, p < 0.01; r = 0.40, p < 0.01, respectively). Using multiple regression analysis, POBF showed a significant correlation with age (partial correlation r = -0.36, p < 0.01), but not with scleral rigidity or systolic or diastolic brachial pressure. The peak systolic velocity in the ophthalmic artery also showed significant correlation with age (partial correlation r = -0.29, p < 0.01). CONCLUSIONS The reduction in POBF with age was significant. Although aging affects scleral rigidity and systemic blood pressure, multiple regression analysis indicates that the most influential factor affecting POBF is aging. The peak systolic velocity in the ophthalmic artery also decreased with age, indicating reduced ocular blood supply.
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Affiliation(s)
- Andrew K C Lam
- Department of Optometry and Radiography, The Hong Kong Polytechnic University, Hong Kong SAR, China.
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Abstract
PURPOSE OF REVIEW There have been many changes in ophthalmic anaesthesia in the past few years. This review charts recent trends in practice. RECENT FINDINGS Topical anaesthesia is gaining widespread use for ophthalmic surgery, but readers need to be aware that definitions vary widely; some 'topical' techniques also include intracameral injections and adjunctive sedation. There is now evidence on the relative effectiveness of different types of local anaesthesia from large systematic reviews. Furthermore, the notion is emerging that the traditional distinction between peribulbar and retrobulbar blocks may not be as clear-cut as previously thought. A new area of investigation is the effect of local blocks on pulsatile ocular blood flow. However, the risk of ocular ischaemia has yet to be quantified. Local anaesthesia has also been tried for posterior segment surgery with apparently successful results. The management of patients taking anticoagulants and anti-platelet agents has been examined, and it appears that there are risks not only in continuing therapy but also in stopping it peri-operatively. The decision thus has to be taken on the balance of risks. SUMMARY There have been significant further gains in our understanding of local anaesthetic eye blocks and the management of patients undergoing such procedures.
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Khan JC, Hughes EH, Tom BD, Diamond JP. Pulsatile ocular blood flow: the effect of the Valsalva manoeuvre in open angle and normal tension glaucoma: a case report and prospective study. Br J Ophthalmol 2002; 86:1089-92. [PMID: 12234884 PMCID: PMC1771331 DOI: 10.1136/bjo.86.10.1089] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIM A case of severe normal tension glaucoma is reported in a trumpet player, along with a study investigating the association between glaucoma and raised intrathoracic pressure, using measurements of pulsatile ocular blood flow (POBF). METHODS Three patient groups were studied; normals (n = 34), untreated primary open angle glaucoma (POAG) (n = 20), and untreated normal tension glaucoma (NTG) (n = 22), with a total of 76 patients who underwent measurements of POBF using the OBF pneumotonometer at rest and while forcibly exhaling through a mouthpiece connected to a mercury manometer (30 mm Hg) (Valsalva manoeuvre). RESULTS POBF fell during Valsalva in all groups with the greatest predictor being the resting value of POBF. There was no evidence of significant differences in the mean change in POBF occurring during the Valsalva manoeuvre for the three groups studied before or after adjusting for the sex, the resting POBF, and the resting IOP of the patients (p = 0.294 and p = 0.542, respectively). However, statistically significant associations were found between the change in POBF and sex (p = 0.049), resting POBF (p<0.0001) and resting IOP (p = 0.032). Males had a greater drop, on average, in POBF during Valsalva manoeuvre than females after adjusting for the other factors. Additionally, there was a significant difference in the mean change in IOP during Valsalva for the three groups (p = 0.002), with the difference occurring between the normal and POAG groups (p<0.005). The POAG group had, on average, a drop in IOP during Valsalva, while the other two groups had an increase in IOP. Also noted was a significant difference in the distributions of the risk factors among the three groups (p = 0.002). CONCLUSIONS This study demonstrates no difference between groups with respect to resting or Valsalva POBF, but does demonstrate a possible trend with respect to IOP, with a drop in IOP occurring during Valsalva in the POAG group. There is, however, much variability in the data left unexplained by our models. Thus, unfortunately, we cannot advise our trumpet player whether his NTG is directly related to his trumpet playing.
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Affiliation(s)
- J C Khan
- AMD Study, Box 261, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK
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Dimitrova G, Tamaki Y, Kato S, Nagahara M. Retrobulbar circulation in myopic patients with or without myopic choroidal neovascularisation. Br J Ophthalmol 2002; 86:771-3. [PMID: 12084747 PMCID: PMC1771207 DOI: 10.1136/bjo.86.7.771] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AIM To investigate the effect of myopia and myopic choroidal neovascularisation (CNV) on retrobulbar circulation in central retinal artery (CRA) and vein (CRV) and posterior ciliary artery (PCA). METHODS 52 subjects with and without myopia were included in the study. Retrobulbar circulation was measured using colour Doppler imaging. Analysis of correlation of degree of myopia with blood flow velocity parameters was done. Circulatory differences between eyes of patients with unilateral neovascular degenerative myopia were estimated. RESULTS The analysis of correlation between dioptry and blood flow velocity in the CRA, CRV, and PCA showed a significant positive correlation. Axial length was also significantly correlated with CRA and CRV blood velocity and had a tendency to be correlated with PCA blood velocity. When compared with the fellow eye, the eye with myopic CNV had significantly higher resistivity index (RI) (p=0.048) in the PCA and no significant difference in the circulatory parameters of the CRA and CRV. CONCLUSION Central retinal and posterior ciliary blood velocity decreases with the increase of the degree of myopia. PCA RI is higher in myopic CNV.
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Affiliation(s)
- G Dimitrova
- Department of Ophthalmology, University of Tokyo, School of Medicine, Tokyo, Japan.
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Mori F, Konno S, Hikichi T, Yamaguchi Y, Ishiko S, Yoshida A. Pulsatile ocular blood flow study: decreases in exudative age related macular degeneration. Br J Ophthalmol 2001; 85:531-3. [PMID: 11316708 PMCID: PMC1723978 DOI: 10.1136/bjo.85.5.531] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Pulsatile ocular blood flow (POBF) is a parameter for evaluating choroidal blood flow. POBF in the patients with non-exudative and exudative age related macular degeneration (AMD) was investigated. METHODS POBF, pulse amplitude (PA), systolic and diastolic blood pressures, intraocular pressure (IOP), refractive error, and axial length were compared among 10 patients with non-exudative AMD, 11 patients with exudative AMD, and 69 age matched controls. A Langham OBF computerised tonometer was used with the participants in the sitting position to measure POBF and PA. RESULTS No significant differences were found in age, systolic and diastolic blood pressures, IOP, or refractive error between patients with exudative and non-exudative AMD and the control subjects. In the patients with exudative AMD the POBF (median, 372.7 microl/min) and PA (median, 1.2 mm Hg) were significantly lower than in the patients with non-exudative AMD (median, 607.0 microl/min (p = 0.02) and 2.2 mm Hg (p = 0.04), respectively) and control subjects (median, 547.4 microl/min (p = 0.01) and 2.0 mm Hg (p = 0.01), respectively). CONCLUSIONS These data show that the POBF and PA in the patients with exudative AMD are lower than in the patients with non-exudative AMD and normal subjects. Decreased choroidal blood flow may have a role in the development of choroidal neovascularisation in AMD.
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Affiliation(s)
- F Mori
- Department of Ophthalmology, Asahikawa Medical College, Asahikawa, Japan. morinaod5.dion.ne.jp
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