Spontaneous Venous Pulsations Research Articles

The retinal venous pressure at different levels of airway pressure measured with a new method.

This study is to investigate the increase in retinal venous pressure (RVP) induced by a stepwise increase in airway pressure (AirP) using the new IOPstim method, which is designed to artificially increase the intraocular pressure (IOP) and thus to stimulate vascular pulsation. Twenty-eight healthy subjects were examined in the left eye. The RVP was measured at baseline and at four different levels of AirP (10, 20, 30, and 40mmHg) using the new IOPstim method: a half balloon of 8mm diameter is inflated laterally to the cornea under observation of the central retinal vein. As soon as the vein pulsates at a certain AirP level, the IOP is measured with a commercially available tonometer, which then corresponds to the RVP. Spontaneous venous pulsation was observed in all study participants. The mean RVP values at baseline and at the AirP levels of 10, 20, 30, and 40 mmHg were 17.6 ± 2.8 mmHg; 20.1 ± 3.0 mmHg; 22.1 ± 3.5 mmHg; 24.3 ± 3.7 mmHg, and 26.6 ± 4.2 mmHg, respectively. The mean RVP values of each AirP level were statistically significantly different from each other in pairwise comparison. In a linear mixed model, the effect of AirP on RVP was highly significant (p < 0.001). In the model, a 10-mmHg increase in AirP resulted in a linear increase in RVP of 2.2 mmHg. An increase in AirP was accompanied by a linear increase in RVP. The influence of AirP on RVP, and thus on retinal perfusion pressure during the Valsalva maneuver, is less than was assumed based on previous studies in which contact lens dynamometry was used.

Autonomous assessment of spontaneous retinal venous pulsations in fundus videos using a deep learning framework

The presence or absence of spontaneous retinal venous pulsations (SVP) provides clinically significant insight into the hemodynamic status of the optic nerve head. Reduced SVP amplitudes have been linked to increased intracranial pressure and glaucoma progression. Currently, monitoring for the presence or absence of SVPs is performed subjectively and is highly dependent on trained clinicians. In this study, we developed a novel end-to-end deep model, called U3D-Net, to objectively classify SVPs as present or absent based on retinal fundus videos. The U3D-Net architecture consists of two distinct modules: an optic disc localizer and a classifier. First, a fast attention recurrent residual U-Net model is applied as the optic disc localizer. Then, the localized optic discs are passed on to a deep convolutional network for SVP classification. We trained and tested various time-series classifiers including 3D Inception, 3D Dense-ResNet, 3D ResNet, Long-term Recurrent Convolutional Network, and ConvLSTM. The optic disc localizer achieved a dice score of 95% for locating the optic disc in 30 milliseconds. Amongst the different tested models, the 3D Inception model achieved an accuracy, sensitivity, and F1-Score of 84 ± 5%, 90 ± 8%, and 81 ± 6% respectively, outperforming the other tested models in classifying SVPs. To the best of our knowledge, this research is the first study that utilizes a deep neural network for an autonomous and objective classification of SVPs using retinal fundus videos.

Prospective evaluation of medical student accuracy conducting direct ophthalmoscopy with an unmodified iPhone X

PurposeTo evaluate fundus examination accuracy of medical students when using an unmodified iPhone X or a direct ophthalmoscope in comparison to a staff ophthalmologist’s retinal examination.MethodsIn this prospective comparative analysis, patients underwent dilated fundus examination by novice medical trainees using either an unmodified iPhone X or standard direct ophthalmoscope. The primary outcome was the mean difference and degree of agreement in cup-to-disc ratio between student examination and the staff ophthalmologist’s cup-to-disc observation.ResultsA total of 18 medical students conducted 230 retinal examinations, 117 with the iPhone X and 113 with the direct ophthalmoscope. A greater proportion of students were unable to report cup-to-disc ratio using the iPhone X (81.2%) vs direct ophthalmoscope (30.1%). Student examination of cup-to-disc ratio led to a systematic bias (95% limits of agreement) of + 0.16 (−0.22 to + 0.54) and + 0.10 (−0.36 to + 0.56) with the iPhone X and direct ophthalmoscope, respectively. iPhone X and direct ophthalmoscope student observation concordance for optic disc colour (88.7 and 82.4%, respectively) and contour (68.3 and 74.2%, respectively) demonstrated low agreement with staff ophthalmologist findings. Student iPhone X observations demonstrated lower agreement with staff findings compared to direct ophthalmoscope observations for spontaneous venous pulsations (Cohen’s Kappa = −0.044 vs 0.099).ConclusionAmongst medical trainees, optic disc visualization using an unmodified iPhone X was inferior to the direct ophthalmoscope. When able to visualize the optic nerve head, there was no significant difference in reported cup-to-disc ratio between modalities. However, both modalities demonstrated poor reliability in comparison to staff ophthalmologist findings.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10792-022-02377-4.

Heart rate and age modulate retinal pulsatile patterns

Theoretical models of retinal hemodynamics showed the modulation of retinal pulsatile patterns (RPPs) by heart rate (HR), yet in-vivo validation and scientific merit of this biological process is lacking. Such evidence is critical for result interpretation, study design, and (patho-)physiological modeling of human biology spanning applications in various medical specialties. In retinal hemodynamic video-recordings, we characterize the morphology of RPPs and assess the impact of modulation by HR or other variables. Principal component analysis isolated two RPPs, i.e., spontaneous venous pulsation (SVP) and optic cup pulsation (OCP). Heart rate modulated SVP and OCP morphology (pFDR < 0.05); age modulated SVP morphology (pFDR < 0.05). In addition, age and HR demonstrated the effect on between-group differences. This knowledge greatly affects future study designs, analyses of between-group differences in RPPs, and biophysical models investigating relationships between RPPs, intracranial, intraocular pressures, and cardiovascular physiology.

At the Pulse of Time: Machine Vision in Retinal Videos.

Spontaneous venous pulsations (SVP) are a common finding in healthy people. The absence of SVP is associated with rapid progression in glaucoma and increased intracranial pressure. Traditionally, SVP has been documented qualitatively by clinicians during biomicroscopy. Nowadays numerous imaging devices recording the fundus exist. Hence, video data for objectification of SVP is readily available. Still, these clinical datasets are afflicted with various quality issues and artifacts. In this machine vision based study, we explore methods to overcome challenges in identifying SVP in fundus videos of varying quality and provide a detailed protocol thereof. Hereby, we aim to lower the burden of access of implementing machine vision in clinical video datasets and quantification of SVP.

Retinal Vein Changes as a Biomarker to Guide Diagnosis and Management of Elevated Intracranial Pressure.

Retinal vein changes, which can be observed on clinical exam or ophthalmic imaging, are promising non-invasive biomarkers for elevated intracranial pressure (ICP) as a complement to other markers of high ICP including optic nerve head swelling. Animal and human studies have demonstrated increase in retinal vein pressure associated with elevated ICP mediated by increase in cerebral venous pressure, compression of venous outflow by elevated cerebral spinal fluid pressure in the optic nerve sheath, and compression of venous outflow by optic nerve head swelling. Retinal vein pressure can be estimated using ophthalmodynamometry. Correlates of retinal vein pressure include spontaneous retinal venous pulsations, retinal vein diameter, and retinal vein tortuosity. All of these have potential for clinical use to diagnose and monitor elevated ICP. Challenges include diagnostic prediction based on single clinical measurements and accurate assessment of retinal vein parameters in cases where optic nerve head swelling limits visualization of the retinal veins.

Non-invasive detection of intracranial pressure related to the optic nerve.

Intracranial pressure (ICP) is associated with a variety of diseases. Early diagnosis and the timely intervention of elevated ICP are effective means to clinically reduce the morbidity and mortality of some diseases. The detection and judgment of reduced ICP are beneficial to glaucoma doctor and neuro ophthalmologist to diagnose optic nerve disease earlier. It is important to evaluate and monitor ICP clinically. Although invasive ICP detection is the gold standard, it can have complications. Most non-invasive ICP tests are related to the optic nerve and surrounding tissues due to their anatomical characteristics. Ultrasound, magnetic resonance imaging, transcranial Doppler, papilledema on optical coherence tomography, visual evoked potential, ophthalmodynamometry, the assessment of spontaneous retinal venous pulsations, and eye-tracking have potential for application. Although none of these methods can completely replace invasive technology; however, its repeatable, low risk, high accuracy, gradually attracted people's attention. This review summarizes the non-invasive ICP detection methods related to the optic nerve and the role of the diagnosis and prognosis of neurological disorders and glaucoma. We discuss the advantages and challenges and predict possible areas of development in the future.

Brain MRI and Ophthalmic Biomarkers of Intracranial Pressure.

To evaluate the utility of brain MRI and ophthalmic biomarkers for the prediction of intracranial hypertension, we have studied the association between 6 biomarkers and 24-hour intracranial pressure (ICP) monitoring results in 45 patients. This single-center observational study includes patients who underwent 24-hour ICP monitoring, brain MRI (within 3 months), and ophthalmic assessment (during ICP monitoring). Six biomarkers were investigated: pituitary gland shape, vertical tortuosity of the optic nerve, distension of the optic nerve sheath, optic disc protrusion (MRI), papilledema (slit lamp biomicroscopy), and spontaneous venous pulsations (SVP, infrared video recordings). Forty-five patients (mean age 39 ± 14 years, 38 women) met the inclusion criteria. All 6 biomarkers had a significant association with 24-hour ICP. Concave pituitary gland was observed with moderately elevated median ICP. Protrusion of the optic disc (MRI), papilledema, and absence of SVP were associated with the highest median ICP values. Twenty patients had raised ICP (median 24-hour ICP >5.96 mm Hg, cutoff obtained through Youden index calculation). Patients with all normal biomarkers had normal median ICP in 94% (standard error 6%) of the cases. All patients with ≥3 abnormal biomarkers had intracranial hypertension. The combination of at least 1 abnormal biomarker in MRI and ophthalmic assessments was highly suggestive of intracranial hypertension (area under the curve 0.94, 95% confidence interval 0.93-0.94) CONCLUSIONS: Brain MRI and ophthalmic biomarkers can noninvasively guide the management of patients with suspected CSF dynamics abnormalities. Patients with multiple abnormal biomarkers (≥3) or a combination of abnormal MRI and ophthalmic biomarkers are likely to have intracranial hypertension and should be managed promptly.

Blind Source Separation of Retinal Pulsatile Patterns in Optic Nerve Head Video-Recordings.

Dynamic optical imaging of retinal hemodynamics is a rapidly evolving technique in vision and eye-disease research. Video-recording, which may be readily accessible and affordable, captures several distinct functional phenomena such as the spontaneous venous pulsations (SVP) of central vein or local arterial blood supply etc. These phenomena display specific dynamic patterns that have been detected using manual or semi-automated methods. We propose a pioneering concept in retina video-imaging using blind source separation (BSS) serving as an automated localizer of distinct areas with temporally synchronized hemodynamics. The feasibility of BSS techniques (such as spatial principal component analysis and spatial independent component analysis) and K-means based post-processing method were successfully tested on the monocular and binocular video-ophthalmoscopic (VO) recordings of optic nerve head (ONH) in healthy subjects. BSSs automatically detected three spatially distinct reproducible areas, i.e. SVP, optic cup pulsations (OCP) that included areas of larger vessels in the nasal part of ONH, and "other" pulsations (OP). The K-means post-processing reduced a spike noise from the patterns' dynamics while high linear dependence between the non-filtered and post-processed signals was preserved. Although the dynamics of all patterns were heart rate related, the morphology analysis demonstrated significant phase shifts between SVP and OCP, and between SVP and OP. In addition, we detected low frequency oscillations that may represent respiratory-induced effects in time-courses of the VO recordings.

Spontaneous Venous Pulsations Detected With Infrared Videography.

Assessment of spontaneous venous pulsation (SVP) is commonly undertaken to help determine whether intracranial pressure (ICP) is elevated. Previous studies using direct ophthalmoscopy or slit-lamp assessments have found that SVP is not observed in 67%-81% of subjects with normal ICP, and that interobserver agreement when grading SVP is poor. Patients (n = 105) undergoing clinically indicated retinal OCT scans, who were all believed to have normal ICP, had 10-second infrared video recordings performed with the Heidelberg Spectralis OCT system (Heidelberg Engineering GmbH, Heidelberg, Germany). The presence and amplitude of SVP in each video was independently graded by 2 neuro-ophthalmologists. The 2 observers found SVP present in 97% and 98% of right eyes and in one or both eyes in 99% and 100% of subjects. Interobserver agreement was high (Cohen's kappa 0.82 for right eyes). Optic discs with a smaller cup had a significantly lower SVP amplitude (Spearman's rho = 0.22, P = 0.02). Infrared video is widely available in eye clinics by the use of OCT imaging systems and is substantially more sensitive in detecting SVP than traditional assessments using ophthalmoscopy. SVP is absent in as few as 1% of people with presumed normal ICP.

Evaluation of spontaneous retinal venous pulsation in primary open-angle and primary angle-closure glaucoma patients

Introduction: Spontaneous retinal venous pulsation (SRVP) is a rhythmic variation in the calibre of one or more retinal veins. The incidence of SRVP was reduced in glaucoma patients. It was also reduced in people with raised intracranial pressure compared to a healthy population.&#x0D; Purpose: The main objective was to report the frequency and rate of SRVP in primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG) patients and to associate these with the severity of glaucoma in Malay patients.&#x0D; Design of study: A comparative cross-sectional study.&#x0D; Materials and methods: A comparative cross-sectional study involving primary glaucoma patients attending the eye clinic at Hospital Universiti Sains Malaysia (HUSM), Kelantan, Malaysia, was performed between December 2015 and June 2017. The main outcomes measured were the presence and rate of SRVP using a confocalscanning laser ophthalmoscope (Spectralis High-Resolution Optical Coherence Tomography Angiography, Heidelberg Engineering GmbH, Heidelberg, Germany). In the presence of SRVP, the rate of SRVP in one minute was counted manually based on the real-time fundus movie recorded using the confocal scanning laser ophthalmoscope.&#x0D; Results: Thirty-eight POAG, 14 PACG, and 51 control group subjects were included. There was a significantly lower incidence of SRVP in primary glaucoma patients than in the control group (p = 0.003). The presence of SRVP was significantly lower in POAG than PACG (p = 0.04). There was no significant difference in the rate ofSRVP between primary glaucoma patients and the control group (p = 0.873) or between the POAG group and PACG group (p = 0.511). There was no association of incidence (p = 0.574) and rate (p = 0.167) of SRVP according to the severity of glaucoma. Systolic blood pressure (95% CI: 0.95–1.00, p = 0.038) and retinal nervefibre layer thickness (95% CI: 1.01–1.09, p = 0.008) showed a significant association with the presence of SRVP.&#x0D; Conclusions: SRVP is a potential predictive factor for detection of primary glaucoma. The role of SRVP in the severity of glaucoma is still unclear. The role of SRVP in PACG patients warrants further studies in the future.

Objective Quantification of Spontaneous Retinal Venous Pulsations Using a Novel Tablet-Based Ophthalmoscope.

PurposeDynamic assessment of retinal vascular characteristics can aid in identifying glaucoma-specific biomarkers. More specifically, a loss of spontaneous retinal venous pulsations (SVPs) has been reported in glaucoma, but a lack of readily available tools has limited the ability to explore the full potential of SVP analysis in glaucoma assessment. Advancements in smart technology have paved the way for the development of portable, noninvasive, and inexpensive imaging modalities. By combining off-the-shelf optical elements and smart devices, the current study aims to determine whether SVPs can be detected and quantified using a novel tablet-based ophthalmoscope in glaucoma and glaucoma suspects.MethodsThirty patients, including 21 with confirmed glaucoma (9 men; average age 75 ± 8 years) and 9 glaucoma suspects (5 men; average age 64 ± 9 years), were studied. All patients had intraocular pressure measurements, Humphrey visual field assessment, optical coherence tomography, and a 10-second videoscopy of the retinal circulation. The retinal vasculature recordings (46° field of view at 30 frames per second) were analyzed to extract SVP amplitudes.ResultsSVPs were detected and quantified in 100% of patients with glaucoma and those with suspected glaucoma using the novel device. The average SVP amplitudes in glaucoma and glaucoma suspects were 42.6% ± 10.7% and 34% ± 6.7%, respectively.ConclusionsOur results suggest that a novel tablet-based ophthalmoscope can aid in documenting and objectively quantifying SVPs in all patients.Translational RelevanceOutcomes of this study provide an innovative, portable, noninvasive, and inexpensive solution for objective assessment of SVPs, which may have clinical relevance in glaucoma screening.

The Detection of Spontaneous Venous Pulsation with Smartphone Video Ophthalmoscopy.

PurposeSpontaneous venous pulsation (SVP) has a high negative predictive value for raised intracranial pressure and is a useful sign when assessing patients with headache. The objective was to determine if smartphone-based video ophthalmoscopy can detect SVP.Patients and MethodsIn total 233 patients and 291 eyes were recruited from the Dunedin Hospital eye clinic from July to November 2018. Patients were examined by a clinician and graded for SVP with a slit lamp and 78 Dioptre lens. Videos were taken with a smartphone ophthalmoscope and graded by two separate clinicians blinded to the slit lamp findings.ResultsOnly 272 eyes of 215 patients were included, as others failed in the inclusion criteria for overall video quality. Sensitivity was calculated as how likely the presence of SVP on video was indicative of the presence of SVP on slit lamp. Sensitivity was 84.77% for Observer 1, with 128 videos graded as positive for SVP on video ophthalmoscopy of the 151 identified as positive on slit lamp examination. Sensitivity was 76.82% for Observer 2 with 116 videos correctly identified. The false positive rate was calculated as the number of videos graded positive for SVP that had been graded as negative on slit lamp examination. This was 10.74% for observer 1 and 31.40% for observer 2.ConclusionThis study demonstrates that SVP is detected by video ophthalmoscopy. This may be a useful triage, telemedicine and referral tool to be used for patients with headache in a primary care setting.

The 45th Annual Meeting of the North American Neuro-Ophthalmology Society in Las Vegas, Nevada

The North American Neuro-Ophthalmology Society (NANOS) held its 45th annual meeting at the Red Rock Casino, Resort and Spa, Las Vegas, Nevada, March 16–21, 2019. The Frank B. Walsh Society meeting was hosted by the University of Pennsylvania group along with special experts in neuroradiology, Dr. Laurie Loevner, and neuropathologist, Dr. Zissimos Mourelatos. The award for best Walsh paper was presented to Dr. Paul R. Freund, and was entitled “Go with your Gut Feeling” (Fig. 1).FIG. 1.: Dr. Paul R. Freund (left) won the award for best Frank B. Walsh session paper presentation by a fellow. The award was presented by Drs. Peter Quiros (middle) and Andrew Lee (right).Once again, the educational symposia were exceptional. “New Information I Should Know” highlighted neuro-immunological therapies from encephalitis to migraine. “Hot Topics” covered treatment of commonly encountered neuro-ophthalmic disorders. An educational session, “Retinal Microvascular Changes and Neurologic Disorders,” provided insight into retinal microvascular changes in relation to acute and chronic neurologic diseases. Dr. Tien Yin Wong reported on the advancement in artificial intelligence in retinal imaging. Drs. David Newman-Toker and Dan Gold thoroughly highlighted the approach to dizziness and vertigo. On the final day, pediatric neuro-ophthalmology topics were highlighted, including the evaluation of children vs. adults and a case-based approach to eye movement disorders in children. The Jacobson Lecture featured Dr. Nancy Newman's talk, “Leber Hereditary Optic Neuropathy: From Bedside to Bench to Bedside.” This presentation traced the history of Leber hereditary optic neuropathy from clinical recognition, to discovery of the first point mutation in mitochondrial DNA, to ground-breaking attempts at gene therapy (Fig. 2).FIG. 2.: Dr. Nancy Newman, our 2019 Jacobson Lecturer.This year's optional symposia were very popular and included a dynamic skills transfer session on extraocular muscle and vestibular testing, along with a session providing updates in headache medicine important for neuro-ophthalmologists. Two additional symposia included “Reading an OCT Like We Read an MRI” and “Worldwide Wonders: Cases Defining the International Language of Neuro-Ophthalmology.” This year's meeting offered two poster sessions, featuring 248 posters divided between 125 Clinical Highlights in Neuro-Ophthalmology on Sunday afternoon during the Walsh Session and 123 posters on Scientific Advancement in Neuro-Ophthalmology on Tuesday afternoon. There were three insightful scientific platform sessions. This year's awardees were as follows: James A. Sharpe Award by a Fellow: Melanie N. Truong-Le, DO, OD—“Reflex Upper and Lower Eyelid Movement in Response to Light Stimuli.” Best Abstract by a Resident: Michael J. Gilhooley, MA, MB, BChir, FRCOphth—“Melanopsin: targeted ectopic expression for optogenetic visual restoration.” Best Abstract by a Student: Perry J. Thompson, BA—“Near Infrared Videography versus Direct Ophthalmoscopy for the Detection of Spontaneous Venous Pulsations.” 2019 Pilot Grant Award: Heather Moss, MD, PhD, for her project “Optic Nerve Biomechanics in High Intracranial Pressure States.” The Thomas and Susan Carlow Young Investigator Award: Ghislaine L. Traber, MD, for her project “The Untuned Visuo-Temporal Cortex in Patients with Visual Snow.” Hoyt Lecture Award (given at the AAO in 2018): Joseph F. Rizzo III, MD, for his presentation of the William F. Hoyt Lecture “Unraveling the Enigma of Non-Arteritic Anterior Ischemic Optic Neuropathy.” NANOS Merit Awards (for extraordinary contributions of time, energy, and resources to NANOS): Sachin Kedar, MD; Lanning Kline, MD; Christian J. Lueck, PhD, FRACP, FRCP (UK), FAAN. J. Lawton Smith Award (given a top original contribution published in the JNO): Hong Jiang, MD, for her paper “Altered Macular Microvasculature in Mild Cognitive Impairment and Alzheimer Disease.” Thomas Carlow Distinguished Service Award: Nancy J. Newman, MD, for her lifetime contributions to NANOS and the field of Neuro-Ophthalmology (Fig. 3).FIG. 3.: Dr. Nancy Newman (middle) received the Thomas Carlow Distinguished Service Award. She was introduced by Dr. Paul Phillips (left).Pilot Grant Leadership Development Award: Barbara Yates, MD. AAO Leadership Development Program Nominee: John Chen, MD, PhD. The 2019 meeting had an all-time high attendance with 738 registrants from 39 countries! Our international members made up 29% of the attendees! The annual banquet was held in the hotel with an amazing NON-STOP dancing frenzy until the end! Janel Fick, Trish Shomion, Toma Ossian, and Tara Thebeau hosted another very well-organized meeting. The 46th NANOS annual meeting will be Amelia Island, Florida, March 7–12, 2020. Thanks to all for their hard work and support of the annual meeting!

This Issue of Acta

This Issue of Acta

Detection and characterization of tree shrew retinal venous pulsations: An animal model to study human retinal venous pulsations

Spontaneous retinal venous pulsations (SRVPs), pulsations of branches of the central retinal vein, are affected by intraocular pressure (IOP) and intracranial pressure (ICP) and thus convey potentially-useful information about ICP. However, the exact relationship between SRVPs, IOP, and ICP is unknown. It is not easily feasible to study this relationship in humans, necessitating the use of an animal model. We here propose tree shrews as a suitable animal model to study the complex relationship between SRVPs, IOP, and ICP. Tree shrew SRVP incidence was determined in a population of animals. Following validation of a modified IOP control system to accurately and quickly control IOP, IOP and/or ICP were manipulated in two tree shrews with SRVPs and the effects on SRVP properties were quantified. SRVPs were present in 75% of tree shrews at physiologic IOP and ICP. Altering IOP or ICP produced changes in tree shrew SRVP properties; specifically, increasing IOP caused SRVP amplitude to increase, while increasing ICP caused SRVP amplitude to decrease. In addition, a higher IOP was necessary to generate SRVPs at a higher ICP than at a lower ICP. SRVPs occur with a similar incidence in tree shrews as in humans, and tree shrew SRVPs are affected by changes in IOP and ICP in a manner qualitatively similar to that reported in humans. In view of anatomic similarities, tree shrews are a promising animal model system to further study the complex relationship between SRVPs, IOP, and ICP.

Investigating spontaneous retinal venous pulsation using Doppler optical coherence tomography

We demonstrate the advantages of optical coherence tomography (OCT) imaging for investigation of spontaneous retinal venous pulsation (SRVP). The pulsatile changes in venous vessel caliber are analyzed qualitatively and quantitatively using conventional intensity-based OCT as well as the functional extension Doppler OCT (DOCT). Single-channel and double-channel line scanning protocols of our multi-channel OCT prototype are employed to investigate venous pulsatile caliber oscillations as well as venous flow pulsatility in the eyes of healthy volunteers. A comparison to recordings of scanning laser ophthalmoscopy (SLO) – a standard en-face imaging modality for evaluation of SRVP – is provided, emphasizing the advantages of tomographic image acquisition. To the best of our knowledge, this is the first quantitative time-resolved investigation of SRVP and associated retinal perfusion characteristics using OCT.

Postural effects on spontaneous retinal venous pulsations in healthy individuals.

To assess amplitudes of spontaneous retinal venous pulsations (SVP) in three various postures (sitting, supine and lateral decubitus) in healthy individuals. Thirty participants (28±8years, 25 females) were included in the study. Intraocular pressure (IOP), blood pressure (BP) and SVP's were measured at three different postures using a calibrated Tono-Pen applanation tonometer, a digital sphygmomanometer, and a custom-built handheld video ophthalmoscope, respectively. Retinal venous pulsations (SVP) amplitudes were extracted from the retinal videos using a custom written MATLAB algorithm. Mean arterial pressure (MAP=(systolic+2diastolic)/3) and mean ocular perfusion pressure (MOPP=(2/3 MAP)-IOP) were also calculated at each posture. A one-way ANOVA was applied to each parameter to determine any significant difference for the various postural changes. Mean IOP increased (p<0.0001) and mean SVP decreased (p<0.0001) from sitting to supine. The mean IOP (mmHg) and SVP (MU; measuring units) in sitting, supine and lateral decubitus were 16.2±2, 19.4±4, 19.8±2mmHg and 5.8±2, 4.5±2, and 4.7±2 MU, respectively. Mean arterial pressure (MAP) and MOPP also decreased significantly from sitting to supine (p<0.001, p<0.001) and sitting to lateral decubitus (p<0.05, p<0.01). There were no significant differences between IOP, SVP, MAP or MOPP during a postural modification from supine to lateral decubitus. In this study, we showed a significant reduction in SVP amplitudes and a significant increase in IOP from sitting to supine position in a healthy young cohort. This supports the rationale to further study such phenomenon in ocular conditions such as glaucoma to determine whether relative SVP change, for a similar postural change, can reveal early signs of vascular dysfunction.

Effects of Physical Loads in Supine Position on Intraocular Pressure

The subjects were 19 young powerlifters aged from 18 to 30 years. Strength training, namely, the jerk in the supine position, was performed either breathing in the usual way or holding breath simultaneously with straining. Ophthalmoscopy, laser scanning ophthalmoscopy, and intraocular pressure measurements using a pneumatic tonometer were conducted before, during, and after training. After jerks, intraocular pressure elevation was observed in all subjects; in three subjects, the ophthalmic tone overpassed normal values. The ophthalmic tone was fitness-dependent and lower in well-trained subjects. Ophthalmoscopy of physically unfit subjects showed an increase in retinal vein diameters, disappearance of spontaneous venous pulsation in the optic disk in four subjects, and exaggerated hyperemia of the optic papilla. The incentive for the investigation was documented unfavorable changes in the human visual organ in long-duration space missions.

Spontaneous Retinal Venous Pulsation in Unilateral Primary Open-angle Glaucoma With Low Intraocular Pressure.

The aim of this study was to investigate the presence of spontaneous retinal venous pulsation (SVP) in patients with unilateral primary open-angle glaucoma (POAG) and low intraocular pressure (IOP). The SVP of 93 POAG patients with unilateral glaucoma and untreated IOP of ≤21 mm Hg was assessed using the movie tool of a confocal scanning laser ophthalmoscope (Spectralis HRA; Heidelberg Engineering). The frequency of SVP was compared between the glaucomatous and fellow eyes. Intereye differences in the frequency of SVP were assessed using McNemar test. A linear mixed-effect model was used to determine the factors associated with glaucomatous eyes, taking into account clustering of eyes within subjects. Forty-five patients had SVP in both eyes and 15 had SVP in neither eye. Of the remaining 33 patients who showed SVP only in 1 eye, 31 had SVP only in the fellow eye, and 2 had SVP only in the glaucomatous eye. The SVP was significantly less prevalent in glaucomatous eyes (50.5%) than in fellow control eyes (81.7%) (P<0.001). In the linear mixed-effect model, the presence of SVP (P<0.001) and higher untreated IOP (P=0.001) were the significant predictors for glaucoma. SVP was less frequently found in glaucomatous eyes than healthy fellow eyes in unilateral POAG patients with low IOP.