Comparing Intraocular Pressure, Ocular Blood Flow, and Retinal Nerve Fiber Layer Thickness in Early and Chronic Hypertensives With Normotensives.

PURPOSE: To compare blood pressure (BP), intraocular pressure (IOP), ophthalmic artery flow (OAF) velocity, retinal nerve fiber layer (RNFL) thickness, and visual fields in newly diagnosed hypertension (HT) patients (before treatment), chronic HT (on antihypertensive medications >5 years) and normotensives. METHODS: A prospective, cross-sectional study at a tertiary care centre in India. Three groups of 45 patients each: group 1 - early HT, group 2 - chronic HT, and Group 3 - normotensives, underwent evaluation of BP, IOP by Goldmann applanation tonometry (GAT), OAF velocity by transcranial doppler (TCD), RNFL analysis by spectral-domain optical coherence tomography (SD-OCT), and visual fields. RESULTS: The BP was highest in early HT > chronic HT > normotensives (p < 0.001). The IOP of early HT, chronic HT, and normotensives were 15.87 ± 2.19 mmHg, 13.47 ± 1.92 mmHg, and 15.67 ± SD 1.75 mmHg (p < 0.001). The OAF velocity [peak systolic velocity (PSV), end-diastolic velocity (EDV) in cm/sec] was lowest in chronic HT (30.80 ± 7.05, 8.58 ± 1.58) < early HT (35.47 ± 5.34, 10.02 ± 1.74) < normotensives (36.29 ± 4.43, 10.44 ± 2.29), (p < 0.001). The average RNFL thickness was significantly lower in chronic HT (p = 0.022). The PSV, EDV, and MFV showed significant correlation with IOP (r = 0.247, p = 0.004; r = 0.206, p = 0.016; r = 0.266, p = 0.002) and average RNFL thickness (r = 0.309, p= <0.001; r = 0.277, p = 0.001; r = 0.341, p < 0.001). CONCLUSIONS: Patients with chronic HT demonstrated the lowest retrobulbar flows, IOP and lower RNFL measurements. Lower ocular perfusion may be associated with lower IOP and may be a risk factor for end-organ damage (RNFL) independent of IOP.

A sex specific approach of ophthalmic and middle cerebral arteries Doppler in smokers.

Vascular dysfunctions can progress and lead to stroke and cardiovascular disease, especially in smokers. The presence of particular vascular changes according to sex has been described and they can be identified by the Doppler method. This study evaluated Doppler velocimetry parameters of the Ophthalmic Artery (OA) and the Middle Cerebral Artery (MCA) according to sex in smokers regarding a non-smoker group. This cross-sectional observational study included 178 subjects: 93 women and 85 men. Doppler parameters were assessed in OA and MCA. Student's t-test was used, with p < 0.05. There were no significant differences in OA and MCA Doppler velocimetry data between male non-smokers and smokers. However, female smokers presented several differences compared with non-smokers: lower pulsatility index (PI) and higher peak ratio in OA, and higher PI and resistance index and lower end diastolic velocity in MCA. There were different brain vascular waveforms in the group of female smokers compared with non-smokers. Cigarette smoking also led to opposite arterial patterns in OA and MCA in the female group, with signs of falling impedance in OA and increased impedance in MCA. An individualized approach regarding arterial changes according to sex is desirable.

Ophthalmic Artery Morphological and Hemodynamic Features in Acute Coronary Syndrome.

Purpose: To examine the morphological and hemodynamic changes of the ophthalmic artery (OA) in patients with acute coronary syndrome (ACS). Methods: This cross-sectional observational study included 31 patients with ACS and 10 healthy controls (HCs). The ACS subgroups were ST-segment elevation myocardial infarction (STEMI; n = 10), non-STEMI (n = 10), and unstable angina (n = 11). OA three-dimensional (3D) models were reconstructed based on computed tomographic angiography, and morphological aspects of the OA were measured quantitatively. Moreover, numerical simulation by computational fluid dynamics was used to obtain hemodynamic information of the OA. Results: The study reconstructed 41 OA models. Hemodynamic simulation revealed a significant decrease in OA blood velocity in patients with ACS compared with the HCs (median velocity, 0.046 vs. 0.147 m/s; P < 0.001). No differences in the morphological data for the OA were observed. Also, no differences in the mass flow ratio of OA to the ipsilateral internal carotid artery was found. Similar differences were observed between the ACS subgroups and HCs. OA blood velocity was negatively correlated with body mass index, abdominal circumference, left ventricular ejection fraction, and triacylglycerol and was positively correlated with early to late transmitral flow velocity, N-terminal pro-brain natriuretic peptide, serum creatinine, and potassium. Conclusions: The initial OA blood velocity was slower in patients with ACS and was associated with ACS-related clinical parameters. To our knowledge, this is the first study to analyze OA characteristics in ACS using 3D model reconstruction and hemodynamic simulation, providing new perspectives on the relationship between ischemic heart disease and ocular manifestations.

Resistive index of ophthalmic artery as an imaging biomarker of hypertension-related vascular and kidney damage.

Aim: Resistive index of ophthalmic artery (RI-OA) is associated with atherosclerotic diseases. The aim of this study was to evaluate the association of RI-OA and hypertension-related vascular and kidney damage. Materials and methods: Two-hundred and eighty hypertensive patients underwent evaluation of RI-OA, carotid atherosclerosis and level of 24 h albuminuria. Results: Albuminuria and carotid atherosclerosis were positively associated with RI-OA independently of other cardiovascular risk factors. Receiver-operating characteristic curve analysis allowed us to calculate a cut-off value of RI-OA >0.625, which would be suspicious about the existence of atherosclerotic disease. Conclusion: The ophthalmic vascular circulation allows to study connections between macro- and microcirculation in vivo. RI-OA could be a useful marker for a better stratification of the risk of developing kidney and cardiovascular disease.

Relationship between ophthalmic artery Doppler and maternal cardiovascular function.

OBJECTIVE: In mid-gestation, the finding of an increase in the ophthalmic artery second to first peak of systolic velocity ratio (PSV ratio) provides useful prediction of subsequent development of pre-eclampsia (PE). The objective of this study of an unselected population at 19-23 weeks' gestation was to gain a better understanding of the factors that influence ophthalmic artery Doppler by examining the possible association between the PSV ratio and maternal cardiovascular function. METHODS: This was a prospective observational study in women attending for a routine hospital visit at 19 + 1 to 23 + 3 weeks' gestation. This visit included assessment of flow velocity waveforms from the maternal ophthalmic arteries and assessment of maternal cardiovascular function. The following nine cardiovascular indices were examined: E/A ratio; E/e' ratio; myocardial performance index; global longitudinal systolic strain; left ventricular ejection fraction; peripheral vascular resistance; left ventricular cardiac output; left ventricular mass indexed for body surface area; and mean arterial pressure. The ophthalmic artery PSV ratio and the nine cardiovascular indices were converted to either log10 multiples of the median (MoM) values or deviations from the median (deltas) values after adjustment for maternal characteristics and elements of medical history. Regression analysis was then used to examine the significance of the association between PSV ratio delta and MoM or delta values of each cardiovascular index in the total population and in the subgroup that developed PE. RESULTS: The study population of 2853 pregnancies contained 76 (2.7%) that developed PE. In the total population, there were significant but weak associations between the PSV ratio and most of the cardiovascular indices, with r-values of < 0.1, except for mean arterial pressure with r = 0.178. In the subgroup that developed PE, a moderately strong association between the PSV ratio and left ventricular mass indexed for body surface area was noted (r = 0.308). CONCLUSIONS: The findings of this study suggest that Doppler assessment of PSV ratio in the ophthalmic artery provides information about peripheral vascular status. The increase in PSV ratio in women who develop PE is associated with increased afterload and an increase in left ventricular thickness. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Ophthalmic artery Doppler in combination with other biomarkers in prediction of pre-eclampsia at 35-37 weeks' gestation.

OBJECTIVE: To examine the potential value of maternal ophthalmic artery Doppler at 35-37 weeks' gestation in combination with the established biomarkers of pre-eclampsia (PE), including mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), serum placental growth factor (PlGF) and serum soluble fms-like tyrosine kinase-1 (sFlt-1), in the prediction of subsequent development of PE. METHODS: This was a prospective observational study in women attending for a routine hospital visit at 35 + 0 to 36 + 6 weeks' gestation. This visit included recording of maternal demographic characteristics and medical history, ultrasound examination for fetal anatomy and growth, assessment of flow velocity waveforms from the maternal ophthalmic arteries, and measurement of MAP, UtA-PI, serum PlGF and serum sFlt-1. The competing-risks model was used to estimate the individual patient-specific risks of delivery with PE at any time and at < 3 weeks after assessment by a combination of maternal demographic characteristics and medical history with biomarkers. The area under the receiver-operating-characteristics curve and detection rate (DR) of delivery with PE, at a 10% false-positive rate (FPR), in screening by combinations of maternal factors with ophthalmic artery second to first peak of systolic velocity ratio (PSV ratio), MAP, UtA-PI, serum PlGF and serum sFlt-1 were determined. The modeled performance of screening for PE was also estimated. RESULTS: The study population of 2287 pregnancies contained 60 (2.6%) that developed PE, including 19 (0.8%) that delivered with PE at < 3 weeks after assessment. The PSV ratio improved the prediction of PE with delivery at any stage after assessment provided by maternal factors alone (from 25.4% to 50.6%), maternal factors and MAP (54.3% to 62.7%), maternal factors, MAP and PlGF (68.3% to 70.8%) and maternal factors, MAP, PlGF and sFlt-1 (75.7% to 76.7%), at a FPR of 10%. The PSV ratio also improved the prediction of PE with delivery at < 3 weeks after assessment provided by maternal factors alone (from 31.0% to 69.4%), maternal factors and MAP (74.1% to 83.4%), maternal factors, MAP and UtA-PI (77.1% to 85.0%) and maternal factors, MAP and PlGF (84.8% to 88.6%). The empirical results for DR at a 10% FPR were consistent with the modeled results. Screening by a combination of maternal factors with MAP and PSV ratio also detected 59.4% (95% CI, 58.6-82.5%) of cases of gestational hypertension with delivery at any stage after assessment, and 86.7% (95% CI, 82.4-100%) of those with delivery at < 3 weeks after assessment. CONCLUSION: Ophthalmic artery Doppler could potentially improve the performance of screening for PE at 35-37 weeks, especially imminent PE with delivery within 3 weeks after assessment, but further studies are needed to validate this finding. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

The Relationship between Ocular Vascular Changes and the Levels of Malondialdehyde and Vascular Endothelial Growth Factor in Patients with Inflammatory Bowel Disease.

Background: We evaluated ocular hemodynamic changes, malondialdehyde(MDA) and vascular endothelial growth factor (VEGF) levels in patients with IBD.Methods: We used ocular color Doppler ultrasonography to analyze 56 eyes with Crohn's disease (CD), 62 eyes with ulcerative colitis (UC), 68 eyes of healthy volunteers. We measured peak systolic velocity (PSV),end-diastolic velocity (EDV),and the resistivity index (RI) of ophthalmic artery (OA) and central retinal artery (CRA). MDA and VEGF levels were measured in the plasma samples.Results: MDA levels were significantly higher in both UC and CD patients, whereas VEGF levels were only higher in the CD group (p = .003,p < .001,p = .01).The PSV and EDV of the OA were significantly lower in CD patients (p = .017,p = .001). The EDV of the CRA was significantly lower in CD patients than UC patients and controls (p = .014,p < .001).Conclusions: CD patients exhibited decreased blood flow in both the OA and CRA. Ocular vascular flow was only affected in CD patients. We found that ocular ischemia may occur in CD patients even in the absence of any clinical finding.

Feasibility of MRI to assess differences in ophthalmic artery blood flow rate in normal tension glaucoma and healthy controls.

PURPOSE: To examine feasibility of phase-contrast magnetic resonance imaging (PCMRI) and to assess blood flow rate in the ophthalmic artery (OA) in patients with normal tension glaucoma (NTG) compared with healthy controls. METHODS: Sixteen patients with treated NTG and 16 age- and sex-matched healthy controls underwent PCMRI using a 3-Tesla scanner and ophthalmological examinations. OA blood flow rate was measured using a 2D PCMRI sequence with a spatial resolution of 0.35 mm2 . RESULTS: The blood flow rate in the NTG group was 9.6 ± 3.9 ml/min [mean ± SD] compared with 11.9 ± 4.8 ml/min in the control group. Resistance Index (RI) and Pulsatility Index (PI) were 0.73 ± 0.08 and 1.36 ± 0.29, respectively, in the NTG group and 0.68 ± 0.13 and 1.22 ± 0.40, respectively, in the healthy group. The mean visual field index (VFI) was 46% ± 25 for the worse NTG eyes. The measured differences observed between the NTG group and the control group in blood flow rate (p = 0.12), RI (p = 0.18) and PI (p = 0.27) were non-significant. CONCLUSIONS: This case-control study, using PCMRI, showed a slight, but non-significant, reduction in OA blood flow rate in the NTG patients compared with the healthy controls. These results indicate that blood flow may be of importance in the pathogenesis of NTG. Considering that only a limited portion of the total OA blood flow supplies the ocular system and the large inter-individual differences, a larger study or more advanced PCMRI technique might give the answer.

Intraocular Pressure Decrease Does Not Affect Blood Flow Rate of Ophthalmic Artery in Ocular Hypertension.

Purpose: To investigate if decrease of IOP affects the volumetric blood flow rate in the ophthalmic artery (OA) in patients with previously untreated ocular hypertension. Methods: Subjects with untreated ocular hypertension (n = 30; mean age 67 ± 8 years; 14 females) underwent ophthalmologic examination and a 3-Tesla magnetic resonance imaging investigation. The magnetic resonance imaging included three-dimensional high-resolution phase-contrast magnetic resonance imaging to measure the OA blood flow rate. The subjects received latanoprost once daily in the eye with higher pressure, the untreated eye served as control. The same measurements were repeated approximately 1 week later. Results: The mean OA blood flow rate before and after treatment was 12.4 ± 4.4 and 12.4 ± 4.6 mL/min in the treated eye (mean ± SD; P = 0.92) and 13.5 ± 5.2 and 13.4 ± 4.1 mL/min in the control eye (P = 0.92). There was no significant difference between the treated and control eye regarding blood flow rate before (P = 0.13) or after treatment (P = 0.18), or change in blood flow rate after treatment (0.1 ± 3.1 vs. -0.1 ± 4.0 mL/min, P = 0.84). Latanoprost decreased the IOP by 7.2 ± 3.1 mm Hg in the treated eye (P < 0.01). Conclusions: The results indicate that a significant lowering of IOP does not affect the blood flow rate of the OA in ocular hypertension subjects. The ability to maintain blood supply to the eye independent of the IOP could be a protective mechanism in preserving vision in subjects with ocular hypertension.

Changing the paradigm of intracranial hypertension in brain tumor patients: a study based on non-invasive ICP measurements.

BACKGROUND: The ultrasound based non-invasive ICP measurement method has been recently validated. Correlation of symptoms and signs of intracranial hypertension with actual ICP measurements in patients with large intracranial tumors is controversial. The purpose of this study was to assess ICP in patients with brain tumors, presenting with neurological signs and symptoms of elevated ICP and to further evaluate the value and utility of non-invasive ICP monitoring. METHODS: Twenty patients underwent non-invasive ICP measurement using a two-depth transcranial Doppler ultrasound designed to simultaneously compare pulse dynamics in the proximal (intracranial), and the distal (extracranial) intraorbital segments of the ophthalmic artery through the closed eyelid. RESULTS: Forty-eight measurements were analyzed. Radiological characteristics included tumor volume (range = 5.45-220.27cm3, mean = 48.81 cm3), perilesional edema (range = 0-238.27cm3, mean = 74.40 cm3), and midline shift (mean = 3.99 mm). All ICP measurements were in the normal range of 7-16 mmHg (ICPmean: 9.19 mmHg). The correlation of demographics, clinical and radiological variables in a bivariate association, showed a statistically significant correlation with neurological deficits and ICPmax (p = 0.02) as well as ICPmean (p = 0.01). The correlation between ICP and neurological deficits, showed a negative value of the estimate. The ICP was not increased in all cases, whether ipsilateral nor contralateral to the tumor. The multivariate model analysis demonstrated that neurological deficits were associated with lower ICPmax values, whereas maximum tumor diameter was associated with larger ICPmax values. CONCLUSIONS: This study demonstrated that ICP in patients with intracranial tumors and mass effect is not necessarily increased. Therefore, clinical signs of intracranial hypertension do not necessarily reflect increased ICP.

Predictive value of ophthalmic artery Doppler velocimetry in relation to hypertensive disorders of pregnancy.

PURPOSE: To test the predictive value of ophthalmic artery (OA) Doppler velocimetry in relation to the occurrence of hypertensive disorders of pregnancy (HDP). METHODS: We compared, by analysis of variance, the values of seven OA Doppler variables (peak systolic velocity, second systolic peak velocity [P2], mean velocity, end diastolic velocity, resistance index [RI], pulsatility index [PI], and peak ratio) of 31 women with preeclampsia and 33 women with gestational hypertension vs those of 227 women without HDP. The prognostic value of these variables in relation to the occurrence of HDP was evaluated by the area under the curve (AUC) receiver operating characteristic curve. RESULTS: All OA Doppler variables except RI and PI showed significant (P < .5) differences between groups. After adjustment for confounders, only P2 was an independent predictor of HDP (P < .001), with an AUC of 0.76. The best cut-off point for predicting HDP was P2 ≥ 21.4 cm/s, with sensitivity 69%, specificity 78%, positive likelihood ratio 3.1, negative likelihood ratio 0.4, positive predictive value 47%, and negative predictive value 90%. P2 improved the predictive ability of a model based on clinical variables, incrementing AUC from 0.77 to 0.84 in the final model containing clinical and Doppler variables. CONCLUSION: The elevation of OA P2 in the second trimester of pregnancy is an independent predictor of hypertensive disorders, and improves the discriminatory ability of clinical markers.

Medial canthal and eyelid reconstruction using the split paramedian forehead flap: a case report / Reconstrucción del canto interno con un colgajo frontal: presentación de un caso

Medial eyelid/canthal defects are difficult to reconstruct. This region has both functional an cosmetic importance in facial esthetics. The lacrimal apparatus drains in the medial canthal area and both eyelids protect the eye from dryness and exposure, so damage to this organs may have severe ophthalmic consequences. Furthermore, the medial canthal area owns a complex concave surface difficult to replace satisfactorily. Poor reconstruction techniques may have undesirable cosmetic outcomes, which may be easily noticeable. The paramedian forehead flap is a mainly used in nasal reconstruction. It has a reliable vascu­larity and allows a wide arc of rotation. Plus, trimming and recontouring of the flap may be done to offer the best RESULTS: Several modifications of the flap have been purposed in the literature. The paramedian forehead flap may be a good choice for medial canthal/eyelid reconstruction as well, given the characteristics aforementioned. We present a case of an 88 year old woman who presented with a medial eyelid/canthal defect following resection of a squamous cell carcinoma. Reconstruction with a contralateral split paramedian forehead flap was achieved. We conclude that the paramedian forehead flap may represent a safe and simple alternative in medial eyelid/canthal reconstruction, preserving eyelid function and offering acceptable cosmetic results with minor donor site morbidity

Los defectos que comprometen el canto interno son difíciles de reconstruir. Esta región tiene importancia funcional y estética en la armonía facial. El aparato lagrimal drena en el área del canto interno y ambos párpados protegen el ojo de la sequedad y la exposición, de tal forma que el dañar estas estructuras puede tener consecuencias oftalmológicas severas. Además, el canto medial es un área con una superficie cóncava y compleja, difícil de reconstruir de manera satisfactoria. Es importante realizar una buena técnica de reconstrucción para evitar resultados cosméticos indeseables. El colgajo frontal se utiliza principalmente en la reconstrucción nasal. Tiene una buena vascularización y permite un amplio arco de rotación. Además, se puede remodelar y adelgazar de manera que ofrezca mejores resultados estéticos. Se han descrito diferentes modificaciones en la literatura. El colgajo frontal puede ser una buena opción para la reconstrucción del área del canto medial dadas las características mencionadas previamente. Presentamos el caso de una paciente de 88 años de edad que presentó un defecto del área del canto medial tras la resección de un carcinoma escamoso. Se realizó la reconstrucción con un colgajo frontal contralateral. Concluimos que el colgajo frontal puede ser una opción segura y sencilla como alternativa en la reconstrucción del canto medial. Permite preservar la función del párpado y ofrece resultados estéticos aceptables con mínima morbilidad de la zona donante

Abnormal retrobulbar blood flow variables in central serous chorioretinopathy.

PURPOSE: To evaluate if the retrobulbar blood flow variables were deteriorated in central serous chorioretinopathy (CSC) patients. METHODS: We included 25 CSC patients and 25 healthy subjects. We used color Doppler ultrasonography to assess the ophthalmic artery (OA), the central retinal artery (CRA), and the posterior ciliary arteries (PCA) for peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistance index (RI). RESULTS: Mean ages of the patients and controls were 42.3 ± 8.5 and 41.3 ± 9.4 years, respectively (P = .853). There were no significant differences between the two groups with regard to the values of PSV, EDV, and RI of CRA (P = .406, P = .627, P = .227) and PCA (P = .785, P = .403, P = .935, respectively). The PSV and EDV of OA were lower in the CSC patients (P = .005, P = .024, respectively). Whereas the RI of OA was not significantly different (P = .729). Submacular choroidal thickness (SCT) was greater in CSC patients (P < .001). There was a negative correlation between SCT and PSV of PCA (P = .022, r = -0.457) and between SCT and EDV of PCA (P = .004, r = -0.560) in CSC patients. CONCLUSION: Hemodynamic changes in OA and a negative correlation between PCA values and SCT suggest ocular circulatory dysfunction in patients with CSC.

Age-related changes in retrobulbar circulation: a literature review.

INTRODUCTION: The advances in research methods used in ophthalmology allow for an increasingly accurate examination of the eyes, as well as the morphology and function of the vessels. Colour Doppler imaging is still the first-line method for the analysis of parameters of retrobulbar circulation. Therefore, the aim of this work was to present the current state of knowledge about anatomical and functional age-related changes in retrobulbar arteries. METHODS: A literature search was performed mainly based on the PubMed database. RESULTS: The anatomy of retrobulbar arteries, histological background of age-related vascular changes, age-related changes in retrobulbar blood flow in the ophthalmic artery, central retinal artery, short posterior ciliary arteries, and the reference values for the age-dependent retrobulbar circulation parameters measured by colour Doppler imaging are discussed in this review. CONCLUSION: The age of the subject should always be taken into account when interpreting the parameters of retrobulbar blood flow measured by colour Doppler imaging.

Waveform parameters of retrobulbar vessels in glaucoma patients with different demographics and disease severity.

INTRODUCTION: To identify novel velocity waveform parameters of the ophthalmic artery and central retinal artery by computer-aided image processing of Doppler ultrasonography measurements, and to evaluate correlations between the waveform parameters and different demographics and disease severity of open-angle glaucoma patients. METHODS: Thirty-six images of 36 open-angle glaucoma patients were considered. A semiautomated image processing code was used to detect the digitalized ophthalmic artery and central retinal artery velocity waveforms and to extract the waveform parameters. Concordance correlation coefficient, two-sample t-test, and Pearson's correlation coefficient were used to test for similarities, differences, and associations among variables. RESULTS: Female glaucoma patients showed a statistically higher ophthalmic artery normalized distance between ascending and descending limb (p = 0.004), hypertensive glaucoma patients a statistically higher ophthalmic artery peak systolic velocity time (p = 0.025), glaucoma patients with hyperlipidemia a statistically higher ophthalmic artery resistivity index (p = 0.023) and a statistically higher ophthalmic artery peak systolic velocity acceleration (p = 0.025), glaucoma patients with cardiovascular diseases a statistically lower central retinal artery normalized distance between ascending and descending limb of the wave (p = 0.033) and a statistically higher central retinal artery period (p = 0.028), and patients with different body mass index a statistically different central retinal artery normalized distance between ascending and descending limb of the wave (p = 0.016). Groups with different disease severity, classified following the Brusini glaucoma staging system 2, showed statistically different central retinal artery normalized distance between ascending and descending limb of the wave (p < 0.001) and central retinal artery period (p = 0.016). No statistical differences were found in regard to race, diabetes status, glaucoma family history, and smoking. DISCUSSION: Ophthalmic artery and central retinal artery computer-aided analysis of velocity waveforms could identify novel waveform parameters capable of differentiating among different demographics and disease severity of open-angle glaucoma patients.

Unraveling the Enigma of Nonarteritic Anterior Ischemic Optic Neuropathy.

Non-arteritic anterior ischemic optic neuropathy (NAON) is the second most common optic neuropathy in adults. Despite extensive study, the etiology of NAION is not definitively known. The best evidence suggests that NAION is caused by an infarction in the region of the optic nerve head (ONH), which is perfused by paraoptic short posterior ciliary arteries (sPCAs) and their branches. To examine the gaps in knowledge that defies our understanding of NAION, a historical review was performed both of anatomical investigations of the ONH and its relevant blood vessels and the evolution of clinical understanding of NAION. Notably, almost all of the in vitro vascular research was performed prior our current understanding of NAION, which has largely precluded a hypothesis-based laboratory approach to study the etiological conundrum of NAION. More recent investigative techniques, like fluorescein angiography, have provided valuable insight into vascular physiology, but such light-based techniques have not been able to image blood vessels located within or behind the dense connective tissue of the sclera and laminar cribrosa, sites that are likely culpable in NAION. The lingering gaps in knowledge clarify investigative paths that might be taken to uncover the pathogenesis of NAION and possibly glaucoma, the most common optic neuropathy for which evidence of a vascular pathology also exists.

Describing a New Mechanism of Retinal Detachment Secondary to Ophthalmic Artery Vasospasm Following Subarachnoid Hemorrhage: An Experimental Study.

BACKGROUND: The pterygopalatine ganglion (PPG) and ophthalmic arteries (OpAs) have important roles in ocular autoregulation and retinal and visual functions. The relationship between PPG neuron density, OpA vasospasm, and retinal detachment in subarachnoid hemorrhage (SAH) has never been studied. METHODS: This study was conducted on 25 rabbits. Five animals were in the control group (GI; n = 5), five in the sham group (GII; n = 5), and 15 in the study group (GIII; n = 15). After injection of 1 cc serum saline into the cisterna magna in the sham group, and autologous blood in the SAH group, the animals were followed for 3 weeks. All animals underwent a retinal examination five times a week for 3 weeks before and after the experiment. After the experiment, the neuron density of PPGs of the facial nerves, vasospasm index (VSI) of OpAs, and total basal surface values of the detached retinal parts (DRPs) were calculated. RESULTS: In the funduscopic examination, intravitreous hemorrhage ( Terson's syndrome) was detected in four animals in the SAH group. In the control groups, neuron density was 12,000 ± 1,240/mm3, VSI = 0.345 ± 0.076, and DRP = 0 to 1.5 mm2. Mean neuron density was 9,450 ± 940/mm3, VSI = 1.645 ± 0.940, and DRP = 6.23 ± 1.61 mm2 in the sham group (p < 0.05). Neuron density was 6,890 ± 932/mm3, VSI = 2.92 ± 0.97, and DRP = 9.43 ± 2.54 mm2 in SAH group. CONCLUSION: Mean neuron density, VSI of OpAs, and DRP values differed statistically significant between the SAH group and other groups (p < 0.005). There is an inverse relationship between PPG neurons and DRP. However, a direct relationship was observed between the mean VSI and DRP values.

Retinal Oxygen Delivery, Metabolism and Extraction Fraction and Retinal Thickness Immediately Following an Interval of Ophthalmic Vessel Occlusion in Rats.

Limited knowledge is currently available about alterations of retinal blood flow (F), oxygen delivery (DO2), oxygen metabolism (MO2), oxygen extraction fraction (OEF), or thickness after the ophthalmic blood vessels have been closed for a substantial interval and then reopened. We ligated the ophthalmic vessels for 120 minutes in one eye of 17 rats, and measured these variables within 20 minutes after release of the ligature in the 10 rats which had immediate reflow. F, DO2 and MO2 were 5.2 ± 3.1 µL/min, 428 ± 271 nL O2/min, and 234 ± 133 nL O2/min, respectively, that is, to 58%, 46% and 60% of values obtained from normal fellow eyes (P < 0.004). OEF was 0.65 ± 0.23, 148% of normal (P = 0.03). Inner and total retinal thicknesses were 195 ± 24 and 293 ± 20 µm, respectively, 117% and 114% of normal, and inversely related to MO2 (P ≤ 0.02). These results reflect how much energy is available to the retina immediately after an interval of nonperfusion for 120 minutes. Thus, they elucidate aspects of the pathophysiology of nonperfusion retinal injury and may improve therapy in patients with retinal artery or ophthalmic artery obstructions.

Hemodynamic impacts of flow diverter devices on the ophthalmic artery.

BACKGROUND: Flow diverter devices are increasingly used for endovascular treatment of internal carotid artery aneurysms. Treatment of ophthalmic segment aneurysms with flow diverter devices also includes coverage of the ophthalmic artery but may result in complications. It is unclear, however, whether these devices mechanically block blood flow in the ophthalmic artery. Also unclear is the relationship between deployment of a flow diverter device and post-treatment occlusion. We studied hemodynamic changes in the ophthalmic artery after deployment of a flow diverter device to determine the relationship between those changes and post-stent occlusion of the artery. METHODS: We analyzed hemodynamic modifications in the ophthalmic artery in 21 patients (19 women, 2 men; mean age 53.43 ± 7.32 years) treated by a single pipeline embolization device. Patient-specific geometries were determined from three-dimensional digital subtraction angiography and the stenting process was simulated. Computational fluid dynamics technology was used to analyze the change in ophthalmic artery hemodynamics. We compared pre-treatment and post-treatment flow velocity of the ophthalmic artery. RESULTS: Among the 21 patients with aneurysms located in the ophthalmic segment, no ophthalmic artery occlusion was found during immediate or follow-up angiography. Post-stent flow velocity in the ophthalmic artery decreased from 0.35 ± 0.19 to 0.33 ± 0.20 m/s, with the difference not being statistically significant (P = 0.106). CONCLUSION: Our results showed no significant change in ophthalmic artery blood flow after pipeline embolization device deployment. Hence, post-stent occlusion of the ophthalmic artery could not be explained by reduced blood flow. Delayed thrombosis and neointimal formation maybe the keys to ophthalmic artery occlusion and need further investigation.

Retinal vessel dynamic functionality in the eyes of asymptomatic patients with significant internal carotid artery stenosis.

BACKGROUND: The goal of this study was to assess the retinal microvascular function in asymptomatic patients with hemodynamically significant internal carotid artery stenosis (ICAS) and to assess the potential efficacy of carotid endarterectomy (CEA) for the improvement of vessel functionality. METHODS: Retinal vessel caliber and reactions to flicker stimulation were assessed in both eyes of 65 asymptomatic patients with unilateral hemodynamically significant ICAS and 34 healthy subjects. Subsequently, the recruited ICAS patients were referred for standard unilateral CEA procedure. The full ophthalmologic examination of both eyes and vessel analysis were performed 1 day before and 3 months after CEA. RESULTS: The venous responses to flicker stimulation were significantly lower in the EIS (eyes ipsilateral to stenosis) and ECS (eyes contralateral to stenosis) compared with those in the controls (P<0.0001 and P<0.0001, respectively). No changes were identified in retinal vascular flicker responses after CEA in both groups of eyes compared with the baseline values. We observed a decrease in CRVE (central retinal venular equivalent) after the CEA both in eyes ipsilateral (P=0.01) and contralateral (P=0.04) to CEA. Likewise, a decrease in CRAE (central retinal arteriolar equivalent) was identified in the eyes ipsilateral to CEA (P<0.001). CONCLUSIONS: This outcome strongly indicates that microvascular dysfunction is long-lasting despite the recovery of the flow in the carotid artery.