Short Posterior Ciliary Arteries Research Articles

Colour Doppler imaging of retrobulbar circulation in different severity of glaucoma optic neuropathy.

To compare retrobulbar hemodynamic measured by colour Doppler imaging (CDI) in patients with a different severity of glaucoma and to correlate variables CDI with the structural parameters of the retina and optic disc. Of 89 eyes studied, 31 had preperimetric, 29 early, 12 moderate and 17 advanced glaucoma. Peak systolic velocity (PSV), end-diastolic velocity (EDV), resistance index (RI) in ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary arteries (SPCAs) were evaluated by CDI and compared between study groups. Retinal nerve fibre layer thickness (RNFL) and optic disc parameters measured with optical coherent tomography (OCT) were correlated with the Doppler variables. In eyes with advanced, moderate and early glaucoma EDV SPCAs were significantly lower as well as RI SPCAs were significantly higher compared to the eyes with preperimetric glaucoma. In eyes with advanced and moderate glaucoma RI CRA (0.74 and 0.71) were significantly higher than in eyes with preperimetric glaucoma (0.68) (p=0.014 and 0.026). In eyes with advanced glaucoma PSV OA and PSV CRA were significantly lower than in eyes with preperimetric glaucoma (32.5 vs. 40.7 cm/s p=0.034 and 8.25 vs. 9.7 cm/s p=0.022, respectively). Positive, variable correlations were found between RNFL and EDV of all measured arteries (0.21<R<0.50, p<0,05). Statistically significant alterations in the Doppler parameters of retrobulbar arteries in association with thinning of the RNFL were observed in patients with glaucoma along with a greater severity of optic neuropathy.

Ocular blood flow and choroidal thickness in ocular hypertension.

Ocular hypertension (OHT) is a clinical entity characterized by elevated intraocular pressure (IOP) without optic nerve damage. In the presence of other risk factors, OHT may progress to glaucoma. This study aimed to evaluate ocular blood flow (OBF) and choroidal thickness (CT), which may be markers and/or risk factors that could assess the progression of OHT to glaucoma. Age and gender matched 60 eyes of 32 patients with OHT and 61 eyes of 31 control patients were included for this study. All participants underwent a detailed ophthalmological examination including best-corrected visual acuity, IOP measurement with Goldmann applanation tonometry, gonioscopy, optic nerve evaluation with 78 D lens, and visual field test with Humphrey visual field analyzer. Retinal nerve fiber layer, ganglion cell complex, and central corneal thickness measurements were performed by optical coherence tomography (OCT). CT was measured with OCT in the fovea, 1.5mm, 2mm, 2.5mm nasal and temporal to the fovea and from nasal and temporal to the optic disk. OBF data including peak systolic velocity (PSV), end-diastolic velocity (EDV), resistivity index (RI) and pulsatility index (PI) were measured with color Doppler imaging (CDI) from the ophthalmic artery (OA), central retinal artery (CRA), medial and lateral branches of short posterior ciliary arteries (MPCA, LPCA). Systolic (SBP) and diastolic arterial blood pressure were also noted. CT measurement at each point in the OHT group compared to the control group were found to be significantly thinner (p = 0.001). There was a decrement in CT from the fovea to the nasal and temporal retina in both groups. In the OHT group, there was a significant decrease in PSV and EDV of OA, CRA, MPCA, and LPCA, and a significant increase in PI and RI of measured arteries. (EDV p = 0.036, PI p = 0.006, RI p = 0.006 for OA and p = 0.001 for other arteries and all OBF measurements). There was a negative correlation between CT and age, IOP and axial length (AL) in OHT group (r = - 0.529, p = 0.001; r = - 0.258, p = 0.047; r = - 0.345, p = 0.007, respectively, for fovea). But there was no statistically significant correlation between CT and other measurements in the control group, except age (r = - 0.860 p = 0.001 for fovea). We found that OBF decrement and choroidal thinning in OHT group compared with controls. Interpretation both of CT measurements with OCT and OBF parameters with CDI and new imaging technologies may help to prevent and reduce the possible optic nerve damage.

Plane-wave ultrasound assessment of ocular blood flow in preeclampsia and correlation with optical coherence tomography angiography

We examined both eyes of 58 post-partum subjects within 72 hours of delivery with plane-wave ultrasound and optical coherence tomography angiography (OCTA). 8 had preeclampsia (PE), 21 severe PE (sPE). 9 chronic or gestational hypertension and 21 were controls. We performed plane-wave ultrasound with a Verasonics Vantage-128 and L22-14vXLF 18 MHz linear array, acquiring 3-angle compound images of the region of the optic nerve and choroid at 6 kHz for 3 s. Data were post-processed to obtain pulsatile flow characteristics of the central retinal artery and vein, the short posterior ciliary arteries and the choroid. Ultrasound revealed significantly elevated blood flow velocity and reduced resistance in sPE compared to controls. Spectral domain OCTA images were acquired with a Zeiss Plex Elite immediately before or after ultrasound. We analyzed 6x6 images centered on the macula and optic nerve to determine vascular density of the superficial and deep retina, and 3 i 3 images centered on the macula to determine foveal avascular zone area and vascular density of the choriocapillaris. Comparison of ultrasound with OCTA findings revealed significant correlations between flow velocity and resistance with vascular density in the superficial retina and choriocapillaris. These findings demonstrate a relationship between functional (ultrasound flow) and structural (OCTA vascular density) parameters in the eye, and especially in the choriocapillaris which we hypothesized would play role in the reduced flow resistance observed in sPE.

Дифференциально-диагностический подход в оценке характера течения частичной атрофии зрительного нерва

Purpose. To determine the diagnostic criteria for the progressive nature of the course of non-glaucomatous etiology of ONA according to the data of electrophysiological and Doppler studies. Material and methods. In accordance with the purpose of the study, 3 groups were formed of 95 patients aged 37 to 72 years, (average age 56±9 years), 53 of them were men and 42 were women. Clinical data of three clinical groups were compared, of which the first group with stationary ONA, the second with progressive ONA, and the third control group, without pathology of the retina and optic nerve. Results. It was revealed that the progressive nature of the course of non-glaucomatous ONA is influenced by changes in indicators such as electrical lability of the optic nerve, maximum systolic and end diastolic blood flow velocity in the ophthalmic artery and in the lateral posterior short ciliary arteries. Conclusion. The results formed the basis for our development of a method for assessing the course of ONA. Key words: partial atrophy of the optic nerve, electrophysiological studies, Doppler studies.

Evaluation of hemodynamic changes in nonarteritic anterior ischemic optic neuropathy using multimodality imaging.

Nonarteritic anterior ischemic optic neuropathy (NAION) patients experience hypo-perfusion in the short posterior ciliary arteries (SPCAs), however, the cause of hypo-perfusion is unclear. Real-time dynamic hemodynamic observations may provide clues into specific NAION pathogenic mechanisms. We aim to analyze hemodynamic changes occurring in NAION using multimodality imaging. Our specific focus is identifying pathogenic mechanisms underlying SPCA insufficiency in NAION. Three-dimensional arterial spin labeling (3D ASL) magnetic resonance imaging (MRI) and three-dimensional time-of-flight (3D-TOF) magnetic resonance angiography (MRA) were performed on 25 NAION patients (50 eyes) and 22 (44 eyes) normal cases were recruited. The diameter of the initial part of the ophthalmic artery and internal carotid artery siphon were measured using MRA. Blood vessel identification and blood flow (BF) were detected using 3D ASL MRI. We measured BF values of the optic nerve head (ONH) region of the retina/choroid complex, optic nerve (ON), temporal lobe, and occipital lobe. We studied 32 NAION affected eyes, 18 NAION uninvolved eyes, and 44 normal eyes. Diameter of the initial part of ophthalmic artery in the NAION affected eyes was significantly larger than the uninvolved eyes (P=0.026). Diameter of the NAION eyes was 1.33±0.19 mm [mean ± standard deviation (SD)], uninvolved eyes were 1.15±0.21 mm. At a photolabeling delay times (PLD) of 1,500 and 2,500 ms, BF of the ONH and ON in NAION affected eyes was significantly less than uninvolved and normal eyes (pONH <0.001 both at 1,500 and 2,500 ms, pON <0.001 and pON =0.001 at 1,500 and 2,500 ms, respectively). ONH of uninvolved eyes was also significantly less than normal eyes. Additionally, BF of the ONH region correlated with temporal lobe BF, with an R2=0.3231 and 0.2397 at 1,500 and 2,500 ms, respectively. BF of the ONH region also correlated with occipital lobe BF, with an R2=0.2534 and 0.4397 at 1,500 and 2,500 ms, respectively. ON and temporal lobe BF also correlated, with an R2=0.226 and 0.1504 at 1,500 and 2,500 ms, respectively. Abnormal hemodynamics of small cerebral vessels existed prior to the onset of NAION. A candidate mechanism underlying NAION appears to be transient insufficiency of blood supply and decompensation of ocular vascular regulation.

En-face analysis of short posterior ciliary arteries crossing the sclera to choroid using wide-field swept-source optical coherence tomography

To study the topographic distribution of the short posterior ciliary arteries (SPCA) entry sites into the choroid in normal eyes using structural en-face swept source optical coherence tomography (SS-OCT). Retrospective analysis of SS-OCT scans (wide-field structural SS-OCT 12 × 12 mm) of 13 healthy subjects was performed. Cross-sectional swept-source OCT scans derived from a volume scan were represented as en-face image display following the Choroid-Scleral Interface to obtain en-face OCT. SPCAs in their last scleral location before choroidal entrance were identified manually, counted and localized by two masked observers. Correlations between two masked observers were analyzed using inter- and intra-class correlation. Accuracy for the choroidal inner and outer border segmentation was 95–99%. Eighteen eyes from 13 normal subjects were included for SPCA analysis. The mean number of arteries was 13.8 ± 3.5 per eye. Thirty-six percent were in the center of the posterior pole image; however, 21% were in the temporal part of the posterior pole. Median accuracy of the detection is 0.94. The correlation between the two observers was fair (0.54). Our algorithm allows visualization of the SPCA at the posterior pole of the eye using wide-field en-face SS-OCT. It can also help the clinicians to study the SPCAs in numerous ocular diseases, particularly its relationship with focal choroidal diseases.

Ocular Blood Flow in Preterm Neonates: A Preliminary Report.

PurposeRetinopathy of prematurity (ROP) is a vision-threatening complication occurring in pre-term neonates. The standard of care entails regular monitoring by dilated ophthalmoscopy examinations, which entail stress and potential morbidity. In this pilot study, we used plane-wave ultrasound (PWUS) to image, measure, and assess the association of blood-flow velocities in the retrobulbar vessels with ROP stages ranging from stage 0 (immature vessels without ROP) to stage 3.MethodsBoth eyes of 14 preterm neonates at risk for ROP were examined by 18 MHz PWUS. All but two subjects had a follow-up examination. PWUS was acquired for 1.5 seconds at 3000 compound B-scans/sec. Data were postprocessed to form color-flow images and spectrograms depicting flow velocity in the central retinal artery (CRA), central retinal vein (CRV), and the short posterior ciliary arteries (SPCA). Flow parameters derived from spectrograms were compared by ROP stage.ResultsROP stage was found to correlate with flow velocities. Velocities were significantly elevated with respect to non-ROP eyes in all vessels at stage 3 and in the SPCAs at stage 2.ConclusionsPWUS measurement of blood flow may provide a quantitative, clinically important, and easily tolerated means for detecting and assessing the risk of ROP in preterm neonates. We speculate that the observed increase in flow velocity results from elevated vascular endothelial growth factor (VEGF) in ROP eyes.Translational RelevancePWUS offers a gentle, nonmydriatic method for monitoring neonates at risk for ROP that would complement ophthalmoscopy.

Normal values of flow velocity and resistance index of the ophthalmic, the central retinal, and the short posterior ciliary arteries by color Doppler ultrasound in Mexican population

Normal values of flow velocity and resistance index of the ophthalmic, the central retinal, and the short posterior ciliary arteries by color Doppler ultrasound in Mexican population

Ocular ischemic changes in thrombotic microangiopathy associated with malignant arterial hypertension (case study)

The article presents a clinical observation of visual organ damage as an extrarenal manifestation of thrombotic microangiopathy in malignant arterial hypertension with an analysis of structural and functional changes in the eye by modern examination methods. The presence of renal thrombotic microangiopathy was verified by kidney biopsy. Optical coherence tomography was used to determine structural changes in the inner and outer layers of the retina in the form of their disorganization, areas of thickening of the nerve fiber layer, intraretinal inclusions and cysts, alterations of the ellipsoid zone and retinal pigment epithelium. Optical coherence tomography angiography revealed areas of vascular pattern attenuation in the deep and superficial retinal plexuses corresponding to OCT-detected foci of disorganization of the inner retinal layers. Color Doppler imaging showed absence of the diastolic component of the Doppler spectrum with an increase in the peripheral resistance index RI up to 1.0 in the central retinal artery and posterior short ciliary arteries in both eyes. Functional changes observed with multifocal electroretinography and microperimetry corresponded to the structural changes. Taking into account the similarity of microcirculation in the kidneys and the eyes, the probable pathogenetic mechanism underlying the detected structural and functional symptoms of ischemic damage to the visual organ in malignant arterial hypertension is chronic thrombotic microangiopathy. An interdisciplinary approach to studying thrombotic microangiopathy, including those associated with malignant arterial hypertension, using high-tech examination methods can be useful for timely diagnosis and treatment of this pathology.

Ocular blood flow study using color doppler imaging: Normative value and its relevance in glaucoma

Aim: The aim was to study the normative pattern of ocular blood flow (OBF) using color Doppler imaging. Materials and Methods: It was a prospective study including healthy volunteers without any ocular pathology. Results: We analyzed ocular blood flow for 25 eyes of consecutive normal patients. Our study had 14 males and 11 females. The standard deviation of the resistive index of Ophthalmic artery, Central retinal artery and short posterior ciliary artery were 0.07, 0.08 and 0.12 respectively. Discussion: Ischemia to the optic nerve and dysfunctional vascular regulation are likely responsible for glaucomatous damage. Ocular hemodynamics, though complex, can be assessed to an extent by many ways. The quantification of blood flow in these vessels can give great lengths of information with regard to the pathological processes behind retinal and optic nerve head diseases such as glaucoma. Lower ocular perfusion pressure, vascular dysregulation, and lower OBF can worsen glaucoma. Conclusion: To our knowledge, there are no South Indian studies showing the normative data.

Макулярный отек на фоне окклюзий ретинальных вен. Особенности морфометрии макулы и хориоретинальной гемодинамики

This review article summarizes current data on the pathogenesis of macular edema after retinal vein occlusions (RVOs) and patterns of macular morphometry and chorioretinal hemodynamics. RVOs account for 60% of acute vascular eye diseases. The major cause of vision loss in RVOs is macular edema which results from subclinical inflammation characterized by leukostasis and enhanced expression of adhesion molecules and production of cytokines increasing retinal capillary permeability. The association between the severity of macular edema and vitreous levels of pro-inflammatory mediators (IL-1β, IL-6, TNF-α, MCP-1, and VEGF) is established. Cystic lesions and detachment of the neuroepithelium (75%) are typical for macular edema after RVOs. Impaired chorioretinal hemodynamics (as demonstrated by a significant reduction of vascular density in the superficial and deep vascular plexus, significant decrease in peak diastolic flow velocity, and increase in resistivity index in the ophthalmic artery and short posterior ciliary arteries) is also reported. The paper addresses etiological factors of RVOs and pathogenesis of macular edema, technical tools for vital assessment of the retina, and choroidal/retinal hemodynamics. This provides great opportunities for a complex in-depth study of the development and course of macular edema to identify potential predictors of its development and persistence. Keywords: retinal vein occlusions, macular edema, morphometry, chorioretinal hemodynamics. For citation: Fil' A.A., Sorokin E.L., Kolenko O.V. Macular edema after retinal vein occlusions. Macular morphometry and chorioretinal hemodynamics. Russian Journal of Clinical Ophthalmology. 2021;21(3):164–168 (in Russ.). DOI: 10.32364/2311-7729-2021-21-3- 164-168.

Optical coherence tomography angiography in the diagnosis of myopic choroidal neovascularization

The study examined 48 patients (40 females, 8 males) aged 18 to 54 years with pathological myopia complicated by SNM. All patients underwent standard ophthalmological examination including optical coherence tomography (OCT). Myopic SNM was detected in 56 eyes of 48 examined PM patients (the process was bilateral in eight patients). A pronounced increase in the axial eye length was accompanied by extreme thinning of the choroid, dystrophic changes in the posterior pole, and decreased visual acuity. In 20% of cases (11 eyes), the disease was detected during its active phase, in 37.5% (21 eyes) - scarring stage, in 43% (27 eyes) - atrophy stage. The blood flow inside the membranes was recordable at all stages of the pathological process. Perforating intrascleral vessels that communicate with neovascular membranes could be seen in all patients. The filling-up of these vessels with contrast in the early arterial phase of fluorescein angiography (FA) suggests that they are the branches of the short posterior ciliary arteries (SPCA). The key link in the pathogenesis of myopic SNM is pathological arteriogenesis, in which the branches of the SPCA are the source of the formation of neovascular membranes.

Imageology of internal carotid artery siphon in non-arteritic anterior ischaemic optic neuropathy.

To evaluate whether narrowing of internal carotid artery siphon (ICAS) may increase the risk of developing non-arteritic anterior ischaemic optic neuropathy (NAION). Totally 30 consecutive patients who had unilateral NAION and 30 gender-matched control subjects were recruited in the present study. The diameter of ICAS of all the participants were measured using head-and-neck computed tomographic angiography (CTA). Color doppler flow imaging (CDI) was used to measure the haemodynamics parameters of ICAS and short posterior ciliary arteries (SPCAs) in all subjects. Comparison of parameters between the NAION patients and controls as well as between the two sides within the patients were performed. The correlation between the diameter of ICAS and NAION was analyzed. A comparison of parameters between the affected side of the NAION patients and the controls, including the diameter of ICAS, the resistance index (RI) of ICAS, the blood flow velocities of SPCAs and RI of SPCAs, showed significantly difference (P<0.01), while there was no significant difference in terms of the mean blood flow velocity (Vm) of ICAS; Similar results were found while comparing all the measurements of the affected and unaffected side of patients (P for RI of SPCAs <0.05). No marked difference was detected in nearly all parameters except for RI of ICAS and SPCAs between the unaffected side of the NAION patients and the controls (P<0.05). The diameter of ICAS were significantly positive correlated with both peak systolic velocity (PSV) of SPCAs and end diastolic velocity (EDV) of SPCAs in patients with NAION (r=0.514, P<0.01 and r=0.418, P<0.05, respectively). Narrowing of ICAS may increase the risk of developing NAION.

Functional results of surgical treatment of retinal detachment

The article analyzes the state of patients visual acuity after successful surgical treatment of retinal detachment. On the basis of gathered data, it was concluded that in case of detachment of the macula only in 50% of cases it is possible to increase visual acuity to 0.4 and higher. Restoration of visual functions continues for at least 6 months after the operation and is determined by the restoration of the structure of the outer segments of the photoreceptor cells. During this time, it is advisable to conduct drug therapy aimed at normalizing blood flow and functional activity of the retina. Visual functions recovery continues for at least 6 months after the operation and is connected with the restored structure of the outer segments of the photoreceptor cells. Important prognostic factors of central vision restoration in the postoperative period are visual acuity before surgery, duration of existence and height of macular detachment. Data on which of the methods of surgical treatment of retinal detachment allows to achieve higher visual acuity are contradictory. There is practically no data on the comparison of the effect on visual acuity of scleral buckling and vitrectomy in the long-term period, in patients with phakic eyes and with artiphakia. On visual acuity after fitting detachment of the macula may affect macular edema, epiretinal membrane formation and retinal folds, and edema of the peripapillary optic nerve head, progressive deterioration of blood flow in the basin of the central retinal artery, short posterior ciliary arteries and ophthalmic artery. It is believed that these factors are significantly more pronounced after scleral buckling than after vitrectomy. Some indicators of optical coherence tomography correlate with visual acuity after surgical treatment of retinal detachment: the state of the articulation line of the external and internal segments of the photoreceptors, as well as the state of the external limiting membrane.

The dynamics of chorioretinal hemodynamics after courses of preventive care in women at risk for the formation of vascular retinal pathology

Objective:Clinical assessment of chorioretinal hemodynamics in women at risk for vascular retinal pathology before and after long-term courses of preventive care.Methods: 60 women having undergone preeclampsia during pregnancy were exam‑ ined. The 1st group of patients (30 people) got courses of medicamentous correction of endothelial dysfunction: sulodexide, ginkgo biloba (Tanakan), ascorbic acid. The 2nd group (30 women) did not get preventive care. The control group included 30 women having undergone physiological pregnancy (vaginal delivery, without complications). Parameters of chorioretinal hemodynamics were determined 6–8 months later and 3–4.5 years later after delivery.Results: By the end of the follow-up, in the 1st group, the blood flow velocity in the posterior short ciliary arteries statistically significantly increased; the density of the retinal vessels and subfoveolar thickness of the choroid and the area of the avascular zone of the retina decreased.Conclusions: The long-term medicamentous correction of endothelial dysfunction reduces the risk of vascular pathology development in women having undergone preeclampsia during the pregnancy.

Hemodynamics of the temporal and nasal short posterior ciliary arteries in pseudoexfoliation syndrome.

The aim of this study was to investigate blood flow changes in the temporal and nasal short posterior ciliary arteries (SPCAs) in pseudoexfoliation syndrome using color Doppler ultrasonography. This prospective clinical study included 67 eyes of 53 patients scheduled for cataract surgery. Pseudophakic eyes, eyes with traumatic cataract, were excluded. The demographic characteristic of the patients were recorded. Ocular blood flow was measured using 6-10MHz Doppler ultrasound. Peak systolic velocity (PSV), end-diastolic velocity (EDV), mean flow velocity (Vm), and resistive index (RI) in the temporal and nasal SPCAs were determined for 39 eyes of 30 patients with pseudoexfoliation syndrome and cataract and a control group comprising 28 eyes of 23 patients with senile cataract. Compared to the control group, patients with pseudoexfoliation syndrome had significantly lower PSV (8.85 ± 2.88cm/s), EDV (3.21 ± 1.12cm/s), and Vm (5.27 ± 1.98cm/s) in the temporal SPCA (PSV P = .001; EDV P = .002; Vm P = .001). There was no difference in velocities in the nasal SPCA. RI of both the temporal and nasal SPCA did not differ statistically between the groups (temporal SPCA P = .517, nasal SPCA P = .752) CONCLUSION: There were significant decreases in temporal SPCA hemodynamic parameters in patients with pseudoexfoliation syndrome. These findings suggest that temporal SPCA ocular blood flow measurements have greater diagnostic value than those of the nasal SPCA.

Plane-Wave Ultrasound Doppler of the Eye in Preeclampsia.

PurposePre-eclampsia (PE) is a serious complication of pregnancy characterized by high blood pressure, proteinuria, compromised fetal blood supply, and potential organ damage. The superficial location of the eye makes it an ideal target for characterization hemodynamics. Our aim was to discern the impact of PE on ocular blood flow.Methods18 MHz plane-wave ophthalmic ultrasound scanning was performed on subjects with PE (n = 26), chronic or gestational hypertension (n = 8), and normal controls (n = 19) within 72 hours of delivery. Duplicate three-second long scans of the posterior pole including the optic nerve were acquired at 6000 images/sec for evaluation of the central retinal artery and vein and the short posterior ciliary arteries. The choroid was scanned at 1000 images/sec. Doppler analysis provided values of pulsatile flow velocity and resistance indexes.ResultsEnd diastolic velocity was higher, and pulsatility and resistive indexes were significantly lower in the choroid, central retinal artery and short posterior ciliary arteries in PE than in controls. Blood pressure was elevated in PE with respect to controls and was negatively correlated with resistance.ConclusionsAlthough vasoconstriction is considered characteristic of PE, we found reduced resistance in the orbital vessels and choroidal arterioles, implying vasodilation at this level. Future studies incorporating optical coherence tomography angiography for characterization of the retina and choriocapillaris in conjunction with plane-wave ultrasound scanning, particularly in late pregnancy, might address this conundrum.Translational RelevanceUse of plane-wave ultrasound scanning for evaluation ocular blood flow in women at risk for PE may offer an avenue towards early detection and clinical intervention.

ROLE OF DILATED SUBFOVEAL CHOROIDAL VEINS IN EYES WITH MYOPIC MACULAR NEOVASCULARIZATION.

To investigate the dilated choroidal veins (DCVs) at or around myopic macular neovascularizations (MNVs) and to determine whether there is a hemodynamic relationship between them. Fifty-eight eyes of 57 patients with myopic MNVs were examined. Dilated choroidal veins were defined as choroidal veins whose diameter was 2X larger than adjacent veins. Indocyanine green angiography and swept-source optical coherence tomography images were reviewed to detect DCVs that crossed the subfoveal area. The filling sequence of the DCVs and MNVs was determined. Patients' mean age was 71.4 ± 10.6 years. The mean axial length was 29.3 ± 1.8 mm. Dilated choroidal veins below or around the MNV were found in 17 eyes (29.3%). Emissaries of the short posterior ciliary arteries were seen at or around MNVs in 8 of the 17 eyes. In these eyes, the short posterior ciliary artery was filled first or almost simultaneously with the filling of the MNV, followed by a laminar filling of the DCVs. In one eye, afferent arterioles from the short posterior ciliary arteries and efferent venules connected to DCVs were seen. Dilated choroidal veins are present below or around MNVs in about 30% of eyes with myopic MNVs. Our findings suggest that an MNV might be a vascular unit consisting of short posterior ciliary arteries, afferent arterioles, efferent venules, and DCVs.

Variations in anterior segment vasculature of the eye and their implication in ophthalmologic surgical procedures

ObjectiveAnterior segment ischemia (ASI) is a complication of strabismus surgery and other ocular procedures. The aim of this study is to determine anatomic variability of the vessels involved in the greater arterial circle of iris including short posterior ciliary arteries (SPCA), the long posterior ciliary artery (LPCA) and anterior ciliary arterial (ACA) anastomosis. Understanding these variations may help decrease the incidence of ASI in patients following strabismus surgery and other ophthalmologic procedures.MethodsA total of 126 preserved cadaveric eyeballs from Kansas City University, Nebraska Medical Center, and Creighton University were dissected. The dissection was performed through an anterior approach following removal of the orbital contents. All further dissection was performed, and photographs taken, using a Zeiss Meditech AG dissection scope. Choroid was exposed by making an incision in the sclera 1–2 cm from the limbus, followed by removal of overlying sclera to a point 2–3 cm proximal to the insertion point of the four rectus muscles.Short posterior ciliary arteries were counted as they entered the major arteriolar circle of iris and their locations were mapped in relation to the vertical and horizontal axes. Long posterior ciliary arteries were located, isolated, and cut prior to removal of the choroid. Distances were measured from the penetration point of the LPCA through the sclera in relation to the optic nerve and the vertical and horizontal axes.The number and location of SPCAs that contribute to the major arteriolar circle of iris and LPCAs as they pierce the sclera was determined. Comparisons were also made to determine if there were significant differences between right and left eyes as well as between males and females.ResultsSpecific locations of SPCAs were determined and mapped to identify their contribution to the anterior segment and generate surgical safe zones during various ophthalmologic procedures. The specific location and number of the LPCAs was also determined and mapped to clarify their contribution to the LPCA – ACA anastomosis, highlighting their importance as the sole source of blood flow following incision of the rectus muscles and corresponding anterior ciliary arteries during strabismus surgery. Surgical safe zones were created using the location where LPCA pierces the sclera which can be used to avoid damage to this artery during invasive ophthalmologic procedures.ConclusionsAs far as the investigators are able to determine, this is the first cadaveric study that uses an anterior approach to map SPCAs and LPCAs as they enter the greater arteriolar circle of iris. The findings of the study enabled the investigators to identify a surgical safe zone for invasive ophthalmologic procedures involving the extraocular muscles, sclera, choroid, and retina. This information should be beneficial to physicians performing strabismus surgery, choroidal effusion drainage, placement of ocular devices, subretinal fluid drainage and other procedures near these vessels. These findings should help surgeons avoid anterior segment ischemia, hemorrhage, and other important complications during invasive ophthalmologic procedures.

A Color Doppler Imaging Study of Ocular Haemodynamic Parameters in Primary Open Angle Glaucoma (POAG)

Aims: To study retrobulbar haemodynamics in primary open angle glaucoma (POAG) patients. Methods: It was a hospital based cross-sectional study carried out in Medical College Out Patient Department (OPD). A total of 26 patients with newly diagnosed POAG and 23 controls were randomly selected for the study. The haemodynamic parameters i.e. Peak systolic velocity (PSV), End diastolic velocity (EDV) and resistivity index (RI) were studied in ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary arteries (SPCA) measured using Color Doppler imaging (CDI). Mean, standard deviation (SD) and Independent t- test was applied to compare the results between the two group. Results: The mean intraocular pressure (IOP) for the POAG group and control group was 26.31±4.51 mmHg and 17.04±1.26 mmHg, respectively (P < 0.001). The mean PSV for both OA and CRA, the mean EDV for all OA, CRA and SPCA were significantly lower whereas the mean RI in the CRA and SPCA were significantly higher in POAG than controls. Conclusions: Retrobulbar blood flow was significantly lower in POAG as compared to controls, thereby suggesting the importance of measuring the retrobulbar blood flow in POAG patients.