Anatomy of the Ophthalmic Artery: A Review concerning Its Modern Surgical and Clinical Applications

Ophthalmic artery branches and adjacent nerves observed on sectioned images of cadaver

The ophthalmic artery plays a vital role in supplying the eyeball and neighboring structures, and is associated with various clinical conditions. In this study, high-resolution cadaver-sectioned images were used to provide an intricate morphology of the ophthalmic artery and its branches, along with the oculomotor, trochlear, ophthalmic, and abducens nerves. This study presents a combination of schematics and cadaver-sectioned images, allowing for a clear representation of intricate anatomic structures. This study elucidated the spatial relationships among the ophthalmic artery, cranial nerves, and adjacent anatomic features. The branches of the ophthalmic artery were classified into three categories. The complex anatomy of the ophthalmic artery and adjacent nerves was examined on cadaver-sectioned images and is schematically illustrated. The utilization of cadaver-sectioned images presents advantages over traditional dissection techniques. This approach maintains the original positioning of the ophthalmic artery and nerves, enhancing accuracy. This study enriches the comprehension of ophthalmic anatomy, offers a helpful resource for interpreting clinical images, and facilitates various medical procedures. As a result, we anticipate that our research will contribute to advancing the diagnosis and management of eye disorders, offering fresh perspectives on the relationship between the ophthalmic artery and the surrounding structures.

Insights into pathologic mechanisms occurring during serious adverse events following live zoster vaccination

An effective live zoster vaccine has been widely used around the world. Although no deaths occurred in the original large clinical trial, we analyzed 10 serious adverse events, including six deaths that have subsequently occurred in four countries. The goal is to define the viral pathogenesis of these unexpected adverse events secondary to a viremia with dissemination of the vaccine virus. We also propose a new hypothesis for acute retinal necrosis that occurs post-immunization.

Retinal ischemic diseases and promising therapeutic molecular targets

Retinal ischemia is a fundamental pathologic condition associated with retinal vascular occlusion, glaucoma, diabetic retinopathy, age-related macular degeneration, and other eye diseases. Extensive inflammation, redox imbalance, apoptosis, and abnormal vascular formation in retinal ischemia could lead to visual impairments. Developing or finding effective treatments is urgently needed to protect the eye against retinal ischemia and related damage. To address the demand, we have searched for promising therapeutic molecular targets in the eye (e.g., hypoxia-inducible factor [HIF], peroxisome proliferator-activated receptor-alpha [PPARα], and nicotinamide adenine dinucleotide [NAD+]), and found that modulations of each molecular target might protect the eye against retinal ischemic damage in terms of complex pathologic mechanisms. In the current article, we review and update the therapeutic evidence of modulation of HIF, PPARα, or NAD+ and discuss future directions for developing promising drugs based on these molecular targets. This summary urges research to obtain more solid evidence of each molecular target in retinal ischemic diseases.

Superior hypophyseal arteries: angiographic re-discovery, comprehensive assessment, and embryologic implications

The superior hypophyseal arteries (SHAs) are well known in anatomical and surgical literature, with a well-established role in supply of the anterior hypophysis and superjacent optic apparatus. However, due to small size and overlap with other vessels, in vivo imaging by any modality has been essentially non-existent. Advances in high resolution cone beam CT angiography (CBCTA) now enables this deficiency to be addressed. This paper presents, to the best of our knowledge, the first comprehensive in vivo imaging evaluation of the SHAs.

METHODS

Twenty-five CBCTA studies of common or internal carotid arteries were obtained for a variety of clinical reasons. Dedicated secondary reconstructions of the siphon were performed, recording the presence, number, and supply territory of SHAs. A spectrum approach, emphasizing balance with adjacent territories (inferior hypophyseal, ophthalmic, posterior and communicating region arteries) was investigated.

RESULTS

The SHAs were present in all cases. Supply of the anterior pituitary was nearly universal (96%) and almost half (44%) originated from the 'cave' region, in excellent agreement with surgical literature. Optic apparatus supply was more difficult to adjudicate, but appeared present in most cases. The relationship with superior hypophyseal aneurysms was consistent. Patency following flow diverter placement was typical, despite a presumably rich collateral network. Embryologic implications with respect to the ophthalmic artery and infraoptic course of the anterior cerebral artery are intriguing.

CONCLUSIONS

SHAs are consistently seen with CBCTA, allowing for correlation with existing anatomical and surgical literature, laying the groundwork for future in vivo investigation.

Abnormal retinal vessel filling in central retinal artery occlusion

CLINICAL RELEVANCE

Central retinal artery occlusion (CRAO) is an ophthalmic emergency with a poor prognosis. Several initial CRAO presentation factors can influence the final visual outcome. Fluorescein angiography filling of retinal vessels in CRAO has not been studied in great detail.

BACKGROUND

The aim of this paper is to study the aberrant filling of the retinal vessels on fluorescein angiography in patients with CRAO and understand its clinical relevance.

METHODS

Cases of CRAO diagnosed between June 2017 and May 2022 and who had undergone a fundus fluorescein angiography were included. Comparisons were made between the cases with and without aberrant filling of the retinal vessel.

RESULTS

Twenty-two eyes of 22 patients (14 males and 8 females) with CRAO underwent fluorescein angiography. Ages of the patients ranged from 18 to 73 years, while time interval between development of acute onset vision problems and presentation to the retinal clinic ranged from a minimum of 1 day to a maximum of 30 days. Snellen visual acuity at presentation ranged from perception of light (PL +) to 6/6. On fluorescein angiography, aberrant flow of the fluorescein dye into the retinal vein was observed in four of the 22 (18%) eyes with CRAO. All these cases showed a patient's temporal cilioretinal artery. The cases with aberrant filling of the retinal vessels showed a better presenting visual acuity (6/6-6/60), lesser severity of inner retinal damage and a better final visual acuity (6/6-6/60) compared to CRAO cases without aberrant filling.

CONCLUSION

Aberrant filling of the retinal vein can be seen on fluorescein angiography in eyes with CRAO and a patent temporal cilioretinal artery. Such eyes with aberrant retinal vessel filling have a better visual prognosis.

The Treatment of Indirect Carotid Cavernous Fistula in a Pediatric Patient With Deep Recurrent Ophthalmic Artery and Hemophilia

The treatment of indirect carotid-cavernous fistula (CCF) poses a unique challenge. Currently, endovascular interventions remain the principal treatment option with high cure rates and acceptable safety profiles. The anatomical characteristics of individual cases determine the optimal vascular access routes (transvenous vs. transarterial), and the devices utilized to achieve therapeutic goals. We present a rare case of an indirect CCF in a 13-year-old patient with an anatomical variant of the ophthalmic artery and hemophilia. CCFs are infrequent in the pediatric population, and an association with a deep recurrent ophthalmic artery (DROA) and hemophilia presents a unique treatment challenge. The patient had been diagnosed with type A hemophilia in 2013. In November 2022, he had presented with insidious conjunctival hyperemia and developed gradual ocular proptosis. He had been referred to Ophthalmology in October 2023, with mild symptoms and no ocular bruit or visual acuity deterioration. Angio CT, angio MRI, and cerebral angiography at that time had shown an indirect CCF. The association of an anatomical variant with the indirect CCF led to adverse anatomy and failed transvenous/transarterial vascular access. Classic treatment options (coils, detachable balloons, and liquid embolic agents) are not feasible when selective microcatheterism is unsuccessful. A FRED flow diverter was placed in the cavernous segment of the internal carotid artery (ICA) as an off-label solution to adverse patient vascular anatomy. Successful device implantation resulted in the gradual resolution of the patient's ocular symptoms.

Central retinal artery occlusion: a stroke of the eye

Central retinal artery occlusion (CRAO), like a stroke in the brain, is a critical eye condition that requiring urgent medical attention. Patients with CRAO present with acute loss of vision and the visual prognosis is poor with low chance of spontaneous visual recovery. Moreover, the risk of developing ischaemic heart disease and cerebral stroke is increased due to the presence of underlying atherosclerotic risk factors. Currently, there is no officially recommended treatment for CRAO. This review will describe the anatomy, pathophysiology, clinical features of CRAO, as well as exploring existing and potential future approaches for managing the condition.

Hollow microneedles for ocular drug delivery

Microneedles (MNs) are micron-sized needles, typically <2 mm in length, arranged either as an array or as single needle. These MNs offer a minimally invasive approach to ocular drug delivery due to their micron size (reducing tissue damage compared to that of hypodermic needles) and overcoming significant barriers in drug administration. While various types of MNs have been extensively researched, significant progress has been made in the use of hollow MNs (HMNs) for ocular drug delivery, specifically through suprachoroidal injections. The suprachoroidal space, situated between the sclera and choroid, has been targeted using optical coherence tomography-guided injections of HMNs for the treatment of uveitis. Unlike other MNs, HMNs can deliver larger volumes of formulations to the eye. This review primarily focuses on the use of HMNs in ocular drug delivery and explores their ocular anatomy and the distribution of formulations following potential HMN administration routes. Additionally, this review focuses on the influence of formulation characteristics (e.g., solution viscosity, particle size), HMN properties (e.g., bore or lumen diameter, MN length), and routes of administration (e.g., periocular transscleral, suprachoroidal, intravitreal) on the ocular distribution of drugs. Overall, this paper highlights the distinctive properties of HMNs, which make them a promising technology for improving drug delivery efficiency, precision, and patient outcomes in the treatment of ocular diseases.

A Computed Tomographic Investigation of the Ophthalmic Artery Volume and Its Relevance to Soft Tissue Filler Injections

BACKGROUND

The measured intraarterial volume of cadaveric ophthalmic arteries was utilized for safety recommendations during facial soft tissue filler injections. However, its clinical practicability and model applicability have become questionable.

OBJECTIVES

To measure the volume of the ophthalmic artery in living individuals by utilizing computed tomography (CT) imaging technology.

METHODS

A total of 40 Chinese patients (23 males, 17 females) were included in this study with a mean age of 61.0 (14.2) years and a mean body mass index of 23.7 (3.3) kg/m2. Patients were investigated with CT imaging technology to evaluate the length, diameter, and volume of the bilateral ophthalmic arteries as well as the length of the bony orbits, resulting in a total of 80 investigated ophthalmic arteries and orbits.

RESULTS

Independent of gender, the average length of the ophthalmic artery was 80.6 (18.7) mm, the calculated volume of the ophthalmic artery was 0.16 (0.05) mL and the minimal and maximal internal diameter of the ophthalmic artery were 0.50 (0.05) mm and 1.06 (0.1) mm, respectively.

CONCLUSIONS

Based on the results obtained from the investigation of 80 ophthalmic arteries it must be concluded that current safety recommendations should be reevaluated. The volume of the ophthalmic artery appears to be 0.2 mL rather than 0.1 mL as previously reported. In addition, it appears impractical to limit the volume of soft tissue filler bolus injections to 0.1 mL due to the aesthetic requirements of each individual patient and treatment plan.

Morphometric Analysis of the Ophthalmic and Central Retinal Arteries via the Endoscopic Endonasal Trans-ethmoidal Approach: Surgical Relevance of Vascular Components Within the Medial Intraconal Zones

BACKGROUND

The endoscopic endonasal approach (EEA) offers a minimally invasive route to treat medial intraconal space (MIS) lesions. Understanding the configuration of the ophthalmic artery (OphA) and the central retinal artery (CRA) is crucial.

METHODS

An EEA to the MIS was performed on 30 orbits. The description of the intraorbital part of the OphA was divided into 3 segments and classified as type 1 and type 2 and the MIS was divided into three surgical zones (A, B, C). The CRA's origin, course, and point of penetration (PP) were analyzed. The relationship between the position of the CRA in the MIS and the OphA type was analyzed.

RESULTS

The OphA type 2 was present in 20% of specimens. The site of origin of the CRA from the OphA was found on the medial surface in type 1 and on the lateral surface of type 2. The point of penetrationof the central retinal arterywas found in 87% of the specimens on the inferomedial surface, just anterior to the inferior muscular trunk, at an average distance of 9.5 mm ± 1 from the globe and 17 mm ± 1.5 from the AZ. The presence of the CRA in Zone C was associated only with OphA type 1.

CONCLUSIONS

OphA type 2 is a common finding and can compromise the feasibility of an EEA to the MIS. A detailed preoperative analysis of the OphA and CRA should be conducted prior to approaching the MIS due to the implications of the anatomical variations that can compromise safe intraconal maneuverability during an EEA.

Combined central retinal artery and medial posterior ciliary artery occlusion: Localizing the lesion

Purpose

To report a rare case of a combined central retinal artery (CRA) and medial posterior ciliary artery (MPCA) occlusion due to an atherosclerotic lesion in the common trunk supplying both arteries.

Observations

A 75-year-old man presented with acute vision loss associated with elevated intraocular pressure in the right eye. Multi-modal imaging revealed a combined retinal and choroidal infarction in the distribution of the CRA and MPCA, localizing the lesion to the common trunk of the ophthalmic artery supplying both the CRA and MPCA. Neurovascular imaging provided supportive evidence for the diagnosis.

Conclusions and importance

A simultaneous retinal and choroidal vascular occlusion is an uncommon presentation. Familiarity with the anatomy of the ophthalmic arteries and its branches facilitates localizing the lesion.

Ophthalmic artery arising from the external carotid artery system: the middle meningeal artery in South African patients

BACKGROUND

The ophthalmic artery is the first branch of the internal carotid artery. It arises from the supraclinoid segment of the internal carotid artery within the subarachnoid space and enters the orbit via the optic canal. However, due to complex embryogenesis, the ophthalmic artery can arise from different parts of the internal carotid artery or the distal branches of the external carotid artery. This is usually associated with a variation in the course of the ophthalmic artery through the superior orbital fissure instead of coursing through the optic canal. The ophthalmic artery and its branches vascularise the eyeball and its contents. Consequently, information about its morphologic variation is essential for treating clinical conditions such as central retinal artery occlusion, retinoblastoma chemoembolization, and ophthalmic artery aneurysm.

CASE PRESENTATION

We report on two cases of the ophthalmic artery arising from the middle meningeal artery in one adult (33-year-old Indian female) and one pediatric (2-year-old African male) South African patient examined by digital subtraction angiography. The patients were diagnosed with arteriovenous malformations and bilateral retinoblastoma, respectively.

CONCLUSIONS

The ophthalmic artery plays a vital role in vision generation. Thus, its anatomy is of clinical interest to neurosurgeons, ophthalmologists, and interventional radiologists.

A Novel Patient-Specific Computational Fluid Dynamics Study of the Activation of Primary Collateral Pathways in the Circle of Willis During Vasospasm

The Circle of Willis (CoW) is a redundant network of blood vessels that perfuses the brain. The ringlike anatomy mitigates the negative effects of stroke by activating collateral pathways that help maintain physiological perfusion. Previous studies have investigated the activation of these pathways during embolic stroke and internal carotid artery occlusion. However, the role of collateral pathways during cerebral vasospasm-an involuntary constriction of blood vessels after subarachnoid hemorrhage-is not well-documented. This study presents a novel technique to create patient-specific computational fluid dynamics (CFD) simulations of the Circle of Willis before and during vasospasm. Computed tomographic angiography (CTA) scans are segmented to model the vasculature, and transcranial Doppler ultrasound (TCD) measurements of blood flow velocity are applied as boundary conditions. Bayesian analysis leverages information about the uncertainty in the measurements of vessel diameters and velocities to find an optimized parameter set that satisfies mass conservation and that is applied in the final simulation. With this optimized parameter set, the diameters, velocities, and flow rates fall within typical literature values. Virtual angiograms modeled using passive scalar transport agree closely with clinical angiography. A sensitivity analysis quantifies the changes in collateral flow rates with respect to changes in the inlet and outlet flow rates. This analysis can be applied in the future to a cohort of patients to investigate the relationship between the locations and severities of vasospasm, the patient-to-patient anatomical variability in the Circle of Willis, and the activation of collateral pathways.

Hemi-central retinal artery occlusion following methanol toxicity

Objective

To describe a patient with hemi-retinal artery occlusion following methanol toxicity.

Methods

Observational case report.

Results

We report a case presented with an acute altitudinal visual field loss in the right eye following consumption of illicit alcoholic drink. In fundus photography, a well demarcated superior hemi-retinal whitening with foveal sparing was noted. Careful inspection of the optic nerve head in the right eye revealed that there was no main trunk of the central retinal artery anterior to the lamina cribrosa. Two separately emerging superior and inferior arterial trunks were noted. In fundus fluorescein angiography, earlier dye filling in the territory of the superior arterial trunk compared to the inferior arterial trunk was evident.

Conclusion

Hemi-central retinal occlusion may happen as an ocular consequence of methanol toxicity in patients with a proximal bifurcation of the central retinal artery.

Orbital compartment syndrome secondary to retrobulbar hematoma after infratrochlear nerve block for nasolacrimal probing

After infratrochlear nerve block for nasolacrimal probing, sudden vision loss, proptosis, pain, loss of light reflexes, and a total limitation of ocular movement was observed in a 71-year-old female patient. She was diagnosed with retrobulbar hemorrhage and orbital compartment syndrome (OCS). Lateral canthotomy, cantholysis, and medial orbitotomy were performed on the patient. She was not taking any oral anticoagulant medication and did not have any disease other than hypothyroidism and systemic hy-pertension. All the clinical findings returned to normal right after the intervention except mild ptosis (~1 mm), which persisted for 2 months. All patients scheduled for periocular anesthesia should be questioned about using oral anticoagulant medications, and the possibility of serious complications should be kept in mind even for patients without any risk factors. Patients with OCS secondary to retrobulbar hemorrhage should be surgically managed within the critical window (90 min) to prevent any irrevers-ible optic nerve injury.

Morphometric study regarding ophthalmic and internal carotid arteries utilizing computed tomography angiography

The aim of the present study was to accurately measure the diameter of the ophthalmic artery (OA) and investigate whether bilateral variations in diameter can be recorded in relation to patient age and sex. A retrospective study including 80 computed tomography angiographic (CTA) examinations and a total of 160 arteries was conducted to demonstrate the morphometric aspects of the OAs analyzed bilaterally by CTA examinations, while considering the references of the internal carotid artery (ICA) caliber. Precise measurements performed on the OA and the ICA below and above the ophthalmic emergence revealed an OA diameter of 1.38±0.24 mm and a narrowing of the ICA between the origin of the OA of 1.5±0.25 mm. Variations in the OA and the ICA calibers were studied in subjects with normal cervical vasculature on CTA. After a thorough statistical study, variations in OA and ICA caliber on each side were identified, between both sex and age-related groups, revealing morphometric parameters of the OA in relation to the ICA.

Bilateral central retinal artery occlusion: An exceptional complication after frontal parasagittal meningioma resection

Background:

Central retinal artery occlusion (CRAO) is a rare acute disease associated with great morbidity. It is reported as a complication of surgical procedures, but rarely associated with brain surgery and no reports before due to parasagittal meningioma resection.

Case Description:

We present the case of a 41-year-old female who underwent surgery for a parasagittal meningioma and developed a bilateral CRAO as an acute postoperative complication. Most common causes, such as cardiac embolism, carotid pathology and coagulation problems, were discussed and all clinical and neuroradiological exams performed were reported.

Conclusion:

Bilateral CRAO as results of brain surgery is extremely rare; however, if it occurs, it should be early recognized and treated to minimize its high morbidity.

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.

Evaluation of macular and peri-papillary blood vessel density following uncomplicated phacoemulsification in diabetics using optical coherence tomography angiography

Purpose:

The aim of this study was to evaluate the macular and peri-papillary blood vessel density following uncomplicated phacoemulsification in diabetics using optical coherence tomography angiography (OCT-A).

Methods:

An observational case-control study was conducted on 60 patients eligible for phacoemulsification, divided equally into diabetic and control groups. Both study groups were matching in sex, age, and axial length. We excluded diabetic patients of any form of macular edema or treatment history for macular edema. All study participants were subjected to preoperative OCT and OCT-A, which was repeated for all study population 1 month postoperatively.

Results:

We had a mean age of 54.5 ± 6.34 years in the non-diabetic group and 57.2 ± 4.09 years in the diabetic group (P = 0.06). There was a significant increase in the mean value of the macular blood vessels density in the nasal area in both study groups (P = 0.047 in non-diabetic group, P = 0.002 in the diabetic group). The percentage of the radial peripapillary capillary plexus vessel density (RPCP VD) change was non-significant on comparing the results for the diabetic group (mean preoperative value = 52.8 ± 4.47, postoperative = 52.0 ± 4.59, P = 0.204, D is the preoperative-postoperative value = 0.8), and also was non-significant for the non-diabetic group (mean preoperative value = 50.9 ± 4.89, postoperative = 52.1 ± 4.89, P = 0. 0.090, D = -1.3). On comparing the results of the diabetic and nondiabetic groups, the RPCP VD D was significantly different (P = 0.034).

Conclusion:

Uncomplicated phacoemulsification results in increase of the nasal macular blood vessel density in the normal population and in diabetic patients without retinopathy.

Anatomical Basis of Clinical Manifestations Seen in Cavernous Sinus Syndrome: A Narrative Review

Pathology involving the Cavernous Sinus (CS), generally referred to as Cavernous Sinus Syndrome (CSS), can arise from vascular disorders, neoplasms, infections, and non-infectious inflammatory disorders. An acute understanding of the CS and its regional anatomical structures is therefore pertinent in expounding the highly variable clinical manifestations seen in CSS as well as laying the groundwork for surgical intervention. Though the neuroanatomy of the cavernous sinus has been substantially chronicled in literature, their correlation to clinical signs has only been minimally described. This narrative review serves to address this knowledge gap and aims to comprehensively correlate the clinical manifestations of CSS with the relevant neuroanatomy, thereby allowing medical practitioners to better navigate the diagnostic quandary. We conducted a scoping review of the literature concerning CS anatomy and CSS, complied through MEDLINE/OVID and cross-referencing of articles on PubMed and Google Scholar with the keywords cavernous sinus, cavernous sinus syndrome, clinical signs/manifestations, neuroanatomy, CS pathology, Cavernous Sinus Thrombus (CST) and cavernous sinus neoplasms/tumours.

How I do it-the posterior question mark incision for decompressive hemicraniectomy

Background

Decompressive hemicraniectomy (DHC) is a lifesaving procedure which every neurosurgeon should master early on. As indications for the procedure are growing, the number of patients eventually requiring skull reconstruction via cranioplasty also increases. The posterior question mark incision is a straightforward alternative to the classic trauma-flap and can easily be adopted. Some particularities exist one should consider beforehand and are discussed here in detail.

Methods

Surgical steps, aids, and pitfalls are comprehensively discussed to prepare surgeons who wish to gain experience with this type of incision.

Conclusion

Due to the lower complication rate after cranioplasty, the posterior question mark incision has superseded the traditional pre-auricular starting anterior question mark incisions, in our department for the performance of decompressive hemicraniectomies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00701-021-04812-4.

Adaptive constrained constructive optimisation for complex vascularisation processes

Mimicking angiogenetic processes in vascular territories acquires importance in the analysis of the multi-scale circulatory cascade and the coupling between blood flow and cell function. The present work extends, in several aspects, the Constrained Constructive Optimisation (CCO) algorithm to tackle complex automatic vascularisation tasks. The main extensions are based on the integration of adaptive optimisation criteria and multi-staged space-filling strategies which enhance the modelling capabilities of CCO for specific vascular architectures. Moreover, this vascular outgrowth can be performed either from scratch or from an existing network of vessels. Hence, the vascular territory is defined as a partition of vascular, avascular and carriage domains (the last one contains vessels but not terminals) allowing one to model complex vascular domains. In turn, the multi-staged space-filling approach allows one to delineate a sequence of biologically-inspired stages during the vascularisation process by exploiting different constraints, optimisation strategies and domain partitions stage by stage, improving the consistency with the architectural hierarchy observed in anatomical structures. With these features, the aDaptive CCO (DCCO) algorithm proposed here aims at improving the modelled network anatomy. The capabilities of the DCCO algorithm are assessed with a number of anatomically realistic scenarios.

Intraoperative Cycling Pressure Variation in the Treatment of Central Retinal Artery Occlusion

A 45-year-old male presented to the clinic of ophthalmology with central retinal artery occlusion (CRAO). There was no response to medical treatment, ocular massage, and anterior chamber paracentesis. CRAO was resolved by pars plana vitrectomy and intraoperative cycling pressure variation. The best-corrected visual acuity improved to 20/100 on the first day and to 20/20 on the first month, postoperatively.

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.

Analysis of the Anatomical Factors Affecting Ability to Navigate Penumbra Catheter through Internal Carotid Siphon

Objective

The efficacy and safety of aspiration thrombectomy using Penumbra catheter with acute large vessel occlusion in the anterior circulation have been reported in previous studies. In some cases, the carotid siphon (CS) is elongated, and with this anatomy, especially where there is bifurcation of the ophthalmic artery (OA), navigation of Penumbra catheters into distal internal carotid artery (ICA) is interrupted, which is known as the 'ledge effect'. We investigate the anatomical characteristics of CS that cause interruption of navigation of the Penumbra catheter.

Methods

Between January 2015 and March 2018, mechanical thrombectomy using Penumbra 60 was performed on 51 patients with middle cerebral artery (MCA) or intracranial ICA occlusion. Patients were divided into two groups: The 'ledge-effect' group those in whom the Penumbra catheter was unable to be navigated into the distal ICA through the CS, and 'no ledge-effect' group those in whom this was possible. The anatomical characteristics of CS, the diameter of ICA, diameter of OA, OA/ICA ratio and radius of the CS were evaluated using angiographical imaging.

Results

The 'ledge-effect' group numbered eight cases (17%). Only the value of the CS radius was significantly smaller in the ledge-effect group (p = 0.0019), other parameters were not significantly different between the groups. The cutoff radius value was 3.62 mm.

Conclusion

The most notable anatomical factor affecting possibility of navigation of the Penumbra catheter through the CS was the CS radius. This could be useful information when devices used in mechanical thrombectomy are selected.

Model informed quantification of the feed-forward stimulation of growth hormone by growth hormone-releasing hormone

Aims

Growth hormone (GH) secretion is pulsatile and secretion varies highly between individuals. To understand and ultimately predict GH secretion, it is important to first delineate and quantify the interaction and variability in the biological processes underlying stimulated GH secretion. This study reports on the development of a population nonlinear mixed effects model for GH stimulation, incorporating individual GH kinetics and the stimulation of GH by GH‐releasing hormone (GHRH).

Methods

Literature data on the systemic circulation, the median eminence, and the anterior pituitary were included as system parameters in the model. Population parameters were estimated on data from 8 healthy normal weight and 16 obese women who received a 33 μg recombinant human GH dose. The next day, a bolus injection of 100 μg GHRH was given to stimulate GH secretion.

Results

The GH kinetics were best described with the addition of 2 distribution compartments with a bodyweight dependent clearance (increasing linearly from 24.7 L/h for a 60‐kg subject to 32.1 L/h for a 100‐kg subject). The model described the data adequately with high parameter precision and significant interindividual variability on the GH clearance and distribution volume. Additionally, high variability in the amount of secreted GH, driven by GHRH receptor activation, was identified (coefficient of variation = 90%).

Conclusion

The stimulation of GH by GHRH was quantified and significant interindividual variability was identified on multiple parameters. This model sets the stage for further development of by inclusion of additional physiological components to quantify GH secretion in humans.

The Supratrochlear Artery Revisited: An Anatomic Review in Favor of Modern Cosmetic Applications in the Area

The supratrochlear artery represents a terminal branch of the ophthalmic artery. Cosmetic interventions may traumatize it, resulting in a circulation in the lesion in glabellar region and in the medial aspect of the forehead.

This review article aims to synopsise the existing knowledge of the anatomy of the supratrochlear artery in close correlation with minimally invasive cosmetic procedures in the facial area such as soft-tissue filler injections. Their possible adverse effects and their safe application based on the topographic anatomy were included.

A literature review was performed in PubMed/Medline online medical database.

The superficial course of the supratrochlear artery, as well as the rich, variable anastomotic network that it forms with the supraorbital, angular and dorsal nasal artery raise clinical questions in the case of soft-tissue filler injections in the nasoglabellar and central forehead area. Accidental cannulation of the supratrochlear artery and ultimately, the risk of embolization of the central retinal artery in a retrograde fashion might lead to injury with questionable cosmetic results.

Although the risk of complications from the use of soft tissue fillers is considered rare, once happen, the results could be devastating for the quality of life. Thus, the comprehension of the anatomy of the supratrochlear artery is paramount for the health practitioners.

Microsurgical Anatomy of the Central Retinal Artery

BACKGROUND

The central retinal artery (CRA) has been described as one of the first branches of the ophthalmic artery.It arises medial to the ciliary ganglion and after a sinuous path within the orbital cavity it penetrates the lower surface of the dura mater that covers the optic nerve, approximately 1 cm behind the eyeball. However, the numerous anatomic descriptions that were made of the CRA have been insufficient or unclear in relation to certain characteristics that are analyzed in the present study.

METHODS

An electronic literature search was made in the PubMed database and a cadaver dissection was performed on 11 orbits fixed in formaldehyde.

RESULTS

Results were obtained regarding the source, collateral branches, curves, direction, length of the optic nerve, dural perforation site, distance, path and relations, diameter, and area of the central artery of the retina.

CONCLUSIONS

Our anatomic study innovates in 2 aspects of the CRA: area and curves. Not only was there a simple count of the number of curves, but it also analyzed the angle presented by each of the curves based on photos obtained in high definition, with a digital program to reduce the margin of error. These curvatures of the CRA were classified according to their spatial disposition within the orbital cavity based on a pattern that was easy to understand. Data were obtained from the area of the CRA on the penetration of the CRA into the dural sheath of the optic nerve.

Effectiveness of alternative routes of intra-arterial chemotherapy administration for retinoblastoma: Potential for response and complications

OBJECTIVE

Intra-arterial chemotherapy (IAC) is now the first line treatment for selected patients with retinoblastoma (Rb). Typically, IAC is infused following the selective catheterization of the ophthalmic artery (OA) on the affected side. However, in some patients, the OA alone may not provide vascular supply to the tumor, whereas in other instances the efficacy of IAC could be compromised due to the presence of prominent collateral vessels from the external carotid artery (ECA). We report our experience with catheterizing vessels other than the OA for IAC treatment for Rb.

METHODS

After institutional review board approval, a retrospective analysis was conducted of electronic medical records and imaging of our Rb population.

RESULTS

We identified 13 patients who received IAC for Rb treatment. Of these, five patients required alternative methods of chemotherapy delivery other than through the OA, totaling 17 treatments. Two patients needed balloon-assisted occlusion of the ECA, two patients required selective catheterization of the middle meningeal artery, and one patient had no internal carotid artery supply to the choroidal blush, thus the superficial temporal artery provided access for IAC. Total globe salvage rate was 76% and 80% with the alternative route subset.

CONCLUSIONS

Alternatives to the OA may be necessary to deliver IAC for selected cases of Rb. These routes can be safe and effective. However, thorough understanding of the orbital blood supply is essential. Whether these alternative IAC methods result in similar outcomes to OA infusions has not been established.

Choroidal Thickness Analysis in Patients with Erectile Dysfunction

Purpose

To investigate the morphological features of choroidal vasculature in patients with erectile dysfunction (ED) by analyzing choroidal thickness using optical coherence tomography.

Materials and Methods

We enrolled 39 patients with ED and 19 controls. ED was defined as an erectile function domain score <26 on the International Index of Erectile Function (IIEF) questionnaire. Small-choroidal-vessel-layer (SCVL) thickness was calculated by subtracting large-choroidal-vessel-layer (which corresponded to Haller's layer) thickness from total choroidal thickness. Choroidal thickness was compared between the ED and control groups.

Results

SCVL thickness was lesser in the ED group than in the control group (control, 69.8±24.3 µm vs. ED, 55.1±19.9 µm; p=0.017). Among patients without diabetes, the ED group showed significantly lesser SCVL thickness than did the control group (control, 77.1±22.7 µm vs. ED, 56.5±20.9 µm; p=0.021). However, among patients with diabetes, choroidal thickness showed no significant intergroup difference. Multiple linear regression analysis revealed that spherical equivalent (standardized coefficient β=0.294; p=0.019) and the IIEF erectile function score (standardized coefficient β=0.315; p=0.012) were significantly associated with SCVL thickness.

Conclusions

SCVL thickness, including the choriocapillaris layer and medium-sized choroidal vascular layer, decreased in proportion to ED severity, suggesting that microvascular changes in choroidal vessels may occur before specific ocular diseases in patients with ED.

Location of the internal carotid artery and ophthalmic artery segments for non-invasive intracranial pressure measurement by multi-depth TCD

The aim of the present study was to locate the ophthalmic artery by using the edge of the internal carotid artery (ICA) as the reference depth to perform a reliable non-invasive intracranial pressure measurement via a multi-depth transcranial Doppler device and to then determine the positions and angles of an ultrasonic transducer (UT) on the closed eyelid in the case of located segments. High tension glaucoma (HTG) patients and healthy volunteers (HVs) undergoing non-invasive intracranial pressure measurement were selected for this prospective study. The depth of the edge of the ICA was identified, followed by a selection of the depths of the IOA and EOA segments. The positions and angles of the UT on the closed eyelid were measured. The mean depth of the identified ICA edge for HTG patients was 64.3 mm and was 63.0 mm for HVs (p = 0.21). The mean depth of the selected IOA segment for HTG patients was 59.2 mm and 59.3 mm for HVs (p = 0.91). The mean depth of the selected EOA segment for HTG patients was 48.5 mm and 49.8 mm for HVs (p = 0.14). The difference in the located depths of the segments between groups was not statistically significant. The results showed a significant difference in the measured UT angles in the case of the identified edge of the ICA and selected ophthalmic artery segments (p = 0.0002). We demonstrated that locating the IOA and EOA segments can be achieved using the edge of the ICA as a reference point.

Abbreviations: OA: ophthalmic artery; IOA: intracranial segments of the ophthalmic artery; EOA: extracranial segments of the ophthalmic artery; ICA: internal carotid artery; UT: ultrasonic transducer; HTG: high tension glaucoma; SD: standard deviation; ICP: intracranial pressure; TCD: transcranial Doppler

Central retinal artery occlusion - rethinking retinal survival time

Background

The critical time from onset of complete occlusion of the central retinal artery (CRA) to functionally significant inner retinal infarction represents a window of opportunity for treatment and also has medical-legal implications, particularly when central retinal artery occlusion (CRAO) complicates therapeutic interventions. Here, we review the evidence for time to infarction from complete CRAO and discuss the implications of our findings.

Methods

A Medline search was performed using each of the terms “central retinal artery occlusion”, “retinal infarction”, “retinal ischemia”, and “cherry red spot” from 1970 to the present including articles in French and German. All retrieved references as well as their reference lists were screened for relevance. An Internet search using these terms was also performed to look for additional references.

Results

We find that the experimental evidence showing that inner retinal infarction occurs after 90–240 min of total CRAO, which is the interval generally accepted in the medical literature and practice guidelines, is flawed in important ways. Moreover, the retinal ganglion cells, supplied by the CRA, are part of the central nervous system which undergoes infarction after non-perfusion of 12–15 min or less.

Conclusions

Retinal infarction is most likely to occur after only 12–15 min of complete CRAO. This helps to explain why therapeutic maneuvers for CRAO are often ineffective. Nevertheless, many CRAOs are incomplete and may benefit from therapy after longer intervals. To try to avoid retinal infarcton from inadvertent ocular compression by a headrest during prone anesthesia, the eyes should be checked at intervals of less than 15′.

Cranial Nerve Foramina Part I: A Review of the Anatomy and Pathology of Cranial Nerve Foramina of the Anterior and Middle Fossa

Cranial nerve foramina are integral exits from the confines of the skull. Despite their significance in cranial nerve pathologies, there has been no comprehensive anatomical review of these structures. Owing to the extensive nature of this topic, Part I of our review, presented here, focuses on the foramina of the anterior and middle cranial fossae, discussing each foramen's shape, orientation, size, surrounding structures, and structures that traverse them. Furthermore, by comparing the size of each foramen against the cross-sectional areas of its contents, we estimate the amount of free space in each. We also review lesions that can obstruct the foramina and discuss their clinical consequences.

Anterior Communicating Artery Aneurysm Treatment with the Pipeline Embolization Device: A Single-Center Experience with Long-Term Follow-Up

Introduction

The pipeline embolization device (PED) is increasingly used in the endovascular management of cerebral aneurysms. Longitudinal data regarding safety and benefit of the PED in anterior communicating (ACOM) artery aneurysms are limited and particularly lacking in residual ACOM artery aneurysms. We report the use of the PED in 3 patients with ACOM artery aneurysms who were previously coiled.

Methods

Three patients with ACOM artery aneurysms, all previously treated with coiling and with recurrence of the aneurysm neck, were treated with the PED. All obtained follow-up diagnostic cerebral angiograms at either 3 or 6 months.

Results

Mean age of patients was 59 years. All patients received cerebral angiograms at a minimum of 3 months after treatment with the PED. Follow-up angiography was performed up to a mean of 10 months at which time point all cases demonstrated complete aneurysm occlusion, without any stenosis in the parent artery.

Conclusion

The PED can be safely used for the treatment of ACOM artery aneurysms. Complete aneurysm obliteration can be achieved in cases refractory to endovascular coiling. These findings warrant replication in a larger data set.

Relationship between the Direction of Ophthalmic Artery Blood Flow and Ocular Microcirculation before and after Carotid Artery Stenting

When internal carotid artery stenosis is accompanied by ocular ischemic syndrome, intervention is recommended to prevent irreversible visual loss. In this study, we used laser speckle flowgraphy to measure the ocular microcirculation in the optic nerve head before and after carotid artery stenting (CAS) of 40 advanced internal carotid stenosis lesions from 37 patients. The aim was to investigate the relationship between ocular microcirculation and the direction of ophthalmic artery blood flow obtained by angiography. We found that there was a significant increase in blood flow after CAS (P = 0.003). Peak systolic velocity as an indicator of the rate of stenosis was also significantly higher in the group with retrograde/undetected flow of the ophthalmic artery than in the group with antegrade flow (P = 0.002). In all cases where retrograde flow of the ophthalmic artery was observed before stenting, the flow changed to antegrade after stenting. Through the use of laser speckle flowgraphy, this study found that CAS can improve ocular microcirculation. Furthermore, while patients displaying retrograde flow of the ophthalmic artery before stenting have a poor prognosis, CAS corrected the flow to antegrade, suggesting that visual loss can be prevented by improving the ocular microcirculation.