THE OPHTHALMIC ARTERY: II. INTRA-ORBITAL COURSE

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.

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.

Investigation into the ophthalmic artery and its branches by superselective angiography

BACKGROUND

The vascular anatomy of orbit is highly complex, and the main blood supply to the orbit is via the ophthalmic artery, which is a branch of the internal carotid artery. The purpose of this study was to determine the morphometry of the ophthalmic artery and its branches by superselective angiography in a large series of pediatric patients.

METHODS

We evaluated 134 angiographies performed on children with intraocular retinoblastoma undergoing intra-arterial chemotherapy. The origin, diameter, and angiographic visibility percentages of the ophthalmic artery and its branches were examined according to age group and sex.

RESULTS

The ophthalmic artery originated 97.8% from the internal carotid artery and 2.2% from the middle meningeal artery. The mean diameter of ophthalmic artery was measured 0.76 ± 0.14 mm in girls, 0.80 ± 0.15 mm in boys and 0.79 ± 0.15 mm in general. The posterior ciliary, lacrimal, inferior muscular, and anterior ethmoidal arteries had a higher angiographic visibility percentages (> 85%) than the other OA branches. Only the diameter of the dorsal nasal artery showed a significant correlation with age. The supratrochlear and posterior ciliary arteries showed statistically significant relationship with sex.

CONCLUSIONS

Present study will make a substantial contribution to the pediatric literature about the ophthalmic artery and its branches. A better understanding of ophthalmic artery morphology can help surgeons and neurointerventional radiologists to avoid possible severe complications during embolization, intra-arterial chemotherapy, cosmetic procedures, endonasal and orbital surgeries.

Levator Palpebrae Superioris With Inferior Oblique Muscle Flaps for Total Ocular Surface Reconstruction

A healthy middle-aged man sustained extensive burns after a motor vehicle accident, including fourth-degree burns to the ocular adnexa. He had bilateral eyelid necrosis with complete tissue loss to the orbital rim. Progressive corneal thinning occurred bilaterally despite frequent lubrication, weekly amniotic membrane placement, and a Gunderson flap, ultimately requiring evisceration of his OS. In accordance with family wishes to perform all interventions for the OD, he underwent ocular surface reconstruction with levator palpebrae superioris (LPS) and inferior oblique (IO) muscle flaps, supplemented with an orbital fat transfer and bucket-handle muscle flap. These flaps were covered with porcine urinary bladder matrix and remained viable with complete globe coverage postoperatively. Although local eyelid flaps traditionally involve tissue supplied by branches of the external carotid artery, this case suggests that orbital-internal carotid artery based flaps utilizing the LPS and IO muscles may achieve ocular surface coverage after complete periocular and facial soft tissue loss.

Variability in Retinal Neuron Populations and Associated Variations in Mass Transport Systems of the Retina in Health and Aging

Aging is associated with a broad range of visual impairments that can have dramatic consequences on the quality of life of those impacted. These changes are driven by a complex series of alterations affecting interactions between multiple cellular and extracellular elements. The resilience of many of these interactions may be key to minimal loss of visual function in aging; yet many of them remain poorly understood. In this review, we focus on the relation between retinal neurons and their respective mass transport systems. These metabolite delivery systems include the retinal vasculature, which lies within the inner portion of the retina, and the choroidal vasculature located externally to the retinal tissue. A framework for investigation is proposed and applied to identify the structures and processes determining retinal mass transport at the cellular and tissue levels. Spatial variability in the structure of the retina and changes observed in aging are then harnessed to explore the relation between variations in neuron populations and those seen among retinal metabolite delivery systems. Existing data demonstrate that the relation between inner retinal neurons and their mass transport systems is different in nature from that observed between the outer retina and choroid. The most prominent structural changes observed across the eye and in aging are seen in Bruch’s membrane, which forms a selective barrier to mass transfers at the interface between the choroidal vasculature and the outer retina.

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.

Effect of Blood Pressure Reduction on Intraocular Pressure and Ophthalmic Artery Blood Flow Velocity in Hypertension

Purpose: To evaluate the effect of reducing blood pressure (BP) by atenolol and amlodipine on (1) intraocular pressure (IOP) and (2) ophthalmic artery blood flow (OAF) velocity in new hypertensives. Methods: A prospective, observational cohort study conducted at a tertiary care center in India after IRB approval. New hypertensives treated with atenolol 25 mg or amlodipine 5 mg were divided into 2 groups of 30 patients each. BP, IOP by Goldmann applanation tonometry and OAF velocity by transcranial doppler sonography was performed before medication and post medication on day 1, 7, and 30. Results: There was a significant decrease in IOP with both drugs; the effect was greater with atenolol. Atenolol: premedication IOP - 16.06 ± 2.13 mmHg and day 30-12.46 ± 1.94 (22.4%) [P < 0.001], amlodipine: premedication IOP-15.13 ± 2.55 mmHg and day 30- 13.06 ± 2.14 (13.68%) [P < 0.001]. A decrease of 0.5 mmHg in IOP with every 10 mmHg (95% CI: 0.121-0.826, P value = 0.01) decrease in systolic BP was noted after oral atenolol. The OAF peak systolic velocity and mean flow velocity were equally reduced with both drugs (P < 0.001). The end-diastolic velocity, reduced only with atenolol (P = 0.049) but returned to baseline with amlodipine at 1 month. Conclusions: BP reduction by atenolol and amlodipine led to decreases in IOP and OAF velocity, greater with atenolol. The IOP decrease was likely due to reduced blood flow. A slight decrease in the diastolic flow of the ophthalmic artery was noted with atenolol.

Role of the ophthalmic artery in the endovascular treatment for intracranial vascular diseases

The ophthalmic artery (OA) is a crucial artery. Centered at the OA, there are numerous extracranial-intracranial anastomoses. The OA and its collaterals can be involved in some intracranial vascular diseases. So, it is very important to understand its specific anatomy, variation, and role in different neurovascular diseases. The OA has various anomalies both in the origin and collateral circulation. When performing endovascular treatment (EVT), the OA may suffer unexpected embolization through the numerous dangerous anastomoses. In case of a dural arteriovenous fistula or brain arteriovenous malformation mainly fed by the OA, the OA can be the passage of EVT, during which the central retinal artery could be injured. During interventional recanalization of steno-occlusive diseases of the internal carotid artery, dissection at the cavernous segment could progress to the OA segment and occlude the origin of OA. Under the circumstance of moyamoya disease, the OA can provide collateral flow to the anterior cerebral artery. When performing EVT for OA aneurysm concurrent with moyamoya disease, the parent OA should be preserved. After placement of a flow-diverting device for ophthalmic ICA aneurysm, the covered OA could experience spontaneous occlusion, leading to visual disturbance. Hence, the OA is an extremely important artery in the EVT for intracranial vascular diseases. In this article, we would extensively review the related literature to increase our understanding of the role of OA in intracranial vascular diseases. In addition, some illustrative cases would also be provided.

The Use of Alternative Routes for the Delivery of Intra-Arterial Chemotherapy for Retinoblastoma

BACKGROUND

The introduction of intra-arterial chemotherapy (IAC) for treatment of retinoblastoma considerably changed the paradigm by which this disease is managed, with event-free survival rates being above 70%.

OBJECTIVE

To analyze efficacy of IAC treatment using alternative approaches to ophthalmic artery catheterization (OAC), such as external carotid artery approach or balloon-assisted drug delivery.

METHODS

This is a retrospective chart review for subjects receiving IAC for retinoblastoma. The primary approach was OAC. In cases in which selective OAC was not feasible, alternative routes including catheterization of the external carotid artery or use of a balloon-assisted drug infusion were used.

RESULTS

This study included 197 consecutive patients with 207 retinoblastomas who underwent 658 IAC procedures overall. The mean age at diagnosis was 24 mo, and 54.5% of the study population was male. Success rate with IAC was 97% (639). Alternative approaches to OAC were, in total, 42 cases (6.4%)-external carotid artery catheterization and use of ICA balloon were performed in 22 (3.3%) and 20 (3%) cases, respectively. A mean of 3.1 IAC cycles were performed for each patient. In total, there were 23 technical failures of the primary OAC technique (3.4%). Periprocedural adverse events occurred in 4 procedures (0.6%). Use of an alternative technique for chemotherapy delivery other than selective OAC in at least one IAC cycle was not a predictor of enucleation.

CONCLUSION

IAC is a safe and effective treatment option for retinoblastoma. Chemotherapy delivery using alternative techniques is as effective as selective OAC.

A systematic review of the surgical anatomy of the orbital apex

Purpose

The orbital apex is the narrowest part of the orbit, housing the link between the intracranial cavity and orbit. Knowledge of orbital apex anatomy is crucial to selecting a surgical approach and reducing the risk of complications. Our purpose is to summarize current knowledge on surgical anatomy and attempt to reach a consensus on definition of the orbital apex.

Methods

The online databases of Embase, the Cochrane library, Web of Science and PubMed (MEDLINE) were queried in a comprehensive bibliographic search on the (surgical) anatomy of the orbital apex and consisted of a combination of two subjects, using indexed terms and free text: “Orbital Apex” and “Orbital Anatomy.”

Results

A total of 114 relevant papers were included in this review. Numerous anatomical variations are described in the literature. Variations of the optic canal include duplication (0.64%) and keyhole anomaly (2.65%). Variations in pneumatization of the anterior clinoid process were unilateral in almost 10%, bilateral in 9%, and normal in 72%. A rare variant of the superior orbital fissure (SOF) is Warwick’s foramen, which appears as if the lowest portion of the SOF was separated from the main fissure by a transverse bony bridge.

Conclusion

The definition of the orbital apex varies in the literature, and further research would most likely identify additional variations. A universal definition reporting these variations and pathology and imaging findings is essential for determining the optimal surgical approach to the orbital apex.

Electronic supplementary material

The online version of this article (10.1007/s00276-020-02573-w) contains supplementary material, which is available to authorized users.

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.

The entry point of the central retinal artery into the outer meningeal sheath of the optic nerve

INTRODUCTION

The entry point of the central retinal artery (CRA) into the outer meningeal sheath of the optic nerve posterior to the globe has been studied and debated for more than one hundred years. The authors have supervised an orbital anatomy course for more than two decades. This article summarizes previous studies of the CRA and presents the results of dissections of 67 orbits.

MATERIALS AND METHODS

Heads were hemisected prior to dissection at the Vagelos College of Physicians and Surgeons of Columbia University. The authors measured the entry point of the CRA with a caliper and noted the meridional orientation of the CRA.

RESULTS

The mean entry point was 10.65 mm posterior to the globe, with a range of 5 to 18 mm. Most commonly, the CRA entered the sheath in the inferior meridian, but some entered slightly inferomedially or inferolaterally.

CONCLUSIONS

The entry point of the CRA into the sheath of the optic nerve is variable, and without detailed angiography the clinician cannot know the course of the CRA prior to performing invasive intraorbital procedures. Knowledge of common variations in CRA entry into the outer meningeal sheath of the optic nerve should help to minimize injury during surgery.

A Case of Anterior Cranial Fossa Dural Arteriovenous Fistula with Transient Ocular Movement Disorder after Embolization

Objective

We report a case of anterior cranial fossa dural arteriovenous fistula (dAVF) in which ocular movement was impaired after Onyx embolization from the ophthalmic artery (OphA).

Case Presentation

A 76-year-old male was admitted to our hospital for treatment of an incidentally found anterior cranial fossa dAVF. Onyx was injected from the right anterior ethmoidal artery (AEA) to close the shunt. Onyx refluxed to the third portion of the OphA to make a plug, but was unable to reach the venous side beyond the shunt; therefore, a small shunt remained. Although his visual acuity and field were normal, vertical diplopia developed after embolization and disappeared 1 month later. Diplopia worsened when the patient tilted his head to the right. Neuro-ophthalmological examination confirmed right superior oblique muscle impairment. The cause of diplopia was considered to be ischemic injury of the superior oblique muscle associated with embolization of the AEA, which provides nutrients to the superior oblique muscle and trochlear nerve.

Conclusion

Embolization from the OphA beyond the third portion may cause external ophthalmoplegia, although it may heal spontaneously.

Traumatic Cranio-Orbital Injury: Reconstruction Using Extraocular Muscles

Cranio-orbital trauma is an uncommon yet devastating injury, especially one in the setting of a high-energy gunshot wound. Such injuries were historically reported in the setting of military conflict, and are associated with vision-threatening complications, often resulting in anophthalmos. The authors report a case of a self-inflicted gunshot wound to the eye, which requires orbital enucleation with exposed frontal lobe dura. To address the exposed dura, the extraocular muscles were utilized from the enucleation procedure to cover the defect in the acute setting prior to final staged reconstruction.

Embryology and anatomical variations of the ophthalmic artery

PURPOSE

The ophthalmic artery (OA) has one of the most complex anatomy and the most fascinating embryological development.

METHODS

The complexity of the embryologic development of the OA resides in the implication of three different embryological systems: the carotid system, the stapedial system, and the ventral pharyngeal system.

RESULTS

This explains very well the numerous variations in origin of the OA and the importance of vascular anastomoses developed with branches of the external carotid artery and with the middle meningeal artery.

CONCLUSION

In this review, authors propose a comprehensive description of different hypotheses on the embryologic development of the OA and, in a second part, explain all anatomical variations and clinical implications of this artery.

Determinants of Radiation Dose in Selective Ophthalmic Artery Chemosurgery for Retinoblastoma

BACKGROUND AND PURPOSE

Retinoblastoma is the most common pediatric ocular neoplasm. Multimodality treatment approaches are commonplace, and selective ophthalmic artery chemosurgery has emerged as a safe and effective treatment in selected patients. Minimizing radiation dose in this highly radiosensitive patient cohort is critical. We explore which procedural factors affect the radiation dose in a single-center cohort of children managed in the UK National Retinoblastoma Service.

MATERIALS AND METHODS

A retrospective review was performed of 177 selective ophthalmic artery chemosurgery procedures in 48 patients with retinoblastoma (2013-2017). Medical records, angiographic imaging, and radiation dosimetry data (including total fluoroscopic screening time, skin dose, and dose-area product) were reviewed.

RESULTS

The mean fluoroscopic time was 13.5 ± 13 minutes, the mean dose-area product was 11.7 ± 9.7 Gy.cm², and the mean total skin dose was 260.9 ± 211.6 mGy. One hundred sixty-three of 177 procedures (92.1%) were technically successful. In 14 (7.9%), the initial attempt was unsuccessful (successful in 13/14 re-attempts). Screening time and radiation dose were associated with drug-delivery microcatheter location and patient age; screening time was associated with treatment cycle.

CONCLUSIONS

In selective ophthalmic artery chemosurgery, a microcatheter tip position in the proximal or ostial ophthalmic artery and patient age 2 years or younger were associated with reduced fluoroscopic screening time and radiation dose; treatment beyond the first cycle was associated with reduced fluoroscopic screening time.

Anatomy of the Ophthalmic Artery: Embryological Consideration

There are considerable variations in the anatomy of the human ophthalmic artery (OphA), such as anomalous origins of the OphA and anastomoses between the OphA and the adjacent arteries. These anatomical variations seem to attribute to complex embryology of the OphA. In human embryos and fetuses, primitive dorsal and ventral ophthalmic arteries (PDOphA and PVOphA) form the ocular branches, and the supraorbital division of the stapedial artery forms the orbital branches of the OphA, and then numerous anastomoses between the internal carotid artery (ICA) and the external carotid artery (ECA) systems emerge in connection with the OphA. These developmental processes can produce anatomical variations of the OphA, and we should notice these variations for neurosurgical and neurointerventional procedures.

Embolisation of Branches of the Ophthalmic Artery

Nine patients presenting various orbital and skull base pathologies embolised through the ophthalmic artery are reported.

All cases were catheterised beyond the bend around the optic nerve (second portion of the intraorbital ophthalmic artery). Embolisation was carried in all with n-butyl cyano-acrylate without post interventional visual disturbance.

Relying on the classic description as well as previous personal work on the ophthalmic artery anatomy and angiographic anatomy, all procedures were performed under general anaesthesia without functional testing. The central retinal artery and the long ciliary arteries arise from the first or second portion of the ophthalmic artery. For embryological reasons no branch to the visual tract can arise from the ophthalmic trunk distal to the origin of the superficial recurrent meningeal artery or the lacrimal artery.

Therefore distal catheterisation at least beyond the second portion, (and injection without reflux) makes safe embolisation possible in all variations of internal carotid origin of the ophthalmic stem.

Independent from the expected goal of the embolisation, the use of particles in this territory should in our opinion be discouraged.

Evaluation of resistive index using color Doppler imaging of orbital arteries in geriatric patients with hypertension

Background and Aim:

Resistive index (RI) is an indirect measurement of blood flow resistance that can be used to evaluate vascular damage in ophthalmologic disease. The purpose of this study was to evaluate the association between RI values of orbital arteries using the color Doppler imaging (CDI) in geriatric hypertensive patients with or without retinopathy.

Setting and Design:

Designed as a cross-sectional study.

Materials and Methods:

We evaluated 60 geriatric patients with hypertension (Group 1) and 30 healthy subjects (Group 2). Further, the patients with hypertension were grouped into two: Group 1a consisted of patients with retinopathy (n = 30), and group 1b consisted of patients without retinopathy (n = 30). The mean RI values of ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary artery (PCA) were measured using CDI.

Results:

Compared to group 2, group 1 had significantly higher mean resistive index of PCA levels (P = 0.017), whereas there were no statistical difference in mean resistive indexes of OA and CRA (both P > 0.05). Besides, there were no statistical difference in mean resistive indexes of OA, CRA, and PCA between the group 1a and group 1b (P > 0.05 for all). Mean resistive indexes of OA, CRA, and PCA were significantly correlated with the duration of hypertension (r = 0.268, P = 0.038; r = 0.315, P = 0.014; r = 0.324, P = 0.012, respectively).

Conclusions:

Our study indicates that RI might be a useful marker for the ocular hemodynamic of retinal vessels, provides morphologic and vascular information in hypertension and hypertensive retinopathy.

Pathogenesis of optic disc edema in raised intracranial pressure

Optic disc edema in raised intracranial pressure was first described in 1853. Ever since, there has been a plethora of controversial hypotheses to explain its pathogenesis. I have explored the subject comprehensively by doing basic, experimental and clinical studies. My objective was to investigate the fundamentals of the subject, to test the validity of the previous theories, and finally, based on all these studies, to find a logical explanation for the pathogenesis. My studies included the following issues pertinent to the pathogenesis of optic disc edema in raised intracranial pressure: the anatomy and blood supply of the optic nerve, the roles of the sheath of the optic nerve, of the centripetal flow of fluids along the optic nerve, of compression of the central retinal vein, and of acute intracranial hypertension and its associated effects. I found that, contrary to some previous claims, an acute rise of intracranial pressure was not quickly followed by production of optic disc edema. Then, in rhesus monkeys, I produced experimentally chronic intracranial hypertension by slowly increasing in size space-occupying lesions, in different parts of the brain. Those produced raised cerebrospinal fluid pressure (CSFP) and optic disc edema, identical to those seen in patients with elevated CSFP. Having achieved that, I investigated various aspects of optic disc edema by ophthalmoscopy, stereoscopic color fundus photography and fluorescein fundus angiography, and light microscopic, electron microscopic, horseradish peroxidase and axoplasmic transport studies, and evaluated the effect of opening the sheath of the optic nerve on the optic disc edema. This latter study showed that opening the sheath resulted in resolution of optic disc edema on the side of the sheath fenestration, in spite of high intracranial CSFP, proving that a rise of CSFP in the sheath was the essential pre-requisite for the development of optic disc edema. I also investigated optic disc edema with raised CSFP in patients, by evaluating optic disc and fundus changes by stereoscopic fundus photography and fluorescein fundus angiography. Based on the combined information from all the studies discussed above, it is clear that the pathogenesis of optic disc edema in raised intracranial pressure is a mechanical phenomenon. It is primarily due to a rise of CSFP in the optic nerve sheath, which produces axoplasmic flow stasis in the optic nerve fibers in the surface nerve fiber layer and prelaminar region of the optic nerve head. Axoplasmic flow stasis then results in swelling of the nerve fibers, and consequently of the optic disc. Swelling of the nerve fibers and of the optic disc secondarily compresses the fine, low-pressure venules in that region, resulting in venous stasis and fluid leakage; that leads to the accumulation of extracellular fluid. Contrary to the previous theories, the various vascular changes seen in optic disc edema are secondary and not primary. Thus, optic disc edema in raised CSFP is due to a combination of swollen nerve fibers and the accumulation of extracellular fluid. My studies also provided information about the pathogeneses of visual disturbances in raised intracranial pressure.

Clinical considerations of the glandular branch of the lacrimal artery

The lacrimal artery is classically described as a branch of the ophthalmic artery supplied by the internal carotid. In this study, 25 orbits were dissected to identify variations in glandular branching and to compare them to previously published accounts. The glandular branching patterns of the lacrimal artery fall into two categories, those that branch (56%) and those that do not branch (44%). We found the medial and lateral glandular branches to be equal in diameter with a divergence of 2.67-40.58 mm proximal to the gland parenchyma. The long glandular branches run alongside the superolateral aspect of the orbit. The lateral branch runs lateral to the lateral rectus muscle. The medial branch runs superomedial to the lateral rectus muscle and lateral to the superior rectus muscle. In relation to the lacrimal gland, the medial branch enters the superior aspect of the gland parenchyma and the lateral branch enters its inferior aspect. The average branch lengths were 17.88 mm (medial) and 13.51 mm (lateral) as measured with a Mitutoyo Absolute 1/100 mm caliper. We could not confirm the existence of a third branch supplying the lacrimal gland, as posited by other authors. The key finding in this study is that the lacrimal gland is predominantly supplied by two significant arterial branches, both of which must be identified during procedures involving the lateral orbit.

Identification of Intraorbital Arteries in Pediatric Age by High Resolution Superselective Angiography

PURPOSE

Angiography is a powerful tool to identify intraorbital arteries. However, the incidence by which these vessels can be identified is unknown. Our purpose was to determine such incidence and which angiographic approach is best for the identification of each artery.

METHODS

A retrospective study of 353 angiographic procedures (via ophthalmic artery and/or external carotid artery) carried out on 79 children affected by intraocular retinoblastoma was made to investigate the arterial anatomy in 87 orbits. For each intraorbital artery two parameters were calculated: the angiographic incidence, as the percentage of times a given artery was identified, and the visibility index, as the ratio between the angiographic incidence and the true anatomic incidence.

RESULTS

All collaterals of the ophthalmic artery could be spotted. Most of them were identified with a high angiographic incidence; some of them were less easily identified because too thin or because frequently shielded. The visibility index paralleled the angiographic incidence of most arteries. However, the lacrimal and meningolacrimal arteries had a higher visibility index suggesting that their identification was more frequent than the angiographic incidence alone could suggest. Statistical analysis demonstrated that the lacrimal artery and some muscular branches had higher chances to be identified if the angiography of the ophthalmic artery was accompanied by the study of the external carotid system.

CONCLUSION

This work provides an objective measure of how powerful angiography is to identify intraorbital arteries as well as useful references for professionals who need to operate in the orbit.

Anatomic evaluation of endoscopic transnasal transorbital approach to the lateral orbital apex

BACKGROUND

This anatomic study investigates the feasibility of an endoscopic transnasal transorbital approach to the lateral orbital apex.

METHODS

Five cadavers with no prior history of sinus surgery were studied bilaterally. Standard techniques and instrumentation for functional endoscopic sinus surgery were used to perform dissections and delineate anatomy of sinuses and orbits.

RESULTS

With resection of the inferior aspect of the lamina papyracea and the medial portion of the orbital floor, followed by incision of the periorbita along the inferomedial aspect of the orbit and removal of minimal orbital fat, a satisfactory view of the surgical field is achieved. The medial and inferior rectus muscles are dissected and retracted to allow visualization of the optic nerve. By dissecting inferior to the optic nerve and using 0 and 30° endoscopes, the lateral orbital apex could be accessed without damage to the optic nerve.

CONCLUSION

In patients whose vision is irreparably damaged, one might consider an endoscopic approach to lesions of the lateral orbital apex. Approach in patients with intact vision should be handled with caution because of possible traction of the optic nerve.

Different ophthalmic artery origins: Embryology and clinical significance

This retrospective study gives a summary of ophthalmic artery (OA) variations to serve as guidelines for surgical interventionists and trainees. Pubmed and Medline searches were conducted. The OA usually arises intradurally (superomedial, anteromedial, or rarely superolateral) from the internal carotid artery (ICA). Rare extradural origin (primitive dorsal OA) (PDOA) remnant and extremely rare interdural origin (primitive ventral OA) (PVOA) remnant are of significance when sectioning the dural ring. Rarely, a persistent PDOA with ICA origin, or a PDOA remnant with inferolateral trunk origin, enters the orbit via the superior orbital fissure (SOF) for sole or partial orbital supply. Extremely rare, the PDOA and PVOA persist and form double OAs that arise from the ICA and run via the SOF and optic foramen. Occasionally, the OA arises from the middle meningeal artery (MMA), when both the PDOA and VDOA regress and enter the orbit via the SOF. Sole orbital supply via the external carotid artery (ECA), i.e. meningo-ophthalmic artery and/or MMA branches, or dual OAs (ECA and ICA origins) may occur. Other rare OA origins include anterior or posterior communicating artery; anterior or middle cerebral artery; basilar artery; posterior inferior cerebellar artery; and the carotid bifurcation. Primitive arteries (persistent or remnant), and/or abnormal anastomoses play pivotal roles in manifestations of OA variations. Of clinical importance are orbital collateral routes and dangerous extracranial-intracranial anastomoses. Awareness of OA origins and collateral routes is imperative for transarterial embolizations or infusion chemotherapy in the ECA territory to prevent visual complications.

Morphological features of the porcine lacrimal gland and its compatibility for human lacrimal gland xenografting

In this study, we present first data concerning the anatomical structure, blood supply and location of the lacrimal gland of the pig. Our data indicate that the porcine lacrimal gland may serve as a potential xenograft candidate in humans or as an animal model for engineering of a bioartificial lacrimal gland tissue construct for clinical application. For this purpose, we used different macroscopic preparation techniques and digital reconstruction of the histological gland morphology to gain new insights and important information concerning the feasibility of a lacrimal gland transplantation from pig to humans in general. Our results show that the lacrimal gland of the pig reveals a lot of morphological similarities to the analogous human lacrimal gland and thus might be regarded as a xenograft in the future. This is true for a similar anatomical location within the orbit as well as for the feeding artery supply to the organ. Functional differences concerning the composition of the tear fluid, due to a different secretory unit distribution within the gland tissue will, however, be a challenge in future investigations.

Humphrey Ridley (1653-1708): 17th century evolution in neuroanatomy and selective cerebrovascular injections for cadaver dissection

Humphrey Ridley, M.D. (1653-1708), is a relatively unknown historical figure, belonging to the postmedieval era of neuroanatomical discovery. He was born in the market town of Mansfield, 14 miles from the county of Nottinghamshire, England. After studying at Merton College, Oxford, he pursued medicine at Leiden University in the Netherlands. In 1688, he was incorporated as an M.D. at Cambridge. Ridley authored the first original treatise in English language on neuroanatomy, The Anatomy of the Brain Containing its Mechanisms and Physiology: Together with Some New Discoveries and Corrections of Ancient and Modern Authors upon that Subject. Ridley described the venous anatomy of the eponymous circular sinus in connection with the parasellar compartment. His methods were novel, unique, and effective. To appreciate the venous anatomy, he preferred to perform his anatomical dissections on recently executed criminals who had been hanged. These cadavers had considerable venous engorgement, which made the skull base venous anatomy clearer. To enhance the appearance of the cerebral vasculature further, he used tinged wax and quicksilver in the injections. He set up experimental models to answer questions definitively, in proving that the arachnoid mater is a separate meningeal layer. The first description of the subarachnoid cisterns, blood-brain barrier, and the fifth cranial nerve ganglion with its branches are also attributed to Ridley. This historical vignette revisits Ridley's life and academic work that influenced neuroscience and neurosurgical understanding in its infancy. It is unfortunate that most of his novel contributions have gone unnoticed and uncited. The authors hope that this article will inform the neurosurgical community of Ridley's contributions to the field of neurosurgery.

Structural and functional effects of hemiretinal endodiathermy axotomy in cynomolgus macaques

PURPOSE

Outer retinal injury has been well described in glaucoma. To better understand the source of this injury, we wanted to develop a reliable model of partial retinal ganglion cell (RGC) axotomy.

METHODS

Endodiathermy spots were placed along the inferior 180° adjacent to the optic nerve margin in the right eyes of four cynomolgus monkeys. Fluorescein angiography, spectral domain optical coherence tomography (SD-OCT), and multifocal electroretinography (mfERG) were performed at various intervals. Two animals were sacrificed at 3 months. Two animals were sacrificed at 4 months, at which time they underwent an injection of fluorescent microspheres to measure regional choroidal blood flow. Retinal immunohistochemistry for glial fibrillary acidic protein (GFAP), rhodopsin, S-cone opsin, and M/L-cone opsin were performed, as were axon counts of the optic nerves.

RESULTS

At 3 months, there was marked thinning of the inferior nerve fiber layer on SD-OCT. The mfERG waveforms were consistent with inner but not outer retinal injury. Greater than 95% reduction in axons was seen in the inferior optic nerves but no secondary degeneration superiorly. There was marked thinning of the nerve fiber and ganglion cell layers in the inferior retinas. However, the photoreceptor histology was similar in the axotomized and nonaxotomized areas. Regional choroidal blood flow was not affected by the axotomy.

CONCLUSIONS

Unlike experimental glaucoma, hemiretinal endodiathermy axotomy (HEA) of the RGCs produces no apparent anatomic, functional, or blood flow effects on the outer retina and choroid.

Optic nerve hemangioblastoma: a case report

Hemangioblastomas are World Health Organization (WHO) grade I tumors of uncertain histologic origin. These central nervous system tumors are most often found in the posterior fossa, brainstem, and spinal cord. There are fewer than 20 reported cases of optic nerve hemangioblastomas in the literature. We present a patient with visual decline found to have a mass arising from within the posterior orbital canal that grossly involved the optic nerve sheath. Neuropathologic evaluation showed hemangioblastoma. Although not a common tumor in this location, consideration of hemangioblastoma in the differential diagnosis is important as they can have a more aggressive course than other tumors of this region and have a detrimental effect on visual prognosis.

Visualization of the ophthalmic artery by phase-contrast magnetic resonance angiography: a pilot study

OBJECTIVE

This study aimed at investigating whether phase-contrast (PC) magnetic resonance (MR) angiography is useful for visualizing the ophthalmic artery (OA).

METHODS

This prospective study enrolled 196 consecutive outpatients who underwent three-dimensional PC MR angiography. The basal image parallel to the anteroposterior dimension of the OA was extracted for analysis from the imaging data.

RESULTS

The 99 male and 97 female subjects were aged from 10 years to 80 years (mean 47.9 years). The OAs were supplied only by the external carotid system or in combination with the internal carotid artery (ICA) in 18 subjects (9.2%). The bilateral OAs were symmetrical in 12%, asymmetrical in 87%, and unidentified in 1%. The contour of the proximal segment of the OAs could be classified into straight, curved, and tortuous types. The ICA-OA angle defined by the angle between the approximate line of the proximal OA and the vertical line was also variable. The first bend of the OA corresponded to the anastomosis site with the external carotid system. The proximal medial bend was the origin of the posterior ethmoidal artery, and the distal medial bend was the origin of the anterior ethmoidal artery.

CONCLUSIONS

According to the results the OA not only possesses three characteristic bends, but also shows prominent individual variability and commonly shows bilateral asymmetry. The contour of the OA may be regulated by the anchor effect at the bend sites. PC MR Angiography is useful for visualizing the main trunk of the OA.

Short-term effects of acupuncture on open-angle glaucoma in retrobulbar circulation: additional therapy to standard medication

Background. The relation between glaucoma and retrobulbar circulation in the prognosis has been indicated. Purpose. To investigate the effects of acupuncture on retrobulbar circulation in open-angle glaucoma (OAG) patients. Methods. Eleven OAG patients (20 eyes with OAG) who were treated by topical antiglaucoma medications for at least 3 months were enrolled. Acupuncture was performed once at acupoints BL2, M-HN9, ST2, ST36, SP6, KI3, LR3, GB20, BL18, and BL23 bilaterally. Retrobulbar circulation was measured with color Doppler imaging, and intraocular pressure (IOP) was also measured at rest and one hour after rest or before and after acupuncture. Results. The Δ value of the resistive index in the short posterior ciliary artery (P < .01) and the Δ value of IOP (P < .01) were decreased significantly by acupuncture compared with no acupuncture treatment. Conclusions. Acupuncture can improve the retrobulbar circulation and IOP, which may indicate the efficacy of acupuncture for OAG.

Developmental anatomy, angiography, and clinical implications of orbital arterial variations involving the stapedial artery

Classical anatomists have provided detailed description of the arterial collateral pathways found in the head and neck. The small branches building this intricate network are difficult to access. The arterial map inherited from the anatomists has been put to the test with detailed high-resolution vascular imaging. Superselective angiography has helped rediscover the complexity of the craniocervical arterial network. The concept of dangerous collaterals or dangerous anastomoses was born with the advent of endovascular therapy. Although dangerous anastomoses of the skull base are described in the literature, variations and collateral pathways have been overlooked or misunderstood. This article reviews normal orbital arterial vascularization and its principal variations.

Arterial vascularization of the extraocular muscles on its importance for orbital approaches

The anatomic description of the arterial supply of the muscles of the eyeball was studied because medial and lateral approaches to the orbit to treat various disorders might severely damage the main trunk of the ophthalmic artery. The different arterial pedicles for each muscle, as well as their origins and points of penetration into the muscle, were studied in 19 male human orbits. In all cases, the muscular branches originated from the ophthalmic artery, and generally from the inferior face of this artery, just after crossing the optic nerve. The inferomedial muscular trunk arose from the distal of the ophthalmic artery (63.16%). The inferolateral muscular trunk, the superior oblique, levator palpebrae superioris, superior rectus, lateral rectus, and medial rectus arose from the lacrimal artery (43.36%), the bend of the ophthalmic artery (36.84%), the supraorbital artery (36.84%), the distal end of the ophthalmic artery (52.6%), the lacrimal artery (89.47%), and the inferomedial muscular trunk (84.51%), respectively. Complications resulting from damaging the artery can cause inadequacy in eye position, mobility, superior oblique function, or binocular vision, which are expected to be corrected postoperatively.

Orbital vascular anatomy

The anatomy of the orbital vascular bed is highly complex, with tremendous interindividual variations. The main source of blood supply to the orbit is by the ophthalmic artery, the first branch of the internal carotid artery. The origin, course, and branches of the ophthalmic artery, and the genesis of the variations in origin, course, and branching pattern of the ophthalmic artery are discussed. The external carotid artery normally contributes only to a small extent to the orbital blood supply via the infraorbital artery and orbital branch of the middle meningeal artery.The complex, highly variable and confusing orbital venous system can be divided into: (i) main orbital veins (superior and inferior ophthalmic veins), (ii) inconstant orbital veins (middle and medial ophthalmic veins and four collateral veins), (iii) orbital venous networks, and (iv) various venous tributaries. All these are described briefly.

A microsurgical study of the anatomy and course of the ophthalmic artery and its possibly dangerous anastomoses

OBJECT

The authors studied the microsurgical anatomy of the ophthalmic artery (OphA), paying particular attention to its possibly dangerous anastomoses with the middle meningeal artery (MMA).

METHODS

The microsurgical anatomy of the OphA and its anastomoses with the MMA were studied in 14 vessels from seven adult cadaveric heads. The origination order of the OphA branches varies in relation to whether the artery, along its intraorbital course, crosses above or below the optic nerve (ON). The central retinal artery is the first branch to course from the OphA when it crosses over the ON, and it is the second branch to course from the OphA when the artery crosses under the ON. Anastomoses between branches of the MMA and the OphA were present in the majority of the specimens examined.

CONCLUSIONS

Detailed knowledge of the microanatomy of the OphA and recognition of anastomoses between the external carotid artery and the OphA are critically important in avoiding disastrous complications during endovascular procedures.

Update on orbital anatomy

The orbit is a confined space bounded by four bony walls. Apart from the globe, orbital fat, and extraocular muscles it contains many important neurovascular structures. It is intimately related to the paranasal sinuses as well as the anterior and middle cranial fossae. Consequently, sinus pathology and intracranial disease may spread to involve the orbit and the converse applies. A thorough understanding of orbital anatomy is essential to fully appreciate the effects of disease on the orbit and is of paramount importance for performing safe orbital surgery. The anatomy of the orbit is discussed with reference to relevant orbital disease.

Importance of the anatomic features of the lacrimal artery for orbital approaches

Knowledge of variations in the possible patterns of origin, course, and distribution of the lacrimal artery are necessary for the diagnosis and important for the treatment of orbital disorders. The vascularization of 38 lacrimal glands was studied by orbital dissection subsequent to injection of the arterial bed with red-dyed latex. The origin, calibration, and branches of the lacrimal artery and its topographic relations were investigated. In all subjects, arteria lacrimalis originated from ophthalmic artery. On the right, the lacrimal artery sprang from the angle of the ophthalmic artery in 63.15% of the cases, from the curve of the ophthalmic artery in 26.31%, and from the first part the ophthalmic artery in 5.26%. The outer diameter of the lacrimal artery was measured as 1.02 +/- 0.17 mm on the right and 1.03 +/- 0.16 mm on the left. In 68.42 of the cases on the right and in 52.63 of the cases on the left, the lacrimal artery was present, and the lacrimal nerve was seen in a superolateral position with respect to the origin of the artery. Variability of the glandular branch in its course toward lacrimal gland was observed. Recurrent meningeal branch was seen in six cases on the right and in five on the left. On the right, of the six cases, two passed through meningoorbital foramen, and four passed through superior orbital fissure and entered middle cranial fossa. On the left, of the five cases, two passed through meningoorbital foramen, and three passed through superior orbital fissure and entered middle cranial fossa. In this case, the lacrimal gland is the site of an intraorbital anastomosis between internal and external carotid systems. This article confirms the well-known variability of the lacrimal arterial branches and their relation to the lacrimal gland. These variations have been discussed and described with respect to the embryonic development. A better understanding of the vascular anatomy of the lacrimal gland should allow modification of surgical techniques to reduce bleeding during biopsy or excision of the lacrimal gland.

A Case of Posterior Ischemic Optic Neuropathy in a Posterior-draining Dural Cavernous Sinus Fistula

A 79-year-old woman presented with sudden unilateral visual loss after an ocular motor disturbance and pulsatile tinnitus. Neuro-ophthalmologic examination showed a presumed right posterior ischemic optic neuropathy (PION), oculosympathetic, and third, sensory fifth, and sixth cranial nerve pareses. Selective angiography of the right internal and external carotid arteries confirmed a posterior-draining dural carotid cavernous sinus fistula (CCF) fed by the right meningohypophyseal trunk and right middle meningeal artery. Angiography also showed an ophthalmic-middle meningeal arterial anastomosis. We postulate that the PION was caused by an arterial steal, because blood was drawn into the fistula and away from the intraorbital optic nerve.

Optic nerve injury secondary to endoscopic sinus surgery: an analysis of three cases

Major orbital complications after the endoscopic sinus surgeries are rare and of these, optic nerve injury is one of the most serious. This study was to undertaken to analyze 3 cases of optic nerve injury after endoscopic sinus surgery. The three cases included one patient with a loss of visual acuity and visual field defect, and two patients with total blindness. In all cases, no improvement of visual acuity was observed despite treatment. It is important to frequently check the location and direction of the endoscope during surgery to avoid optic nerve injury. In addition, surgeons must have a precise knowledge of the detailed anatomy through cadaver dissections, an ability to interpret the PNS CT scan and experienced procedural surgical skills.

Dopplervelocimetria colorida dos vasos orbitais: técnica de exame e anatomia vascular normal

A dopplervelocimetria colorida é uma modalidade do exame ultra-sonográfico que se expandiu rapidamente em todas as áreas da medicina, em virtude da sua riqueza de informações. A dopplervelocimetria colorida das artérias orbitais tem sido empregada no auxílio diagnóstico de doenças oftalmológicas, bem como para o estudo de doenças específicas como a pré-eclâmpsia. O objetivo deste estudo é descrever a anatomia normal da região orbital e detalhar a técnica de exame dopplervelocimétrico colorido, tendo em vista ser este um exame acessível e reprodutível. Acreditamos que surgirão novas aplicações deste método, que deverá ser inserido na prática diária do radiologista, visando à melhoria da qualidade do diagnóstico e seguimento das doenças oculares e sistêmicas.

Distribution of pterygopalatine ganglion efferents to the lacrimal gland in man

To trace the path taken by the putative postganglionic secretomotor fibres to the lacrimal gland the contents of the orbital and pterygopalatine fossa were removed whole, cut coronally into slabs and embedded in resin. Thin sections were cut at varying intervals to reconstruct the pathway taken. One group of rami orbitales issuing from the pterygopalatine ganglion passed dorsally adjacent to the lateral wall of the orbit, joined the retro-orbital plexus at the apex, and 5-10 rami lacrimales advanced from the plexus to enter the gland. An accessory ophthalmic artery, a branch of the middle meningeal artery, entered the orbit through the superior fissure orbital joining the ophthalmic or lacrimal artery. Perivascular nerves of the artery continued to the gland as supplementary rami lacrimales and in some orbits others served the vasculature of the eye and orbit. The nerves are presumably derived from the middle meningeal supply and may include otic parasympathetic fibres. The route taken by parasympathetic nerves serving the human lacrimal gland is demonstrated here for the first time and apart from the perivascular meningeal artery source, it is similar to that described in monkeys. The traditional assumption that secretomotor nerves pass to the gland via the zygomatic and lacrimal nerves is therefore unlikely and clinical measures to reduce lacrimation based on that assumption and involving severance of ophthalmic branches is not indicated.

Effects of hypertension and antihypertensive treatment on retrobulbar circulation detected on Doppler sonography

OBJECTIVE

To study the effect of antihypertensive drugs in essential hypertension and in the central retinal, posterior ciliary, and ophthalmic arteries by using Doppler sonography.

METHODS

Thirty patients with essential hypertension and 32 control subjects were enrolled in the study. The pulsatility and resistive indices were evaluated in the central retinal, posterior ciliary, and ophthalmic arteries before and 2 months after treatment with antihypertensive drugs as well as in the control group. The pulsatility and resistive index values for each artery in each group were compared statistically.

RESULTS

There were significant differences in the retrobulbar pulsatility and resistive index values in each artery among the patients with initially diagnosed hypertension and the control group (P < .05). There were significant reductions in the resistive and pulsatility index values of the posterior ciliary and ophthalmic arteries after treatment (P < .05). For the ophthalmic artery, posttreatment pulsatility and resistive index values did not reach the level of flow measured in the control subjects.

CONCLUSIONS

The alteration of Doppler parameters of medication-free patients with hypertension may result from a peripheral vasospasm in the retrobulbar circulation, and the improvement in the Doppler parameters with oral antihypertensive drugs may indicate the importance of early diagnosis in ameliorating hypertension-induced retrobulbar circulation changes.

Topoanatomic relations of the ophthalmic artery viewed in four horizontal layers

In the present paper we have studied the gross anatomy of the ophthalmic artery in 200 human cadaver dissections viewed in four horizontal layers. The ophthalmic artery can be divided into the origin, intracranial, intracanalicular and intraorbital parts. The most common origin of the artery was from the medial half of the anterior side of the internal carotid artery (ICA) in its upper curve (52%), followed by the medial half of the superior side (44%), and in only 4% from the medial side of the upper curve of the ICA. We have examined the topographic anatomy of the ophthalmic artery in detail, and found a rare anastomosis of the ophthalmic artery with the frontal branch of the middle meningeal artery.

Anatomy of the orbital apex and cavernous sinus on high-resolution magnetic resonance images

Diseases of the orbital apex and cavernous sinus usually present with involvement of multiple cranial nerves, corresponding to the complex anatomy of the region. In nontraumatic disorders, magnetic resonance imaging is the diagnostic modality of choice. However, its capabilities can be fully used only with thorough knowledge of the complicated topographic relationships in this region. This article describes the imaging anatomy of the cranio-orbital junction and adjacent subarachnoid spaces. High-resolution magnetic resonance images of normal subjects are presented, and the results are compared with findings reported in the literature. The following anatomic structures can be visualized on high-resolution magnetic resonance images: extraocular muscles and corresponding connective tissue, major orbital and cerebral arteries, ophthalmic veins, cavernous sinus, and all sensory and motor cranial nerves of the eye along their intraorbital and intracranial course.

Embolization of neurosurgical lesions involving the ophthalmic artery

OBJECTIVE

A number of anteriorly located cranial base and extracranial lesions receive their vascular supply wholly or in part from the ophthalmic artery, and embolization of the ophthalmic artery can be helpful in the management of these lesions, either as the primary treatment or as an adjunct to surgery. We present situations in which the embolization of lesions involving the ophthalmic artery was performed to effect a partial or total cure of the lesion.

METHODS

Twelve patients underwent a total of 15 embolization attempts on lesions involving the ophthalmic artery. Four patients had arteriovenous malformations of the orbit, four had dural arteriovenous fistulae, two had orbital meningiomas, one had a planum sphenoidale meningioma, and one had a juvenile nasal angiofibroma. In each case, a Tracker No. 18 microcatheter (Target Therapeutics, Inc., Fremont, CA) was navigated into the ophthalmic artery using a steerable guidewire and digital road mapping. Embolic agents included polyvinyl alcohol particles ranging from 350 to 1500 microm in diameter, 2-mm platinum microcoils, and n-butyl-cyanoacrylate. In 12 of 15 cases, lidocaine and amytal provocation tests were conducted before any attempt at embolization to assess the role of the ophthalmic artery in vision.

RESULTS

Embolization was successfully performed in the 14 situations in which it was attempted. Positive results of two lidocaine/amytal tests were noted. In one case, embolization was not attempted. In the other case, a larger caliber embolic agent (2-mm platinum coils) was used. A single transient decrease in visual acuity lasting 4 days was the only embolization-related complication.

CONCLUSION

Proper case selection, judicious use of embolic agents, and use of provocative testing can result in safe embolization of lesions supplied by the ophthalmic artery.

High-resolution MR imaging anatomy of the orbit. Correlation with comparative cryosectional anatomy

High resolution MR imaging of the orbit enables visualization of anatomic details in the orbit, including important blood vessels, muscles, nerves and connective tissue structures. The best resolution of anatomic details currently is obtained by using surface coils and T1-weighted spin echo sequences. Some examples of clinical applications demonstrate that a detailed knowledge of orbital imaging anatomy is a prerequisite for successful interpretation of clinical MR images. Additionally, this noninvasive diagnostic technique may be used for anatomical in vivo studies.