Assessment of optic nerve vascularity in healthy eyes using superb microvascular imaging: a preliminary study.

BACKGROUND: Changes in optic nerve vascularity are observed in many diseases. Superb microvascular imaging (SMI) has the potential to become the method of choice for detecting microvasculature in the optic nerves. PURPOSE: To evaluate optic nerve vascularity in healthy individuals through power Doppler sonography (PDUS) and SMI. MATERIAL AND METHODS: Twenty-seven healthy patients with 54 eyes were prospectively evaluated. The duration of the examination for optic nerve vascularity lasted until the posterior ciliary artery blood supply was observed in PDUS and SMI. The visibility of vascularity, as well as the ratio of the vascular structures to the optic nerves (vascular index [VI]), was evaluated. RESULTS: Fifty-four eyes were evaluated from a total of 27 patients (mean age = 49.0 ± 19.42 years). The VI value for the right optic nerve was 29.58 ± 4.00 while for the left optic nerve, it was 31.21 ± 3.52. Vascularity was clearly observed in both eyes (n = 54) in all 27 cases in the evaluation performed with the SMI technique. However, with the power Doppler examination, vascular flow was not observed in 14 right eyes and in 10 left eyes within the specified timeframe. CONCLUSION: The results indicate that imaging of vascular structures can be done faster and better with SMI than PDUS examination. The normal VI values may provide important information about the blood supply of the optic nerve, which is of relevance in orbital pathologies and many systemic conditions.

A Unique Radiologic Case of Optic Nerve Infarction in a Patient With Mucormycosis.

ABSTRACT: This is a rare presentation of a unilateral optic nerve infarction of the left eye caused by mucormycosis in a 51-year-old man with poorly controlled Type 2 diabetes. Diffusion-weighted MRI of the orbit demonstrated extensive infarction of the left optic nerve with ipsilateral cavernous sinus thrombosis and periorbital adnexal inflammation. Left orbital exenteration and sinus debridement were performed, and mucormycosis involving the optic nerve sheath was confirmed on histopathology.

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.

Cilioretinal artery occlusion and anterior ischemic optic neuropathy as the initial presentation in a child female carrier of Fabry disease.

PURPOSE: To report the youngest female carrier of Fabry disease, complicated by cilioretinal artery occlusion and anterior ischemic optic neuropathy (AION). METHODS: Case report. RESULTS: An 11-year-old girl was referred to our clinic with painless, acute loss of vision in her right eye. Posterior segment examination and fluorescein angiography revealed cilioretinal artery occlusion and AION. Systemic evaluations were unremarkable, except for a low blood α-galactosidase A enzyme level of 242.27 pmol/spot*20 h (reference range: 450-2000 pmol/spot*20 h). The patient was diagnosed with female carrier of Fabry disease. CONCLUSION: Retinal vascular occlusions are rare in childhood, and Fabry disease may present with retinal vascular occlusion. Ophthalmological examinations may be contributing for early detection of the disease. To the best of our knowledge, this is the first report of a child female carrier of Fabry disease, complicated by cilioretinal artery occlusion and AION.

GlyCAM1 negatively regulates monocyte entry into the optic nerve head and contributes to radiation-based protection in glaucoma.

BACKGROUND: We previously reported a profound long-term neuroprotection subsequent to a single radiation-therapy in the DBA/2J mouse model of glaucoma. This neuroprotection prevents entry of monocyte-like immune cells into the optic nerve head during glaucoma. Gene expression studies in radiation-treated mice implicated Glycam1 in this protection. Glycam1 encodes a proteoglycan ligand for L-selectin and is an excellent candidate to modulate immune cell entry into the eye. Here, we experimentally test the hypothesis that radiation-induced over-expression of Glycam1 is a key component of the neuroprotection. METHODS: We generated a null allele of Glycam1 on a DBA/2J background. Gene and protein expression of Glycam1, monocyte entry into the optic nerve head, retinal ganglion cell death, and axon loss in the optic nerve were assessed. RESULTS: Radiation therapy potently inhibits monocyte entry into the optic nerve head and prevents retinal ganglion cell death and axon loss. DBA/2J mice carrying a null allele of Glycam1 show increased monocyte entry and increased retinal ganglion cell death and axon loss following radiation therapy, but the majority of optic nerves were still protected by radiation therapy. CONCLUSIONS: Although GlyCAM1 is an L-selectin ligand, its roles in immunity are not yet fully defined. The current study demonstrates a partial role for GlyCAM1 in radiation-mediated protection. Furthermore, our results clearly show that GlyCAM1 levels modulate immune cell entry from the vasculature into neural tissues. As Glycam1 deficiency has a more profound effect on cell entry than on neurodegeneration, further experiments are needed to precisely define the role of monocyte entry in DBA/2J glaucoma. Nevertheless, GlyCAM1's function as a negative regulator of extravasation may lead to novel therapeutic strategies for an array of common conditions involving inflammation.

Lymphatic and vascular markers in an optic nerve crush model in rat.

Only few tissues lack lymphatic supply, such as the CNS or the inner eye. However, if the scleral border is compromised due to trauma or tumor, lymphatics are detected in the eye. Since the situation in the optic nerve (ON), part of the CNS, is not clear, the aim of this study is to screen for the presence of lymphatic markers in the healthy and lesioned ON. Brown Norway rats received an unilateral optic nerve crush (ONC) with defined force, leaving the dura intact. Lesioned ONs and unlesioned contralateral controls were analyzed 7 days (n = 5) and 14 days (n = 5) after ONC, with the following markers: PDGFRb (pericyte), Iba1 (microglia), CD68 (macrophages), RECA (endothelial cell), GFAP (astrocyte) as well as LYVE-1 and podoplanin (PDPN; lymphatic markers). Rat skin sections served as positive controls and confocal microscopy in single optical section mode was used for documentation. In healthy ONs, PDGFRb is detected in vessel-like structures, which are associated to RECA positive structures. Some of these PDGFRb+/RECA+ structures are closely associated with LYVE-1+ cells. Homogenous PDPN-immunoreactivity (IR) was detected in healthy ON without vascular appearance, showing no co-localization with LYVE-1 or PDGFRb but co-localization with GFAP. However, in rat skin controls PDPN-IR was co-localized with LYVE-1 and further with RECA in vessel-like structures. In lesioned ONs, numerous PDGFRb+ cells were detected with network-like appearance in the lesion core. The majority of these PDGFRb+ cells were not associated with RECA-IR, but were immunopositive for Iba1 and CD68. Further, single LYVE-1+ cells were detected here. These LYVE-1+ cells were Iba1-positive but PDPN-negative. PDPN-IR was also clearly absent within the lesion site, while LYVE-1+ and PDPN+ structures were both unaltered outside the lesion. In the lesioned area, PDGFRb+/Iba1+/CD68+ network-like cells without vascular association might represent a subtype of microglia/macrophages, potentially involved in repair and phagocytosis. PDPN was detected in non-lymphatic structures in the healthy ON, co-localizing with GFAP but lacking LYVE-1, therefore most likely representing astrocytes. Both, PDPN and GFAP positive structures are absent in the lesion core. At both time points investigated, no lymphatic structures can be identified in the lesioned ON. However, single markers used to identify lymphatics, detected non-lymphatic structures, highlighting the importance of using a panel of markers to properly identify lymphatic structures.

Impairment of autoregulation of optic nerve head blood flow during vitreous surgery in patients with hypertension and hyperlipidemia.

PURPOSE: To examine whether hypertension (HTN) and hyperlipidemia (HL) affect autoregulation of optic nerve head (ONH) blood flow during vitrectomy. DESIGN: Cohort study. METHODS: Seventeen eyes from 17 subjects with HTN and HL and 19 eyes from 19 control subjects without systemic disorders underwent vitrectomy for the treatment of epiretinal membrane or macular hole. Following standard 25-gauge microincision vitrectomy, the mean blur rate (MBR), which is an index of relative ONH blood flow, in the vascular area (vascular MBR) and MBR in the tissue area (tissue MBR) were measured using laser speckle flowgraphy. Measurements were conducted before and 5 and 10 min after an approximately 15-mmHg rise in intraocular pressure (IOP). Both parameters represent relative values of ONH blood flow (%, compared to baseline). The recovery rate of blood flow to the ONH was calculated using the following equation: (MBR at 10 min - MBR at 5 min)/(MBR at baseline - MBR at 5 min). RESULTS: Ocular perfusion pressure in all subjects was reduced both 5 and 10 min after the increase in IOP. Vascular MBR in subjects with HTN and HL (75.5 ± 14.8) was significantly lower than that in control subjects (86.7 ± 12.1) 10 min after IOP elevation (P = 0.019). The recovery rate of vascular blood flow was significantly lower in the HTN and HL groups than in the control group (P = 0.002). CONCLUSIONS: Our results suggest that HTN and HL impair autoregulation in the vascular component of ONH blood flow during vitrectomy.

PERIPAPILLARY ARTERIAL RING OF ZINN-HALLER IN HIGHLY MYOPIC EYES AS DETECTED BY OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

PURPOSE: To visualize the arterial circle of Zinn-Haller (ZHAC) in highly myopic patients by using OCT-A. METHODS: Two hundred and fifty-three eyes of 146 consecutive patients with axial length ≥26.5 mm who underwent OCT-A centered onto the optic disk were studied. RESULTS: Arterial circle of Zinn-Haller was detectable on OCT-A images within the area of the parapapillary myopic conus in 26 (10%) of 253 eyes. The ZHAC was annular in 18 (69%) eyes, triangular in (15%) 4 eyes, and irregular (15%) in 4 eyes. The visibility of the ZHAC on OCT-A images was similar to the visibility on indocyanine green angiograms and significantly better than on conventional fundus photos. Optical coherence tomography angiography visualized details of the ZHAC including the entry of the short posterior ciliary arteries into the circle up to the branches in direction to the optic nerve and ZHAC-associated cilioretinal arteries. In three eyes, the ZHAC was composed of multiple rings. CONCLUSION: Noninvasive OCT-A allowed the visualization of ZHAC up to smaller vessel branches in 10% of highly myopic eyes. Because ZHAC is the main blood supply to lamina cribrosa of optic nerve, OCT-A-based assessment of ZHAC could become of interest in diseases such as glaucomatous optic neuropathy.

Evaluation of ocular pulse amplitude in non-arteritic anterior ischaemic optic neuropathy.

BACKGROUND: To evaluate the ocular pulse amplitude (OPA) in patients with chronic non-arteritic anterior ischaemic optic neuropathy (NAION). METHODS: This cross-sectional study comprised a study group of 30 eyes from 30 patients with NAION and a control group of 31 eyes from 31 age and gender-matched healthy subjects. Bilateral OPA was measured with dynamic contour tonometry (DCT) and was compared between the study and control groups. RESULTS: No statistically significant difference was found between the study and control groups in terms of hypertension, diabetes mellitus, ischaemic heart disease and hyperlipidemia. The mean intraocular pressure (IOP) measured with Goldmann Applanation Tonometry and DCT in the study and control groups was not statistically different (p1 = 0.094, p2 = 0.240). The mean OPA in the study group and the control group were 2.01 ± 0.69 mmHg and 1.97 ± 0.68 mmHg (p = 0.839). CONCLUSION: No significant difference was determined in the OPA levels of eyes with NAION at the chronic stage and eyes in the control group.

[Traumatic asphyxia with permanent visual loss. Case report]. / Traumás asphyxia maradandó látásvesztéssel.

Traumatic asphyxia is a rare condition that occurs after compressive thoracoabdominal trauma, which is characterized by subconjunctival hemorrhage, cervicofacial cyanosis, edema and petechiae. Serious life-threatening thoracic and abdominal injuries may coexist. After conservatory treatment in most cases complete recovery is achieved, but in isolated cases permanent neurological lesions may occur. We present the case of the 39-year-old male patient who suffered a compressive thoracoabdominal trauma. The physical examination showed the characteristic "ecchymotic mask". After surgical treatment of the abdominal injuries and intensive therapy the patient was discharged with permanent vision loss. The high retrograde venous pressure in the head and neck may be associated with neuronal ischemia, which can lead to irreversible optic nerve atrophy. It is therefore important to carry out an early, routine and complete ophtalmologic examination, especially in the intubated and poorly cooperative patients. Orv Hetil. 2017; 158(22): 864-868.

Effects of environmental enrichment on blood vessels in the optic tract of malnourished rats: A morphological and morphometric analysis.

OBJECTIVES: This study aimed to compare the effects of environmental enrichment in nourished (on a diet containing 16% protein) and malnourished (on a diet containing 6% protein) rats during the critical period of brain development, specifically focusing on the optic nerve. METHODS: By means of morphologic and morphometric assessment of the optic nerve, we analyzed the changes caused by diet and stimulation (environmental enrichment) on postnatal day 35, a time point ideal for such morphological analysis since developmental processes are considered complete at this age. RESULTS: Malnourished animals presented low body and brain weights and high body-to-brain weight ratio compared to well-nourished rats. Furthermore, malnourished animals showed morphological changes in the optic nerve such as edema and vacuolization characterized by increased interstitial space. The malnourished-stimulated group presented lesions characteristic of early protein malnutrition but were milder than lesions exhibited by malnourished-non-stimulated group. The morphometric analysis revealed no difference in glial cell density between groups, but there was significantly higher blood vessel density in the stimulated rats, independent of their nutritional condition. DISCUSSION: Our data indicate that protein malnutrition imposed during the critical period of brain development alters the cytoarchitecture of the optic nerve. In addition, we affirm that a 1-hour exposure to an enriched environment everyday was sufficient for tissue preservation in rats maintained on a low-protein diet. This protective effect might be related to angiogenesis, as confirmed by the increased vascular density observed in morphometric analyses.

An energy theory of glaucoma.

A radial array of fortified astrocytes (FASTs) is the load bearing structure of the rat optic nerve head (ONH). At the retinal end the ONH is suspended on a fluid filled extracellular space occupied by modified pigment cells which generate a glomerular-like formation of villi. We propose that regulation of fluid in and out of this space may contribute to buffering the normal fluctuations of intraocular pressure. The energy requirement for the fluid transfer process is provided by the dense vascularity of the ONH and is reflected in the giant mitochondria of the FASTs. We propose that glaucoma occurs when a maintained rise in pressure overwhelms the capacity of this regulatory system. Under these circumstances the FAST array becomes detached from its anchorage in the surrounding ONH sheath. Progressively driven backwards by the pressure, the FASTs degenerate. We propose that the degeneration of the FASTs is associated with ischemic damage caused by the backward stretching of their blood supply. Retraction of the FAST processes deprives the retinal ganglion cell axons of their energy support, resulting in axotomy. We consider that our previously observed rescue of axons and FASTs by transplantation of olfactory ensheathing cells is due to replacement of this lost energy source.

Retrobulbar magnetic resonance angiography using binomial off-resonant rectangular (BORR) pulse.

PURPOSE: Applying a newly developed binomial off-resonant rectangular (BORR) pulse method for high resolution three-dimensional MR angiography (MRA) on retrobulbar ocular vessels, which has not been possible with routine MRA due to background fatty tissues. METHODS: BORR pulse was implemented in a gradient echo sequence by replacing the original excitation pulse, and were optimized for robust orbital fat suppression. Several other MRA methods, with or without fat suppression, were also compared, including time-of-flight, contrast enhanced MRA, and hybrid of opposite-contrast MRA. Nine healthy subjects participated with written informed consents. To reduce eye motion, the subjects were instructed to casually stare at a projected cross during each MRA scan. Major vessels were evaluated by three independent radiologists using a 4-point scale. RESULTS: The BORR method yielded the best MRA results for retrobulbar vessels without contrast enhancement, significantly superior than other MRA methods. BORR results had significantly higher visibility scores than all other methods for small vessels. CONCLUSION: We have successfully revealed orbital vessels in retrobulbar space for the first time using MRA, by using the BORR pulse method. With a clear depiction of the vasculature without the need for contrast enhancement, our method has the potential to provide important diagnostic information for ocular vascular diseases.

Arterial supply of the upper cranial nerves: a comprehensive review.

The arterial supply to the upper cranial nerves is derived from a complex network of branches derived from the anterior and posterior cerebral circulations. We performed a comprehensive literature review of the arterial supply of the upper cranial nerves with an emphasis on clinical considerations. Arteries coursing in close proximity to the cranial nerves regularly give rise to small vessels that supply the nerve. Knowledge of the arteries supplying the cranial nerves is of particular importance during surgical approaches to the skull base.

[Determination of the individual normal range of intraocular pressure in differential diagnosis between pseudonormal tension glaucoma and ischemic optic neuropathies].

The study investigated the relation between the actual intraocular pressure (IOP) and its individual normal range in normal-tension glaucoma (NTG) and ischemic optic neuropathy (ION) outcome. A total of 39 patients (61 eyes) were examined. Group 1 included 19 patients (35 eyes) with newly diagnosed NTG, group 2--20 patients (26 eyes) with the ION outcome. Besides conventional tests, the ophthalmic assessment in all patients included determination of the individual normal range of IOP and evaluation of biomechanical properties of the cornea. It is showed that determination of the individual normal range of IOP may play a key role in confusing cases of differential diagnosis between NTG and ION. The average actual IOP in patients with NTG generally exceeds the individual normal range by 40% (more than 5 mmHg), whereas in patients with the ION outcome--by only 11.7% (less than 5 mmHg - buffer range). No statistically significant difference in IOP measurements by different tonometry methods was found in either NTG or ION patients with corneal compensated IOP less than 21 mmHg.

OCTA on the density of optic nerve microvessels in myopic population with ocular hypertension.

OBJECTIVE: To measure functional, structural, and blood flow parameters of the optic disk in myopic patients with ocular hypertension (OHT) and myopic patients using optical coherence tomography angiography (OCTA), this study aims to investigate the variability of each parameter between the two groups, and to analyze the correlation between the RNFL thickness and blood flow parameters, as well as the diagnostic value of these blood flow parameters for myopic patients with OHT. METHODS: This was a cross-sectional study. Myopic adults who were attending the Eye Center of Jinan Second People's Hospital between December 2020 and January 2022, and who had a confirmed diagnosis of OHT, were enrolled. This cohort constituted the myopic group. In these subjects, retinal nerve fiber layer (RNFL) thickness and blood flow parameters within the superficial optic disk 6 × 6 mm area were measured using OCTA. The optic disk blood flow parameters included radial peripapillary capillaries (RPC) perfusion density (PD) in nasal, temporal, superior, and inferior sectors. Visual field assessments were conducted using a Humphrey visual field meter to obtain the visual field index (VFI) and pattern standard deviation (PSD). SPSS 22.0 statistical software was utilized to determine if statistical differences existed between the parameters of the two groups and to analyze the correlation between blood flow parameters and RNFL thickness. Additionally, the area under the subject's operating characteristic curve (AUROC) was used to assess the diagnostic value of blood flow parameters for myopic patients with OHT. RESULTS: There was no statistical difference in PSD and VFI in the OHT group compared with the myopic group (P = 0.351, 0.242). The RNFL thickness was (103.64 ± 8.13) µm and (97.56 ± 12.94) µm in the myopic and OHT groups, respectively. There was no statistical difference in RNFL thickness between the OHT and myopic group (P = 0.052). The PD of radial peripapillary capillaries (RPC) in nasal, temporal, superior, and inferior sectors showed an overall decreasing trend between the myopic and OHT groups, but there was a statistical difference only in the temporal sector (P = 0.008). Correlation analysis of blood flow parameters and structural parameters showed that the PD in the temporal sector and RNFL thickness were not correlated (P = 0.263). By plotting the AUROC of blood flow parameter, it was found that OCTA had good value in diagnosing myopic patients with OHT, and the PD of the temporal sector had higher diagnostic value for differentiating the OHT group from myopic group (AUROC = 0.718, P = 0.008) CONCLUSIONS: Compared with the myopic group, blood flow parameters decreased in the OHT group, while structural and functional parameters did not change significantly, suggesting that blood flow damage may have occurred earlier in myopic patients with OHT, by the correlation analysis between structural and blood flow parameters. OCTA has good diagnostic value for myopic patients with OHT.