Length Of Optic Nerve Research Articles

Relationship between optic nerve length and interoptic angle in the prediction of optic chiasm location

Introduction and objectivesThe sellar region is an area in the base of the skull that is among the most common sites for tumors of the central nervous system. Surgical interventions are currently performed via different routes. While the optic chiasm occupies its expected position in 70% of the population, it can deviate from this position. In such cases, surgery involving this region becomes more difficult as the known surgical routes are narrowed. Advance awareness of these variations can help surgeons to identify the optimal route for safe surgical intervention in the sellar region. By performing simple measurements of both the lengths of the optic nerves and the angle between them, a surgeon can predict the location of the chiasm. Materials and methodsTwenty specimens collected from autopsies performed at Bursa Forensic Medicine İnstitute were examined to determine the optic chiasm types and the relationships between the surrounding subchiasmal structures. ResultsAmong the 20 specimens, we found two prefixed (10%), 10 normo-fixed (50%), and eight postfixed chiasms (40%). The mean interoptic angle was 81.03 (±17.41)⁰. Prefixed chiasms had angles in the range 115.36°–124.76 ° (mean 120.06 [±6.65]⁰), normo-fixed chiasm angles were between 83.11° and 97.53 ° (mean 86.07 [±6.73]⁰), and postfixed chiasms ranged between 53.01 ° and 78.71 ° (mean 69.20 [±9.13]⁰). The length of the right optic nerve ranged between 6.95 and 13.83 mm (mean 10.25 [±1.81] mm), and the length of the left between 7.25 and 12.51 mm (mean 10.40 [±1.47] mm). Obtuse angles indicated that the chiasm was prefixed, and acute angles were indicative of a postfixed chiasm. There was a strong negative correlation between optic nerve lengths and the interoptic angle; thus, as the length of the nerves increases, the interoptic angle becomes more acute. ConclusionsWe have proposed a simple measurement of the optic nerve lengths and the angle between them to predict the relative location of the OC, which can be done easily on MRI.

Acute optic neuritis: What are the clues to the aetiological diagnosis in real life?

Previous cross-sectional studies have reported distinct clinical and radiological features among the different acute optic neuritis (ON) aetiologies. Nevertheless, these reports often included the same number of patients in each group, not taking into account the disparity in frequencies of ON aetiologies in a real-life setting and thus, it remains unclear what are the truly useful features for distinguishing the different ON causes. To determine whether clinical evaluation, ophthalmological assessment including the optical coherence tomography (OCT), CSF analysis, and MRI imaging may help to discriminate the different causes of acute ON in a real-life cohort. In this prospective monocentric study, adult patients with recent acute ON (<1 month) underwent evaluation at baseline and 1 and 12 months, including, high- and low-contrast visual acuity, visual field assessment and OCT measurements, baseline CSF analysis and MRI. Among 108 patients, 71 (65.7%) had multiple sclerosis (MS), 19 (17.6%) had idiopathic ON, 13 (12.0%) and 5 (4.6%) had myelin oligodendrocyte glycoprotein and aquaporin-4 antibodies, at last follow up respectively.At baseline, the distribution of bilateral ON, CSF-restricted oligoclonal bands, optic perineuritis, optic nerve length lesions and positive dissemination in space and dissemination in time criteria on MRI were significantly different between the four groups (p <0.001). No significant difference in visual acuity nor inner retinal layer thickness was found between the different ON aetiologies. In this large prospective study, bilateral visual involvement, CSF and MRI results are the most useful clues in distinguishing the different aetiologies of acute ON, whereas ophthalmological assessments including OCT measurements revealed no significant difference between the aetiologies.

Extraocular muscle volume index at the orbital apex with optic neuritis: a combined parameter for diagnosis of dysthyroid optic neuropathy.

To evaluate the diagnostic performance of the extraocular muscle volume index at the orbital apex (AMI) and the signal intensity ratio (SIR) of the optic nerve in dysthyroid optic neuropathy (DON). Clinical data and magnetic resonance imaging were collected retrospectively from 63 Graves' ophthalmopathy patients, including 24 patients with DON and 39 without DON. The volume of these structures was obtained by reconstructing their orbital fat and extraocular muscles. The SIR of the optic nerve and axial length of eyeball were also measured. The posterior 3/5 of the retrobulbar space volume was used as the orbital apex to compare parameters in patients with or without DON. Area under the receiver operating characteristic curve (AUC) analysis was used to select the morphological and inflammatory parameters with the highest diagnostic value. A logistic regression was performed to identify the risk factors of DON. One hundred twenty-six orbits (35 with DON and 91 without DON) were analyzed. Most of the parameters in DON patients were significantly higher than in non-DON patients. However, the SIR 3mm behind the eyeball of the optic nerve and AMI had the highest diagnostic value in these parameters and are independent risk factors of DON by stepwise multivariate logistic regression analysis. Combining AMI and SIR had a higher diagnostic value than a single index. Combining AMI with SIR 3mm behind the eyeball's orbital nerve can be a potential parameter for diagnosing DON. The present study provided a quantitative index based on morphological and signal changes to assess the DON, allowing clinicians and radiologists to monitor DON patients timely. The extraocular muscle volume index at the orbital apex (AMI) has excellent diagnostic performance for dysthyroid optic neuropathy. A signal intensity ratio (SIR) of 3mm behind the eyeball has a higher AUC compared to other slices. Combining AMI and SIR has a higher diagnostic value than a single index.

Imaging the Tight Orbit: Radiologic Manifestations of Orbital Compartment Syndrome.

Orbital compartment syndrome is a sight-threatening emergency caused by rising pressure inside the orbit. It is usually diagnosed clinically, but imaging might help when clinical findings are inconclusive. This study aimed to systematically evaluate imaging features of orbital compartment syndrome. This retrospective study included patients from 2 trauma centers. Proptosis, optic nerve length, posterior globe angle, morphology of the extraocular muscles, fracture patterns, active bleeding, and superior ophthalmic vein caliber were assessed on pretreatment CT. Etiology, clinical findings, and visual outcome were obtained from patient records. Twenty-nine cases of orbital compartment syndrome were included; most were secondary to traumatic hematoma. Pathologies occurred in the extraconal space in all patients, whereas intraconal abnormalities occurred in 59% (17/29), and subperiosteal hematoma in 34% (10/29). We observed proptosis (affected orbit: mean, 24.4 [SD, 3.1] mm versus contralateral: 17.7 [SD, 3.1] mm; P < .01) as well as stretching of the optic nerve (mean, 32.0 [SD, 2.5] mm versus 25.8 [SD, 3.4] mm; P < .01). The posterior globe angle was decreased (mean, 128.7° [SD, 18.9°] versus 146.9° [SD, 6.4°]; P < .01). In 69% (20/29), the superior ophthalmic was vein smaller in the affected orbit. No significant differences were detected regarding the size and shape of extraocular muscles. Orbital compartment syndrome is characterized by proptosis and optic nerve stretching. In some cases, the posterior globe is deformed. Orbital compartment syndrome can be caused by an expanding pathology anywhere within the orbit with or without direct contact to the optic nerve, confirming the pathophysiologic concept of a compartment mechanism.

Reproducibility and feasibility of optic nerve diffusion MRI techniques: single-shot echo-planar imaging (EPI), readout-segmented EPI, and reduced field-of-view diffusion-weighted imaging

BackgroundDiffusion-weighted imaging (DWI) is an essential technique for optic nerve diseases. However, the image quality of optic nerve DWI is decreased by the distortions and artifacts associated with conventional techniques. In order to establish this method as a critical tool in optic nerve diseases, reproducibility and feasibility of new technical and conventional approaches of DWI need to be systematically investigated.MethodsDWIs were acquired using ss-EPI, readout-segmented EPI (rs-EPI) DWI, and reduced field-of-view (rFOV) DWI. 26 volunteers (mean age 31.2 years) underwent repeated MRI examinations in order to assess scan–rescan reproducibility and accuracy. The apparent diffusion coefficient (ADC) values (three ROIs were measured on each side) were determined to evaluate the reproducibility of each sequence and the differences between the three techniques. To quantify the geometric distortion artifacts, the length of optic nerve and the maximum angle of optic nerve were defined and compared to T2-weighted imaging. In addition, two readers evaluated four different aspects of image quality on 5-point Likert scales.Resultsrs-EPI DWI (ICCs: 0.916, 0.797 and 0.781) and rFOV DWI (ICCs: 0.850, 0.595 and 0.750) showed higher reproducibility (ICCs: ROI1, ROI2 and ROI3) of mean ADC value in all three ROIs than ss-EPI DWI (ICCs: 0.810, 0.442 and 0.379). The quantitative analysis of geometric distortion yielded a higher agreement of both rs-EPI DWI and rFOV DWI with T2-weighted imaging than ss-EPI. rs-EPI DWI (2.38 ± 0.90) and rFOV DWI (2.46 ± 0.58) were superior to ss-EPI DWI (1.58 ± 0.64) with respect to overall image quality and other aspects of image quality, each with P < 0.05. The mean ADC values of rFOV DWI were significantly lower than those of rs-EPI DWI and ss-EPI DWI in all three ROIs (P < 0.001).ConclusionsBoth rs-EPI DWI and rFOV-EPI DWI are suitable techniques for the assessment of diffusion restriction and provide significantly improved image quality compared with ss-EPI DWI. For methods using the same acquisition time, rFOV DWI is superior to ss-EPI DWI, while rs-EPI showed an overall superiority, although this technique took 47% longer to perform.

Anatomical study of the scleral ring and eyeball of the long-eared owl (Asio otus) with anatomical methods and diagnostic imaging techniques.

BackgroundThe scleral ring in birds consists of ossicles that are fixed as small plates by cartilage joints and have no articulation to other parts of the skeleton.ObjectiveDue to inadequate examination of the scleral ring anatomy and its specific form in owls, this study aimed to investigate the exact structure of the scleral ring and some morphometric characteristics of the eyeball in a long‐eared owl (Asio otus).MethodsThe eyes of 20 alive and 10 dead male and female owls were examined. In addition to common anatomical methods, computed tomography scans and radiographic and ultrasonographic imaging techniques were used in this study.ResultsThe structure consisted of 15 ossicles. In the ventral part of the ring, these tubercles were observed in the scleral rings of all owls; in each ring, there were four bones with these tubercles. Additionally, there was no significant difference between the left and right eye parameters. Most ocular parameters in female owls were larger than those in males, but in the case of some parameters, such as optic nerve length and optic nerve sheath diameter, this difference was not observed.ConclusionsAccording to this study, the scleral ring in the Asio otus has anterior and posterior parts, and the lens is in the immediate vicinity of the anterior part. The right and left scleral rings and eyeballs are bilaterally symmetrical in terms of the shape, size, and number of ossicles that form the ring.

Methodology and Rationale for Ophthalmic Examinations in the Seventh and Eighth Korea National Health and Nutrition Examination Surveys (2017-2021).

This report provides a detailed description of the methodology for ophthalmic examinations according to the Korea National Health and Nutrition Examination Survey (KNHANES) VII and VIII (from 2017 to 2021). The KNHANES is a nationwide survey which has been performed since 1998 in representatives of whole Korean population. During the KNHANES VII and VIII, in addition to the ophthalmic questionnaire, intraocular pressure measurement, visual field test, auto refractometry, axial length and optical coherence tomography measurements were included. This new survey will provide not only provide normative and pathologic ophthalmic data including intraocular pressure, refractive error, axial length, visual field and precise measurement of anterior segment, macula and optic nerve with optical coherence tomography, but also a more accurate diagnosis for major adult blindness diseases, including age-related macular degeneration, diabetic retinopathy, glaucoma, and other ocular diseases, for the national Korean population.

Optic Nerve Length before and after Spaceflight

The spaceflight-associated neuro-ocular syndrome (SANS) affects astronauts on missions to the International Space Station (ISS). The SANS has blurred vision and ocular changes as typical features. The objective of this study was to investigate if microgravity can create deformations or movements of the eye or optic nerve, and if such changes could be linked to SANS. Cohort study. Twenty-two astronauts (age 48 ± 4 years). The intervention consisted of time in microgravity at the ISS. We co-registered pre- and postspaceflight magnetic resonance imaging (MRI) scans and generated centerline representations of the optic nerve. The coordinates for the optic nerve head (ONH) and optic chiasm (OC) ends of the optic nerve were recorded along with the entire centerline path. Optic nerve length, ONH movement, and OC movement after time in microgravity. Optic nerve length increased (0.80 ± 0.74 mm, P < 0.001), primarily reflecting forward ONH displacement (0.63 ± 0.53 mm, P < 0.001). The forward displacement was positively related to mission duration, preflight body weight, and clinical manifestations of SANS. We also detected upward displacement of the OC (0.39 ± 0.50 mm, P= 0.002), indicative of brain movement, but this observation could not be linked to SANS. The spaceflight-induced optic nerve lengthening and anterior movement of the ONH support that SANS is caused by an altered pressure difference between the brain and the eye, leading to a forward push on the posterior of the eye. Body weight is a potential contributing risk factor. Direct assessment of intracranial pressure in space is required to verify the implicated mechanism behind the ocular findings in SANS.

B-Mode and Doppler Ocular Ultrasound Evaluation in Healthy and Positive Dogs for Visceral Canine Leishmaniasis

Background: The use of ultrasound examination in the evaluation of ophthalmopathies has been gaining more and more space within the ophthalmologic clinical routine. The hemodynamic study of ocular vascularization may anticipate future changes, aiding in the adequate establishment of therapeutic conduits. The objective of this study was to evaluate the structures of the ocular bulb and to perform the hemodynamic evaluation of the flow of the external ophthalmic artery of dogs with canine visceral leishmaniasis (CVL) correlating with healthy animals.Materials, Methods &amp; Results: For this purpose, 100 animals were used, of these 70 positive for CVL and 30 healthy animals, submitted to B-mode and Doppler ultrasound examination. Two-dimensional evaluation included identification of ocular changes and biometry of the following segments: axial length (M1), anterior chamber depth (M2), lens thickness (M3), lens length (M4), glass chamber depth (M5), optical disc length (M6) and optic nerve length (M7). The Doppler velocimetric evaluation included the identification and hemodynamic evaluation of the external ophthalmic artery, being measured: systolic peak velocity (SPV), final diastolic velocity (FDV), resistivity index (RI) and pulsatility index (PI). Ophthalmopathies were frequent in animals with leishmaniasis in both right (91.42%) and left (29.14%) eyes, with identification of capsular cataract, lens dislocation, retinal detachment and lens rupture. No significant statistical difference (P &gt; 0.05) was observed when comparing the biometric values between the right and left eyes of the animals with CVL, as well as for the measurements between healthy and CVL animals. Hemodynamic indexes of the flow of the external ophthalmic artery presented narrow limits for the right and left eyes of the positive animals, not statistically different from each other. However, a significant difference was observed when compared to hemodynamic evaluations of the flow of the ophthalmic artery between the right eyes of the group of normal animals and that of the carriers of leishmaniasis, with the latter presenting values superior to the first one. The B-mode and Doppler ultrasonographic evaluation enabled the morphological characterization of the ocular bulb, the identification of ophthalmopathies and the hemodynamic evaluation of the external ophthalmic artery of dogs with canine visceral leishmaniasis, establishing values that could be used in clinical ophthalmologic routine.Discussion: The presence of ocular changes diagnosed by B-mode ultrasonography were common in dogs with canine visceral leishmaniasis. Ocular lesions were observed in 80.5% of dogs with leishmaniasis, presenting a high frequency, corroborating with the results in the present research. In 22% of the animals, B-mode ultrasonographic lesions were identified in both eyes, 64 of these presented changes only in the right eye and 16 in the left eye. Ophthalmopathies can be uni or bilateral and cause more than one alteration in the same eye, resulting from both the immune-mediated mechanisms caused by the agent and direct parasitism. Although the literature reports that the highest frequency of lesions is bilateral, only 16 animals had alterations in both eyes. The origin of ophthalmopathies may be related to the species and tropism of the parasite, type and duration of the immune response developed by the host. The greater frequency of bilateral ophthalmopathies can have correlation with the systemic disease, in which in the initial stages of the disease only one eye is affected and the occurrence of bilateral manifestations is related to the chronic cases.

Optic Nerve Tortuosity and Globe Proptosis in Normal and Glaucoma Subjects.

The purpose of this study was to assess the difference in optic nerve tortuosity during eye movements and globe proptosis between primary open angle glaucoma and normal subjects using orbital magnetic resonance imaging (MRI). Ten Chinese subjects matched for ethnicity and refractive errors were recruited, including 5 normal controls and 5 patients with primary open angle glaucoma. All subjects underwent MRI to assess their optic nerves and globes for 3 eye positions: primary gaze, adduction, and abduction. Optic nerve tortuosity (optic nerve length divided by the distance between 2 ends) and globe proptosis (maximum distance between the cornea and interzygomatic line) were measured from MRI images. In adduction, the tortuosity of normal eyes was significantly larger than that of the glaucomatous eyes. Optic nerve tortuosity in adduction in the control and glaucoma groups were 1.004±0.003 (mean±SD) and 1.001±0.001, respectively (P=0.037). Globe proptosis (primary gaze) in glaucoma subjects (19.14±2.11 mm) was significantly higher than that in control subjects (15.32±2.79 mm; P=0.046). In this sample, subjects with glaucoma exhibited tauter optic nerves and more protruding eye globes compared with normal eyes. This may impact optic nerve head deformations in anatomically predisposed patients.

Quantification of optic nerve length and tortuosity in thyroid eye disease

To objectively quantify the length and tortuosity of optic nerves (ONs) in patients with thyroid eye disease (TED), in relation to the occurrence of dysthyroid optic neuropathy (DON). All patients seen by 2 of the senior authors over a period of 12 years were screened for study entry. The primary outcome was the quantitative measurement of ON tortuosity and length in relation to the occurrence of DON. Image analysis involved the creation of a 3-dimensional reconstruction of the ON from the anterior clinoid process to the posterior globe using image analysis software. A centreline was created through the middle of the reconstruction, and the length of the ON was calculated as the length of this centreline. Tortuosity was calculated by creating a ratio between the straight-line length of the ON and the actual length (centreline length). The final sample included 50 patients who contributed 100 orbits, of which 26 orbits had DON. There were no differences in the Hertel exophthalmometry readings between patients with and without DON (p = 0.56). There was no significant relationship between the length (p = 0.39) and tortuosity (p = 0.82) of the ON and occurrence of DON. There is no significant relationship between the length and tortuosity of the ON and development of DON in patients with TED.

Non-commutative, nonlinear, and non-analytic aspects of the ocular motor plant.

The ocular motor plant, consisting of the globe, extraocular muscles (EOMs), and connective tissue suspension, constitutes an intricate and non-linear actuator of eye movements. The pulley system of the rectus EOMs constitutes a non-linear inner gimbal actuated by the orbital layers of these EOMs that renders the sequence of ocular rotations effectively commutative to the central controller, and can be rotated by the outer gimbal driven by the oblique EOMs. Optic nerve (ON) length is insufficient to permit large angle adduction without tethering by the ON and sheath, creating at and beyond this threshold a large additional load on the medial rectus muscle. Finite element modeling suggests that adduction may eventually cause repetitive strain injury to the ON and glaucomatous optic nerve damage.

Analysis of anterior and posterior maneuvers to enhance intraconal exposure.

The medial and inferior recti encompass the ideal surgical corridor to approach the intraconal space endonasally. Here, we describe 3 different maneuvers to achieve greater access to orbital contents through an expanded endonasal approach (EEA). Four human cadaver heads were dissected bilaterally (n = 8). EEA to the medial intraconal orbit was executed. The following 3 maneuvers were performed: (1) anterior: extraocular muscles control (EOM); (2) posterior: annulus of Zinn (AZ) release; and (3) anterior/posterior combined. Measurements of the inferior and medial rectus corridor at the level of anterior ethmoidal artery (AEA) and posterior ethmoidal artery (PEA) and extent of optic nerve and medial rectus visualization was performed before and after each maneuver. Medial rectus length (MRL) and optic nerve length (ONL) achieved were 1.72 ± 0.28 cm and 0.85 ± 0.2 cm, respectively. Mean caudal-rostral distances between the rectus muscles at the level of the AEA and PEA were 3.45 ± 0.7 mm and 1.30 ± 0.3 mm, respectively. After EOM control, mean caudal-rostral distances at the same level were as follows: AEA 4.90 ± 1.15 mm (p = 0.009) and PEA 1.70 ± 0.20 mm (p = 0.016). With AZ release, MRL was 2.20 ± 0.7 cm (p = 0.002) and ONL was 1.30 ± 0.2 cm (p = 0.003), with mean rostral-caudal distance at the level of AEA at 4.03 ± 0.8 mm (p = 0.16) and PEA at 1.71 ± 0.36 mm (p = 0.039). Mean caudal-rostral distances achieved with AZ release and EOM control were as follows: AEA 5.6 ± 1.2 mm (p = 0.001) and PEA 2.15 ± 0.4 mm (p = 0.001). Progressive access to the orbital contents is afforded with the 3 delineated maneuvers. The magnitude of access is optimized with the combined maneuver. The actual anterior/posterior location of the target will determine which maneuvers are required.

Measurement of Intra-Orbital Structures in Normal Chinese Adults Based on a Three-Dimensional Coordinate System

ABSTRACT Purpose of the study This study was to establish a three-dimensional (3D) coordinate system and to study the normal dimensions of intra-orbital structures in Chinese adults. Materials and methods One hundred and forty-five adult Chinese were selected from patients who had undergone cranio-facial computed tomography scans with diagnosis other than orbital or ocular abnormality. An orbital 3D coordinate system was built on the basis of the scans. Morphological variables of intra-orbital structures were measured in this coordinate system. Bilateral symmetry, sexual dimorphism, and correlations between variables were investigated. Results No evident laterality was found in bilateral intra-orbital structures. The distance from the center of the eyeball to the prechiasmatic groove, the length of the optic nerve, and the thickness of rectus extraocular muscles were larger in males than in females. No sex-related difference was observed in the anteroposterior diameter of the eyeball or the exophthalmometric value. The exophthalmometric value was found to be related to the anteroposterior diameter of the eyeball, whereas the y-coordinate of the center of the eyeball had no correlation with the anteroposterior diameter of the eyeball. The optic nerve length was closely correlated to the distance from the center of the eyeball to the prechiasmatic groove. Conclusions The 3D coordinate system and measurement method established in this study can be applied to the standardization of orbital morphometry. The measurements obtained from normal Chinese adults may provide reference values for the morphology of intra-orbital structures.

Proton Beam Ocular Treatment in Eyes with Intraocular Silicone Oil: Effects on Physical Beam Parameters and Clinical Relevance of Silicone Oil in EYEPLAN Dose-Volume Histograms

Proton beam therapy (PBRT) is an essential tool in the treatment of certain ocular tumors due to its characteristic fall-off and sharp beam parameters at critical structures. Review of clinical cases in our ocular PBRT program identified patients with silicone oil used as an intraocular tamponade following pars plana vitrectomy for repair of retinal detachment. Patient’s eye may be filled with silicone oil prior to PBRT for an ocular tumor. The objective of this study was to extend our knowledge of the physical characteristics of proton beams in silicone oil by measuring dose within a silicone tank itself, hence better representing the surgical eye, as well as applying the range changes to EYEPLAN software to estimate clinical impact. The relevant proton beam physical parameters in silicone oil were studied using a 67.5 MeV un-modulated proton beam. The beam parameters being defined included: 1) residual range; 2) peak/plateau ratio; 3) full width at half maximum (FWHM) of the Bragg peak; and 4) distal penumbra. Initially, the dose uniformity of the proton beam was confirmed at 10 mm and 28 mm depth, corresponding to plateau and peak region of the Bragg peak using Gefchromic film. Once the beam was established as expected, three sets of measurements of the beam parameters were taken in: a) water (control); b) silicone-1000 oil and water; and c) silicone-1000 oil only. Central-axis depth-ionization measurements were performed in a tank (“main tank”) with a 0.1cc ionization chamber (Model IC-18, Far west) having walls made of Shonka A150 plastic. The tank was 92 mm (length) × 40 mm (height) × 40 mm (depth). The tank had a 0.13 mm thick kapton entrance window through which the proton beam was incident. The ionization chamber was always positioned in the center of the circular field of diameter 30 mm with the phantom surface at isocenter. The ionization chamber measurements were taken at defined depths in increments of 2 mm, from 0 to 35 mm. To define the effect of silicone oil on the physical characteristics of proton beam, the above-defined three sets of measurements were made. In the first run (a), the Bragg-peak measurements were made in the main tank filled with water. In the second run (b), a second smaller tank filled with 10 mm depth silicone oil was placed in front of the water tank and the measurements were repeated in water. In the third run (c), the water in the main tank was replaced with silicone oil and the measurements were repeated in silicone directly (no second tank in runs “a” and “c”). Finally, the effects of change in range on dose distribution based on the EYEPLAN® treatment planning software of patients with lesions in close proximity to the disc/macula as well as ciliary body tumors were studied. The uniformity of the radiation across the treatment volume shows that the radiation field was uniform within ± 3% at 10 mm depth and within ±4% at 28 mm depth. Parameters evaluated for the three runs (a, b, c) included: 1) residual range; 2) peak/plateau ratio; 3) FWHM of the Bragg curve; and 4) distal penumbra. The measured data revealed that the un-modulated Bragg peak had a penetration at the isocenter of: a) 30 mm in water; b) 31.5 mm in silicone and water; and c) 32 mm range in silicone oil. The peak/plateau ratio of the depth dose curve is 3.1:1 in all three set-ups. The FWHM is: a) 9 mm in water; b) 10 mm in silicone and water; and c) 11 mm in silicone oil. The distal penumbra (from 90% to 20%) was: a) 1.1 mm; b) 1.4 mm; and c) 2 mm. Clinical relevance of the extended distal range in silicone was studied for impact in EYEPLAN treatment software, including cases in which tumors were in close proximity to the optic disc/nerve and macula as well as cases in which anterior ciliary body tumors were treated. The potential change of range by 2 mm in silicone would impact the dose-volume histograms (DVH) importantly for the posterior structures. In ciliary body/anterior tumors, an increase in distal range in silicone could result in optic disc/macula dose and length of optic nerve treated, compared with original EYEPLAN model DVHs. The use of silicone oil as a surgical tamponade in the treatment of retinal detachments has important implications for PBRT treatment planning. In patients with intraocular silicone oil, the physical parameters of the beam should be closely examined and DVHs for posterior structures should be analyzed for potential increased doses to the macula, disc, and length of optic nerve in the field. The change in beam parameters due to silicone oil is essential to consider in treatment planning and DVH interpretation for ocular patients with posterior as well as anterior ocular tumors.

Analysis of clinical characteristics of demyelinating optic neuritis in children under the age of 16

Objective To observe the clinical characteristics of demyelinating optic neuritis (DON) in Chinese children under the age of 16. Methods A retrospective review of the medical charts of 42 pediatric patients with DON was conducted in this study. Twenty-two patients (52.4%) were male, and 20 patients(47.6%) were female. The patients aged from 3 to 15 years, with the mean age of (9.5±2.3) years. There were 35 bilateral patients and 7 unilateral patients. Twenty-seven patients (64.3%) had prodromal symptoms before onset. All patients underwent visual function and imaging tests, such as best corrected visual acuity (BCVA), fundus photography, visual evoked potential (VEP), visual field, MRI. The patients were tested for serum levels of antibodies for aquaporin 4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) with a cell-based assay. All patients were received corticosteroid therapy. The mean follow-up was (1.17±0.42) years. The children who had coordination ability and with BCVA≥0.3 were received examination of Humphery automatic perimeter. Data were collected on the age, gender, clinical features, neuroimaging, serological specific antibodies, treatment and vision prognosis. Results 23.8% of the children were bilateral optic neuritis in onset stages. 64.2% were recurrent optic neuritis and 83.3% exhibited bilateral diseases eventually. BCVA had decreased to ≤0.1 in 87.0%% eyes and disc swelling was observed in 77.9% eyes during the onset stages. All eyes had visual field defects and abnormal VEP exam results, with delayed latency of P100 and P2, and varying degrees of amplitude reduction. Serum AQP4 antibody and MOG antibody were tested by cell-based assay, 2/42 children (4.7%) were positive for AQP4 antibody and 5/24 children (20.8%) were positive for MOG antibody. All of anti-AQP4+ and anti- MOG+ cases relapsed. All children underwent orbital magnetic resonance imaging (MRI), 40 cases (95.2%) showed demyelination features of optic nerve, and 5 cases (11.9%) showed long segments lesion (more than 1/2 length of the optic nerve). There were 2 anti-AQP4+ cases and 3 anti- MOG+ cases from the 5 cases with long segments lesion. MRI also showed brain demyelinating lesions in 4 children (3 of them were anti- MOG+) or spinal cord demyelinating lesions in 3 children (2 of them were anti- MOG+). After treatment with glucocorticoid, visual acuity improved in all eyes, of which 84.4% with BCVA≥0.5. Forty-eight eyes of 26 children accept dynamic visual field during the course of treatment, showed the vision abnormalities associated with optic nerve damage. Conclusions Children under the age of 16 with DON can experience severe visual impairment, higher recurrence tendencies, and higher rate of disc involvement, but good response to glucocorticoid therapy. AQP4 or MOG antibodies positive might be concurrent with brain and (or) spinal cord demyelinating lesions and indicated a poorer prognosis. Key words: Optic neuritis; Demyelinating diseases; Child; Disease attributes

3D Visualization of Individual Regenerating Retinal Ganglion Cell Axons Reveals Surprisingly Complex Growth Paths.

Retinal ganglion cells (RGCs), the sole output cells of the retina, are a heterogeneous population of neurons that project axons to visual targets in the brain. Like most CNS neurons, RGCs are considered incapable of mounting long distance axon regeneration. Using immunolabeling-enabled 3D imaging of solvent-cleared organs (iDISCO) in transgenic mice, we tracked the entire paths of individual RGC axons and show that adult RGCs are highly capable of spontaneous long-distance regeneration, even without any treatment. Our results show that the Thy1-H-YFP mouse sparsely labels RGCs, consisting predominantly of regeneration-competent α-type RGCs (αRGCs). Following optic nerve crush, many of the YFP-labeled RGC axons extend considerable distances proximal to the injury site with only a few penetrating through the lesion. This tortuous axon growth proximal to the lesion site is even more striking with intravitreal ciliary neurotrophic factor (CNTF) treatment. We further demonstrate that despite traveling more than 5 mm (i.e., a distance equal to the length of mouse optic nerve), many of these circuitous axons are confined to the injury area and fail to reach the brain. Our results re-evaluate the view that RGCs are naturally incapable of re-extending long axons, and shift the focus from promoting axon elongation, to understanding factors that prevent direct growth of axons through the lesion and the injured nerve.

Trans-eyebrow supraorbital approach in large suprasellar craniopharyngioma surgery in adults: analysis of optic nerve length and extent of tumor resection. Original article.

One of the main drawbacks in the surgery of large craniopharyngiomas is the presence of a prefixed optic chiasm. Our main objective in this study is to compare the predictive value of the optic nerve length and optic chiasm location on large craniopharyngiomas' extent of resection. We retrospectively studied 21 consecutive patients with large craniopharyngiomas who underwent tumor resection through the trans-eyebrow supraorbital approach. Clinical and radiological findings on preoperative MRI were recorded, including the optic chiasm location classified as prefixed, postfixed or normal. We registered the optic nerve length measured intraoperatively prior to tumor removal and confirmed the measurements on preoperative MRI. Using a linear regression model, we calculated a prediction formula of the percentage of the extent of resection as a function of optic nerve length. On preoperative MRI, 15 patients were considered to have an optic chiasm in a normal location, 3 cases had a prefixed chiasm, and the remaining 3 had a postfixed chiasm. In the group with normal optic chiasm location, a wide range of percentage of extent of resection was observed (75-100%). The percentage of extent of resection of large craniopharyngiomas was observed to be dependent on the optic nerve length in a linear regression model (p < 0.0001). According to this model in the normal optic chiasm location group, we obtained an 87% resection in 9-mm optic nerve length patients, a 90.5% resection in 10-mm optic nerve length patients and 100% resection in 11-mm optic nerve length patients. Optic chiasm location provides useful information to predict the percentage of resection in both prefixed and postfixed chiasm patients but not in the normal optic chiasm location group. Optic nerve length was proven to provide a more accurate way to predict the percentage of resection than the optic chiasm location in the normal optic chiasm location group.

Structural-Functional Relationships Between Eye Orbital Imaging Biomarkers and Clinical Visual Assessments.

Eye diseases and visual impairment affect millions of Americans and induce billions of dollars in annual economic burdens. Expounding upon existing knowledge of eye diseases could lead to improved treatment and disease prevention. This research investigated the relationship between structural metrics of the eye orbit and visual function measurements in a cohort of 470 patients from a retrospective study of ophthalmology records for patients (with thyroid eye disease, orbital inflammation, optic nerve edema, glaucoma, intrinsic optic nerve disease), clinical imaging, and visual function assessments. Orbital magnetic resonance imaging (MRI) and computed tomography (CT) images were retrieved and labeled in 3D using multi-atlas label fusion. Based on the 3D structures, both traditional radiology measures (e.g., Barrett index, volumetric crowding index, optic nerve length) and novel volumetric metrics were computed. Using stepwise regression, the associations between structural metrics and visual field scores (visual acuity, functional acuity, visual field, functional field, and functional vision) were assessed. Across all models, the explained variance was reasonable (R2 ~ 0.1-0.2) but highly significant (p < 0.001). Instead of analyzing a specific pathology, this study aimed to analyze data across a variety of pathologies. This approach yielded a general model for the connection between orbital structural imaging biomarkers and visual function.

Synergistic effect of olfactory ensheathing cells and alpha-crystallin on restoration of adult rat optic nerve injury

Olfactory enshesathing cells (OECs) and α-crystallin all can promote axonal regeneration after optic nerve injury. However, their mechanisms were different. Here, we study the synergistic effect of OECs and α-crystallin on the optic nerve regeneration. α-Crystallin was injected into vitreous cavity, and OECs were transplanted to the optic nerve injury area. The regeneration length of optic nerve were measured by anterograde tracing using cholera toxin subunit B (CTB). The survival of RGCs were assessed by counting the numbers of βIII-tubulin-labeled RGCs in a retinal whole mount. The results that OECs and α-crystallin all could promoted RGCs survival and axonal regeneration (P<0.01). Especially in the combination group, the length of axonal regeneration was 5.6mm after optic nerve injury for 3 months. These findings indicated that compared to OECs and α-crystallin alone, the combination of OECs and α-crystallin could promote axonal regeneration more effectively.