Length Of Optic Nerve Research Articles

Total Human Eye Allotransplantation: Developing Surgical Protocols for Donor and Recipient Procedures.

Vascularized composite allotransplantation of the eye is an appealing, novel method for reconstruction of the nonfunctioning eye. The authors' group has established the first orthotopic model for eye transplantation in the rat. With advancements in immunomodulation strategies together with new therapies in neuroregeneration, parallel development of human surgical protocols is vital for ensuring momentum toward eye transplantation in actual patients. Cadaveric donor tissue harvest (n = 8) was performed with orbital exenteration, combined open craniotomy, and endonasal approach to ligate the ophthalmic artery with a cuff of paraclival internal carotid artery, for transection of the optic nerve at the optic chiasm and transection of cranial nerves III to VI and the superior ophthalmic vein at the cavernous sinus. Candidate recipient vessels (superficial temporal/internal maxillary/facial artery and superficial temporal/facial vein) were exposed. Vein grafts were required for all anastomoses. Donor tissue was secured in recipient orbits followed by sequential venous and arterial anastomoses and nerve coaptation. Pedicle lengths and calibers were measured. All steps were timed, photographed, video recorded, and critically analyzed after each operative session. The technical feasibility of cadaveric donor procurement and transplantation to cadaveric recipient was established. Mean measurements included optic nerve length (39 mm) and caliber (5 mm), donor artery length (33 mm) and caliber (3 mm), and superior ophthalmic vein length (15 mm) and caliber (0.5 mm). Recipient superficial temporal, internal maxillary artery, and facial artery calibers were 0.8, 2, and 2 mm, respectively; and superior temporal and facial vein calibers were 0.8 and 2.5 mm, respectively. This surgical protocol serves as a benchmark for optimization of technique, large-animal model development, and ultimately potentiating the possibility of vision restoration transplantation surgery. Therapeutic, V.

Evaluation of Eyeball and Orbit in Relation to Gender and Age.

The orbital aperture is the entrance to the orbit in which most important visual structures such as the eyeball and the optic nerve are found. It is vital not only for the visual system but also for the evaluation and recognition of the face. Eyeball volume is essential for diagnosing microphthalmos or buphthalmos in several eye disorders. Knowing the length of the optic nerve is necessary in selecting the right instruments for enucleation. Therefore, the aim of this study was to evaluate eyeball volume, orbital aperture, and optic nerve dimensions for a morphological description in a Turkish population sample according to gender and body side.Paranasal sinus computed tomography (CT) scans of 198 individuals (83 females, 115 males) aged between 5 and 74 years were evaluated retrospectively. The dimensions of orbital aperture, axial length and volume of eyeball, and diameter and length of the intraorbital part of the optic nerve were measured. Computed tomography examinations were performed on an Activion 16 CT Scanner (Toshiba Medical Systems, 2008 Japan). The CT measurements were calculated by using OsiriX software on a personal computer. All parameters were evaluated according to gender and right/left sides. A statistically significant difference between genders was found with respect to axial length of eyeball, optic nerve diameter, dimensions of orbital aperture on both sides, and right optic nerve length. Furthermore, certain statistically significant side differences were also found. There were statistically significant correlations between age and the axial length of the eyeball, optic nerve diameter, and the transverse length of the orbital aperture on both sides for the whole study group.In this study we determined certain morphometric parameters of the orbit. These outcomes may be helpful in developing a database to determine normal orbit values for the Turkish population so that quantitative assessment of orbital disease and orbital deformities will be evaluated both for preoperative planning and for assessing postoperative outcomes.

Optic Nerve Sheath as a Novel Mechanical Load on the Globe in Ocular Duction.

PurposeThe optic nerve (ON) sheath's role in limiting duction has been previously unappreciated. This study employed magnetic resonance imaging (MRI) to demonstrate this constraint on adduction.MethodsHigh-resolution, surface coil axial MRI was obtained in 11 normal adults, 14 subjects with esotropia (ET) having normal axial length (AL) < 25.8 mm, 13 myopic subjects with ET and mean AL 29.3 ± 3.3 (SD) mm, and 7 subjects with exotropia (XT). Gaze angles and ON lengths were measured for scans employing eccentric lateral fixation in which an ON became completely straightened.ResultsIn all groups, ON straightening occurred only in the adducting, not abducting, eye. Adduction at ON straightening was 26.0 ± 8.8° in normal subjects, not significantly different from XT at 22.2 ± 11.8°. However, there was significant increase in comparable adduction in ET to 36.3 ± 9.3°, and in myopic ET to 33.6 ± 10.7° (P < 0.04). Optic nerve length at straightening was 27.6 ± 2.7 mm in normals, not significantly different from 28.2 ± 2.8 mm in ET and 27.8 ± 2.7 mm in XT. In myopic ET, ON length at straightening was significantly reduced to 24.0 ± 2.9 mm (P < 0.002) and was associated with globe retraction in adduction, suggesting ON tethering.ConclusionsLarge adduction may exhaust length redundancy in the normally sinuous ON and sheath, so that additional adduction must stretch the sheath and retract or deform the globe. These mechanical effects are most significant in ET with axial myopia, but may also exert traction on the posterior sclera absent strabismus or myopia. Tethering by the ON sheath in adduction is an important, novel mechanical load on the globe.

Visual Outcomes of Parapapillary Uveal Melanomas Following Proton Beam Therapy

In parapapillary melanoma patients, radiation-induced optic complications are frequent and visual acuity is often compromised. We investigated dose-effect relationships for the optic nerve with respect to visual acuity after proton therapy. Of 5205 patients treated between 1991 and 2014, those treated using computed tomography (CT)-based planning to 52 Gy (prescribed dose, not accounting for relative biologic effectiveness correction of 1.1) in 4 fractions, with minimal 6-month follow-up and documented initial and last visual acuity, were included. Deterioration of ≥0.3 logMAR between initial and last visual acuity results was reported. A total of 865 consecutive patients were included. Median follow-up was 69 months, mean age was 61.7 years, tumor abutted the papilla in 35.1% of patients, and tumor-to-fovea distance was ≤3 mm in 74.2% of patients. Five-year relapse-free survival rate was 92.7%. Visual acuity was ≥20/200 in 72.6% of patients initially and 47.2% at last follow-up. A wedge filter was used in 47.8% of the patients, with a positive impact on vision and no impact on relapse. Glaucoma, radiation-induced optic neuropathy, maculopathy were reported in 17.9%, 47.5%, and 33.6% of patients, respectively. On multivariate analysis, age, diabetes, thickness, initial visual acuity and percentage of macula receiving 26 Gy were predictive of visual acuity. Furthermore, patients irradiated to ≥80% of their papilla had better visual acuity when limiting the 50% (30-Gy) and 20% (12-Gy) isodoses to ≤2 mm and 6 mm of optic nerve length, respectively. A personalized proton therapy plan with optic nerve and macular sparing can be used efficiently with good oncological and functional results in parapapillary melanoma patients.

Axonal transport rate decreased at the onset of optic neuritis in EAE mice

Optic neuritis is frequently the first symptom of multiple sclerosis (MS), an inflammatory demyelinating neurodegenerative disease. Impaired axonal transport has been considered as an early event of neurodegenerative diseases. However, few studies have assessed the integrity of axonal transport in MS or its animal models. We hypothesize that axonal transport impairment occurs at the onset of optic neuritis in experimental autoimmune encephalomyelitis (EAE) mice. In this study, we employed manganese-enhanced MRI (MEMRI) to assess axonal transport in optic nerves in EAE mice at the onset of optic neuritis. Axonal transport was assessed as (a) optic nerve Mn2+ accumulation rate (in % signal change/h) by measuring the rate of increased total optic nerve signal enhancement, and (b) Mn2+ transport rate (in mm/h) by measuring the rate of change in optic nerve length enhanced by Mn2+. Compared to sham-treated healthy mice, Mn2+ accumulation rate was significantly decreased by 19% and 38% for EAE mice with moderate and severe optic neuritis, respectively. The axonal transport rate of Mn2+ was significantly decreased by 43% and 65% for EAE mice with moderate and severe optic neuritis, respectively. The degree of axonal transport deficit correlated with the extent of impaired visual function and diminished microtubule-associated tubulins, as well as the severity of inflammation, demyelination, and axonal injury at the onset of optic neuritis.

Intraoperative Sub-Tenon Injection Increases Optic Nerve Length Transection During Enucleation

To determine the effect of sub-Tenon injection on the length of optic nerve resected during enucleation. Case-control laboratory study on 22 orbits of 11 unpreserved, fresh-frozen human cadavers. Each cadaver underwent a conventional enucleation technique on one side and an otherwise identical technique on the contralateral side that included sub-Tenon injection of 2.5 ml normal saline in each oblique quadrant. Resected optic nerve lengths were measured and compared using Student t tests. The mean optic nerve length was 15.2 mm (range, 5.0-21.0 mm) in the sub-Tenon injection group and 11.3 mm (range, 5.0-19.0 mm) in control group (p = 0.015). Sub-Tenon injection during enucleation allows for significantly longer optic nerve resection lengths in unpreserved, fresh-frozen human cadavers.

Risk Factors for Neovascular Glaucoma After Proton Beam Therapy of Uveal Melanoma: A Detailed Analysis of Tumor and Dose–Volume Parameters

To determine neovascular glaucoma (NVG) incidence and identify contributing tumor and dosing factors in uveal melanoma patients treated with proton beam radiation therapy (PBRT). A total of 704 PBRT patients treated by a single surgeon (DHC) for uveal melanoma (1996-2010) were reviewed for NVG in our prospectively maintained database. All patients received 56 GyE in 4 fractions. Median follow-up was 58.3 months. Analyses included the Kaplan-Meier method to estimate NVG distributions, univariate log-rank tests, and Cox's proportional hazards multivariate analysis using likelihood ratio tests to identify independent risk factors of NVG among patient, tumor, and dose-volume histogram parameters. The 5-year PBRT NVG rate was 12.7% (95% confidence interval [CI] 10.2%-15.9%). The 5-year rate of enucleation due to NVG was 4.9% (95% CI 3.4%-7.2%). Univariately, the NVG rate increased significantly with larger tumor diameter (P<.0001), greater height (P<.0001), higher T stage (P<.0001), and closer proximity to the disc (P=.002). Dose-volume histogram analysis revealed that if >30% of the lens or ciliary body received ≥50% dose (≥28 GyE), there was a higher probability of NVG (P<.0001 for both). Furthermore, if 100% of the disc or macula received ≥28 GyE, the NVG rate was higher (P<.0001 and P=.03, respectively). If both anterior and posterior doses were above specified cut points, NVG risk was highest (P<.0001). Multivariate analysis confirmed significant independent risk factors to include tumor height (P<.0001), age (P<.0001), %disc treated to ≥50% Dose (<100% vs 100%) (P=.0007), larger tumor diameter (P=.01), %lens treated to ≥90% Dose (0 vs >0%-30% vs >30%) (P=.01), and optic nerve length treated to ≥90% Dose (≤1 mm vs >1 mm) (P=.02). Our current PBRT patients experience a low rate of NVG and resultant enucleation compared with historical data. The present analysis shows that tumor height, diameter, and anterior as well as posterior critical structure dose-volume parameters may be used to predict NVG risk.

Measurement of Critical Structures around Paraclinoidal Area : A Cadaveric Morphometric Study.

ObjectiveAlthough removal of the anterior clinoid process (ACP) is essential surgical technique, studies about quantitative measurements of the space broadening by the anterior clinoidectomy are rare. The purposes of this study are to investigate the dimension of the ACP, to quantify the improved exposure of the parasellar space after extradural anterior clinoidectomy and to measure the correlation of each structure around the paraclinoidal area.MethodsEleven formalin-fixed Korean adult cadaveric heads were used and frontotemporal craniotomies were done bilaterally. The length of C6 segment of the internal carotid artery on its lateral and medial side and optic nerve length were checked before and after anterior clinoidectomy. The basal width and height of the ACP were measured. The relationships among the paraclinoidal structures were assessed. The origin and projection of the ophthalmic artery (OA) were investigated.ResultsThe mean values of intradural basal width and height of the ACP were 10.82 mm and 7.61 mm respectively. The mean length of the C6 lateral and medial side increased 49%. The mean length of optic nerve increased 97%. At the parasellar area, the lengths from the optic strut to the falciform liament, distal dural ring, origin of OA were 6.69 mm, 9.36 mm and 5.99 mm, respectively. The distance between CN III and IV was 11.06 mm.ConclusionWith the removal of ACP, exposure of the C6 segments and optic nerve can expand 49% and 97%, respectively. This technique should be among a surgeon's essential skills for treating lesions around the parasellar area.

Snare Technique for Enucleation of Eyes With Advanced Retinoblastoma

Retrospective analysis of surgical outcomes for enucleation in pediatric retinoblastoma stage 5B using the snare wire loop (n = 55) and standard curved enucleation scissors (n = 22) revealed that a statistically significant longer mean optic nerve length was obtained with the snare (13.35 mm) compared with scissors (11.05 mm; P = .005). Four scissor cases had prolonged bleeding and required thrombin (18.2%), but no snare cases had difficulty with hemostasis (P = .005). More crush artifact was seen with the snare than with scissors (P<.001), but this did not affect the ability to determine tumor involvement at the surgical margin. The enucleation snare should be considered a valuable surgical instrument in the small pediatric orbit since obtaining the longest optic nerve segment has prognostic implications in retinoblastoma.

Optic nerve length in enucleated specimens of retinoblastoma eyes: A surgical approach to retinoblastoma

Optic nerve length in enucleated specimens of retinoblastoma eyes: A surgical approach to retinoblastoma

Clinicoradiologic Relationships in Case of Grave's Orbitopathy

Purpose. To evaluate the relationship of clinical and radiologic findings in improving of diagnostics and amendment of the outcome.Material and methods. 52 patients (104 orbial cavities) in the age of 18–61 years were examined. Patients with the clinical symptoms of Grave’s orbitopathy were examined using ophthalmological evaluation and MSCT-visualization of orbial cavities.Results. The most significant MSCT-parameters for the determination of severity are: prolapse of orbital fat (р = 0.0009), protrusion of eye bulb (р = 0.001), apical inspissations (р = 0.019), density of RBCmin (р = 0.004), size of external terminal membrane (р = 0.001), size of LRM (р = 0.002), size of MRM (р = 0.006), length of optic nerve (р = 0.0001), diameter of optic nerve in 1 cm from the macula (р = 0.01), width of lacrimal gland (р = 0.0002).Conclusions. There is significant relationship between clinical and radiologic (MSCT) features. It lets develop the protocolof examination for diagnostics and treatment of Grave’s orbitopathy.

Optic nerve tissue shrinkage during pathologic processing after enucleation for retinoblastoma.

To quantify and analyze the differences between the length of the optic nerve as measured by the ophthalmologist in the operating room after enucleation and the length as measured by the pathologist after fixation. The authors performed a retrospective review of patients who underwent either primary or secondary enucleation for retinoblastoma at the Ophthalmic Oncology Center of the New York-Presbyterian Hospital-Cornell campus between November 1979 and August 2001. Intraoperative notes and pathologic reports were reviewed to determine the length of the resected optic nerve as recorded by both the surgeon and pathologist. Sufficient data for inclusion in the study were available from 100 enucleation specimens belonging to 96 patients. A significant degree of shrinkage of the optic nerve occurred after fixation, with a mean shrinkage of 30.3% from the time of enucleation to the time of measurement by the pathologist. Age at enucleation affected the degree of optic nerve shrinkage; nerves from younger children underwent more shrinkage than nerves from older patients. Sex of the patient and the laterality of disease did not significantly affect optic nerve shrinkage. A significant degree of shrinkage of the optic nerve occurs in retinoblastoma enucleation specimens after fixation prior to pathologic analysis. This finding must be taken into account when comparing different series and making recommendations for chemoprophylaxis based solely on histopathologic examination.

Magnetic Resonance Imaging in Patients With Low-Tension Glaucoma

To study diagnoses and anatomic findings found on magnetic resonance imaging in patients with low-tension glaucoma. We included in this study magnetic resonance images of 20 consecutive patients with low-tension glaucoma. We individually matched each patient with low-tension glaucoma to a control with normal ocular findings who had magnetic resonance imaging for reasons unrelated to the visual pathway. We studied axial and coronal images of the orbit and optic nerve with digitizing software (Image-Pro Plus, Media Cybernetics, Silver Spring, Md). Statistical evaluation was with a Wilcoxon Signed Rank Test for anatomic findings and a McNemar Test for diagnosis. We found no difference between groups in the optic nerve diameter or length, the carotid artery area, or the distance from the optic nerve to the carotid artery (P > .05). Left optic nerve area was greater in the control patients than patients with low-tension glaucoma (P = .026). The prevalence of intracranial abnormalities, including meningioma, aneurysm, and arteriovenous abnormality, was similar between groups (P > .05). However, diffuse cerebral small-vessel ischemic changes were found more in patients with low-tension glaucoma (n = 8) than control patients (n = 1) (P = .0196). This study proposes a hypothesis that cerebral small-vessel ischemia is more common in patients with low-tension glaucoma and potentially reflects indirectly a vascular cause of the optic nerve head damage at least in a subgroup of patients. Importantly, further research still is required to provide direct evidence for a vascular cause involved in low-tension glaucoma.

Retinoblastoma with micrometastasis to CSF

A 28 mth old male presented with a squint and leukocoria. Clinical examination and computerized tomography (CT) suggested a unilateral retinoblastoma with distal optic nerve involvement. Investigations for distant metastasis including lumbar puncture cytology were negative. The eye was enucleated and 12 mm of optic nerve was excised via a combined neurosurgical/ophthalmological approach. Histopathological examination confirmed the optic nerve to the point of excision was free of tumor. However, cytology of cerebrospinal fluid (CSF) from the Sylvian fissure, taken at the time of surgery, revealed malignant retinoblastoma cells. The patient was treated with intrathecal and intravenous chemotherapy, and cranial radiotherapy. He is alive and well 4 yrs later. This case displays the importance of CSF cytology from the Sylvian fissure, as it dramatically changed the management and prognosis for the child. The role of lumbar puncture cytology in excluding CSF micrometastasis can be unreliable. A neurosurgical approach to the optic nerve has the potential to gain access to a long length of optic nerve, should it be involved with tumor, and also allows direct CSF sampling.

Intraocular retinoblastoma group V: an analysis of prognostic factors.

A retrospective analysis of the University of Minnesota (Minneapolis) experience with retinoblastoma is presented. Seventy-five patients were diagnosed with retinoblastoma between 1958 and 1983, of which 53 (71%) had at least one Reese-Ellsworth group V eye. Nineteen group V patients and one group II patient developed extraocular disease recurrence. The cumulative actuarial rate of recurrence at 12 years was 36% for patients with group V disease. The median time from diagnosis to recurrence for unilateral patients was seven months and for bilateral patients 28 months (P = .001). Patients developing extraocular disease had a 10-year actuarial survival rate postrecurrence of 34%. The four long-term survivors of extraocular recurrences had had isolated orbital or local soft tissue recurrences only. Features of group V patients associated with extraocular recurrences were identified by univariate life table analyses. Clinical poor-risk factors included the nongenetic form of the disease (P = .03) and male sex (P = .02). Pathologic poor risk factors included rubeosis (P = .01), undifferentiated histology (P = .03), large tumor size (P = .05), and intraocular extension to the anterior segment (P = .02), retinal pigment epithelium (P = .03), choroid (P less than .001), and optic nerve beyond the lamina cribrosa (P = .02). Treatment-associated poor-risk factors included an optic nerve length of less than 5 mm removed at enucleation (P = .003). Multivariate life table analyses demonstrated the following parameters to be independent poor-prognostic factors: optic nerve length of less than 5 mm removed at enucleation (P = .001), optic nerve involvement (P = .004), and large tumor size (P = .01). These results will help to identify patients with retinoblastoma who are at greatest risk for extraocular recurrence.

Optic Nerve Retrieval After Enucleation

SUMMARY Occasionally a surgeon does not obtain an adequate length of optic nerve during enucleation surgery for a suspected intraocular malignancy. Retrieval of an additional nerve segment can be accomplished rapidly utilizing a glass test tube containing a few milliliters of water as an orbital endoscope. Under direct visualization, the remainder of the optic nerve can be located, grasped with a curved clamp, and sectioned with scissors.

Changes in the osmiophilia of myelin and lipid content in the kitten optic nerve.

Abstract—Myelin osmiophilia has been shown to develop significantly later than myelin staining by Luxol fast blue and Sudan black, in the developing kitten optic nerve. These histological changes are accompanied by alterations in the lipid composition of the optic nerve. Although myelination commences at about 10 days post partum in the nerve the appearance of cerebrosides is unexpectedly delayed. Changes in fatty acid chain length and lipid composition of optic nerve are consistent with the suggestion that ‘early’ myelin may be unchanged glial plasma membrane.

NEW ENUCLEATION SCISSORS COMBINED WITH HEMOSTAT BLADES

A frequently troublesome phase in the performance of enucleation is the control of hemorrhage after section of the optic nerve. The commonest practice is to section the nerve with scissors, remove the globe, and then pack the socket until hemorrhage has ceased. This frequently prolongs the operation and does not always result in satisfactory hemostasis, particularly when a glass ball is to be inserted in Tenon's capsule. Another practice is first to apply a small curved hemostat to the optic nerve well back toward the apex of the orbit, then to insert the scissors, the curve of which fits that of the hemostat, between the hemostat and the globe and thus sever the optic nerve. This prevents hemorrhage satisfactorily, but it is often difficult to manipulate the two separate instruments within the orbit. Frequently there is left only a short length of optic nerve attached to the globe, as in