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Background: Optic nerve sheath fenestration (ONSF) is commonly used in idiopathic intracranial hypertension (IIH) with visual deterioration and visual improvement is observed post operatively in these patients. Objective: Retrospective evaluation of MRI observations in IIH patients who underwent optic nerve sheath fenestration (ONSF) with postoperative visual improvement. Materials and method: Optic nerve sheath fenestration (ONSF) was done in twenty four (24) patients with IIH having severe visual impairment. Post operatively all patients improved in their visual functions. The recorded pre operative MRI (of brain and orbit) of patients were reviewed and evaluated retrospectively. Results: Total number of MRI studied was 24. Male female ratio was 1:11. Posterior globe flattening was found in all 24 (100%) cases. Other findings were horizontal tortuosity of optic nerve (92%), optic nerve head protrusion (87.5%), optic nerve sheath distension (87%), and vertical buckling (62.5%). Ventricular size was normal in 92% cases and slit ventricle was found only in 8% cases. On magnetic resonance venogram (MRV) one sided transverse sinus abnormality was found in 25% cases. There was empty sella in 79% cases, more marked in three cases. Conclusion: The MRI findings in IIH patients with positive post ONSF result are of variable degree and prevalence except posterior globe flattening which was found in all cases. Delta Med Col J. Jul 2020 8(1): 21-27

This study aimed to assess the safety and efficacy of optic nerve sheath fenestration (ONSF) in leukemic children having increased intracranial pressure with severe uncontrolled visual loss on medical treatment and not eligible for venous sinus stenting. In this non-randomized clinical trial, we included patients presenting with severe sight-threatening papilledema due to increased intracranial pressure following leukemia treatment. All included patients were subjected to a complete history taking, assessment of the visual acuity and fundus examination with fundus photography and grading of papilledema using Frisen scale. Patients were evaluated at 2 weeks and 3 months postoperative by recording the best-corrected visual acuity, assessment of the pupillary reaction and fundus examination and fundus photography with grading of papilledema. Among 20 patients included in this study, there was a statistically significant improvement in visual acuity of both eyes in all patients. The mean postoperative visual acuity was 0.28 ± 0.10 two weeks after surgery in the right eye and it was 0.42 ± 0.16 in the left eye. The mean visual acuity in the right eye three months after surgery was 0.78 ± 0.19 and it was 0.87 ± 0.17 in the left eye. Three months postoperatively, papilledema resolved completely in both eyes. There were no recorded ocular complications. In this study, ONSF was sight-saving procedure in all leukemic patients with a significant improvement in the visual acuity, stabilization of the visual function and resolving of the papilledema over follow-up period. There were no recorded intraoperative or postoperative complications. Further well-designed studies are needed to assert upon these results.

To evaluate the change in intraocular pressure (IOP) in patients with idiopathic intracranial hypertension (IIH) who underwent optic nerve sheath fenestration (ONSF) and to determine if radiographic evidence of posterior scleral or globe indentation influenced IOP.This is a retrospective analysis of IOP in IIH patients who underwent ONSF. The study included all patients from September 2010 to March 2018 operated on by a single surgeon (R.M.). IOPs preoperatively and postoperatively were recorded along with the acetazolamide dosage and whether there was evidence of posterior scleral or globe indentation on preoperative MRI.A total of 29 patients (35 eyes) with IIH underwent ONSF. The average reduction in IOP among all patients was 1.24 mm Hg (P = 0.0218), but this increased to 2.69 mm Hg (P = 0.004) in patients who were maintained on the same dosage of acetazolamide in the preoperative and postoperative period. Furthermore, the reduction in IOP in those with posterior scleral or globe indentation was 2.5 mm Hg (P = 0.0095). When the perioperative period was evaluated, the mean decrease in IOP was 1.83 mm Hg (P = 0.0217).Reducing the cerebral spinal fluid pressure (CSFP) at the level of the intraorbital optic nerve through an ONSF can slightly reduce the IOP. In those with evidence of posterior globe or scleral indentation/flattening, the reduction in IOP was higher, which supports the theory that CSF pressure indents the globe and leads to an increase in IOP. Although these changes in IOP are small, this study provides further evidence for a connection between IOP and CSFP.

Optic nerve sheath fenestration (ONSF) is a surgical procedure commonly performed in the Anglo-Saxon countries for the treatment of medically refractory idiopathic intracranial hypertension (IIH). We chose to compare 6 different trans-orbital surgical approaches to ONSF. We also desired to determine the number of optic nerve decompression procedures performed in France in 2019 and 2020.Four fresh frozen orbits were dissected at the University of Nice anatomy laboratory. We performed the following surgical approaches: (i) eyelid crease, (ii) lid-split, (iii) medial transconjunctival with medial rectus disinsertion, (iv) medial transconjunctival without rectus disinsertion, (v) lateral transconjunctival and (vi) lateral orbitotomy. For each surgical approach, we measured the distance between the incision and the optic nerve dura mater. We also extracted data from the French National PMSI (Programme de Médicalisation des Systèmes d' Information) database from January 2019 through December 2020 to determine the annual number of optic nerve decompression procedures.The lid crease and medial transconjunctival approaches provided the shortest distance to the optic nerve (average 21mm and 24mm, respectively) and the lowest levels of difficulty compared to the other surgical routes. A total of 23 and 45 optic nerve decompressions were performed in France in 2019 and 2020, respectively. Among them, only 2 and 7 procedures, respectively, were performed through a trans-orbital approach.Upper lid crease incision and medial transconjunctival approaches are the most direct and easiest surgical routes when performing an ONSF. We found that ONSF was rarely performed in France. We strongly recommend close cooperation between ophthalmologists, neurologists, neurosurgeons and interventional radiologists.

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Objectives. Optic nerve sheath fenestration (ONSF) is commonly used in idiopathic intracranial hypertension (IIH). Here we will present our experiences of ONSF in 26 patients with special attention to indications, surgical techniques and results Methods. The recorded data of patient management (with the result) who underwent ONSF were reviewed and studied retrospectively. Results. The total number of patients who underwent ONSF was 26. The male-female ratio was 1:12. Indications of ONSF were: 1. Idiopathic Intracranial Hypertension (IIH)-23 cases; 2. Cerebral Venous Sinus Thrombosis (CVST)-02 cases; 3. CNS Tuberculosis-01case. All patient underwent bilateral ONSF with post-operative continues lumbar CSF drain for 04 days. After fenestration gush of CSF came out with force in all-first operated eyes whereas 13-second operated eyes showed very little CSF flow after fenestration. Vision improved in different grades in all cases at discharge except in three cases. Preoperatively, visual acuity was either PL&PR or hand movement in 40 eyes where 04 eyes were preoperatively total blind (no PL&PR). Visual acuity improved in 48 eyes (92.3% eyes) where the patient can do his/her daily life activities including self-care. Improvement in IIH is 100% (23 cases i.e-46 eyes) whereas 01 case out of 02 cases in CVST. Though vision was improved dramatically fundal appearances changes very slowly and very less frequently returned to normal appearance. Conclusion. Due to the delicate and technically demanding nature of the surgery, safety is a major concern of the ONSF. Our experience showed ONSF is a technically safe operation with very good results where indicated.

This article presents a medical robotic system for deep orbital interventions, with a focus on Optic Nerve Sheath Fenestration (ONSF). ONSF is a currently invasive ophthalmic surgical approach that can reduce potentially blinding elevated hydrostatic intracranial pressure on the optic disc via an incision on the optic nerve. The prototype is a multi-arm system capable of dexterous manipulation and visualization of the optic nerve area, allowing for a minimally invasive approach. Each arm is an independently controlled concentric tube robot collimated by a bespoke guide that is secured on the eye sclera via sutures. In this article, we consider the robot’s end-effector design in order to reach/navigate the optic nerve according to the clinical requirements of ONSF. A prototype of the robot was engineered, and its ability to penetrate the optic nerve was analysed by conducting ex vivo experiments on porcine optic nerves and comparing their stiffness to human ones. The robot was successfully deployed in a custom-made realistic eye phantom. Our simulation studies and experimental results demonstrate that the robot can successfully navigate to the operation site and carry out the intervention.

To evaluate the effect of optic nerve sheath fenestration (ONSF) on the rate of visual function improvement in patients with pseudotumor cerebri syndrome (PTCS). Retrospective chart review of patients with PTCS who underwent ONSF between 1998 and 2017. Visual function was evaluated by evaluating visual field (VF), mean deviation (MD), retinal nerve fiber layer (RNFL) thickness, papilledema grade, and visual acuity (VA) prior to and after ONSF. Seventeen female patients aged 17 to 36 years underwent unilateral ONSF. Follow-up averaged 40.1 months. VF MD improved steadily in both eyes up to 12 months. Average RNFL thickness improved in the operated eye from 347 ± 166 mm to 92 ± 27 mm (p < .001) and the non-operated eyes from 306 ± 165 mm to 109 ± 46 mm (p < .001). The grade of papilledema improved in the operated eye from 3.3 ± 1.3 to 0.3 ± 0.7 and the non-operated eye from 3.0 ± 1.6 to 0.18 ± 0.4. There was an exponential rate of improvement in papilledema and RNFL thickness, with the greatest improvement occurring within the first 30 days. Average visual acuity remained intact in both eyes before and after surgery. ONSF in appropriately selected patients leads to rapid improvement in papilledema and a steady recovery in VF.

Idiopathic Intracranial Hypertension is one of the causes of blindness in the modern world. It affects usually overweight female patients in their childbearing age. Unfortunately, there are no clear quidelines in respect of the best possible approach to treat this rare condition. Conservative treatment which means weight loss, acetazolamide prescription and close follow up and on the other hand surgical treatments are the main options. Ventriculoperitoneal shunt to relieve intracranial pressure and Optic Sheath Fenestration are both surgical options that can be also combined treat patients and save their vision decline [1,2]. In this study, we retrospectively reviewed different techniques of optic sheath fenestration and measured the outcome and the complication rate of each one.