An Atypical Paediatric Optic Nerve Sheath Meningioma.

A 16-year-old male presented with a three year history of right proptosis. All other ocular findings were normal. Imaging demonstrated a large, calcified, contrast-enhancing mass in the apical orbit. The tumour had high gallium-68-DOTATATE uptake and low 18F-2-fluoro-2-deoxy-D-glucose uptake. An incisional biopsy revealed a diagnosis of psammomatous optic nerve sheath meningioma (ONSM). One year later stereotactic radiotherapy was performed due to tumour growth. Tumour size and visual acuity remained stable in the six months after treatment. This case differs from previously reported paediatric ONSMs by its histo-clinical characteristics (exophytic-calcified mass, visual preservation, psammomatous histology).

Efficacy of intensity-modulated radiation therapy for optic nerve sheath meningioma.

PURPOSE: The present study examined the efficacy and complications associated with intensity-modulated radiation therapy (IMRT) for optic nerve sheath meningioma (ONSM) in 15 cases and compared visual function before and after treatment. METHODS: Consecutively diagnosed patients with ONSM treated with IMRT were evaluated from 2012 to 2017. We categorized ONSM with three growth patterns (diffuse, fusiform, or globular). Visual acuity, visual fields, and optic disc findings were assessed before and after IMRT. Ocular and systemic complications were evaluated during and after treatment. RESULTS: The 15 patients selected for analysis ranged in age from 33 to 77 years. Post-treatment observation periods were 8 to 57 months. After IMRT, tumor enlargement was not detected in any eyes, and tumor reduction was seen in 2 eyes. At final post-treatment follow-up, eyes with fusiform and globular growth maintained better visual acuity compared with pre-treatment, whereas 2 of 5 eyes with diffuse growth showed reduced vision. Five eyes with no apparent optic disc abnormality maintained better visual acuity compared with pre-treatment, whereas 8 of 10 eyes with disc edema and atrophy remained stable or showed reduced vision. Improvements were seen in all 5 eyes with optic discs negative for pre-treatment abnormalities. Final post-treatment visual field abnormalities improved in 11 eyes. All adverse events identified during IMRT improved rapidly during the treatment period. CONCLUSION: IMRT for the treatment of ONSM achieved improvement and preserved visual function. In particular, early treatment with IMRT before the appearance of optic disc abnormalities can be more effective for improving visual function.

Unilateral papilledema revealing an intracanalicular optic nerve sheath meningioma.

A 43-year-old female is referred to our clinic for evaluation of an incidentally discovered unilateral papilledema in her right eye of unknown cause. She had no past ocular or medical history. Examination revealed a corrected-distance visual acuity of 20/20 in both eyes. Posterior segment examination showed an elevated right optic nerve head with blurred edges. Ultrasonography failed to reveal optic disc drusen. Visual field testing showed enlargement of the blind spot in the right eye. Magnetic resonance imaging of the brain and orbit was done and revealed enlargement of the intracanalicular and prechiasmatic part of the right optic nerve and a diagnosis of a presumed right intracanalicular optic nerve sheath meningioma was made. She was managed conservatively and several years later remains asymptomatic.

Early intervention using high-precision radiotherapy preserved visual function for five consecutive patients with optic nerve sheath meningioma.

BACKGROUND: There has been a paradigm shift in the treatment for optic nerve sheath meningioma (ONSM) from surgery to fractionated stereotactic radiotherapy (FSRT) in other countries. However, FSRT has seldom been performed in Japan. The purpose of this retrospective study is to reconfirm the effectiveness of early intervention with precision radiotherapy for ONSM reported in our previous study. METHODS: Five consecutive patients with ONSM were retrospectively analyzed. All patients underwent intensity-modulated radiotherapy (IMRT) or FSRT. They received the early interventions between 1.5 and 7 months after deterioration of the disease. The median dose was 52.8 Gy (range 46.0-59.4 Gy) and the median number of fractions was 25 (range 22-33). RESULTS: All patients experienced reestablishment of vision at the median follow-up time of 36 months (range 18-54 months). Four of them noted early improvement of visual deficits during the treatment course (range 2-4 weeks) and the remaining patient improved 3 weeks after completion of IMRT. The median tumor reduction was 53% (range 39-75%). One patient with diabetes mellitus developed retinal bleeding as a result of radiation retinopathy 16 months after IMRT, although the doses were acceptable. The remaining 4 patients have no late toxicity at the follow-up time of 31-54 months. CONCLUSIONS: A paradigm shift is necessary from surgery to early intervention using precision radiotherapy for the treatment of ONSM in Japan.

Retrospective chart review of the use of imaging and biopsy in the diagnosis of optic nerve sheath meningiomas and intra-conal orbital lymphomas at a single institution.

Optic nerve sheath meningiomas (ONSM) and intra-conal orbital lymphomas are common entities on the differential of a retrobulbar optic nerve involving space-occupying lesion. In this study, we compare the pre-surgical diagnosis, based on clinical presentation and neuroimaging, to the surgical pathology results of intra-conal orbital lymphomas and ONSM. This is an IRB approved retrospective chart review of orbital lymphomas and optic nerve sheath meningiomas biopsied by a single surgeon over a 4-year period at a single institution. Pre-surgical diagnosis and surgical pathology were compared. Fifteen cases of orbital lymphoma were identified. Fourteen were excluded based on extra-conal location. The single histologically confirmed intra-conal orbital lymphoma had a pre-surgical diagnosis of ONSM. Four cases of optic nerve sheath meningioma were identified. Three of the 4 cases of histologically confirmed ONSM had a pre-surgical diagnosis of ONSM. One of the 4 had a pre-surgical diagnosis of lymphoma. Diagnosis based on surgical pathology differed from the pre-surgical diagnosis in 2 out of 5 cases showing that clinical diagnosis does not always correlate with histologic diagnosis. Although both diseases are typically managed with radiation therapy, the treatment dosage and systemic disease implications are very different. These findings emphasis the importance of biopsy in the diagnosis of orbital lesions surrounding the optic nerve.

Diagnosis of optic nerve sheath meningioma during optic nerve sheath decompression.

Optic nerve sheath meningioma (ONSM) is typically diagnosed based on clinical suspicion and imaging characteristics and is most often treated with radiation. Historically, biopsy, optic nerve sheath decompression, and debulking surgeries have been avoided for fear of optic nerve vascular disruption and tumor spread into the orbit. This is a case of a 48-year-old man who presented with unilateral optic disc edema, declining visual acuity, and a visual field defect. Despite an initial improvement with acetazolamide, his vision subsequently worsened. With an elevated lumbar puncture opening pressure and imaging showing right optic nerve sheath enhancement, the differential diagnosis included ONSM, perineuritis and idiopathic intracranial hypertension (IIH). Optic nerve sheath decompression (ONSD) with biopsy was performed, simultaneously decompressing the nerve and yielding a sample for pathologic analysis. A pathologic diagnosis of ONSM was made and treatment with radiation was subsequently initiated, but vision began to improve after the surgical decompression alone.

Analysis of safety and efficacy of proton radiotherapy for optic nerve sheath meningioma.

Background: Primary optic nerve sheath meningiomas (ONSMs) represent a group of benign tumors originating from the optic nerve sheath, typically causing painless, gradual onset monocular visual loss, which can result in blindness if left untreated. Radiation therapy represents an important treatment option for patients with ONSM, allowing for preservation and potential improvement in visual function. In particular, proton radiotherapy may enable a reduction of the side effects due to its physical advantage of an inverted dose profile with a steep dose gradient. The study investigates the visual acuity, local tumor control, and treatment-related toxicities following proton beam radiotherapy with a single institutional cohort comprising 32 patients treated for ONSM. Methods: Patients with primary ONSM, either histologically (16/32) or radiologically confirmed (16/32), which were treated at the Department of Radiation Oncology at the University Hospital Heidelberg (Germany) were assessed in regard to their visual outcomes, treatment toxicity, and local tumor control following radiotherapy according to response assessment in neuro-oncology criteria. Results: After a median follow-up time of 39.5 months, the 5-year local progression-free survival was estimated at 100%, with 84.4% of patients reporting improvement or stability in visual acuity during their last follow-up. Radiation-induced optic neuropathy (RION) was encountered in 9.4%. Conclusions: Our study demonstrates proton beam therapy as a safe and effective treatment alternative in the therapeutic management of ONSMs. RION represents a rare but dreaded complication after treatment. Future head-to-head comparisons with photon radiotherapy in a prospective setting are required to demonstrate a potential, additional clinical benefit.

Role of hypofractionated stereotactic radiotherapy for primary optic nerve sheath meningioma.

Background: Optic nerve sheath meningiomas (ONSM) are rare tumors potentially causing visual deficits. This study aims to report the anatomic and visual outcomes of patients with primary ONSM treated with hypofractionated stereotactic radiotherapy (HF-SRT). Methods: Data of 36 patients treated with HF-SRT between 2008 and 2019 were retrospectively collected. The clinical target volume (CTV) was equal to the gross tumor volume and a 2 mm was added for the planning target volume. All responses other than progression were accepted as local control (LC). The VA grading was performed under 3 groups to provide an even distribution; 20/400 or worse, 20/40-20/400, and 20/40 or better. Results: Median HF-SRT dose was 25 Gy and the median CTV was 1.94 cc. After a median of 106 months of follow-up, the tumor regressed in 23 (64%), was stable in 9 (25%), and progressed in 4 (11%) eyes. The overall rate of LC was 89% with 2-, 5-, 10-, and 15-year rate of 100%, 94%, 84%, and 84%, respectively. Treatment-related late toxicity rate was 11%. The VA was stable in 27 (75%) eyes, improved in 5 (14%) eyes, and worsened in 4 (11%) eyes, respectively, after HF-SRT. Female gender was the only independent predictor of an improved VA. Conclusions: Hypofractionated stereotactic radiotherapy is a safe and satisfactory treatment option for primary ONSM without severe toxicity. It may be advisable to commence treatment before an established visual deficit of 20/400 or worse occurs, to make the most of the functional benefit.

Radiation therapy for optic nerve sheath meningiomas: Local control and treatment related visual changes.

Objective: Our primary objective is to evaluate the local control of optic nerve sheath meningiomas (ONSMs) treated with ionizing radiation and related visual changes after treatment. Our secondary objective is to describe the clinical characteristics and perform an analysis of the treatment impact on the functional status of this group of patients. Methods: We present our series of 19 patients treated with ionizing radiation therapy at our radio-neurosurgery unit between 2016 and 2022. The setting, ophthalmological follow-up, morbidity, and survival are analyzed and discussed. Results: Patients were followed up, and the impact of treatment on local disease control, visual alterations of the affected eye, and functional status of the patient were analyzed. The progression-free survival (PFS) median was 60 months (95% CI 50.3-69.6 months). The estimated PFS rates at 48 and 66 months were 100% and 66%, respectively. At diagnosis, nine (47.3%) eyes were in amaurosis and ten (52.6%) with vision. Of the ten patients without amaurosis at the time of diagnosis, three (30%) maintained unchanged visual acuity, and seven (70%) had decreased visual acuity; three of them developed amaurosis during the first year after treatment (p = 0.018). Conclusions: Using ionizing radiation therapy is a successful treatment for the local control of ONSMs. This therapeutic modality can compromise the visual acuity of the affected eye and improve dyschromatopsia and campimetry defects. The life prognosis is good for these patients, with a zero mortality rate, but their vision prognosis is poor.

Optic nerve sheath meningioma presenting as progressive visual disturbance during pregnancy: A case report.

Meningiomas are often reported to be sensitive to progesterone, but it is not clear how pregnancy and childbirth affect this. A 41-year-old woman experienced two pregnancies and two deliveries. During the first pregnancy, her right visual acuity was impaired, but it recovered after delivery. However, during the second pregnancy, the right visual acuity was impaired again and did not recover after the second delivery. The magnetic resonance imaging revealed a right optic nerve sheath meningioma (ONSM). Surgical resection of the intracranial extension of the tumor was performed to prevent tumor invasion of the left optic nerve and optic chiasm. Pathological examination diagnosed meningioma with positive immunostaining for progesterone receptor. The present study provided clinical features of ONSM associated with pregnancy. ONSM may present with increased tumor growth and impaired vision with pregnancy.

Optic Nerve Sheath Meningiomas: Solving Diagnostic Challenges with 68Ga-DOTATOC PET/CT.

68Ga-DOTATOC PET could be a noninvasive, highly sensitive, and specific technique for the challenging diagnosis of optic nerve sheath meningioma (ONSM). Our objective was to report the use and results of 68Ga-DOTATOC PET in suspected ONSM. Twelve subjects who underwent 68Ga-DOTATOC PET for suspected ONSM in our department were retrospectively included. Standardised clinical and radiological data were collected. The PET examination results were classified as positive or negative, and lesion standardised uptake values (SUVmax) were recorded. 68Ga-DOTATOC PET confirmed positive uptake in six cases (SUVmax > 5), leading to ONSM diagnoses followed by radiation therapy in patients with vision loss. Six 68Ga-DOTATOC PET scans were considered negative (SUVmax < 5); these comprised one case of neurosarcoidosis, one cavernous malformation, and four uncertain diagnoses, leading to further investigation. 68Ga-DOTATOC PET was helpful in tumour volume delineation before radiation therapy, leading to a decrease in dose exposure. Noninvasive 68Ga-DOTATOC PET should be performed before treating nonhistologically proven meningiomas with radiotherapy or stereotactic radiosurgery, particularly in cases of uncertain diagnosis with MRI, which characterises most ONSM cases. PET SUVmax thresholds to distinguish meningioma from nonspecific uptake in other lesions need to be adapted to ONSM. 68Ga-DOTATOC PET improves the intraorbital lesion diagnostic approach and therefore impacts therapeutic management.

Investigating variation of dose gradient index by different grid sizes in intensity-modulated radiation therapy of optic nerve sheath meningioma.

In optic nerve sheath meningioma (ONSM) radiotherapy, vital organs with a low tolerance dose are very close to the target volume. Thus dose fall-off steepness around the target volume is the most critical parameter in intensity-modulated radiation therapy (IMRT) planning for this malignancy. We hypothesized that one of the parameters that can impact the dose fall-off steepness is dose calculation grid sizes. This study aimed to assess the impact of different dose calculation grid sizes on the newly introduced dose gradient indices (DGIs) for the steepness of dose fall-off around the target volume. Results showed that decreasing the dose calculation grid size in IMRT treatment planning of ONSM patients had a significant difference in the dosimetric parameters and DGIs of the target volume and at-risk organs. This study demonstrates that using a finer dose calculation grid size is preferred in treating ONSM patients.

Investigating the number of radiation fields in intensity-modulated radiotherapy plans of optic nerve sheath meningioma patients using dose gradient index.

Purpose: In optic nerve radiotherapy, vital organs are very close to the target volume, they are highly sensitive to radiation and have low dose tolerance. In this regard, evaluating dose fall-off steepness around the target volume is required to assess various intensity-modulated radiation therapy (IMRT) plans in the treatment of the optic nerve sheath meningioma (ONSM) patients.Materials and Methods: Thirteen ONSM patients were analyzed with three IMRT techniques, including three (IMRT-3F), five (IMRT-5F), and seven fields (IMRT-7F). These plans were studied using Dmean, Dmax, D2%, D98%, V100%, uniformity index (UI), homogeneity index (HI), conformity index (CI), and specifically the dose gradient indices (DGIs).Results: The values of Dmaxand Dmeanfor IMRT-3F, IMRT-5F and IMRT-7F were (5637.42 ± 57.08, 5322.84 ± 83.86), (5670.51 ± 67.87, 5383.00 ± 58.45), and (5692.99 ± 31.65, 5405.72 ± 51.73), respectively, which were increased with increment in the number of IMRT fields from 3 to 7. The UI and HI indices were significantly different between IMRT-3F and IMRT-7F (p = 0.010 and p = 0.005, respectively), and CI was close to the ideal value (0.99 ± 0.01) in IMRT-7F. The significant findings of the dose gradient indices represented smaller values in IMRT-7F, which led to a faster dose fall-off, particularly at the 70%-85% isodose levels around the target.Conclusion: Increasing the number of radiation fields in IMRT treatment plans of ONSM patients had a considerable difference in both the dosimetric parameters of the target volume and at-risk organs, as well as the dose gradient indices. Overall, IMRT-7F could be considered as a preferred technique in the treatment of this meningioma.

Orbital indications.

GKNS for uveal melanoma has become a recognized valued treatment which avoids enucleation of the eye. In the early days, the eccentric location of these tumors made treatment difficult, but Gamma Knife Perfexion has solved that problem. It is known that larger tumors and tumors with an anterior location have a worse prognosis. GKNS has also been of rather unexpected benefit in optic nerve gliomas that require treatment. Choroidal hemangiomas may benefit from treatment as can secondary glaucoma. It has also been found to be beneficial in the treatment of thyrotoxic ophthalmopathy.

Long-Term Visual Function After Fractionated Stereotactic Radiotherapy for Primary Optic Nerve Sheath Meningioma: A Retrospective Analysis of 34 Subjects.

Objective: To evaluate long-term visual function after fractionated stereotactic radiotherapy (FSRT) for primary optic nerve sheath meningioma (PONSM). Methods: This 22-year retrospective study included 34 subjects (34 affected eyes) with PONSM who were treated with FSRT exclusively. Subjects with a history of biopsy/resection were excluded. Visual function, including visual acuity (VA) and visual field mean deviation (VF MD), was evaluated at presentation (pre-radiotherapy; pre-RT) and at the final follow-up (post-radiotherapy; post-RT); treatment complications were also evaluated. Treatment success was defined as either stabilization or improvement of visual function. Results: The median pre-RT VA and pre-RT VF MD were 0.70 logarithm of the minimum angle of resolution (logMAR; range: 0.0-2.9 logMAR) and -15.4 decibels (dB) (range: -31.4 to -3.2 dB), respectively. The median total dose of FSRT was 50 Gy (range: 45-54 Gy) and the median number of fractions was 25 (range: 25-30). The median follow-up interval was 89 months (range: 6-251 months). The median post-RT VA and post-RT VF MD were 0.48 logMAR (range: 0.0-2.9 logMAR) (p = 0.010) and -6.8 dB (range: -20.6 to -1.6 dB) (p = 0.005), respectively. Among the 34 included eyes, VA was successfully treated in 29 eyes (85.3%) and worsened in 5 eyes (14.7%). Of the 14 eyes with both VA and reliable VF MD at pre-RT and post-RT time points, VF MD was successfully treated in 13 eyes (92.8%) and worsened in one (7.2%); overall visual function was successfully treated in 13 eyes (92.8%) and worsened in 1 eye (7.2%). Complications occurred in one subject (2.9%; radiation retinopathy). Conclusion: Approximately 90% of PONSM subjects exhibited long-term treatment success in terms of VA, VF MD, and overall visual function after FSRT. Additionally, the incidence of complications was low. Therefore, FSRT is effective and safe treatment for PONSM.

Peripapillary choroidal neovascularization associated with optic nerve sheath meningioma.

Peripapillary choroidal neovascularization (PPCNV), a rare presentation of optic nerve sheath meningioma (ONSM), is associated with various ocular pathologies. Herein, we report a case with characteristics of age-related macular degeneration, PPCNV, optic disc edema, and a retinal-choroidal venous collateral. In addition to the recognition of an orbital base ONSM, magnetic resonance imaging revealed a distended perioptic subarachnoid space with the accumulation of cerebrospinal fluid anterior to the tumor. On the basis of these clinical findings, we postulated the pathogenesis of PPCNV-associated ONSMs.

Radiotherapy and Radiosurgery in the Management of Optic Nerve Sheath Meningiomas: An International Systematic Review and Meta-Analysis of Twenty Studies.

BACKGROUND: Optic nerve sheath meningiomas (ONMs) are often managed with radiotherapy (RT) with the goal of achieving radiographic local control (LC) and preventing deterioration of visual acuity (VA). We aimed to perform a systematic review and meta-analysis of outcomes for patients with ONM treated with RT. METHODS: The PICOS/PRISMA/MOOSE selection criteria were used to identify studies. Primary outcomes were stable or improved VA and radiographic LC at last follow-up. The secondary outcomes were incidences of radiation-induced retinopathy and xerophthalmia and stable or improved visual fields (VFs). Weighted random-effects meta-analyses using the DerSimonian and Laird methods were conducted to characterize effect sizes. Mixed-effects regression models were used to examine potential correlations between gross tumor volume (GTV) and outcomes. RESULTS: In total, 444 patients with ONM across 20 published studies were included. The estimated LC rate was 99.8% (95% confidence interval [CI], 98.3%-100%), and the estimated proportion of patients with stable or improved VA or VF was 89.7% (95% CI, 86.2%-92.4%) and 93.3% (95% CI, 89.5%-95.8%), respectively. Estimated incidences of radiation-induced retinopathy and xerophthalmia were 7.2% and 10.1%, respectively. GTV was significantly associated with VA (P = 0.014) with estimated VA rates of 96.4%, 91.4%, and 80.5% for GTVs of 2.0, 3.0, and 4.0 cm3, respectively. CONCLUSIONS: RT was well tolerated, with excellent LC achieved. Nearly 90% of patients noted either stability or improvement in VA and VF. Larger ONMs were associated with poorer VA.

Combined endoscopic transethmoid and transconjunctival en bloc resection of optic nerve tumors in patients lacking functional vision.

Background: Surgical treatment of optic nerve tumors is challenging. The study's objective was to evaluate the efficacy of a combined endoscopic transethmoid and transconjunctival approach in patients without functional vision. Design: A retrospective, noncomparative case series. Methods: Retrospective data were collected from all patients who had undergone tumor resection using this approach at the authors' institution between 2015 and 2021. Preoperative assessments included magnetic resonance imaging and ophthalmological examinations, and re-assessments were conducted three months after surgery and regularly during the follow-up period. Results: Seventeen patients, mean age 35 ± 19.0 years, were enrolled. Of these, 64.7% presented with visual acuity (VA) of light perception or no light perception. Gross total resection was realized in all patients. The average decline in exophthalmos was 3.63 ± 1.93 mm. Tumor histopathological analysis identified 12 optic nerve sheath meningiomas and 5 optic gliomas. The mean follow-up time was 30 months during which there was no local recurrence in any of the patients. Conclusions: The combined endoscopic transethmoid and transconjunctival approach offers an additional choice for accessing optic nerve tumors. The procedure is both safe and effective and provides an alternative transcranial route to the orbit.

Radiotherapy for the treatment of optic nerve sheath meningioma: A systematic review and meta-analysis.

OBJECTIVES: The management of Optic Nerve Sheath Meningiomas (ONSM) has suffered a significant shift due to new radiation techniques. However, there is no conclusive information on which approach presents better results in the literature. This meta-analysis aims to evaluate the outcomes of different radiotherapy (RT) modalities in the management of ONSM. METHODS: A systematic review based on an electronic search was performed in MEDLINE, EMBASE, Cochrane, and Lilacs databases. Eligible studies included patients with ONSM treated with RT. Two reviewers independently assessed the eligibility of potential studies, extracted data, and performed the meta-analysis. Outcomes of interest were tumor control, visual acuity (VA), visual field, and complications. RESULTS: Thirty-nine non-comparative studies involving 736 eyes with ONSM treated with RT were included. Six different techniques were studied: 2-dimensional RT (2DRT), 3D-conformal RT (3CRT), Stereotactic Fractionation RT (SFRT), stereotactic radiosurgery (SRS), intensity-modulated RT (IMRT), and proton beam therapy (PBT). With a mean follow-up period of 46 months, tumor control was 97,4% (95% CI: 98-100%). No difference was observed regarding the rate of final VA post-treatment among the modalities. The 3CRT showed substantially higher rates of complication than other techniques. CONCLUSIONS: RT produces remarkable tumor control. New radiation modalities such as SFRT, IMRT, SRS, and PBT resulted in better therapeutic results with fewer complications than 2DRT and 3CRT. Thus, they should be the preferential choices for treating ONSM regardless of initial clinical presentation.

Effectiveness and Safety of Robotic Radiosurgery for Optic Nerve Sheath Meningiomas: A Single Institution Series.

The role of robotic radiosurgery (RRS) in the treatment of optic nerve sheath meningiomas (ONSM) remains controversial and it is only performed in specialized institutions due to tight dose constraints. We evaluated the effectiveness and safety of RRS in the management of ONSM. Twenty-five patients with 27 ONSM lesions who underwent RRS using the Cyberknife (CK) system were retrospectively analyzed (median age, 47.9 years; 84.0% women). Multisession RRS was used with 4-5 fractions with a cumulative dose of 20.0-25.0 Gy in 84.0% of patients and a single fraction at a dose of 14.0-15.0 Gy in 16% of patients. Prior to RRS, seven (28%) patients experienced blindness on the lesion side. In those patients with preserved vision prior to radiosurgery, the visual acuity remained the same in 90.0% and improved in 10.0% of the patients. Overall local tumor control was 96.0% (mean follow-up period; 37.4 ± 27.2 months). Neither patient age, previous surgery, or the period from the initial diagnosis to RRS showed a dependency on visual acuity before or after radiosurgery. RRS is a safe and effective treatment for the management of ONSM. Hypofractionation of radiosurgery in patients with preserved vision before CK treatment results in stable or improved vision.