Chiasmal Lesions Research Articles

Validation of a new static perimetric thresholding strategy (GATE)

AimsTo validate the EyeSuite version of German Adaptive Threshold Estimation (GATE), a new thresholding algorithm for automated static perimetry.MethodsSpecification of agreement and its clinical evaluation as validation criteria. Comparison of...

Development and Validation of an Improved Neurological Hemifield Test to Identify Chiasmal and Postchiasmal Lesions by Automated Perimetry

To improve the neurological hemifield test (NHT) using visual field data from both eyes to detect and classify visual field loss caused by chiasmal or postchiasmal lesions. Visual field and clinical data for 633 patients were divided into a training set (474 cases) and a validation set (159 cases). Each set had equal numbers of neurological, glaucoma, or glaucoma suspect cases, matched for age and for mean deviation between neurological and glaucoma cases. NHT scores as previously described and a new NHT laterality score were calculated. The ability of these scores to distinguish neurological from other fields was assessed with receiver operating characteristic (ROC) analysis. Three machine classifier algorithms were also evaluated: decision tree, random forest, and least absolute shrinkage and selection operator (LASSO). We also evaluated the ability of NHT to identify the type of neurological field defect (homonymous or bitemporal). The area under the ROC curve (AUC) for the maximum NHT score was 0.92 (confidence interval [CI]: 0.87, 0.97). Using NHT laterality scores from each eye combined with the sum of NHT scores, the AUC improved to 0.93 (CI: 0.88, 0.98). The largest AUC for machine learning algorithms was for the LASSO method (0.96, CI: 0.92, 0.99). The NHT scores identified the type of neurological defect in 96% (158/164) of patients. The new NHT distinguished neurological field defects from those of glaucoma and glaucoma suspects, providing accurate categorization of defect type. Its implementation may identify unsuspected neurological disease in clinical visual field testing.

Damage to the optic chiasm in myelin oligodendrocyte glycoprotein-experimental autoimmune encephalomyelitis mice.

Optic chiasm lesions in myelin oligodendrocyte glycoprotein (MOG)–experimental autoimmune encephalomyelitis (EAE) mice were characterized using magnetic resonance imaging (MRI) and validated using electron microscopy (EM). MR images were collected from 3 days after induction to remission, approximately 20 days after induction. Hematoxylin and eosin, solochrome cyanin–stained sections, and EM images were obtained from the optic chiasms of some mice approximately 4 days after disease onset when their scores were thought to be the highest. T2-weighted imaging and apparent diffusion coefficient map hyperintensities corresponded to abnormalities in the optic chiasms of EAE mice. Mixed inflammation was concentrated at the lateral surface. Degeneration of oligodendrocytes, myelin, and early axonal damage were also apparent. A marked increase in chiasm thickness was observed. T2-weighted and diffusion-weighted MRI can detect abnormalities in the optic chiasms of MOG-EAE mice. MRI is an important method in the study of this model toward understanding optic neuritis.

Hémianopsie bitemporale révélatrice d’une atteinte toxique sévère à l’éthambutol

Optic neuropathy is a severe and well-known complication of ethambutol treatment. If not detected early, it may lead to profound and irreversible vision loss. We report the case of a 83-year-old female patient, referred for rapidly progressive, painless, bilateral visual loss, unimproved after bilateral cataract surgery. Automated Humphrey 24-2 visual field demonstrated bitemporal hemianopia associated with bilateral central scotoma. Brain MRI did not demonstrate any compressive lesion in the chiasmal region. However, on T2-weighted sequences, an area of elevated signal intensity appeared within the optic chiasm, enhancing after gadolinium injection. On detailed history, it was noted that the patient had been on ethambutol for the last 18months, for the treatment of a Mycobacterium avium-related pneumonitis. The incidence of ethambutol-related toxic optic neuropathy has dramatically decreased since the recommendations for regular follow-up of patients treated with ethambutol. This treatment is classically responsible for bilateral central or ceco-central scotoma due to optic neuropathy, although a few cases of bitemporal hemianopia have been reported in the literature, mimicking a compressive chiasmal lesion. However, none of these cases demonstrated a hypersignal in the optic chiasm on brain magnetic resonance imaging (MRI). Bitemporal hemianopia on visual field testing is very suggestive of a chiasmal lesion, which is generally due to a compressive, or more rarely inflammatory, lesion in the sellar region. Toxic chiasmal lesions are rare, but in the absence of any tumoral lesion in the sellar area, a detailed history must be obtained in order to rule out drug toxicity, so as to prevent irreversible visual loss.

Application of diffusion tensor tractography in pediatric optic pathway glioma

Magnetic resonance imaging is commonly used in diagnosis and surveillance for optic pathway glioma (OPG). The authors investigated the role of diffusion tensor (DT) tractography in assessing the location of visual pathway fibers in the presence of tumor. Data in 10 children with OPG were acquired using a 3T MRI generalized autocalibrating parallel acquisitions DT-echo planar imaging sequence (25 isotropic directions with a b value of 1000 seconds/mm(2), slice thickness 3 mm). Fiber tractography was performed, with seed regions placed within the optic chiasm and bilateral nerves on the coronal plane, including the tumor and surrounding normal-appearing tissue. Tracking was performed with a curvature threshold of 30°. For prechiasmatic lesions, fibers either stopped abruptly at the tumor or traversed abnormally dilated nerve segments. Similar findings were seen with chiasmatic lesions, with an additional arrangement in which fibers diverged around the tumor. For each patient, DT tractography provided additional information about visual fiber arrangement in relation to the tumor that was not evident by using conventional MRI methods. Retrospective reconstruction of visual fibers in 1 patient with new postoperative hemianopia revealed an unexpected superior displacement of the optic tract that might have been helpful information had it been applied to preoperative planning or surgical navigation. Optic pathway DT tractography is feasible in patients with OPG and provides new information about the arrangement of visual fibers in relation to tumors that could be incorporated into surgical navigation for tumor biopsy or debulking procedures.

Evaluation of an Algorithm for Detecting Visual Field Defects Due to Chiasmal and Postchiasmal Lesions: The Neurological Hemifield Test

To develop an automated neurologic hemifield test (NHT) to detect visual field loss caused by chiasmal or postchiasmal lesions. Visual field locations from 24-2 pattern automated visual fields were grouped into two symmetric regions with 16 points on either side of the vertical meridian. A scoring system similar to the Glaucoma Hemifield Test (GHT) was used to calculate point scores using the pattern deviation values from the right and left regions. The cross-vertical difference in the sum of these values was the NHT score. The NHT was evaluated using visual fields from subjects with known neurologic disease, subjects with glaucoma, and glaucoma suspects (92 pairs of eyes each). The NHT score was calculated for each eye. Four masked reviewers scored all pairs of visual fields with regard to the likelihood of neurologic and glaucomatous optic neuropathy. Both NHT score and expert field ratings were compared with clinical diagnosis by receiver operating characteristic (ROC) analysis. The NHT effectively discriminated neurologic fields from those of glaucoma patients and glaucoma suspects (area under the ROC curve [AUC] = 0.90; 95% confidence interval [CI], 0.86-0.94). The NHT score correlated well with clinician grading (Pearson correlation estimates, 0.74-0.78). Even when field defects were subtle, the NHT had some ability to discriminate neurologic from nonneurologic fields (AUC 0.68; 95% CI, 0.56-0.79). The NHT distinguished neurologic field defects from those of glaucoma and glaucoma suspects, rivaling the performance of subspecialist clinicians. Its implementation may help identify unsuspected neurologic disease.

Abnormalities of optical coherence tomography and visual evoked potentials in patients with chiasmal compression syndrome

AbstractPurpose To report abnormalities of retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) and visual evoked potentials (VEP) in patients with compressive chiasmal tumors confirmed on MRI examination.Methods 22 eyes of 12 patients with parasellar tumors causing chiasmal compression syndrome were included to the study and compared to 59 eyes of 30 healthy patients. Exclusion criteria were any other ophthalmic or general condition that can affect both VEP and OCT measurements. All patients underwent MRI of the head to confirm the diagnosis, retinal nerve fiber thickness measurements with OCT and visual evoked potentials examination.Results Average RNFL thickness in patients with chiasmal compression (OD=96,06 ± 14,2µm, OS=92,4 ± 10,2µm) was significantly lower (p=0.016 and p=0.005) than in normal eyes (OD=104,7 ± 10µm, OS=104,5 ± 15µm respectively). It was noticed also reduced RNFL thickness in nasal quadrants. Visual evoked potentials showed mean P100 latency prolongation in examined patients (OD=112 ± 8,7ms and OS=108,4 ± 7,4ms), which was statistically significant (p<0.001 and p=0.001 respectively) in comparison to control group (103,1± 4,5ms and 102,5 ± 4,2ms respectively).Conclusion In patients with compressive chiasmal syndrome both RNFL thickness measurements with OCT and visual evoked potentials were significantly changed. These methods provide useful information in the diagnosis of chiasmal lesions.

Vincristine and carboplatin chemotherapy for unresectable and/or recurrent low‐grade astrocytoma of the brainstem

Radiotherapy remains a widely accepted postoperative treatment modality for unresectable or recurrent low-grade glioma (LGG). However, there is increasing evidence to suggest that chemotherapy can delay and may obviate the need for radiotherapy in progressive/recurrent LGG. The majority of the published experience is in children with hypothalamic/optic chiasmatic lesions and little information is available regarding its use in LGG of the brainstem. We describe clinical characteristics and course of children with LGG of the brainstem who received carboplatin-based chemotherapy in two institutions over 10 years (1996-2006). This was a retrospective review of consecutively treated children with LGG of the brainstem (midbrain, pons, medulla, and upper cervical cord). Vincristine and carboplatin were first-line chemotherapy regimen used in all patients. In this series, there were 16 children (9 males) with median age at diagnosis of 4.2 years (range 0.5-8). Eight children were treated at diagnosis while the remaining eight received chemotherapy after either radiological progression or clinical deterioration. After a median follow-up of 57 months (range 20-136) from initiation of chemotherapy all children are alive and 11 remain progression free (1 complete response, 8 with partial response + minor response, and 2 stable diseases). The efficacy of this chemotherapy regimen in this series supports its role in children with progressive unresectable LGG of brainstem.

Rehabilitation bei Sehbahnschäden

This review considers diseases of the visual pathways at different levels, their consequences for relevant everyday functions and their rehabilitation. Infrachiasmatic lesions are mostly associated with central or ring scotomas causing reading problems. The use of an eccentric fixation locus in combination with text magnification often allows the patient to maintain reading ability. Chiasmatic lesions can cause orientation disability by bitemporal hemianopia and reading problems by slide phenomena along the vertical midline. Suprachiasmatic lesions lead to homonymous visual field defects. Regarding the hemianopic orientation disorder, there are two different training approaches, which have been discussed controversially: restitution of the visual field by visual stimulation versus compensation by explorative eye movements towards the hemianopic side. Previously described positive effects of exploration training were not entirely convincing due to the lack of control groups. A new randomised and controlled study has proved the effectiveness of exploration training and showed that the patients apply the improved exploration strategy to everyday life. In the control group, which received a visual field stimulation training--a potential restitution training--neither exploration nor visual fields changed. The hemianopic reading disorder depends on the distance of the field defect from the centre, i. e., the size of the reading visual field, the side of the field defect in regard to the reading direction and the presence of spontaneous adaptive strategies, such as eccentric fixation or predictive saccades. Specific reading training can be helpful. Cerebral visual impairments with visual field defects are often associated with disorders of information processing in higher cortical areas. These complex disorders usually require an interdisciplinary rehabilitation. Specific examination methods to assess functions of everyday relevance and their use as a basis for rehabilitation measures are discussed. Visual rehabilitation can be very successful in many cases and improves the patients' quality of life. One should expect that the demand for neuro-ophthalmological rehabilitation will increase, because the survival rate after severe cerebral lesions and the general lifespan are rising.

Temporal visual field defects are associated with monocular inattention in chiasmal pathology

Chiasmal lesions have been shown to give rise occasionally to uni-ocular temporal inattention, which cannot be compensated for by volitional eye movement. This article describes the assessments of 46 such patients with chiasmal pathology. It aims to determine the clinical spectrum of this disorder, including interference with reading. Retrospective consecutive observational clinical case study over a 7-year period comprising 46 patients with chiasmal field loss of varying degrees. Observation of reading behaviour during monocular visual acuity testing ascertained from consecutive patients who appeared unable to read optotypes on the temporal side of the chart. Visual fields were evaluated by kinetic (Goldmann) and static (Octopus) techniques. Five patients who clearly manifested this condition are presented in more detail. The results of visual field testing were related to absence or presence of uni-ocular visual inattentive behaviour for distance visual acuity testing and/or reading printed text. Despite normal eye movements, the 46 patients making up the clinical series perceived only optotypes in the nasal part of the chart, in one eye or in both, when tested for each eye in turn. The temporal optotypes were ignored, and this behaviour persisted despite instruction to search for any additional letters temporal to those, which had been seen. This phenomenon of unilateral visual inattention held for both eyes in 18 and was unilateral in the remaining 28 patients. Partial or full reversibility after treatment was recorded in 21 of the 39 for whom reliable follow-up data were available. Reading a text was affected in 24 individuals, and permanently so in six. A neglect-like spatial unawareness and a lack of cognitive compensation for varying degrees of temporal visual field loss were present in all the patients observed. Not only is visual field loss a feature of chiasmal pathology, but the higher visual function of affording attention within the temporal visual field by means of using conscious thought to invoke appropriate compensatory eye movement was also absent. This suggests the possibility of 'trans-synaptic dysfunction' caused by loss of visual input to higher visual centres. When inattention to the temporal side is manifest on monocular visual testing it should raise the suspicion of chiasmal pathology.

Treating CNS sarcoidosis with infliximab and mycophenolate mofetil

Introduction: Neurosarcoidosis is a complication of systemic sarcoidosis that is frequently diffi cult to manage. Manifestations of central nervous system (CNS) sarcoidosis are quite variable. They include infi ltration of the optic nerve, perivascular retinopathy, leptomeningitis and pachymeningitis, chiasmal and hypothalamic lesions, cortical en plaque meningioma-like lesions, and spinal cord and cauda equina nodules and infi ltration. The rarity of this condition (5%– 10% of all sarcoidosis) makes any systematic randomized masked trial of treatment alternatives problematic. Most patients with neurosarcoidosis are treated with systemic corticosteroids with fair success. Problems arise when the neurosarcoidosis fails to yield to corticosteroids or fl ares as the corticosteroids are tapered, leading to the use of a long list of variably effective immunosuppressant alternative or adjunctive treatments [1]. None of these anecdotally recommended drugs have been subjected to a randomized prospective study. The paper by Moravan and Segal is typical of reports published since 2002 on the use of infl iximab as a next step in the treatment of corticosteroidand immunosuppressant drug–resistant CNS sarcoidosis.

The Influence of “Blind” Distractors on Eye Movement Trajectories in Visual Hemifield Defects

There is evidence that some visual information in blind regions may still be processed in patients with hemifield defects after cerebral lesions ("blindsight"). We tested the hypothesis that, in the absence of retinogeniculostriate processing, residual retinotectal processing may still be detected as modifications of saccades to seen targets by irrelevant distractors in the blind hemifield. Six patients were presented with distractors in the blind and intact portions of their visual field and participants were instructed to make eye movements to targets in the intact field. Eye movements were recorded to determine if blind-field distractors caused deviation in saccadic trajectories. No deviation was found in one patient with an optic chiasm lesion, which affect both retinotectal and retinogeniculostriate pathways. In five patients with lesions of the optic radiations or the striate cortex, the results were mixed, with two of the five patients showing significant deviations of saccadic trajectory away from the "blind" distractor. In a second experiment, two of the five patients were tested with the target and the distractor more closely aligned. Both patients showed a "global effect," in that saccades deviated toward the distractor, but the effect was stronger in the patient who also showed significant trajectory deviation in the first experiment. Although our study confirms that distractor effects on saccadic trajectory can occur in patients with damage to the retinogeniculostriate visual pathway but preserved retinotectal projections, there remain questions regarding what additional factors are required for these effects to manifest themselves in a given patient.

Tilted disc syndrome may mimic false visual field deterioration

Tilted disc syndrome is a congenital anomaly of the eye characterized by mostly upper temporal visual field defects. The aim of the present study was to evaluate the effect of gradual myopic correction in the improvement of visual field defects associated with tilted disc syndrome. The visual field was examined in 38 eyes of 24 patients using standard Goldmann perimetry. The isoptres IV-4e, I-4e, I-3e and I-2e were plotted. The defective isoptres were tested again with gradually increasing myopic correction until no further change was noted. The most common type of defect was a relative upper temporal defect (19 eyes). Temporal relative defects were found in five eyes, upper altitudinal field defects in six eyes, an enlarged blind spot in four eyes, and an inferior field defect in one eye. The visual field defect partly or totally disappeared with increased myopic correction in 18 (50%) eyes. The mean improvement was 17.0 +/- 6.2 degrees and the mean additional myopic correction was 3.1 +/- 1.5 D. Even a small change in near correction during visual field examination may imply worsened or improved visual field defects in tilted disc syndrome. To prevent a false interpretation of field deterioration in a patient with tilted disc syndrome and glaucoma, visual field assessment should include examination with the myopic correction that provides the maximal improvement of the defective visual field.

Reversible dysfunction of retinal ganglion cells in non-secreting pituitary tumors

A large cohort of patients participated in a longitudinal study of early glaucoma progression. During follow up, six eyes of three patients displayed a relatively rapid deterioration of pattern electroretinogram (PERG) signal compared to changes in visual acuity, IOP, Standard Automated Perimetry, and Retinal Nerve Fiber Layer thickness measured by OCT. This deterioration prompted further testing including magnetic resonance imaging (MRI), which revealed pituitary tumors in all three patients, two of which were abutting but not compressing the chiasm. Following tumor resection, the PERG signal gradually recovered to baseline values in all six eyes. Results indicate that pituitary tumors may cause retrograde dysfunction of retinal ganglion cells (RGC) even in the absence of visible mechanical compression of the visual pathway, and such dysfunction may be reversed by tumor reduction. The results suggest that PERG is a useful tool in the early diagnosis and management of patients with chiasmal mass lesions.

Autoenucleation in a 84-year-old dementia patient

Autoenucleation is a severe, rare form of self-mutilation. The majority of cases have been reported in the 15- to 60-year age group, usually in psychiatric patients with a history of depression or schizophrenia, sometimes caused by drug abuse. We report a case of left-sided autoenucleation in an 84-year-old dementia patient suffering from reactive depression. Medical reports mentioned a suicide attempt 2 weeks prior to the incident, whereupon the patient was admitted to the locked ward of a psychiatric hospital. During one night of inpatient stay, the patient manually autoenucleated his left eye. Inspection of the enucleated organ revealed a completely intact globe with an attached optic nerve 5.5 cm in length. The orbit was filled with a massive haematoma. A contrast-enhanced computed tomography (CT) scan showed an orbital haematoma, absence of the left globe and optic nerve and a chiasmatic lesion, accompanied by an intracranial bleeding into the subarachnoid space. Primary wound closure was performed without complications. Visual acuity of the right eye could not be tested due to the patient's lack of cooperation. To the best of our knowledge, this is the only reported case of an elderly patient with primary dementia who performed autoenucleation. Other aspects, such as patient history, suicide attempt, manual eye extraction and chiasma lesion are similar to cases reported earlier. The identification and evaluation of intracranial bleedings and chiasmatic lesions that can be associated with autoenucleation requires a contrast-enhanced CT, especially if a long optic nerve fragment is attached to the enucleated globe.

In Vivo Retinal Nerve Fiber Layer Thickness Measured by Optical Coherence Tomography Predicts Visual Recovery after Surgery for Parachiasmal Tumors

Restoration of visual function after neurosurgery for parachiasmal tumors is variable and unpredictable. The current study was conducted to determine whether in vivo retinal nerve fiber layer (RNFL) thickness measurements predict the visual recovery of such patients. Forty patients undergoing surgical resection of parachiasmal lesions were prospectively assessed before surgery with a neuro-ophthalmic examination, involving standard automated visual field (VF) testing and optical coherence tomography (OCT) measurements of RNFL thickness, which was the prespecified marker for axonal loss. Tests were repeated within 6 weeks after surgery. Thinner preoperative RNFL thickness was associated with worse visual acuity (VA) and VF mean deviation (MD). Patients with normal preoperative RNFL had significant improvement in mean VA after surgery, from 20/40 to 20/25 (P = 0.028), whereas patients with thin RNFL did not improve (20/80 to 20/60, P = 0.177). Eyes with normal RNFL showed improvement in MD (-7.0 dB before surgery, -3.5 dB after surgery, P = 0.0007) unlike eyes with thin RNFLs, which had no significant improvement after surgery (-15.3 dB before and -13.3 dB after surgery, P = 0.191). RNFL thickness increased by 1% after surgery among all eyes (P = 0.04). Eyes with severe VF defects (MD </= -10 dB) but normal preoperative RNFL thickness showed a postoperative improvement in MD of 14.6 dB compared with 1.6 dB (P < 0.0001) in eyes with thin RNFL before surgery, despite no difference in MD before surgery (normal RNFL MD, -22.3 dB; thin RNFL MD, -20.8 dB; P = 0.7). Patients who have objectively measurable RNFL loss at the time of surgery for chiasmal compressive lesions are less likely to have return of VA or VF after surgery.

Syndromic and sporadic pediatric optic pathway gliomas: review of clinical and histopathological differences and treatment implications

Optic pathway gliomas (OPGs) are the most common primary neoplasm of the optic pathway. These lesions usually present in childhood and can arise anywhere along the optic pathway; they occur more frequently in women; and they rarely undergo late progression. Management strategies after the initial diagnosis are controversial, compounded by the different behaviors exhibited by sporadic and syndromic tumors. Neurofibromatosis Type 1 (NF1), with aberrant oncogenic signaling and consequent predisposition to intracranial tumors, is the most common associated syndrome, with nearly 20% of NF1 patients developing OPGs. A comorbid NF1 diagnosis has implications for tumor location with greater predilection for optic nerve involvement, whereas chiasmal and postchiasmal lesions are more frequently seen in sporadic cases. Syndromic OPGs often exhibit more indolent behavior and lower rates of clinical progression, and the majority of these are diagnosed by routine neuroophthalmological screening. When treatment is indicated, however, the molecular abnormalities that constitute this syndrome can limit the available chemotherapy and radiotherapy options because clinicians fear secondary malignancy and cerebrovascular complications. Furthermore, radiotherapy early in life can impair an individual's intellectual development, endocrine function, and physical growth, thereby limiting the role of this modality in the treatment of this childhood lesion. Differential gene expression and histogenesis among sporadic and syndromic OPGs may account for the different tumor behaviors, but studies correlating specific genetic and proteomic changes with patient outcome are pending. Loss of heterozygosity at 10 and 17q are more common among patients with NF1, and Ki67 labeling intensity of 2-3% and low p53 labeling intensity seem prognostic of aggressive tumor behavior. Recent advances in the development of a preclinical mouse model of NF1-associated OPG will permit investigation into improved detection strategies and chemotherapeutic and radiotherapy treatment protocols.

Syndromic and sporadic pediatric optic pathway gliomas: review of clinical and histopathological differences and treatment implications

✓Optic pathway gliomas (OPGs) are the most common primary neoplasm of the optic pathway. These lesions usually present in childhood and can arise anywhere along the optic pathway; they occur more frequently in women; and they rarely undergo late progression. Management strategies after the initial diagnosis are controversial, compounded by the different behaviors exhibited by sporadic and syndromic tumors. Neurofibromatosis Type 1 (NF1), with aberrant oncogenic signaling and consequent predisposition to intracranial tumors, is the most common associated syndrome, with nearly 20% of NF1 patients developing OPGs. A comorbid NF1 diagnosis has implications for tumor location with greater predilection for optic nerve involvement, whereas chiasmal and postchiasmal lesions are more frequently seen in sporadic cases. Syndromic OPGs often exhibit more indolent behavior and lower rates of clinical progression, and the majority of these are diagnosed by routine neuroophthalmological screening. When treatment is indicated, however, the molecular abnormalities that constitute this syndrome can limit the available chemotherapy and radiotherapy options because clinicians fear secondary malignancy and cerebrovascular complications. Furthermore, radiotherapy early in life can impair an individual's intellectual development, endocrine function, and physical growth, thereby limiting the role of this modality in the treatment of this childhood lesion. Differential gene expression and histogenesis among sporadic and syndromic OPGs may account for the different tumor behaviors, but studies correlating specific genetic and proteomic changes with patient outcome are pending. Loss of heterozygosity at 10 and 17q are more common among patients with NF1, and Ki67 labeling intensity of 2–3% and low p53 labeling intensity seem prognostic of aggressive tumor behavior. Recent advances in the development of a preclinical mouse model of NF1-associated OPG will permit investigation into improved detection strategies and chemotherapeutic and radiotherapy treatment protocols.

Tilted disc syndrome and colour vision

To study colour vision in patients with tilted disc syndrome. Colour vision was examined using Boström-Kugelberg (B-K) plates, Farnsworth-Munsell 100-hue test (FM-100) and Farnsworth panel D-15 and Lanthony desaturated panel tests. A total of 35 eyes of 21 patients were examined. Seventeen eyes (49%) of 11 patients were found to have a colour vision defect in at least one eye. The severity of the colour vision defect differed between eyes for six of eight patients with bilateral tilted discs. In two of these patients, colour vision was normal in one eye. Seven patients had a unilateral tilted disc and three of these individuals had a colour vision defect in the affected eye. Of all eyes with a colour vision defect, a red-green defect was found in four eyes (24%), a blue defect in one eye (6%), and a mixed defect in 12 eyes (70%). Colour vision defects were not related to visual acuity or to severity of visual field defects. This is the first report of colour vision defects in tilted disc syndrome. In the differential diagnosis of tilted disc syndrome, chiasmal lesions and glaucoma, the examination of colour vision may add valuable information. Further, it is recommended that young people with tilted disc syndrome undergo an examination of colour vision so that they can be given appropriate career guidance.

Interpretation of visual field defects respecting the vertical meridian and not related to distinct chiasmal or postchiasmal lesions

Hemianopia respecting the vertical meridian generally results from a disturbance in the optic chiasm or the postchiasmal visual pathway. We present five unusual patients with visual field defects respecting the vertical meridian that were not related to distinct chiasmal or postchiasmal lesions, as determined by magnetic resonance imaging (MRI). Optic neuritis, plus the influence of the testing algorithm for perimetry, was a possible cause in two cases. The symptoms of one patient with homonymous hemianopia were a functional deficit. In the two other cases, the visual field defects may have been caused by optic disc abnormalities. Although visual field defects respecting the vertical meridian, and without any evidence of distinct disease, are uncommon, neurologists and neuro-ophthalmologists should consider the differential diagnosis if MRI is negative for distinct lesions in the optic chiasm or the postchiasmal visual pathway.