Permanent Visual Field Defect Research Articles

Ocular ischemic complications from retinal migraine

Retinal migraine is defined by ICHD 3rd edition as fully reversible monocular visual phenomena, accompanied, or followed within 60 min by headache. We report two patients with persistent visual phenomena that complicated with either severe disabling visual loss or permanent visual field defect. We emphasize the importance of retinal migraine acute and preventive management.

SURG-39. 5-AMINOLEVULINIC ACID FLUORESCENCE (5-ALA) GUIDED RESECTION OF GLIOBLASTOMA, LESSON LEARNED FROM 26 CASES

Abstract INTRODUCTION 5-ALA is known as useful tool for high grade glioma resection and the accumulation extent of 5-ALA is known as far beyond gadolinium enhancement. Extent of resection is key factor for favorable outcome and long-term survival for high grade glioma patients and 5-ALA might increase extent of resection. We present our experience of 5-ALA guided glioma surgeries. MATERIALS AND METHODS Total 26 patients were performed 5-ALA guided surgery. They ingested 20mg/kg, four hours before craniotomy. We tried to perform supra-total resection rather than gross total resection according to the tumor consistency and if the tumor located relatively non-eloquent area, we tried to perform lobectomy rather than lesionectomy. After tumor resection, we inspect the tumor bed under 5-ALA fluorescence, and we confirmed the complete loss of fluorescence on the tumor resected bed. We check the MRI within 48 hour after operation and assess the extent of resection. RESULTS Among the 26 patients, 22 patients were confirmed glioblastoma and 3 anaplastic astrocytoma and 1 anaplastic oligoastrocytoma. We confirmed all enhancing lesion was completely removed, however, 4 patients show residual non-enhancing lesion in post-operative MRI. Two patients suffered temporary hemiparesis and 2 patients show permanent visual field defect. CONCLUSION 5-ALA is useful tool for glioma surgery. Resection extent could be increased, however, non-enhancing lesion in the high grade gliomas, might be missed under 5-ALA guidance.

SURG-18. 5-AMINOLEVULINIC ACID FLUORESCENCE (5-ALA) GUIDED RESECTION OF GLIOBLASTOMA, LESSON LEARNED FROM 19 CASES

Abstract BACKGROUND 5-ALA is known as useful tool for high grade glioma resection and the accumulation extent of 5-ALA is known as far beyond gadolinium enhancement. Extent of resection is key factor for favorable outcome and long-term survival for high grade glioma patients and 5-ALA might increase extent of resection. We present our experience of 5-ALA guided glioma surgeries METHODS Total 19 patients were performed 5-ALA guided surgery. They ingested 20mg/kg, four hours before craniotomy. We tried to perform supra-total resection rather than gross total resection according to the tumor consistency and if the tumor located relatively non-eloquent area, we tried to perform lobectomy rather than lesionectomy. After tumor resection, we inspect the tumor bed under 5-ALA fluorescence, and we confirmed the complete loss of fluorescence on the tumor resected bed. We check the MRI within 48 hour after operation and assess the extent of resection RESULTS Among the 19 patients, 15 patients were confirmed glioblastoma and 3 anaplastic astrocytoma and 1 anaplastic oligoastrocytoma. We confirmed all enhancing lesion was completely removed, however, 2 patients show residual non-enhancing lesion in post-operative MRI. Two patients suffered temporary hemiparesis and 2 patients show permanent visual field defect. CONCLUSION 5-ALA is useful tool for glioma surgery. Resection extent could be increased, however, non-enhancing lesion in the high grade gliomas, might be missed under 5-ALA guidance.

Outcome of partially irradiated recurrent nonfunctioning pituitary macroadenoma by gamma knife radiosurgery.

Gamma knife treatment outcome of large pituitary tumors which are only partially irradiated secondary to immediate proximity to critical structures such as the optic apparatus have not been rigorously studied. From July 2003 to December 2013, there were 41 cases of recurrent or residual nonfunctioning pituitary macroadenoma partially treated with gamma knife radiosurgery (GKRS) because the adenoma obscured part of the optic apparatus on planning SRS MR imaging. The follow up period after GKRS was 92.3 ± 5.6months. The percentage of tumor coverage with the full dose was 88.5 ± 0.7%. Five of 43 (11.6%) patients experienced a transient visional decrease and one patient experienced a permanent visual field defect. During the follow up, two patients underwent transphenoidal surgery and one patient had a craniotomy due to tumor progression. Seven patients (16.2%) developed cortisol and thyroxine deficiencies. In multiple variant analyses, transient visual decline was correlated to the tumor volume (> 3.5cc), percentage of tumor coverage (< 90%), the distance from the optic apparatus to the pituitary stalk (> 15mm) and percentage of tumor above the orbital apex (65%). In the limited case of this cohort, we found that partially treated pituitary nonfunctioning macroadenoma yielded a high tumor control rate. However, visual decline as a result of tumor progression or radiation effect can occur in a minority of patients. The radiosurgical technique warrants further study to better define the long-term risk to benefit profile for its use in complex pituitary macroadenoma obscuring part of the optic apparatus.

Branch retinal artery occlusion combined with branch retinal vein occlusion in a patient with hepatitis C treated with interferon and ribavirin.

To report a case of a combined branch retinal artery and vein occlusion in a patient with hepatitis C treated with interferon and ribavirin. A 29-year-old man with a 1-week history of sudden visual field defect and decrease of central visual acuity was examined. Ophthalmoscopy and fluorescein angiography demonstrated an ischemic whitening of the inferior hemi-retina involving part of the macular region, numerous intraretinal hemorrhages, and a significant delay in arterial and vein filling of the dye. The findings of a retinopathy associated with interferon and ribavirin treatment of hepatitis C are important. The symptomatic permanent visual field defect and decrease of central visual acuity developing following a branch retinal artery and vein occlusion event emphasizes the need for careful and regular ocular monitoring of patients receiving interferon for hepatitis C.

RP-HPLC method for simultaneous estimation of vigabatrin, gamma-aminobutyric acid and taurine in biological samples

Vigabatrin is used as first line drug in treatment of infantile spasms for its potential benefit overweighing risk of causing permanent peripheral visual field defects and retinal damage. Chronic administration of vigabatrin in rats has demonstrated these ocular events are result of GABA accumulation and depletion of taurine levels in retinal tissues. In vigabatrin clinical studies taurine plasma level is considered as biomarker for studying structure and function of retina. The analytical method is essential to monitor taurine levels along with vigabatrin and GABA. A RP-HPLC method has been developed and validated for simultaneous estimation of vigabatrin, GABA and taurine using surrogate matrix. Analytes were extracted from human plasma, rat plasma, retina and brain by simple protein precipitation method and derivatized by naphthalene 2, 3‑dicarboxaldehyde to produce stable fluorescent active isoindole derivatives. The chromatographic analysis was performed on Zorbax Eclipse AAA column using gradient elution profile and eluent was monitored using fluorescence detector. A linear plot of calibration curve was observed in concentration range of 64.6 to 6458, 51.5 to 5150 and 62.5 to 6258 ng/mL for vigabatrin, GABA and taurine, respectively with r2 ≥ 0.997 for all analytes. The method was successfully applied for estimating levels of vigabatrin and its modulator effect on GABA and taurine levels in rat plasma, brain and retinal tissue. This RP-HPLC method can be applied in clinical and preclinical studies to explore the effect of taurine deficiency and to investigate novel approaches for alleviating vigabatrin induced ocular toxicity.

Multifocal Visual Evoked Potential in Eyes With Temporal Hemianopia From Chiasmal Compression: Correlation With Standard Automated Perimetry and OCT Findings.

To verify whether multifocal visual evoked potential (mfVEP) can differentiate eyes with temporal hemianopia due to chiasmal compression from healthy controls. To assess the relationship between mfVEP, standard automated perimetry (SAP), and Fourier domain-optical coherence tomography (FD-OCT) macular and peripapillary retinal nerve fiber layer (RNFL) thickness measurements. Twenty-seven eyes with permanent temporal visual field (VF) defects from chiasmal compression on SAP and 43 eyes of healthy controls were submitted to mfVEP and FD-OCT scanning. Multifocal visual evoked potential was elicited using a stimulus pattern of 60 sectors and the responses were averaged for the four quadrants and two hemifields. Optical coherence tomography macular measurements were averaged in quadrants and halves, while peripapillary RNFL thickness was averaged in four sectors around the disc. Visual field loss was estimated in four quadrants and each half of the 24-2 strategy test points. Multifocal visual evoked potential measurements in the two groups were compared using generalized estimated equations, and the correlations between mfVEP, VF, and OCT findings were quantified. Multifocal visual evoked potential-measured temporal P1 and N2 amplitudes were significantly smaller in patients than in controls. No significant difference in amplitude was observed for nasal parameters. A significant correlation was found between mfVEP amplitudes and temporal VF loss, and between mfVEP amplitudes and the corresponding OCT-measured macular and RNFL thickness parameters. Multifocal visual evoked potential amplitude parameters were able to differentiate eyes with temporal hemianopia from controls and were significantly correlated with VF and OCT findings, suggesting mfVEP is a useful tool for the detection of visual abnormalities in patients with chiasmal compression.

Prehospital pathways of occipital stroke patients with mainly visual symptoms.

Occipital ischemic strokes typically cause homonymous visual field defects, for which means of rehabilitation are limited. Intravenous thrombolysis is increasingly and successfully used for their acute treatment. However, recognition of strokes presenting with mainly visual field defects is challenging for both patients and healthcare professionals. We studied prehospital pathways of occipital stroke patients with mainly visual symptoms to define obstacles in their early recognition. This observational, retrospective, registry-based study comprises occipital stroke patients with isolated visual symptoms treated at the neurological emergency department of Helsinki University Central Hospital in 2010-2015. We analyzed their prehospital pathways, including time from symptom onset to admission at the neurological emergency department (ODT), the number of points of care, the percentage of patients with ODT≤4.5hours, and factors associated with delay. Among 245 patients, only 20.8% arrived within 4.5hours and 6.5% received IV thrombolysis. Delayed arrival was most often due to patients' late contact to health care. Of the patients, 27.3% arrived through at least two points of care, and differential diagnostics to ophthalmologic disorders proved particularly challenging. ODT≤4.5hours was associated with EMS utilization, direct arrival, and atrial fibrillation; a visit at an ophthalmologist and initial misdiagnosis were associated with ODT>4.5hours. After multivariable analysis, only direct arrival predicted ODT≤4.5hours. Occipital stroke patients with visual symptoms contact health care late, are inadequately recognized, and present with complex prehospital pathways. Consequently, they are often ineligible for IV thrombolysis. This presents a missed opportunity for preventing permanent visual field defects.

Intraoperative Subcortical Electrical Mapping of the Optic Tract in Awake Surgery Using a Virtual Reality Headset

Brain mapping during awake craniotomy is a well-known technique to preserve neurological functions, especially the language. It is still challenging to map the optic radiations due to the difficulty to test the visual field intraoperatively. To assess the visual field during awake craniotomy, we developed the Functions' Explorer based on a virtual reality headset (FEX-VRH). The impaired visual field of 10 patients was tested with automated perimetry (the gold standard examination) and the FEX-VRH. The proof-of-concept test was done during the surgery performed on a patient who was blind in his right eye and presenting with a left parietotemporal glioblastoma. The FEX-VRH was used intraoperatively, simultaneously with direct subcortical electrostimulation, allowing identification and preservation of the optic radiations. The FEX-VRH detected 9 of the 10 visual field defects found by automated perimetry. The patient who underwent an awake craniotomy with intraoperative mapping of the optic tract using the FEX-VRH had no permanent postoperative visual field defect. Intraoperative visual field assessment with the FEX-VRH during direct subcortical electrostimulation is a promising approach to mapping the optical radiations and preventing a permanent visual field defect during awake surgery for epilepsy or tumor.

Reversible homonymous hemianopia secondary to occipital lobe seizures

Occipital lobe infarcts, hemorrhages, or metastatic tumors can present with complex visual hallucinations, sensory or proprioceptive abnormalities, speech dysfunction, visual loss, and homonymous hemianopia (HH). Treatment of occipital lobe seizures is by single or multiple antiepileptic drugs. We present a case of idiopathic occipital lobe epilepsy where the seizures were controlled by antiepileptic drugs, but the HH did not subside until treated with high dose intravenous (IV) steroids.

Improved resection in lesional temporal lobe epilepsy surgery using neuronavigation and intraoperative MR imaging: Favourable long term surgical and seizure outcome in 88 consecutive cases

PurposeTo investigate the value of intraoperative MR imaging (iopMRI) combined with neuronavigation to avoid intraoperative underestimation of the resection amount during surgery of lesional temporal lobe epilepsy (LTLE) patients. MethodsWe retrospectively investigated 88 patients (40 female, 48 male, mean age 37.2yrs, from 12 to 69yrs, 41 left sided lesions) with LTLE operated at our department, including 40.9% gangliogliomas (GG), 26.1% cavernomas (CM), 10.2% dysembryoplastic neuroepithelial tumours (DNT) and 11.4% focal cortical dysplasias (FCD), excluding hippocampal sclerosis. ResultsComplete resection was achieved in 85 of 88 patients (96.6%), as proven by postoperative MRI 6 months after surgery. In contrast, the routine first iopMR imaging before closure revealed radical resection in only 66 of these 88 patients (75%). After re-intervention, the second iopMR imaging demonstrated complete resection in 19 more patients. Thus, as a direct effect of iopMRI and neuronavigation, overall resection rate was increased by 21.6%. An excellent seizure outcome Engel Class I was found in 76.1% of patients during a mean follow-up of 26.4 months, irrespective of histological entity (74% in CM, 75% in GG, 78% in DNT and 60% in FCD). No severe postoperative complications occurred; permanent superior visual field defects were detected in 10.2% and permanent dysphasia/dyscalculia in 1.1%. ConclusionRefined surgery using neuronavigation combined with iopMR imaging in LTLE surgery led to radical resection in 96.6% of the patients, due to immediate correction of underestimated resection in 21.6% of patients. This protocol resulted in a favourable seizure outcome and a low complication rate.

Type III Sturge‐Weber Syndrome With Migraine‐Like Attacks Associated With Prolonged Visual Aura

Sturge-Weber syndrome is known to be associated with migraine attacks and prolong aura even without cerebral infarction. We report the case of a 36-year-old woman with type III Sturge-Weber syndrome developing with prolonged left homonymous hemianopsia after an intractable migraine-like headache and becoming a permanent visual field defect at 18-month follow up. By adopting a multimodality imaging study, we suggested that the underlying mechanism of prolonged visual field defect was due to blood flow disturbance and vasogenic leakage under the leptomeningeal angioma combining with atrophy and the damaged integrity of white matter in right occipital lobe.

Arginine vasopressin immunoreactivity is decreased in the hypothalamic suprachiasmatic nucleus of subjects with suprasellar tumors.

Suprasellar tumors with compression of the optic chiasm are associated with an impaired sleep-wake rhythm. We hypothesized that this reflects a disorder of the biological clock of the human brain, the suprachiasmatic nucleus (SCN), which is located just above the optic chiasm. In order to test this hypothesis, we investigated the expression of two key neuropeptides of the SCN, that is, arginine vasopressin (AVP) and vasoactive intestinal peptide (VIP), as assessed by quantitative immunocytochemistry in post-mortem hypothalamic tissue of patients with a suprasellar tumor inducing permanent visual field defects. Post-mortem hypothalamic tissue of 5 patients with a suprasellar tumor inducing permanent visual field defects (acromegaly n = 2, nonfunctioning macro-adenoma n = 1, macroprolactinoma n = 1, infundibular metastasis of a colorectal adenocarcinoma n = 1) and 15 age- and gender-matched controls was obtained from the Netherlands Brain Bank. Total AVP immunoreactivity in the SCN was lower in patients with a suprasellar tumor than in controls (P = 0.03). By contrast, total VIP immunoreactivity was not different between patients and controls (P = 0.44). Suprasellar tumors leading to permanent visual field defects are associated with reduced AVP, but not VIP immunoreactivity, in the SCN. These findings raise the possibility that selective impairment of the SCN contributes to sleep-wake disturbances in these patients.

Clinical features and pathophysiological mechanism of the hemianoptic complication after the occipital transtentorial approach

ObjectiveTo obtain detailed insight into neuro-ophthalmological characteristics and pathophysiology of hemianoptic complications after occipital transtentorial surgery. MethodsWe reviewed the cases of 14 patients surgically treated by the occipital transtentorial approach. Treated lesions included 6 posterior third ventricle tumors, including pineal and tectal lesions, 3 falco-tentorial meningiomas, and 5 superior cerebellar lesions. The surgeries were performed by the unilateral occipital transtentorial approach with patients in the prone position. ResultsVisual functions were preoperatively normal in all patients. After surgery, 11 patients (79%) showed hemianoptic complications detected by a confrontation test in the immediate postoperative period. The condition began to improve in the early postoperative days. The visual field recovered completely in 6 patients within 10 days, 2 patients recovered within 3 months, and 3 patients complained of permanent visual field defects. Optometric neuro-ophthalmic evaluation in the early postoperative period failed to detect complete homonymous hemianopsia, but homonymous inferior quadrantanopia and scotomatous defects were observed in 6 patients. These visual field defects were permanent in 3 patients. Postoperative MRI showed no morphological abnormality except these three patients. Atrophic change of the occipital lobe with preservation of striate cortex was associated with persistent visual field defects in two patients. Cerebral blood flow evaluation by single photon emission computed tomography suggested that temporary local hyperperfusion of the retracted occipital region when visual field defect was present. ConclusionHemianoptic visual field defects can recover via inferior quadrantanopia or scotomatous defect. All of these defects are attributable to injury to the optic radiation as well to the occipital lobe. Hyperperfusion of the retracted occipital region may underlie the pathophysiology of hemianoptic complications after the occipital transtentorial approach.

Correlation between multifocal pattern electroretinography and Fourier-domain OCT in eyes with temporal hemianopia from chiasmal compression

To evaluate the correlation between multifocal pattern electroretinography (mfPERG) and Fourier-domain optical coherence tomography (FD-OCT) with regard to macular and retinal nerve fiber layer (RNFL) thickness in eyes with temporal hemianopia from chiasmal compression. Twenty-five eyes from 25 patients with permanent temporal visual field defects from chiasmal compression and 25 healthy eyes were submitted to mfPERG using a stimulus pattern of 19 rectangles, standard automated perimetry and FD-OCT measurements. The mfPERG response was determined for groups of three rectangles for the nasal and temporal hemifields and for each quadrant. Macular thickness measurements were registered according to an overlaid OCT-generated checkerboard with 36 checks and averaged for the central area, and for each scanned quadrant and hemifield. RNFL thickness was determined for all twelve 30-degree segments around the disc, and averaged for the segments corresponding to the 6, 7, 8, 9, 10, 11 and 12 o'clock position. Correlations were verified with Pearson's correlation coefficients and linear regression analysis. Both mfPERG amplitudes and OCT measurements were significantly smaller in eyes with temporal visual field defects than in normals. A significant and strong correlation was found between most mfPERG and macular or RNFL thickness OCT parameters. mfPERG amplitudes and OCT measurements are significantly correlated in patients with chiasmal compression. Both technologies can quantify neuronal loss and, if used in combination, may help clarify structure-function relationships in this patient population.

Primer on visual field testing, electroretinography, and other visual assessments for patients treated with vigabatrin

Vigabatrin, an irreversible inhibitor of γ-aminobutyric acid transaminase, is an antiepileptic drug indicated in the United States as adjunctive therapy for adult patients with refractory complex partial seizures who have responded inadequately to several alternative treatments and for monotherapy treatment of infantile spasms in patients 1 month to 2 years of age. Approval of vigabatrin in the United States was contingent on the implementation of a Risk Evaluation and Mitigation Strategy (REMS) to manage the threat of a progressive, permanent bilateral concentric peripheral visual field defects (pVFDs) that may occur in patients treated with vigabatrin. The REMS is designed to promote compliance with evidence-based recommendations for baseline (within 4 weeks of the start of treatment) ophthalmologic evaluations and ongoing vision monitoring in all patients treated with vigabatrin. In view of the challenges associated with visual field testing in patients with epilepsy and in infants, clinicians must understand the qualitative (pattern of damage), quantitative (degree of damage), electrophysiologic, and adjunctive techniques recommended for monitoring vigabatrin-treated patients. The objectives of ongoing research are to characterize the onset, progression, and risk of developing vision loss during the first year of vigabatrin treatment and to evaluate the potential of noninvasive imaging as a method for monitoring retinal changes corresponding to the pVFD. This article provides an overview of visual field testing procedures and electroretinography, summarizes the clinical characteristics of vigabatrin-associated pVFDs, and provides recommendations for visual field and visual electrophysiology testing relevant to both adult and infant patients treated with vigabatrin.

Vigabatrin for Infantile Spasms

Infantile spasms describe a pediatric epilepsy syndrome characterized by frequent clusters of brief symmetric muscle contractions; the condition is often associated with developmental delay. When infantile spasms are accompanied by hypsarrhythmia on electroencephalogram, the condition is labeled West syndrome. The mainstay of treatment for infantile spasms is adrenocorticotropic hormone; however, vigabatrin, a vinyl derivative of γ-aminobutyric acid, has been used for the treatment of infantile spasms in Europe since 1989. In 2009, vigabatrin was approved by the United States Food and Drug Adminstration (FDA) for use as monotherapy in the treatment of infantile spasms in patients aged 1 month-2 years when the benefits of treatment outweigh the risks. Results from numerous trials examining the role of vigabatrin in infantile spasms have been published; many of these trials were small, open-label, or noncontrolled. Although clinical trials have provided some insight into the utility of vigabatrin for the treatment of infantile spasms, these studies have notable limitations. In addition, vigabatrin is associated with a black-box warning that describes the potential for permanent bilateral concentric visual field defects. Currently, vigabatrin is available through a manufacturer-sponsored program in accordance with its FDA-approved Risk Evaluation and Mitigation Strategy. Although several guidelines recommend vigabatrin as a first-line therapy for infantile spasms, specifically infantile spasms related to tuberous sclerosis, it is still unclear whether vigabatrin should supersede hormone therapy as first-line therapy. Further research comparing the two therapies is needed.

Pretreatment Predictors of Adverse Radiation Effects After Radiosurgery for Arteriovenous Malformation

To identify vascular and dosimetric predictors of symptomatic T2 signal change and adverse radiation effects after radiosurgery for arteriovenous malformation, in order to define and validate preexisting risk models. A total of 125 patients with arteriovenous malformations (AVM) were treated at our institution between 2005 and 2009. Eighty-five patients have at least 12 months of clinical and radiological follow-up. Any new-onset headaches, new or worsening seizures, or neurological deficit were considered adverse events. Follow-up magnetic resonance images were assessed for new onset T2 signal change and the volume calculated. Pretreatment characteristics and dosimetric variables were analyzed to identify predictors of adverse radiation effects. There were 19 children and 66 adults in the study cohort, with a mean age of 34 (range 6-74). Twenty-three (27%) patients suffered adverse radiation effects (ARE), 9 patients with permanent neurological deficit (10.6%). Of these, 5 developed fixed visual field deficits. Target volume and 12 Gy volume were the most significant predictors of adverse radiation effects on univariate analysis (p < 0.001). Location and cortical eloquence were not significantly associated with the development of adverse events (p = 0.12). No additional vascular parameters were identified as predictive of ARE. There was a significant target volume threshold of 4 cm(3), above which the rate of ARE increased dramatically. Multivariate analysis target volume and the absence of prior hemorrhage are the only significant predictors of ARE. The volume of T2 signal change correlates to ARE, but only target volume is predictive of a higher volume of T2 signal change. Target volume and the absence of prior hemorrhage is the most accurate predictor of adverse radiation effects and complications after radiosurgery for AVMs. A high percentage of permanent visual field defects in this series suggest the optic radiation is a critical radiosensitive structure.

Bilateral permanent concentric visual field defect secondary to severe pre-eclampsia

To present a patient with bilateral permanent concentric visual field defect secondary to severe pre-eclampsia. A forty-year-old woman presented to the ophthalmology department with partial visual field defect affecting her both eyes. She gave a history of emergent uterine curettage for severe uncontrolled pre-eclampsia in the 24th week of her second gestation which was 10 years before. Two days after the procedure, the patient complained of peripheral visual field defect in her both eyes which persisted until her last presentation. Her best-corrected visual acuity, color vision, intraocular pressures, and anterior segment examination findings were normal bilaterally. Fundus examination showed a normal optic nerve head with reduction of arteriole to vein ratio in both eyes. Humphrey Field Analyzer revealed a bilateral concentric visual field defect. Visual Evoked Potentials (VEP) and Electroretinography (ERG) were within normal limits in both eyes. Cranial magnetic resonance imaging (MRI) was normal. Herein, we presented a case of permanent concentric visual field defect which developed as a complication of severe uncontrolled pre-eclampsia. To the best of our knowledge; such a case has not been reported to date.

Pattern electroretinograms for the detection of neural loss in patients with permanent temporal visual field defect from chiasmal compression

To evaluate the ability of full-field and hemifield pattern electroretinogram (PERG) parameters to differentiate between healthy eyes and eyes with band atrophy (BA) of the optic nerve. Twenty-six eyes from 26 consecutive patients with permanent temporal hemianopic visual field defects and BA of the optic nerve from previous chiasmal compression and 26 healthy subjects were studied prospectively. All patients were submitted to an ophthalmic examination including Humphrey 24-2 SITA Standard automated perimetry. Full-field and hemifield (nasal and temporal) stimulation transient pattern electroretinograms (PERG) were recorded using checkerboard screens. Amplitudes and peak times for the P50 and N95 as well as the overall P50+N95 amplitude were measured. The intraocular N95:P50 amplitude ratio was calculated. Comparisons were made using Student's t-test. Receiver operating characteristic (ROC) curves were used to describe the ability of PERG parameters to discriminate the groups. Full-field P50, N95, and P50+N95 amplitude values were significantly smaller in eyes with BA than in control eyes (P < 0.001). Nasal and temporal hemifield PERG studies revealed significant differences in N95 and P50+N95 amplitudes measurements. No significant difference was observed regarding peak times or N95:P50 amplitude ratios. Nasal and temporal hemifield PERG values did not differ significantly in eyes with BA or in controls. Using the 10th percentile of normals as the lower limit of normal, 16 of 26 eyes were considered abnormal according to the best discriminating parameters. Transient PERG amplitude measurements were efficient at differentiating eyes with BA and permanent visual field defects from normal controls. Hemifield stimulation PERG parameters were unable to detect asymmetric hemifield neural loss, but further studies are required to clarify this issue.