Retinal nerve fibre layer attenuation: clinical indicator for vigabatrin toxicity

Purpose: To investigate whether persistent visual field defects among patients exposed once to the antiepileptic drug vigabatrin (VGB) were associated with peripapillary retinal nerve fibre layer thickness (RNFLT) attenuation. Methods: Nine individuals with partial epilepsy and VGB‐attributed visual field loss (group 1; 18 eyes) and seven age‐ and gender‐matched individuals with epilepsy and no previous VGB exposure (group 2; 14 eyes) were included in the study. Full‐field 120 point screening perimetry out to 60 degrees from central fixation using the Humphrey Field Analyzer was performed. RNFLT was quantified by optical coherence tomography (OCT) using Fast RNFLT protocol, Stratus OCT (3.0) after pupillary dilation. The results from the right eye are presented in this article. Results: Among the patients with VGB‐attributed visual field loss, five patients had only peripheral field defect (group 1a) and the remaining four had advanced field defects both in the periphery and within 30° from central fixation (group 1b). None of the patients in the control group had manifest visual field loss. The mean RNFLT among the patients with VGB‐attributed visual field loss was significantly attenuated compared to the controls [mean total RNFLT: group 1: 75.6 ± 12.7 μm, group 2: 103.5 ± 9.7 μm, mean difference 27.9 μm, (CI 15.9–39.9; p < 0.001)]. RNFLT values classified as borderline according to normative database (Stratus OCT) occurred more frequently among individuals with VGB‐attributed visual field loss than in controls (frequency in group 1: 6/9; group 2: 0/7, p = 0.011). The nasal, superior and inferior quadrants of RNFLT in individuals with VGB‐attributed visual field loss were significantly attenuated, while no difference was detected in temporal quadrants compared to controls. Both individuals with peripheral and those with advanced visual field losses in the VGB group had attenuated mean total RNFLT compared to controls (p = 0.006, p = 0.002, respectively). Occurrence of borderline classification of total RNFLT ≤5th percentile was more frequent among individuals with advanced visual field loss than among controls (p = 0.048). Conclusion: Persistent visual field loss attributed to VGB is associated with reduced peripapillary RNFLT and was detected both among patients with advanced and among patients with only peripheral visual field defects. Measurements of RNFLT with OCT might be considered as a diagnostic supplement in the follow‐up of patients exposed to vigabatrin.     

Contrast and glare sensitivity in epilepsy patients treated with vigabatrin or carbamazepine monotherapy compared with healthy volunteers

BACKGROUND/AIM: Many antiepileptic drugs have influence on visual functions. The aim of this study was to investigate possible changes in contrast sensitivity, macular photostress, and brightness acuity (glare) tests in patients with epilepsy undergoing vigabatrin (VGB) or carbamazepine (CBZ) monotherapy compared with healthy volunteers. METHODS: 32 patients undergoing VGB therapy, 18 patients undergoing CBZ therapy, and 35 healthy volunteers were asked to participate in an ophthalmological examination. In the previous study, visual field constrictions were reported in 40% of the patients treated with VGB monotherapy. In the present study, these VGB and CBZ monotherapy patients were examined for photopic contrast sensitivity with the Pelli-Robson letter chart and brightness acuity and macular photostress with the Mentor BAT brightness acuity tester. RESULTS: Contrast sensitivity with the Pelli-Robson letter chart showed no difference between these groups and normal subjects (ANOVA: p= 0.534 in the right eye, p= 0.692 in the left eye) but the VGB therapy patients showed a positive correlation between the contrast sensitivity values and the extents of the visual fields in linear regression (R = 0.498, p = 0.05 in the right eye, R = 0.476, p = 0. 06 in the left eye). Macular photostress and glare tests were equal in both groups and did not differ from normal values. CONCLUSION: The results of this study indicate that carbamazepine therapy has no effect on contrast sensitivity. Vigabatrin seems to impair contrast sensitivity in those patients who have concentrically constricted in their visual fields. Neither GBZ nor VGB affect glare sensitivity.     

Contrast sensitivity is reduced in children with infantile spasms

PURPOSE: To investigate whether visual deficits in children with infantile spasm (IS) are the result of seizure activity or of treatment with the anticonvulsant drug vigabatrin (VGB). METHODS: Vision function was determined in three experiments by determining peak contrast sensitivity (CS) and grating acuity (GA) with the sweep visual evoked potential. Cross-sectional study A: 34 children, including 11 patients with childhood epilepsy with exposure to VGB for at least 6 months, 10 with childhood epilepsy exposed to antiepileptic drugs other than VGB, and 13 normally developing children. Cross-sectional study B: 32 children, including 16 with IS na?ve to VGB and 16 normally developing children. Longitudinal study: seven children with IS na?ve to VGB, with subsequent follow-up 5 to 10 months after starting VGB. RESULTS: In cross-sectional study A, the median CS was reduced by 0.5 log units (P = 0.025) in children with epilepsy exposed to VGB compared with those exposed to other antiepileptic drugs and normally developing children. In cross-sectional study B, the median CS was reduced by 0.25 log units (P = 0.0015) in children with IS (VGB na?ve) compared with normally developing children. Longitudinal assessment showed no decrease in CS in children with IS who were followed up 5 to 10 months after starting VGB. There was no difference in GA among groups in any of the experiments. CONCLUSIONS: Patients with IS have CS deficits, but a sparing of GA. This deficit is present before VGB treatment and does not worsen with treatment onset. Results suggest that visual dysfunction is largely the result of the seizures themselves.     

Electroretinographic (ERG) responses in pediatric patients using vigabatrin

The antiepileptic drug vigabatrin is known to cause retinal and visual dysfunction, particularly visual field defects, in some patients. Electroretinography (ERG) is used in an attempt to identify adverse effects of vigabatrin (VGB) in patients who are not candidates for conventional perimetry. We report data from 114 pediatric patients taking VGB referred for clinical evaluation; median age at test was 22.9 (2.4 to 266.1) months, and median duration of VGB use was 9.7 (0.3 to 140.7) months. Twenty-seven of them were tested longitudinally (3 to 12 ERG tests). ERG responses to full-field stimuli were recorded in scotopic and photopic conditions, and results were compared to responses from healthy control subjects. We found that abnormalities of photoreceptor and post-receptor ERG responses are frequent in these young patients. The most frequently abnormal scotopic parameter was post-receptor sensitivity, log σ, derived from the b-wave stimulus-response function; the most frequently abnormal photopic parameter was the implicit time of the OFF response (d-wave) to a long (150 ms) flash. Abnormal 30-Hz flicker response amplitude, previously reported to be a predictor of visual field loss, occurred infrequently. For the group as a whole, none of the ERG parameters changed significantly with increasing duration of VGB use. Four of the 27 patients tested longitudinally showed systematic worsening of log σ with duration of VGB use. In a subset of patients who underwent perimetry (N = 39), there was no significant association of any ERG parameter with visual field defects. We cannot determine whether the ERG abnormalities we found were due solely to the effects of VGB. We caution against over-reliance on the ERG to monitor pediatric patients for VGB toxicity and recommend further development of a reliable test of peripheral vision to supplant ERG testing.     

Comparison of pattern visual-evoked potentials to perimetry in the detection of visual loss in children with optic pathway gliomas.

PURPOSE: We sought to compare visual evoked potentials (VEPs) with standard visual field testing in children with visual pathway gliomas. METHODS: Fifteen of 40 children with visual pathway gliomas verified on magnetic resonance imaging scan who cooperated with Goldmann visual field (GVF) and 3-channel VEPs were studied. GVFs were obtained in 25 eyes with adequate vision. VEP amplitudes, latencies, and signal-to-noise ratios (SNRs) were compared with control subjects. Four of the patients (5 eyes) also had Humphrey visual field testing. RESULTS: Twenty-two of 25 eyes had a field defect, 15 eyes showed a relative or absolute hemianopia, 7 eyes showed a central or generalized depression, and 3 eyes were normal. In hemianopic eyes, 87% showed a depression (GVF) or reduced sensitivity (Humphrey field) in the opposite hemifield. VEP amplitudes and SNRs, normally largest at the midline electrode, were significantly reduced in all eyes with visual field loss. By comparison, lateral electrodes showed significantly lower amplitudes and SNRs in patients and controls. Interhemispheric VEP asymmetry (>2:1 ratio) was seen in 67% of patients with hemianopia and 53% of controls. CONCLUSIONS: Reduction of amplitude and SNR at the midline VEP electrode was a sensitive indicator of visual field loss. Interhemispheric VEP asymmetry was not reliable in detection of a hemianopic field defect. VEPs can be a reliable and objective alternative for the detection of visual loss due to optic pathway glioma in children who are intolerant to visual field testing. We recommend the test protocol include pattern-onset and check reversal stimuli of at least one high and one low spatial frequency.     

Attenuation of the retinal nerve fibre layer and reduced retinal function assessed by optical coherence tomography and full‐field electroretinography in patients exposed to vigabatrin medication

Purpose: To investigate the clinical value of assessment of peripapillary retinal nerve fibre layer (RNFL) thickness with OCT in addition to the evaluation of retinal function measured by full‐field electroretinography (ff‐ERG) in patients with suspected vigabatrin (VGB)‐attributed visual field defects. Methods: Visual fields from adult patients in our clinical follow‐up program for VGB medication were analysed. Twelve patients with suspected VGB‐attributed visual field defects were selected for the study. They were re‐examined with computerized kinetic perimetry, ff‐ERG and OCT (2D circle scan). Results: Constricted visual fields were found in all patients. Comparative analysis of ff‐ERG parameters showed reduced b‐wave amplitudes for the isolated and the combined rod and cone responses (p < 0.0001). The a‐wave, reflecting photoreceptor activity, was reduced (p = 0.001), as well as the summed amplitude of oscillatory potentials (p = 0.029), corresponding to inner retinal function. OCT measurements demonstrated attenuation of the RNFL in nine of 12 patients, most frequently superiorly and/or inferiorly. No temporal attenuation was found. Significant positive correlations were found between the total averaged RNFL thickness, superior and inferior RNFL thickness and reduced ff‐ERG parameters. Positive correlations were also found between RNFL thickness and isopter areas. Conclusion: OCT measurements can detect attenuation of the RNFL in patients exposed to VGB medication. RNFL thickness correlates with reduced ff‐ERG parameters and isopter areas of constricted visual fields, indicating that VGB is retino‐toxic on several levels, from photoreceptors to ganglion cells. The study also supports previous studies, suggesting that OCT measurement of the RNFL thickness may be of clinical value in monitoring patients on vigabatrin therapy.     

Long term changes in the visual fields of patients with temporal lobe epilepsy using vigabatrin

AIM: To study the long term changes in the concentric contraction of the visual field in patients with temporal lobe epilepsy on vigabatrin medication. METHODS: Repeated Goldmann visual field examinations were compared in 27 patients with drug resistant temporal lobe epilepsy and concentric contraction of the visual field. Two groups were studied: 16 patients who had already stopped vigabatrin medication before surgery and 11 patients who continued vigabatrin medication. RESULTS: Concentric contraction of the visual field did not change in 16 patients who stopped vigabatrin before the first examination; there was slight but significant progress in visual field loss in 11 patients who continued the use of vigabatrin. CONCLUSION: Long term follow up of concentric contraction in this selected group of patients indicates that vigabatrin associated visual field loss is not reversible and that progression is possible when vigabatrin is continued.     

Study of visual field and vigabatrin treatment in children

INTRODUCTION: Concentric visual field defects have been described in association with vigabatrin, a GABA mimetic antiepileptic agent. Few cases have been reported in children. METHODS: A systematic ophthalmological examination was performed in 14 children treated with vigabatrin for seizures. A manual kinetic perimetry test (Goldmann) was done in 11 cases. The ERG was recorded in the 3 cases where perimetry could not be done. RESULTS: All children were asymptomatic. The mean age was 9.6 years. The mean duration of vigabatrin treatment was 41 months. The visual field was abnormal when central and peripheral fields were constricted. A visual field defect was discovered in 6 cases: 4 were severe, 2 were mild. When vigabatrin treatment was stopped, 1 case became worse, 1 case was slightly better, and 1 case remained stationary. A disturbed ERG was found in 3 children (depressed b-wave, raised a/b ratio). CONCLUSION: The visual field defects discovered in children treated with vigabatrin are similar to those described in adults. The incidence and progression of visual field constriction in children with and after vigabatrin treatment are not yet well known. Children treated with vigabatrin should therefore have systematic and regular ophthalmological perimetry, and ERG examinations.     

Visual loss associated with pediatric uveitis in english primary and referral centers

PURPOSE: Pediatric uveitis is rare and has been reported to cause increased rates of visual loss compared with adult patients. The reasons for this are unclear. Only one study has been population-based, so the effect of referral bias is not known. We examined the pattern of disease in primary and referral centers to establish the unique characteristics of uveitis in children. DESIGN: Case control study. METHODS: Retrospective, multicenter, observational study of uveitis starting before the age of 20 years. Two hundred forty-nine patients were recruited from three primary and two referral ophthalmic units. Age-related differences in types of uveitis and systemic disease between hospitals were characterized, as were associations with visual loss. RESULTS: The incidence of uveitis in district hospitals at less than 16 years of age was 4.9/100,000: the most frequent diagnosis was idiopathic uveitis (78%). In referral cohorts the most frequent diagnosis was juvenile idiopathic arthritis-associated uveitis (67%). Other systemic diseases were rare. The most frequent type of uveitis at 0 to 7 years of age was chronic anterior uveitis, posterior uveitis in 8- to 15-year-olds, and acute anterior uveitis in 16- to 19-year-olds. Visual loss (any eye < 6/12) occurred in 17% and was not associated with age, sex, or hospital cohort. It was most frequent in posterior uveitis (25%). Treatment variables were independent predictors of visual loss: systemic treatment 2.2 (1.1- 4.6), surgical intervention 8.2 (3.8-17.6). CONCLUSIONS: Idiopathic uveitis was three times more common in district hospitals. Visual loss was similar to adult uveitis in this study. The increased frequency of severe chronic anterior uveitis in children aged 0 to 7 years and posterior uveitis in older children aged 8 to 15 years accounts for the rate of visual loss seen in previous studies.     

Progression of visual field loss in open angle glaucoma in the Melbourne Visual Impairment Project

PURPOSE: To quantify the progression of visual field loss in participants with open angle glaucoma. METHODS: Cluster random samples of 3271 participants participated in this study. Each participant underwent a standardized ophthalmic examination, which included intraocular pressure measurement, Humphrey 24-2 Fastpac visual field testing and stereophotography of the optic disc. At baseline 118 participants were identified as possible, probable or definite open angle glaucoma and 74 (62.7%) of these were seen again at the follow-up examination. Progression of visual field loss was defined using three methods: the Advanced Glaucoma Intervention Study criteria, the modified Anderson criteria and the Blumenthal method. RESULTS: In total, 49% of subjects showed progressive visual field loss with at least one method. The Blumenthal criteria yielded the highest rate of progression (37%), followed by the modified Anderson method (33%) and the Advanced Glaucoma Intervention Study method (16%). The progressive visual field loss was associated with baseline glaucoma status (P = 0.02); 65% of the definite glaucoma progressed, compared with 57% of the probable glaucoma and 25% of the possible glaucoma. Participants who had been previously diagnosed with glaucoma had a higher rate of progression (54%) when compared with those who had not been diagnosed previously (47%). In total, 50% (four of eight) of those receiving glaucoma medication at baseline had progressive visual field loss; all were in the definite glaucoma category. CONCLUSION: Despite use of glaucoma medications the majority of glaucoma patients managed by their regular ophthalmologist experienced progressive visual field loss over a 5-year period.     

Visual acuity in unilateral cataract.

BACKGROUND: Patching the fellow eye in infancy is a well recognised therapy to encourage visual development in the lensectomised eye in cases of unilateral congenital cataract. The possibility of iatrogenic deficits of the fellow eye was investigated by comparing the vision of these patients with untreated unilateral patients and binocularly normal controls. METHODS: Sweep visual evoked potentials (VEPs) offer a rapid and objective method for estimating grating acuity. Sweep VEPs were used to estimate acuity in 12 children aged between 4 and 16 years who had had a congenital cataract removed in the first 13 weeks of life. The acuities of aphakic and fellow phakic eye were compared with the monocular acuities of similarly aged children who have good binocular vision, and with children with severe untreated uniocular visual impairment. Recognition linear acuities were measured with a linear Bailey-Lovie logMAR chart and compared with the sweep VEP estimates. RESULTS: A significant difference was found between Bailey-Lovie acuity of the fellow eye of the patient group and the right eye of binocular controls, and the good eye of uniocular impaired patients (one way ANOVA, p < 0.01). However, this was not evident for a similar comparison with sweep VEP estimates. There was no significant difference between the right and left eye acuities in binocular controls measured by the two techniques (paired t test). CONCLUSION: A loss of recognition acuity in the fellow phakic eye of patients treated for unilateral congenital cataract has been demonstrated with a logMAR chart. This loss was not apparent in children who have severe untreated uniocular visual impairment and may therefore be an iatrogenic effect of occlusion. An acuity loss was not apparent in the patient group using the sweep VEP method. Sweep VEP techniques have a place for objectively studying acuity in infants and in those whose communication difficulties preclude other forms of behavioural test. The mean sweep VEP acuity for the control groups is 20 cpd--that is, about 6/9. When acuities higher than this are under investigation--for example, in older children, slower transient VEP recording may be more appropriate, because higher spatial frequency patterns are not as visible at higher temporal rates (for example, 8 Hz used in sweep VEP recordings).     

Infantile spasms as a cause of acquired perinatal visual loss

BACKGROUND: Visual abnormalities have been described in patients with infantile spasms (IS), an epileptic syndrome of early childhood. METHODS: We report on 3 children who exhibited cortically mediated visual regression in association with the development of IS. RESULTS: In 1 patient, loss of visual behavior was the presenting complaint. In all patients, visual behavior improved with treatment of seizures. CONCLUSIONS: IS are a potentially treatable cause of cortically impaired vision in early childhood. Because visual behavior might improve when the seizures are treated, patients should be referred appropriately.     

The visual field following acute primary angle closure

PURPOSE: To determine the frequency and type of visual field loss six months after an episode of acute primary angle closure (APAC), and to identify risk factors for the development of such field loss. METHODS: This was a cross sectional observational study. All patients who suffered from an episode of APAC at two Singapore hospitals over a one-year period underwent static automated threshold perimetry six months after presentation. RESULTS: 38% of (29) patients with APAC have significant visual field defects six months after the acute episode. The majority of those with abnormal fields had hemifield defects, consistent with nerve fiber bundle pattern loss. Those with pre-existing chronic glaucoma or who develop a rise in intraocular pressure during follow-up are at risk of visual field loss. The risk of visual field loss is also significant if the duration of symptoms exceeds 7 days. CONCLUSIONS: The frequency of visual field loss at 6 months after APAC was low at only 38%. As the majority of eyes have no evidence of detectable functional damage developing as a consequence of the acute episode, APAC may not be blinding if treated promptly and adequately.     

Visual acuity and contrast sensitivity after posterior lamellar keratoplasty

Purpose: It has previously been reported that patients who suffer from Fuchs’ endothelial dystrophy (Fuchs’ ED) have decreased contrast sensibility threshold. The removal of endothelial guttata by Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) surgery has also been demonstrated to decrease intraocular light scatter and improve contrast thresholds. The purpose of this study was to compare different visual qualities in patients that had undergone DSAEK surgery in one eye while having untreated Fuchs’ dystrophy in the other eye. Methods: Thirty‐two eyes of 16 patients with bilateral Fuchs’ ED who had DSAEK surgery performed in one eye were enrolled. Visual acuity at 100% contrast and contrast sensitivity (CS) as evaluated by a modified simulation of the Freiburg Acuity and Contrast Test, was measured in both eyes of each patient. Results: Snellen visual acuity improved in treated eyes from 0.66 ± 0.35 (SD) before surgery to 0.38 ± 0.18 after surgery (log MAR units; p < 0.01). In eyes with untreated Fuchs’ dystrophy, visual acuity was 0.46 ± 0.14. In a pairwise comparison, there was no difference in Snellen visual acuity between treated and nontreated eyes (p = 0.12). Contrast sensitivity was significantly better in DSAEK‐treated eyes compared with untreated eyes. Mean log CS in DSAEK‐treated eyes was 1.06 ± 0.25 compared with a mean log CS of 0.84 ± 0.16 in untreated eyes (p < 0.01). Fourteen of 16 patients (88%) reported that vision in their DSAEK‐treated eye had the best visual quality. Conclusion: In this study, using a paired design, we demonstrate improved CS in DSAEK‐operated eyes when compared with the other eye that had untreated Fuchs’ ED despite the fact that no difference in visual quality was detected with standard Snellen visual acuity. Contrast sensitivity appears to be superior to normal visual acuity measurements in the evaluation of overall visual quality after DSAEK.     

Pseudotumor cerebri in children.

PURPOSE: Demographic and outcome data in the era of modern neuroimaging are needed to describe pseudotumor cerebri in children. METHODS: We reviewed the medical records of children less than 18 years old who were diagnosed with pseudotumor cerebri between 1977 and 1997. We defined pseudotumor cerebri as (1) increased intracranial pressure, (2) normal or small ventricles, and (3) normal cerebrospinal fluid composition. The condition might be idiopathic or the result of a nontumor etiology. RESULTS: Thirty-seven patients had an initial diagnosis of pseudotumor cerebri. Two patients were subsequently diagnosed with a central nervous system malignancy and were excluded from further analysis. The remaining 35 patients included 10 patients with idiopathic pseudotumor cerebri and 25 patients with disorders reported to be associated with pseudotumor cerebri. The mean age was 10.6 years with a range of 3 to 17 years. Twenty patients (57%) were female and 13 patients (37%) were obese. At presentation 4 patients had a visual acuity less than 20/40 in the best eye and 10 patients had visual field deficits. Seventeen patients (49%) had cranial nerve deficits, all of which resolved with normalization of the intracranial pressure. Follow-up data were obtained on 30 patients. Only one patient had a final visual acuity less than 20/40 in the best eye, whereas six patients had residual visual field deficits. Ten patients (33%) had optic nerve atrophy. CONCLUSIONS: There was no gender predominance, and associated etiologic factors were common in these children with pseudotumor cerebri. Permanent visual loss occurs in some children with pseudotumor cerebri. Quantitative perimetry and optic nerve examination were more sensitive than visual acuity determination in detecting damage to the visual sensory system. In rare instances the patient diagnosed with pseudotumor cerebri will be found after extended follow-up to harbor an intracranial neoplasm.     

Pediatric airbag-associated ocular trauma and endothelial cell loss

BACKGROUND: Airbag-associated ocular trauma among the adult population has been widely reported, but reports of these injuries in children are sparse. Laboratory experiments suggest that airbag-associated ocular trauma may cause endothelial cell loss, but reports of in vivo human endothelial cell counts are anecdotal. METHODS: A retrospective chart review was performed of all patients with airbag-associated ocular trauma at a pediatric hospital from 1995 to 2001. From 2001 to 2002, endothelial cell counts were obtained from 9 eyes of airbag-associated ocular trauma subjects and 22 eyes of control subjects. RESULTS: Sixteen patients were identified; all had periocular abrasions, edema, and/or ecchymosis. Other ocular injuries included corneal abrasions (n = 9 or 56%), corneal edema (n = 8 or 50%), hyphema (n = 7 or 44%), lens opacities (n = 5 or 31%), and macular scars (n = 2 or 12%). Three eyes of three patients required intraocular surgery. Unilateral visual loss (hand-motions, 20/100) occurred in two patients. A decrease in mean endothelial cell count of 547 cell/mm2 (P =.01) was found in the airbag-associated ocular trauma group eyes when compared with control group eyes. CONCLUSIONS: The present study includes the largest reported case series of pediatric airbag-associated ocular trauma. Airbag-associated ocular trauma may necessitate intraocular surgery, may result in permanent visual loss, and may cause endothelial cell loss in pediatric patients.     

Levodopa may improve vision loss in recent-onset, nonarteritic anterior ischemic optic neuropathy

OBJECTIVE: To study the effect of levodopa in improving visual function in patients treated within 45 days of onset of nonarteritic anterior ischemic optic neuropathy (NAION). DESIGN: Nonrandomized, retrospective, comparative trial. PARTICIPANTS: The study involved 37 patients with NAION of less than 45 days duration. METHODS: Eighteen patients who had been treated with levodopa were assigned to the case group, and 19 untreated patients were assigned to the control group. Snellen visual acuity converted to logMAR and mean deviation on Humphrey automated perimetry (Program 24-2, Humphrey Instruments, San Leardro, CA) were evaluated at the initial and 6-month visits. INTERVENTION: The 18 patients in the case group were administered a capsule of 100 mg levodopa/25 mg carbidopa (Sinemet 25-100) three times daily for 3 weeks. MAIN OUTCOME MEASURES: The primary outcome measures were changes in visual acuity and visual field at 6 months from baseline. Improvement in visual acuity was defined as a difference of -0.3 logMAR or less between the 6-month and initial visual acuities, whereas worsened visual acuity was a difference of +0.3 logMAR or more. Each 0.3 LogMar represented a doubling of the visual angle, i.e., a change by three lines on the eye chart. Improvement in visual field was defined as a difference in mean deviation of +3.0 dB or more between the 6-month and initial visual field tests, whereas worsened visual field was a difference in mean deviation of -3.0 dB or less. RESULTS: The proportions of patients with worsened, unchanged, and improved visual acuity at 6 months were compared for the levodopa and control groups. There was a significant difference (P = 0.012) between the groups. Examination of the proportions showed that a higher proportion of patients who received levodopa had improved visual acuity with a corresponding lower proportion having worsened visual acuity as compared with the control patients. Ten of 13 patients (76.9%) in the levodopa group with 20/40 visual acuity or worse at baseline had improved visual acuity at 6 months, and none of the 18 patients had worsened visual acuity. In contrast, 3 of 10 control patients (30%) with 20/40 visual acuity or worse at baseline had improved visual acuity at 6 months, and 3 of 19 control patients (16.3%) had worsened visual acuity. The proportions of patients with worsened, unchanged, and improved visual fields at 6 months were compared for the levodopa and control groups. There was no significant difference between the groups (P = 0.25). CONCLUSIONS: Patients treated with levodopa within 45 days of onset of NAION were more likely to experience improvement and less likely to have worsened visual acuity than untreated patients. Levodopa appears to be beneficial in the treatment of recent-onset NAION.     

Chiasmal compression misdiagnosed as normal-tension glaucoma: can we avoid the pitfalls?

Routine neuroimaging for patients with presumed normal-tension glaucoma (NTG) is a contentious issue and it has been suggested that it may be unnecessary due to the low yield for detecting intracranial pathology. However, it has also been reported that 8% of patients diagnosed with NTG have associated compressive lesions of the anterior visual pathways. We present three patients in whom the initial diagnosis of NTG was eventually revealed to be chiasmal compression secondary to a pituitary tumour. Case 1: a 79-year-old woman was treated for NTG for several months before a bitemporal haemianopia developed and imaging showed a pituitary tumour. Case 2: an 83-year-old man was treated for NTG while a magnetic resonance imaging (MRI) scan was requested routinely. This subsequently revealed a pituitary tumour. Case 3: a 52-year-old man with left inferior arcuate visual field loss plus disc pallor was treated for NTG. His visual field deteriorated over 8 years, despite his intraocular pressure (IOP) being well controlled. An MRI was eventually requested, which revealed a pituitary tumour. All of our patients had signs that, with hindsight, should have raised suspicions about the presumptive diagnosis of NTG and initiated neuroimaging at an earlier stage. Whilst compression of the anterior visual pathways is an uncommon finding in patients thought to have NTG, features such as bitemporal field loss, optic disc pallor, poor colour vision and, particularly, poor disc/field correlation should alert the clinician to the possibility of an intracranial mass lesion.     

Low-contrast visual acuity test for pediatric use

Single-letter flash cards were made at contrast values of 96%, 7% and 4% to compare high-, intermediate- and low-contrast visual performance in amblyopic children young enough to benefit from occlusion therapy. The single-letter format was intended to differentiate the effect of contrast on reading performance from any effects of nearby contours. Two groups of patients were tested: 37 children aged 3 to 8 years who had completed occlusion therapy and 15 children aged 4 to 8 years who were still receiving occlusion therapy. Their results were compared with the results of 45 control subjects aged 3 to 8 years. Three patterns of visual loss were identified in the patients: predominantly for high-contrast acuity, fairly uniform at high-, intermediate- and low-contrast levels, and, in two patients, loss at low- and intermediate-contrast levels with relative sparing at the high-contrast level. The incidence of high-contrast acuity loss was not significantly different between the two groups, but the proportion of children with no acuity loss at any contrast level was 54% in the group that had completed treatment, compared with 17% of those who were still receiving treatment.     

500例鞍区肿瘤的眼部改变

目的：分析鞍区肿瘤眼部病变的特点，有利于鞍区肿瘤的早期诊断和早期治疗。方法：回顾必总结我院近2年来收治的500例鞍区肿瘤患者视力，视野，眼底及眼肌麻痹等症状和体征。结果：鞍区肿瘤患者早期 可出现视力减退，视野缺损，眼底改变等眼部症状，在眼科可能引起误诊。结论：鞍区肿瘤如果能早期发现，早期治疗，能有效改善视功能。对有视力和视野障碍的患者，在除外眼科疾病的基础上，要有全身疾病的概念，及时行头颅CT与MRI检查。