Should visual field examination be a routine part of ophthalmic practice?

Visual field screening conducted on indication was compared with routine visual field screening to determine the effectiveness of these strategies in identifying patients with normal and abnormal visual fields. The sample consisted of 1,500 consecutively presenting patients. Each patient was screened with the Friedmann Visual Field Analyser Mark II. Visual field defects were detected in 3.0% of eyes. Routine visual field screening detected a very high proportion of these defects. The two indications approaches which were tested achieved only slightly lower sensitivities and specificities, while necessitating that only approximately 20% of patients required screening. The most effective strategy for screening on indication was based on overall clinical assessment of each case, although the optimal criteria relied on low levels of suspicion.     

Detection and recognition of visual field defects resulting from lesions involving the visual pathways

Abstract
A prospective study of visual field defects associated with lesions of the visual pathway was carried out using kinetic and suprathreshold static stimuli with a view to establishing the most effective screening method for these field defects. The 215 abnormal fields so obtained showed that all field defects due to lesions of the visual pathways are detectable within 30 degrees of fixation and that not only is central field testing mandatory in excluding such a field defect, but more peripheral field testing alone is ineffecve. This study also revealed that when kinetic fields are charted, it is probably not worthwhile searching for scotomata other than within the most central part of the field. Furthermore, where outer and inner isopter depression is not coextensive, inner isopters are always depressed more than outer isopters when the field defect is due to a lesion of the visual pathway.     

Evaluation of diagnostic capabilities of interactive test strategies in automated perimetry

Simple strategies for visual field screening with automated perimeters can detect abnormalities at acceptable rates. However, the information available from a screening field chart is often insufficient to assign the field into a diagnostic category, and further field testing is necessary. Automated perimeters can be programmed to alter the suprathreshold stimulus intensity based on patient response or do further testing in areas of detected abnormality. Two such programs were compared to a simple screening method using a single automated perimeter in 75 eyes. The charts generated by the interactive programs were more diagnostically useful than those produced by the simple strategy. However, these interactive strategies produced an increased rate of false alarms and testing time which substantially reduced their value as screening visual field tests.     

倍频视野计检测青光眼性视野缺损能力的研究

目的评估倍频视野计检测青光眼性视野缺损的能力以及与OCTOPUS101全自动视野计检查结果之间的相关性。方法应用倍频视野计的C-20—5筛选程序以及OC—TOPUS101全自动视野计的G2-TOP程序对23例正常对照者、20例早期青光眼患者、35例中晚期青光眼患者、11例高眼压患者及13例疑似青光眼患者进行视野检测。正常对照组、高眼压组及疑似青光眼组随机选择一眼进行测试，青光眼组选择具有较严重视野缺损的一眼进行测试。结果倍频视野计的C-20—5筛选程序在检测青光眼时ROC曲线下面积为0．925（敏感性85％，特异性91％），与OCTOPUS视野指数-平均缺损、偏离缺失之间的Pearson系数分别为0．702与0．429（P〈0．001），倍频视野计与OCTOPUS101视野计检查平均所需时间分别为1．00min与2．33min．2者之间有明显差异（P〈0．001）。结论倍频视野计检测青光眼性视野缺损具有良好的敏感性与特异性，与OCTOPUS101视野计的视野指数之间亦存在理想的相关性，而且前者比后者检测速度更快，使大规模人群筛查成为可能。     

Visual fields in neuro-ophthalmology

Visual field assessment is important in the evaluation of lesions involving the visual pathways and should be performed at baseline and periodically in the follow-up. Standard automated perimetry has been shown to be adequate in neuro-ophthalmic practise and is now the technique of choice for a majority of practitioners. Goldman kinetic visual fields are useful for patients with severe visual and neurologic deficits and patients with peripheral visual field defects. Visual fields are useful in monitoring progression or recurrence of disease and guide treatment for conditions such as idiopathic intracranial hypertension (IIH), optic neuropathy from multiple sclerosis, pituitary adenomas, and other sellar lesions. They are used as screening tools for toxic optic neuropathy from medications such as ethambutol and vigabatrin. Visual field defects can adversely affect activities of daily living such as personal hygiene, reading, and driving and should be taken into consideration when planning rehabilitation strategies. Visual field testing must be performed in all patients with lesions of the visual pathway.     

Screening for visual field abnormalities with automated perimetry

Recent studies indicate that automated perimetry can serve as an effective method of screening for visual field abnormalities associated with ophthalmologic and neurologic disorders. The techniques have been successfully applied to the private practitioner's office for screening of patients and to mass visual field screening of the general population. This paper describes the principles underlying automated perimetric screening, evaluates the capabilities and limitations of such techniques, and provides some general guidelines for using automated perimetric screening procedures.     

Cost-benefit analysis in screening. Unexplained visual loss

Cost-effectiveness analysis (CEA) and cost-benefit analysis (CBA) are accounting techniques that have been applied to medical decision-making. These techniques are applied here to two alternative diagnostic strategies in the work-up of patients with "unexplained visual loss." The first uses the results of visual field examination to decide if patients should have a CT scan ("visual field strategy"), the second bypasses visual fields and orders a CT scan on all patients ("CT strategy"). The analysis reveals that the visual field strategy is cost-effective only if perimetrists are able to identify hemianopic field defects in more than 80% of cases. It is doubtful that perimetrists are presently as accurate as that. These conclusions must be considered tentative since the epidemiologic data that support them are often weak. Another drawback in applying such an analysis to medical problem-solving is that costs may not accurately reflect patient valuations and choices. Nevertheless, in forcing a more comprehensive consideration of the effects of medical decisions, CEA/CBA is likely to promote increased cost-consciousness and epidemiologic research.     

Visual impairment and the useful field of vision

The aim of this study was to measure the useful field of vision (UFoV) in people with visual impairment and to compare results with clinical measures of vision. UFoV, visual acuity, contrast sensitivity and visual fields were measured in 36 participants with low vision and 22 age-matched controls in two age groups. For both the low vision and control groups the presence of distractors (cluttered field) increased the error rates on our UFoV measure but there was no significant effect of the presence of a central task (divided attention). Participants with low vision made more errors on UFoV than did controls, but this difference disappeared once their visual field defects were accounted for. By multiple regression analysis, age, visual fields and contrast sensitivity were shown to predict the different UFoV scores. As for observers with normal vision, standard clinical visual field tests may not fully describe the difficulties that may be encountered by people with visual impairment undertaking tasks in the cluttered environments and multiple demands of everyday life.     

Current licensing authority standards for peripheral visual field and safe on-road senior aged automobile driving performance

BACKGROUND: The current licensing authority's (Austroads) visual field standards are met when a person demonstrates an intact visual field extending horizontally at least 120 degrees within 10 degrees above and below the horizontal midline. A person cannot be licensed unconditionally if they have a hemianopia, quadrantanopia or any significant visual field loss (scotoma) that is likely to impede driving performance. Despite fairly rigorous implementation of these vision standards by licensing authorities, there is little scientific evidence available to demonstrate that a driver will or will not be safe on road depending on the extent of their visual field. METHODS: This study was developed to examine if the current licensing authority vision standards predict safe on-road driver performance in a cohort of 100 senior drivers. The study consisted of four stages in which participants underwent on-road assessment by a multidisciplinary team including a driving instructor, orthoptist and occupational therapist; off-road occupational therapy cognitive skills assessment using the Visual Recognition Slide Test (VRST-USyd); off-road orthoptic assessment including history, visual acuity and visual fields; and feedback from the team regarding the participant's visual and driving status. Visual fields were assessed using both the Goldmann and Esterman tests. Correlations were calculated to determine the relationship between visual field results and on-road driving performance. RESULTS: Generally it was found that visual field test results did not predict driving performance accurately for both participants with and without visual field loss. CONCLUSION: The results bring into question the current Austroads visual field standards for safe driving.     

Field restriction and vignetting in contact lenses with opaque peripheries

Background : Some previous researchers have shown empirically that visual fields can be restricted by contact lenses with opaque and semi-opaque peripheral zones. However, there has been no formal statement of the optical theory behind such restriction. Methods : Calculations are made of fields of view with opaque periphery contact lenses, based on paraxial theory and meridional finite ray tracing in the Gullstrand-Emsley schematic eye. Results : This analysis shows that paraxial theory is adequate for predicting ‘half fields of full illumination’ for ocular pupil diameters smaller than six millimetres, although paraxial estimates of ‘half total field’ can substantially underestimate those obtained by finite ray tracing for a wide range of ocular pupil sizes. Therefore finite ray tracing may be a more appropriate method of calculating half total field. ‘Total field’ will be smaller with smaller ocular pupils and smaller contact lens apertures. A clinical method is suggested for assessing total field with such contact lenses in situ. The analysis applied to opaque periphery contact lenses is extended to the semi-opaque periphery contact lenses used for cosmetic alteration of eye appearance. Conclusion : Semi-opaque periphery contact lenses will decrease retinal illuminance most at regions outside those tested by previous empirical static perimetry studies.     

Multifocal Magnetoencephalogram Applied to Objective Visual Field Analysis

Purpose To establish an objective visual field analysis by visual evoked magnetic fields.Methods Forty-eight focal areas of the visual field were stimulated by the visual evoked response imaging system (VERIS). The multifocal visual evoked magnetic fields (mfVEFs) of 11 healthy subjects were recorded. The output signals were recorded with VERIS, and the second-order kernel was calculated. The equivalent current dipoles (ECDs) were estimated, and the relative positioning of ECDs was determined by a magnetoencephalography (MEG) system.Results The mfVEFs consisted of either two- or three-peak waves. Large amplitude mfVEFs were elicited when the stimulus was confined to 6° of the central visual field, but a strong response could not always be obtained between 6° and 12°. All ECDs were estimated to originate in the occipital striate cortex. The ECDs for the upper (lower) field stimulations were estimated to be on the lower (upper) cortex, while those for right (left) field stimulations were on the left (right) cortex.Conclusions The locations of mfVEF peak ECDs were correlated with the stimulated visual field and generally matched the cruciform model. In combination with the multifocal technique, MEG can be used for objective visual field analysis. Jpn J Ophthalmol 2004;48:115–122 © Japanese Ophthalmological Society 2004     

Clinical analysis of screening and threshold visual field data for glaucoma detection

The value of clinical interpretation in differentiating between glaucomatous and normal fields from threshold (Humphrey Field Analyser) and screening (Henson CFS3000) measures was determined using a masked prospective experimental design. The visual field plots of 20 primary open-angle glaucoma (POAG) patients, 19 ocular hypertensive and 19 normotensive glaucoma suspects, and 21 age- matched normals measured with the Humphrey Field Analyser (Humphrey) and Henson CFS3000 (Henson) were categorised by two experienced clinicians. Significant differences in interpretation of the field plots were demonstrated between the two clinicians (χ^{2 McNemars}= 19–36; p<0.001). The sensitivity of clinical interpretation was shown to lie between 65 per cent and 90 per cent (dependent upon the individual clinician) for the Humphrey plots, but was as low as 40 per cent with the Henson plots. Specificity was, however, higher for the Henson overall, regardless of the clinician (between 90 per cent and 95 per cent) compared to the Humphrey (between 75 per cent and 100 per cent). These levels of sensitivity and specificity do not reach the levels reported when interpretation is based on the visual field indices alone. It was concluded that a screening instrument, such as the Henson, should only be employed for testing large unselected populations, in which the prevalence of glaucoma is low. Visual fields should not be judged in isolation, but in conjunction with measures of optic nerve and nerve fibre layer integrity, intra-ocular pressure and family history.     

高度近视患者的视野改变与屈光性角膜手术

目的　探讨高度近视患者的视野改变及屈光性角膜手术的效果。方法　35例患者(70眼)按屈光度分为2组Ⅰ组为高度近视组，屈光度-8.00～-10.00D，34眼；Ⅱ组为超高度近视组，屈光度＞-10.00D,36眼。常规眼前节及后节检查。应用Octopus(瑞士)视野计进行视野检查并分析。视野正常者可行屈光性角膜手术。结果　70例患者中15眼(21.43%)视野正常，Ⅰ组(10眼)高于Ⅱ组(5眼)。55眼(78.57%)显示不同程度的缺损，Ⅱ组(24眼)明显高于Ⅰ组(31眼)(P＜0.05)；≤30a视野缺损比例低于＞30a(P＜0.05)；男女间无显著差异。视野缺损与视网膜退行性变化、近视度数、年龄等因素有关，其缺损形状无典型的特征性改变，颞上方较多见。24眼行PRK或LASIK，3mo、6mo时实际矫正度在预期矫正度±1.0D范围内分别为92.4%、96.2%.结论　高度近视常伴视野缺损。因此，对高度近视眼患者进行视野检查，特别是对屈光性角膜手术的筛选非常重要。     

Mass Visual Field Screening in a Driving Population

With the cooperation of the California Department of Motor Vehicles and Synemed; Inc., visual field screening tests were administered to 1,027 eyes of driver's license appl-icants using the Fieldmaster Model 101-PRA automated perimeter. Approximately 5% of the eyes tested demonstrated significant visual field loss. These results indicate that mass visual field screening in a driving population is feasible and may become a valuable technique for early detection of eye disease in large populations. It may also be an important factor in traffic safety.     

Functional and structural change in diabetic eyes. Interim results from an ongoing longitudinal prospective study

Purpose: To presents results after 18 months of follow‐up of a longitudinal study aiming at exploring the correlation between diabetic retinal vascular lesions and functional change. Methods: Patients were consecutively recruited from attendees to the screening program for diabetic retinopathy. Subjects are followed every sixth month for the first 3 years and thereafter annually up to 5 years. Progression of diabetic retinopathy is evaluated using the Early Treatment Diabetic Retinopathy Study (ETDRS) scale and improvement/deterioration in visual fields by predefined significance limits for change. Results: Of 81 subjects, with no/mild/moderate diabetic retinopathy included, 76 have passed the 18‐month visit. At that time, retinal progression by two steps according to the ETDRS scale had occurred in two subjects. Visual acuity was ?0.14 logMAR and had decreased with two letters (0.04 logMAR) (p < 0.001) from baseline. The global visual field index mean deviation was almost unchanged with a negligible improvement of 0.03 dB (p = 0.79). In 21 subjects, repeated significant deterioration was seen in ≥10% of all points tested in the field, while almost no improved points were noted. The two subjects with retinal progression were not among those 21 with indication of perimetric progression. Conclusions: This is, to our knowledge, the first longitudinal study evaluating change of visual fields in a representative diabetic cohort with no or mild/moderate retinopathy. In this interim report, we demonstrate deteriorated perimetric sensitivity in subjects already at 18 months of follow‐up. The results will have implications for evaluating change in visual function in future clinical trials.     

Clinical application of the multifocal visual evoked potential

Background: Measures of visual function thresholds such as visual acuity and visual fields are generally dependent on subjective responses and assume maintenance of fixation, attention and motivation. In the young, elderly, cognitively impaired or malingering populations, such measures may be inaccurate or difficult to obtain. The Visual Evoked Response Imaging System (VERIS) has been claimed to give more objective topographic recordings of retinal and cortical function. This paper aims to explore the adequacy of this technique in four unusual, unrelated, clinically difficult cases. Methods: Multifocal visual evoked potentials (mfVEPs) recorded on the VERIS System 3.01 are used to assess visual function in four cases with contradictory clinical findings or unreliable subjective responses. Results: Patient 1 had sustained a head injury and had normal ocular and pupil examination but light perception in the right eye and 6/5 acuity in the left. Multifocal VEPs showed a marked depression of the right visual field with little macular response. Patient 2 had sustained a head injury, had a left field hemianopia, possible macular sparing and loss of much of the right field, reduced but variable visual acuities, good near vision and normal ocular fundi. Multifocal VEPs showed a severe depression in both visual fields (L more than R) with little macular response. Patient 3 had a left optic nerve meningioma and experienced great difficulty with visual field assessment. mfVEPs showed a bilateral depression in the superior field particularly the left field, with a larger deficit in the left eye. Patient 4 had unexplained visual acuity and peripheral field deficits. mfVEP results were inconclusive in this case. Discussion: Where there is difficulty performing traditional techniques or conflicting clinical findings, mfVEPs may provide additional objective information to aid in the assessment of patients.     

Cluster analysis in visual field quantification

The central visual fields of 2165 normal and 106 glaucoma eyes were measured using a threshold related suprathreshold strategy. The effects of altering the cluster radius in normals and glaucoma eyes sheds light on the nature of defects in these two groups. It is estimated that approximately 13% of normals have clusters; the great majority of these individuals have one cluster of two defects. Most clusters in normals are formed artefactually due to angioscotoma and/or physiological variations in the blind spot position. Clusters due to other factors occur rarely. Clusters are found with equal frequencies in the superior and inferior fields in normal eyes, but with a greater frequency in the superior field in glaucoma eyes.The use of clusters in quantification is both sensitive and specific. Using results from this large sample and looking at other visual field properties, it is possible to devise weighted probability indices to score visual fields.     

Visual function tests for glaucoma practice - What is relevant?

Glaucoma represents one of the most important ocular diseases causing irreversible ganglion cell death. It is one of the most common causes of visual impairment and morbidity in the elderly population. There are various tests for measuring visual function in glaucoma. While visual field remains the undisputed method for screening, diagnosis, and monitoring disease progression, other tests have been studied for their utility in glaucoma practice. This review discusses some of the commonly used tests of visual function that can be routinely used in clinics for glaucoma management. Among the various modalities of testing visual function in glaucoma, this review highlights the tests that are most clinically relevant.     

多焦视诱发电位的双眼对称性分析

目的 观察正常人多焦视诱发电位(mfVEP)的双眼对称性。 方法 应用VERIS Science 4.0视觉诱发反应图像系统对36名正常人的72只眼进行mfVEP测试，刺激图形为带图形的飞镖盘，对应的视角为25°。图形中有60个小块，每个小块包括4×4个黑白相间的格子，由二元伪随机m-序列控制其黑白翻转形成视觉刺激。 结果 左右眼各对应象限的P1波潜伏期及振幅配对 t 检验显示差异无统计学意义。双眼同侧视野的潜伏期与振幅的数据差异大于相应视野象限的数据差异。右眼或左眼4个象限组间比较显示双眼各自鼻上与颞下、鼻下象限P1波潜伏期之间差异有统计学意义，振幅方面仅左眼颞上与颞下象限之间差异有统计学意义。 结论 正常人双眼mfVEP以视网膜对称性优于视皮层的对称性。 (中华眼底病杂志, 2006, 22: 42-44)