Field of dreamers and dreamed-up fields: functional and fake perimetry

Functional vision disorder: a review of diagnosis, management and costs

Functional vision disorder (FVD) is a relatively common diagnosis in ophthalmic practice which can be difficult to make because of clinician's apprehension to miss organic pathology. We review the diagnostic approach to patients with FVD, organic mimics of FVD, its diagnostic and management strategies and associated cost burden. Patients with FVD typically present with visual acuity and/or field loss. Diagnostic work-up should include patient observation, detailed history, pupillary examination, dilated ophthalmoscopy, visual field testing and ganglion cell analysis of the macular complex. Most common organic mimickers of FVD are amblyopia, cortical blindness, retrobulbar optic neuritis, cone dystrophy and chiasmal tumours; however, all could be ruled out by structured diagnostic approach. For patients with unilateral visual loss, bottom-up refraction, fogging of the well-seeing eye in the phoropter, convex lens and base-down prism tests could aid in diagnosis. For patients claiming binocular vision loss, checking for eye movement during the mirror test or nystagmus elicited by an optokinetic drum can be helpful. Effective management of FVD involves reassurance, stress reduction and, if agreed on, management of comorbid anxiety and/or depression. The social cost of FVD is predominately economic as patients typically meet several healthcare providers over multiple visits and often undergo several neuroimaging studies before neuro-ophthalmology referral. Further, inappropriate granting of disability benefits confers additional stigma to patients with organic vision loss.

Functional vision disorders in adults: a paradigm and nomenclature shift for ophthalmology

Vision loss with clinical findings that are incompatible with the symptoms and recognized neurological or ophthalmic conditions is a common presentation of patients to neurologists, ophthalmologists, and neuro-ophthalmologists. The accepted terminology to describe such patients has evolved over time, including functional visual disorder (FVD), non-organic vision loss, non-physiologic vision loss, functional vision loss, psychogenic, psychosomatic, and medically unexplained visual loss. Likewise, attitudes and recommended management options have changed over the years in the fields of psychiatry and neurology. FVD is a diagnosis of inclusion, and it is critical that the diagnosis be made and delivered efficiently and effectively to reduce patient and physician duress. We review the current Diagnostic and Statistical Manual (DSM V) terminology and the prior literature on FVD and describe how the approaches to diagnosis and management have changed. We provide recommendations on the appropriate techniques and diagnostic approach for patients with FVD. We also propose a protocol for consistent and standardized discussion with the patient of the diagnosis of FVD. We believe that the adoption of FVD as both a paradigm and nomenclature shift in ophthalmology will improve patient care.

Artifactual Visual Field Defects Identified on Technically "Reliable" Visual Field Studies in a Neuro-Ophthalmology Practice

Purpose

To assess the reliability of automated visual field studies with neurological abnormalities and normal reliability indices that were inconsistent with the remainder of the neuro-ophthalmic assessment.

Methods

Retrospective observational study from the clinical practice of a neuro-ophthalmologist at a tertiary referral center.

Results

From 2230 patient charts, ten cases were identified that met the inclusion criteria. In eight of the cases repeat visual field testing had no reproducible abnormality. Four of these cases were concerning for a bitemporal or homonymous hemianopia. None of the patients, including the two cases with a reproducible defect, developed any convincing manifestations of an organic disease related to the visual field defect.

Conclusion

Our findings suggest that even marked neurological abnormalities on reliable automated visual field tests can be false. When the remainder of the neuro-ophthalmic evaluation is inconsistent with the test result, we recommend that clinicians attempt to immediately repeat the visual field study.

Perimetry and visual field defects

Perimetry is the quantitation of the visual field. This is done with a perimeter and usually involves measuring visual thresholds to a range of light stimuli. It is used clinically to map patterns of visual loss due to damage to the sensory visual system. This chapter discusses the types of perimetric testing and the psychophysics of perimetry. This is followed by the interpretation of perimetric results, the relevant visual system anatomy, and patterns of loss helpful for neurologic localization. Lastly, the difficult issue of deciding whether the visual field has changed is reviewed. Patterns of visual loss are the key to anatomic diagnosis. Strictly monocular defects map to the prechiasmal sensory visual system. Bitemporal hemianopia is the signature of damage to the optic chiasm. Incongruous homonymous hemianopia points to an optic tract lesion. The closer a lesion gets to the occipital cortex, the more congruous or similar are the patterns of homonymous hemianopia. Understanding these patterns, the basics of perimetry and other rules of localization will add an important dimension to the neurologist's localization arsenal.

[Testing and approach when non-organic visual loss is suspected]

Approximately 5% of the patients in the ophthalmological practice suffer from non-organic vision loss. In children non-organic vision loss has been observed from the age of 6 years. In order to be able to make a rapid diagnosis knowledge of the relevant clinical tests is decisive. If a patient shows signs of non-organic visual loss, diagnostic externalization of the visual function is crucial. Depending on the symptoms there are various tests, which can be used to differentiate between organic and non-organic disorders. For therapeutic and economic reasons an early diagnosis of a non-organic visual loss is crucial. Ophthalmologists need to differentiate between malingering and augmentation, where the patient is aware of the fraud and tries to gain personal benefit from it, and somatoform disorders. In the latter, a more sensitive approach is recommended.

An atypical presentation of functional visual loss: A case report

RATIONALE

Functional visual loss (FVL) can manifest as various symptoms. Decreased distant visual acuity is the most common symptom and visual field defect is the second most common symptom. Hemianopsia is rarely reported. In an atypical situation of FVL, it is important to prove that no organic pathology exists, through detailed history taking and appropriate examinations.

PATIENT CONCERNS

This review presents the case of a 48-year-old male patient presented with decreased bilateral visual acuity and visual field defect after a traffic accident 3 weeks ago. Visual field test showed atypical features of FVL in which visual field change from binasal hemianopsia to left homonymous hemianopsia.

DIAGNOSIS

The best corrected visual acuities (BCVA) were 20/63 in both eyes and binasal hemianopsia was observed on a Humphrey visual field test. Brain computed tomography (CT) scan and magnetic resonance imaging (MRI) showed no abnormalities in the brain and optic chiasm. Two weeks after presentation, however, the patient's visual field defect changed from binasal hemianopsia to left homonymous hemianopsia. We diagnosed it as FVL due to conversion disorder.

INTERVENTION AND OUTCOMES

We decided to cooperate with a psychiatrist for cognitive behavioral therapy and the patient is under observation.

LESSONS

Binasal hemianopsia and homonymous hemianopsia are rare; however, it may occur simultaneously in 1 patient with FVL. The possibility of FVL should be considered when there is atypical visual field defect and no organic abnormalities are observed. Repeated Humphrey field test and VEP may be helpful in diagnosis of FVL.

Functional and simulated visual loss

Nonorganic visual loss (NOVL) is the cause of a large number of referrals to neurologists and ophthalmologists and is a frequent area of overlap between neurologists, ophthalmologists, and psychiatrists. NOVL is the presence of visual impairment without an organic cause for disease despite a thorough and comprehensive investigation. A diagnosis of NOVL requires both the absence of any findings on examination and proof of the integrity and functioning of the visual system. Although sometimes a challenging diagnosis to make, there are a number of techniques and maneuvers which can be utilized fairly easily, either at the bedside or in the clinic, to help determine if a patient has NOVL. In some instances specialized testing, such as formal visual field testing, optical coherence tomography, visual evoked responses, electroretinogram, and various imaging modalities (magnetic resonance imaging) are performed to help determine if the cause of visual loss is organic or nonorganic. Once a diagnosis of NOVL is made, treatment centers around reassurance of the patient, close follow-up, and, if necessary, referral to a psychiatrist, as these patients may have underlying psychiatric disorders and a preceding strong emotional event leading to the current symptoms, and may be more likely to develop depression and anxiety.

Assessing medical students' communication skills by the use of standardized patients: emphasizing standardized patients' quality assurance

OBJECTIVE

The objective structured examination is one of the most valid, reliable, and effective tools for assessing clinical and communication skills, often by use of standard patients (SPs). SPs can also be assessors of those skills. One of the crucial areas when utilizing SP-based assessment is the quality and consistency assurance of their portrayal of the case and their ability to fill in checklists in an adequate way. The aim of this study was to assess the validity and reliability of SPs' ability to assess students' communication skill via a Calgary-Cambridge checklist.

METHOD

This cross-sectional and correlational study was conducted at the Tehran University of Medical Science. We first analyzed validity; the criterion validity of the SPs' filling in the checklists was assessed through determining the correlation between the SPs' completed checklists and the checklists filled in by three physician raters individually and then reproducibility: it was assessed by a test-retest approach inter-rater reliability.

RESULT

The mean correlation for assessing the validity of SPs' completed checklists by individual SPs was 0.81. The inter-rater reliability was calculated by kappa coefficient, and the total correlation among the three raters was 0.85. The reliability of the test-retest approach showed no significant differences between the test and re-test results.

CONCLUSION

The increased number of medical students and different faculties' responsibilities such as doing educational, research, and health services duties assessing medical student communication skills is a complex issue. The results of our study showed that trained SPs can be used as a valid tool to assess medical students' communication skills, which is also more cost effective and reduces work load of medical faculties.

The ability of healthy volunteers to simulate a neurologic field defect on automated perimetry

OBJECTIVE

To determine if volunteers can simulate and reproduce 3 types of neurologic field defects: hemianopia, quadrantanopia, and central scotoma.

DESIGN

Cross-sectional study.

PARTICIPANTS

Thirty healthy volunteers new to perimetry (including automated perimetry).

METHODS

After informed consent, volunteers were randomized to 1 of the 3 visual field defects listed above. All visual field testing was performed on the right eye using the Humphrey Field Analyzer (HFA; Carl Zeiss Meditec, Dublin, CA) SITA Fast 24-2 protocol. Each volunteer was provided with standard new patient instructions and was shown a diagram of the defect to be simulated. Two sets of visual fields were performed on the right eye with 10 minutes between tests. Three experts used the Ocular Hypertension Treatment Study reading center criteria and determined if the simulation was successful.

MAIN OUTCOME MEASURES

Proportion of volunteers able to simulate the assigned visual field.

RESULTS

All 10 volunteers (100%) successfully simulated a hemianopia on the first and second fields. All 10 volunteers (100%) simulated a quadrantanopia on the first field and 9 (90%) did so on the second field. Eight volunteers (80%) successfully simulated a central scotoma in the first field and all 10 (100%) did so on in the second field. Reliability criteria were excellent. Forty-seven fields (78%) had 0 fixation losses, 48 (80%) had 0 false-positive results, and 44 (73%) had 0 false-negative results.

CONCLUSIONS

It is easy to simulate reproducible and reliable neurologic field defects on automated perimetry using HFA.

Tests for malingering in ophthalmology

Simulation can be defined as malingering, or sometimes functional visual loss (FVL). It manifests as either simulating an ophthalmic disease (positive simulation), or denial of ophthalmic disease (negative simulation). Conscious behavior and compensation or indemnity claims are prominent features of simulation. Since some authors suggest that this is a manifestation of underlying psychopathology, even conversion is included in this context. In today's world, every ophthalmologist can face with simulation of ophthalmic disease or disorder. In case of simulation suspect, the physician's responsibility is to prove the simulation considering the disease/disorder first, and simulation as an exclusion. In simulation examinations, the physician should be firm and smart to select appropriate test(s) to convince not only the subject, but also the judge in case of indemnity or compensation trials. Almost all ophthalmic sensory and motor functions including visual acuity, visual field, color vision and night vision can be the subject of simulation. Examiner must be skillful in selecting the most appropriate test. Apart from those in the literature, we included all kinds of simulation in ophthalmology. In addition, simulation examination techniques, such as, use of optical coherence tomography, frequency doubling perimetry (FDP), and modified polarization tests were also included. In this review, we made a thorough literature search, and added our experiences to give the readers up-to-date information on malingering or simulation in ophthalmology.

Functional neuro-ophthalmology

Patients with physical signs and symptoms for which no adequate organic cause can be found may receive any one of a large range of diagnostic labels, including functional illness, functional overlay, hysteria, hysterical overlay, conversion reaction, psychophysiological reaction, somatization reaction, hypochondriasis, invalid reaction, neurasthenia, psychogenic reaction, psychosomatic illness, malingering, and Münchausen syndrome. In this chapter, we describe both common and uncommon "functional" ocular symptoms and signs, including visual loss in one or both eyes, constricted visual fields and other field defects, various types of ocular motor dysfunction, including disorders of ocular motility and alignment, disorders of pupillary size and reactivity, and abnormalities of eyelid position and function. We also discuss and illustrate the methods by which the nonorganic nature of these manifestations can be determined. In many cases simple techniques performed in the clinic are sufficient to establish a diagnosis of nonorganic ocular disease, whereas in other cases ancillary studies such as electrophysiological testing may be necessary. The chapter also describes the appropriate approach that the physician should take when dealing with a patient who has proven functional ocular signs and symptoms.

Practical clinical approaches to functional visual loss

Functional visual loss (FVL) refers to subnormal vision or altered visual fields where no underlying pathology of the visual system can be found. It may be seen in a continuum from frank malingering to hysteria. FVL may first present to the general practitioner or physician and the financial burden of evaluation and potential disability-related claims may be substantial. Diagnosis relies on a high index of suspicion and demonstration with a few simple tests that the patient has better vision than alleged. The aim of this review is to provide a practical approach to examination of patients with suspected functional visual loss. An accurate and early diagnosis of FVL starts with a high index of suspicion. Only a few of the tests need to be learned well, performed smoothly and confidently. These clinical tests obviate the need to perform expensive imaging such as magnetic resonance imaging and if used in the correct setting have the potential to reduce further the cost of diagnosis. Management requires an understanding approach and confrontation is seldom helpful. It is important to stress to the patient that FVL has a good prognosis, thereby providing "a way out" and giving the patient the opportunity to recover.

Diagnosis and management of functional visual deficits

Patients with functional or nonorganic visual disturbances are often seen in general ophthalmology practice and then referred to neurology and/or neuro-ophthalmology. The diagnosis of functional vision loss requires comprehensive examinations and diagnostic testing to eliminate possible organic entities. Inconsistencies between examinations may be key to the functional/nonorganic nature. These cases represent some of the most time-consuming diagnoses that an ophthalmologist sees. These patients may be malingering or may have already seen multiple physicians. The more sophisticated patients may go online to learn about an entity that they are trying to mimic. Large amounts of time and money may be spent on diagnostic workups that are thought necessary to prove that there is nothing organic involved. Occasionally there are legal elements of the vision loss, such as minor trauma, in which case the history is key; the complaints tend to resolve when the legal issues are resolved. Another issue to consider is whether someone claiming to be blind is trying to qualify for workmen's compensation or disability.

Functional Visual Loss

Patients who present with visual loss that cannot be explained by organic lesions represent a wide spectrum of patients from those with no physiologic problem to those patients who have a true underlying condition. Regardless of where a patient falls within this spectrum, all patients need to be approached with a clinical evaluation to ensure that no underlying physiologic deficit exists. After excluding organic causes with appropriate examination and testing, a patient's visual loss still should not be labeled as functional until it is proven that they can see better than they claim to see. Only after convincingly demonstrating better vision can the physician begin to consider treatment options to help the patient's vision recover. Although functional visual loss places the physician in an unusual adversarial position of refuting a patient's symptoms, exposing the patient in a confrontational manner rarely helps. Instead, an approach that allows patients to resolve the symptoms on their own through reassurance and support often leads to successful restoration of vision. Reassurance that their condition is not serious, and may recover with time, allows patients to slowly admit their vision is improving without ever suggesting that the concern and medical attention they sought was unwarranted.

Using standardised patients to measure physicians' practice: validation study using audio recordings

OBJECTIVE

To assess the validity of standardised patients to measure the quality of physicians' practice.

DESIGN

Validation study of standardised patients' assessments. Physicians saw unannounced standardised patients presenting with common outpatient conditions. The standardised patients covertly tape recorded their visit and completed a checklist of quality criteria immediately afterwards. Their assessments were compared against independent assessments of the recordings by a trained medical records abstractor.

SETTING

Four general internal medicine primary care clinics in California.

PARTICIPANTS

144 randomly selected consenting physicians.

MAIN OUTCOME MEASURES

Rates of agreement between the patients' assessments and independent assessment.

RESULTS

40 visits, one per standardised patient, were recorded. The overall rate of agreement between the standardised patients' checklists and the independent assessment of the audio transcripts was 91% (kappa=0.81). Disaggregating the data by medical condition, site, level of physicians' training, and domain (stage of the consultation) gave similar rates of agreement. Sensitivity of the standardised patients' assessments was 95%, and specificity was 85%. The area under the receiver operator characteristic curve was 90%.

CONCLUSIONS

Standardised patients' assessments seem to be a valid measure of the quality of physicians' care for a variety of common medical conditions in actual outpatient settings. Properly trained standardised patients compare well with independent assessment of recordings of the consultations and may justify their use as a "gold standard" in comparing the quality of care across sites or evaluating data obtained from other sources, such as medical records and clinical vignettes.

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.

Non-organic visual loss

Visual complaints without a physical basis are not uncommon presentations to the general physician, the neurologist, or the ophthalmologist. These alleged visual disturbances may be psychogenic or feigned. The diagnosis is made when all possible contributory pathology of the visual system is excluded, and reassurance remains the cornerstone of management.

Threshold perimetry of each eye with both eyes open in patients with monocular functional (nonorganic) and organic vision loss

PURPOSE

To report a novel binocular perimetry test to identify monocular functional vision loss.

METHODS

In a prospective study, 10 patients with monocular functional vision loss, 10 patients with monocular organic vision loss, and 10 normal subjects were tested using a Humphrey automated perimeter attachment that performs central threshold perimetry of both eyes in a single test. First, patients were tested after being told their "good" (unaffected) eye was being tested; this was followed by a second identical test said to be on the "bad" (affected) eye. Two measurements were calculated for each subject: the functional component (deltaF), defined as the difference (in dB) between the mean threshold of the first and second tests, and the organic component (deltaO), the difference (in dB) between the mean threshold of the unaffected and affected eyes.

RESULTS

Patients with monocular functional vision loss produced lower thresholds when they thought their affected eye alone was being tested but little intereye difference (mean deltaF +/- SD = 17.35 +/- 7.50 dB; mean deltaO = 0.01 +/- 1.40 dB). Patients with monocular organic vision loss had little difference between tests and lower thresholds in their affected eye (mean deltaF = 0.84 +/- 1.15 dB; mean deltaO = 9.01 +/- 4.71 dB). Normal subjects demonstrated little intertest or intereye differences (mean deltaF = -0.15 +/- 0.78 dB; mean deltaO = -0.05 +/- 0.51 dB).

CONCLUSION

This perimetry method effectively distinguished between normal subjects, patients with monocular functional vision loss, and patients with monocular organic vision loss.