Diagnosis Of Functional Visual Loss Research Articles

English

BACKGROUND Attenuation of vision may be due to underlying organic condition or due to functional visual disorder or malingering if secondary gain is associated. Causes of pathological vision loss include advanced primary open angle glaucoma, hereditary macular dystrophies and optic neuropathies. Problem in establishing diagnosis is faced where superimposition of organic and functional visual loss is there. Distinction between functional visual loss and pathological visual loss is made by thorough and careful examination of the patient by applying basic rules and tools of ophthalmology in which examining surgeon is well versed, but patient is unaware. During routine practice, every ophthalmologist encounters patients with nonorganic vision loss. The purpose of the article is to demonstrate how to distinguish between normal visual function without missing any organic visual loss. Examination of such patients requires number of tests including baseline visual acuity, pupillary reactions, slit lamp examination of anterior segment, fundus examination, visual field analysis, optical coherence tomography, visual evoked potential and electroretinography. By proving integrity and functioning of visual system, diagnosis of functional visual loss can be confirmed. Once the conclusive diagnosis is established, it is to be revealed with caution to the patient/patient’s attendant as it can lead to medico legal issues. Here, we present series of cases who presented to us in a tertiary care center of North India during a period of six months in the year of 2019 where case 1 and case 2 presented with decreased vision due to underlying pathological condition, case 3 presented with reduced vision due to functional visual disorder. Case 4, 5 and 6 provided decisive evidence of malingering. KEY WORDS Fogging, Hysterical Visual Loss, Malingering, Menace Reflex, Optokinetic Nystagmus.

Conversion Disorder Manifesting as Functional Visual Loss.

Children with conversion disorder experience neurological symptoms without a definable organic cause. Clinical presentation of conversion disorders is uncommon in the emergency department (ED). An 11-year-old previously healthy girl presented to the ED for management of lobar pneumonia. She developed acute visual loss subsequent to accidental placement of an intra-arterial cannula in her arm. Clinical assessments by the emergency physician, neurology, ophthalmology, and psychiatry services, and negative neuroimaging studies established the diagnosis of functional visual loss as a manifestation of conversion disorder. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Conversion disorder symptoms are often without any specific markers and do not fit standard clinical guidelines. A comprehensive and step-wise evaluation of unusual clinical presentation by multiple specialties and ancillary test results should be considered to rule out organic causes and establish the diagnosis of conversion disorder, as seen in our patient.

Bilateral Concurrent Eye Examination with a Head-Mounted Perimeter for Diagnosing Functional Visual Loss

ABSTRACTThe authors here report a case series where bilateral concurrent eye examination, using a head-mounted perimeter (imo®), was employed to facilitate diagnosis of functional visual loss, as regular ophthalmological tests were ineffective. Subjects (11-year-old female, 15-year-old male, and 24-year-old male) were diagnosed with unilateral functional visual loss by using the imo®, at the Kitasato University hospital. The results of the imo® and those of Goldmann perimetry or Humphrey Field Analyzer II differed for all subjects, which is indicative of potential functional visual loss. Bilateral concurrent examination with the imo® may become a standard for future diagnosis of unilateral functional visual loss.

Sensitivity and specificity of the step VEP in suspected functional visual acuity loss

Early and accurate diagnosis of functional visual loss (FVL) allows optimum management. Visual evoked potentials (VEPs) offer a means of objectively estimating acuity and therefore could assist with early and accurate diagnosis. The aim of this study was to assess the sensitivity and specificity of the step VEP in diagnosing FVL. A retrospective audit was conducted in 36 school-aged children presenting with reduced visual acuity and clinical suspicion of FVL. All had undergone step VEP testing as part of their investigation. Medical notes were reviewed, and where necessary, referring centres, general practitioners or electronic clinical portals were consulted to obtain longer-term outcome data. Twenty-seven of the 36 patients (75%) were classified as having had FVL: all had a normal step VEP spatial threshold. Nine patients (25 %) had an organic cause for their acuity loss, of whom seven had abnormal step VEP spatial thresholds: the other two patients had some functional overlay to their organic disease. The step VEP sensitivity was 78% (95% confidence interval 40-96%), and specificity was 100% (95% confidence interval 84-100%). The high specificity of the step VEP for FVL warrants increased suspicion of an organic cause should the step VEP spatial threshold be abnormal.

Normal sensory and absent cognitive electrophysiological responses in functional visual loss following chemical eye burn

To present a unique case of a 34-year-old patient with unilateral functional visual loss after chemical burn with normal visual evoked potentials (VEPs) and absent cognitive response (P300 wave). Visual functions, complete ophthalmic and neurologic examinations including computed tomography of the brain, electrophysiological testing of the visual pathway up to the cognitive brain cortex were evaluated. Data were collected prospectively during 1-year follow-up and compared with data from published case series and a literature review. No abnormalities were found that could account for such a rapid monocular loss of vision with exception of absence of the P300 wave in the affected eye during cognitive tasks. Vision slowly improved during 1year without any treatment. Functional vision loss is a diagnosis of exclusion. In the event of reduced vision in the context of a normal ocular health examination, all other pathology must be ruled out before the diagnosis of functional visual loss is established. Complex visual electrophysiological testing is the preferred tool for objective examination of such disorders.

The Role of Visual Evoked Potentials in the Differential Diagnosis of Functional Visual Loss and Optic Neuritis in Children

This study aims to determine whether visual evoked potentials can aid the diagnosis of functional visual loss and differentiate it from optic neuritis in children. The medical records and visual evoked potentials of 72 patients registered in the neurophysiological database of our Institution in the period 2000-2009, with diagnoses of functional visual loss or optic neuritis were reviewed retrospectively. In 61 children, visual evoked potentials confirmed the diagnosis: 49 functional visual loss and 12 optic neuritis. Visual evoked potentials were normal in all patients but 1 in the functional visual loss group, while all were abnormal in the optic neuritis group. Overlapping clinical features occurred between the 2 groups as well as prevalent severe visual loss, relative afferent pupillary defect, and papillitis in optic neuritis. Visual evoked potentials are of value in confirming clinical suspicion of functional visual loss, particularly when clinical overlap with optic neuritis occurs.

Functional Visual Loss in Idiopathic Intracranial Hypertension

To identify and describe patients with idiopathic intracranial hypertension (IIH) with concurrent functional visual loss (FVL). Observational, retrospective case series. Seventeen patients with IIH and FVL. Clinical features were collected retrospectively. Data from 281 cases of IIH were analyzed for concurrence of FVL. Occurrence of FVL diagnosed at presentation or on subsequent follow-up. Seventeen patients had FVL and IIH. Of the 17 patients with FVL and IIH, 11 (65%) had FVL on presentation, with the remaining 6 patients developing FVL after initial presentation. Two patients in this cohort had documented recurrence of their IIH. There were several common patterns of FVL. All 17 patients had functional visual fields, with 82% having tubular fields and 71% exhibiting nonphysiologic constriction on perimetry testing. Seventy-six percent of patients had nerve/field mismatch showing no atrophic disc changes. Eighty-eight percent of patients had significant psychiatric, psychosocial, or other medical comorbidities. The majority of patients were managed surgically at some point in their clinical history, with 53% having nerve decompression, shunt, or both. Three patients had optic nerve sheath fenestrations after the diagnosis of FVL. Results suggest a high prevalence of FVL in IIH with a potential association with psychiatric illness and psychosocial stressors requiring careful consideration before surgical intervention. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Medically unexplained visual loss in adult patients

In this review, we discuss the investigation and management of patients with visual loss that cannot be accounted for by organic pathology. Because visual loss in these patients often has a psychosocial basis, we do not like the term 'medically unexplained visual loss' as a diagnostic label. 'Unexplained visual loss' is a useful working diagnosis until occult pathology is excluded and a positive diagnosis of functional visual loss (FVL) can be established. Recent literature highlights the utility and limitations of visually evoked potentials in estimating objective visual acuity. Multifocal electroretinography and ocular coherence tomography are invaluable in revealing occult macular pathology that may not be apparent to clinical examination and full-field electroretinography testing. Cortical visual loss can be mistaken for FVL. There is still no evidence base to guide our management of patients with FVL. However, useful insights can be gained from the literature on functional symptoms in other specialties. Making the diagnosis of FVL demands vigilance but is important to do. It should mark not just the end of investigation, but the start of treatment. More research is needed to see if treatments used in other functional disorders work in FVL.

Prevalence of organic Neuro-ophthalmologic disease in patients with functional visual loss

PurposeTo determine the concurrence of various patterns of functional visual loss (FVL) and organic disease. DesignA retrospective case series in a university neuro-ophthalmology practice. MethodsA retrospective case series in which we reviewed the clinical histories and neuro-ophthalmologic examinations of 133 consecutive patients diagnosed with FVL between July 1999 and August 2001. Functional visual loss was defined as an apparent afferent or efferent dysfunction that was unassociated with or far out of proportion with an identifiable lesion of the visual pathways. ResultsA total of 133 patients were identified. Nineteen were pediatric, and 76 were female. Fifty-six had concurrent head or eye pain. Nineteen had a recent history of trauma, and 17 had a recent surgical procedure. The most common pattern of FVL was a normal visual field in the presence of reduced visual acuity. Seventy-one patients (53%) with FVL presented with abnormal neuro-ophthalmologic examinations. Thirteen patients had central scotomata, and all had concurrent retinal or optic nerve pathology. Only 18 patients had a known disability claim pending. ConclusionAlthough FVL was found in patients with no pathology, it was more common to find objective abnormalities on examination. This concurrence rate underscores the clinical necessity for following patients closely despite the diagnosis of FVL. No pattern of visual field constriction was routinely predictive of ophthalmologic or neurologic pathology except the presence of a central scotoma. The presence of a central scotoma in a nonorganic visual field should alert the practitioner to search for organic pathology.

Foveale Zapfendystrophie: Diagnostischer Stellenwert des multifokalen Elektroretinogramms

In case of visual loss without morphologic pathology differentiation between a functional visual loss and a retinal disorder may be difficult. We report on two women, aged 33 and 44, who were complaining of a progressive visual loss occurring over the past several weeks to months. They were referred to our department with the presumed diagnosis of functional visual loss. Biomicroscopy of the anterior and posterior segments, perimetry (Goldmann), colour (FM-100-Hue-Test) and stereopsis testing (Lang-Stereotest), fluorescein angiography (FLAG) and electrophysiological testing (P-ERG, VECP, EOG, multifocal electroretinography [mfERG]) were performed. Visual acuity was 0.16 OU and 0.25 OU respectively. A small relative central scotoma (I/1) was detected by dynamic perimetry. Colour vision, random-dot stereopsis and the results of electrophysiological testing except multifocal electroretinography (mfERG) were normal. The mfERG was able to detect a cone dysfunction which was related to the fovea. In case of visual loss of unknown etiology electrophysiological testing is indicated. The mfERG as an objective diagnostic method is able to detect a foveal cone dystrophy.

Pattern visual evoked potential in the diagnosis of functional visual loss

Objective To study the pattern visual evoked potential (P-VEP) in the diagnosis of functional visual loss. Study design Retrospective study of observational case series. Participants Seventy-two subjects whose best corrected visual acuity (VA) was 20/50 or worse, with or without visual field defect, and whose visual abnormalities could not be explained by the findings of ophthalmologic and neurologic examination were included in this study. Main outcome measures To compare the P-VEP estimated acuity to the initial subjective VA and to the best-performed VA. Results Seventy-two subjects with functional visual loss had normal P-VEPs. The initial subjective VA was 20/50 in 9 subjects and ≤20/200 in 42 subjects. After clinical examination and reassurance, the best-performed VA was ≥20/50 in 53 subjects and ≤20/200 in 8 subjects. The discrepancy between the P-VEP estimated acuity and the best-performed VA was less than 3 lines of Snellen acuity in 63 of 72 (87.5%) subjects and more than 4 lines in 6 subjects. These six subjects were three women with loss of vision of unknown origin and three men with injury-related visual loss. Conclusions P-VEP has the advantage of objectively predicting VA and is a useful test in the diagnosis of functional visual loss.