[Functional reduction of vision symptomatic of a conversion reaction in paediatric population]

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.

Colour Vision Disorder due to Conversion Disorders in Childhood

BACKGROUND

Non-organic vision loss can manifest in various ways, most commonly in the form of reduced vision and visual field defects. Colour vision disorders in the context of a conversion disorder have only rarely been reported.

MATERIALS AND METHODS

This review presents the case of a 9-year-old boy with a colour vision disorder as the isolated symptom of a conversion disorder. The challenging in this case was an additional somatic comorbidity - a congenital red-green deficiency. Consequently it was difficult to make a diagnosis and to convince the parents.

CONCLUSION

It is important to rule out organic causes and establish the diagnosis of a conversion disorder. In these cases, multidisciplinary treatment is crucial for a successful outcome. The diagnosis may be especially challenging when the patients have both somatic and psychogenic complaints.

Dissociative Visual Loss in Children and Adolescents

Psychogenic vision disorders in children and adolescents are a common disorder primarily encountered by ophthalmologists at the onset because, as with other disorders of dissociation, the presentation suggests a neurologic or other somatic condition. Loss of visual acuity, blurred vision and visual field restriction-often described as tunnel vision-appears to be typical. The onset may be sudden, frequently related to a wide range of stressful life events (school failure, family conflicts, accidents). While the majority of these children quickly recover from their symptoms, a substantial percentage experience persistent symptoms or a fluctuating course. Due to the lack of efficacy studies of specific treatment protocols, diagnostic work-up and treatment suffer from a high degree of uncertainty. Differentiating dissociative visual loss from physical illness requires special expertise. The uncertainty of ophthalmologists and the other specialists involved in dealing with this clinical condition often delays the specialised treatment and may also trigger inadequate therapy with the iatrogenic risk of harming the patient. This article primarily describes the disorder-specific psychiatric diagnostic as well as the somatic differential diagnostic work-up and outlines the therapeutic principles of dissociative visual loss.

[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.

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.