Navigating the differential diagnoses of possible malingerers within the paediatric population

KEYWORDS:

• Functional vision loss
• malingering
• paediatrics
• Streff syndrome

Introduction

Streff syndrome poses as a significant clinical challenge, with complex environmental, physical, and emotional components necessitating a flexible and in-depth diagnostic approach. With prevalence highest within the paediatric population, objective clinical testing, and thorough history-taking are imperative to determine the most accurate diagnosis.

Streff syndrome is an involuntary condition characterised by bilateral amblyopia, near point stress and decreased ocular function, including motilities.¹ Such changes often present in the absence of any significant refractive error or ocular pathology. Unlike the more common forms of amblyopia (attributed to anisometropia, strabismus or visual deprivation), Streff syndrome does not result in chronic retinal blur. It is a misperception of the visual environment, whereby psychological stress manifests as a functional change in vision.²

Streff syndrome is defined as having a visual acuity of 6/7.5 or worse, refractive error between plano to +1.00 DS, no improvement in visual function with refractive correction, lowered achievement in school, reduced stereopsis, colour vision and/or constricted visual fields.^1,3 This condition does not usually present with visual acuity deficits in isolation, but secondary to some form of accommodative/vergence disorder.⁴

This psychogenic condition most often presents in juvenile patients between the ages of 6 and 12, with prevalence almost double in the female population comparative to males.⁵ Studies have revealed a significant correlation between visual processing and emotional states.⁶ This case report emphasises the need to investigate and treat patients beyond the realm of ocular health, that is, in a holistic manner that encompasses social, physical, and emotional aspects.

Case report

An 8-year-old female presented to the clinic with broken spectacles. The patient was quite shy on initial presentation and did not divulge much information, apart from difficulty with seeing the board at school. Underlying systemic health issues were investigated through a comprehensive history, which was unremarkable. She had been prescribed low plus distance spectacles (+0.25 DS) previously, but felt that they were ineffective. There was no family history of strabismus – only mild astigmatism amongst siblings.

While the reported history of mild hyperopia suggested that perhaps a refractive issue was the most likely culprit, further clinical investigation was warranted. Best-corrected visual acuity was measured as R&L: 6/9.5. Examination via dry retinoscopy revealed mild long sightedness, with R: +0.25/-0.25×180, L: +0.50/-0.25×10.

Upon gross observation, the patient appeared to have a small right ptosis, which became more evident as the consult progressed. Ocular motilities revealed a full range of movement; however, diplopia was reported on abduction in all lateral gazes in both eyes. No observable over-action or under-action was observed in the eight cardinal positions of gaze. There was no evidence of any ocular misalignment or strabismus via cover testing.

Further assessment of binocular vision, however, did reveal intermittent suppression of the right eye (at both 6 m and 30 cm). Randot stereopsis assessment (at 30 cm) revealed poor stereoacuity, with 250 s of arc. Both near point of convergence and accommodative posture were within normal limits. However, the patient was unable to clear ± 2.00DS, suggesting potential infacility. The ratio of accommodative convergence per dioptre of accommodation was relatively flat to both plus and minus.

Ishihara colour vision testing was subsequently attempted; however, the patient failed to correctly identify the number on the practice plate. As a diagnostic tool, an additional isochromatic test plate was presented to the patient. She verbally responded with a numerical value, which was similarly incorrect. A final test was attempted, and instead of providing a verbal response, the patient was asked to trace the snake line, which she completed successfully. Such findings aroused suspicions of malingering.

The patient returned that afternoon for cycloplegic examination. Before instilling cycloplegic drops, visual acuity was re-assessed, and the same results were obtained (R&L: 6/9.5). To further rule out potential malingering, the patient was asked to stand in front of the mirror, facing the visual acuity chart, so measurements were now, effectively at 3 m. Logically, the patient should have been able to surpass the 6/9.5 line, given this measurement was originally obtained at a further distance away (6 m). Despite this, visual acuity did not improve. Consequently, a plano lens was placed in front of the dry retinoscopy result, with the emphasis that, ‘this lens should help’. The patient (correctly) indicated there was no improvement. Cycloplegic refraction revealed only a minor amount of additional plus in both eyes.

Given these preliminary findings, exclusion of any organic or neurological pathology was important. Dilated fundus examination of the posterior pole and optic nerve was unremarkable. No disc pallor was noted nor any sign of papilloedema in either eye. Analysis of the ganglion cell complex and macula via optical coherence tomography were similarly unremarkable. Red cap testing was equal between the eyes, pupils were reactive to light, and there was no evidence of a relative afferent pupillary defect in either eye.

Automated threshold perimetry (Humphrey 24-2C SITA Faster) was performed and revealed generalised loss in both eyes. Although the visual field results did not reflect a ‘textbook’ clover leaf pattern (as typical in functional loss), a similar, but more diffuse pattern was noted. The Glaucoma Hemifield Index was outside normal limits, with corresponding visual field indices <95% in both eyes.

Despite the expanse of clinical data implicating visual impairment, no underlying pathology could be identified. Thus, a more in-depth consideration of contextual factors was warranted. Through a more circumspective discussion, the patient divulged recent physical abuse at school. Her father elaborated on the severity of such abuse, whereby confluent bruising could be seen over the entirety of her back torso.

Discussion

The discrepancy in findings between subjective and objective tests prompted further exploration of underlying aetiology. Subjective clinical testing revealed a decrease in visual acuity, significant diplopia in lateral gazes, and reduced stereopsis.

Bilateral visual field deficits were noted, the pattern of which resembled a diffuse clover-leaf. In contrast, objective evaluation revealed minimal hyperopia on cycloplegic refraction, and no abnormalities on optical coherence tomography or fundoscopy. The discrepancy between objective and subjective results is suggestive of functional vision loss – a broad term which often encompasses malingering or neurological dysfunction.

Malingering was considered as a preliminary diagnosis, given the negligible improvement in visual acuity at 3 m compared to 6 m. In addition, the incongruous colour vision deficit to numbers but not patterns aroused further suspicion. Despite this, the patient (correctly) reported no improvement in the ‘plano lens test’. However, as her acuity was only a few lines off 6/6, the level of disparity inferred by the plano lens may have been insufficient to elicit a perceptual difference.

In future, similar clinical presentations may benefit from alternative acuity-based tests, particularly in cases where vision is close to normal. For example, using a cylindrical lens to blur vision and incrementally reduce power, reviewing acuity at each step, to gauge ability to achieve 6/6.

Given the well-documented association between external stressors (such as bullying) and mental ill health – in concordance with the reported visual strain and discrepancy between subjective and objective findings – a condition of neurogenic aetiology, such as Streff syndrome, was considered most likely.^6,7

For effective treatment, it is important to recognise that Streff syndrome is a psychological problem with a visual manifestation. This condition exemplifies the interplay between environmental/social pressures and their ability to elicit abnormal ocular presentations in the absence of pathology. Consequently, lifestyle modification and supportive therapy are essential for recovery, with psychotherapy forming the central pillar of treatment.^3,8

It should also be noted that limited evidence exists to suggest that low-plus therapy, or any additional treatment paradigms, is more effective than placebo.³ A range of treatment options pertaining to psychotherapy, counselling, and school-based restorative practice were discussed, with consideration given to social, emotional, and environmental factors. A referral was sent to the family doctor and school counselling team, which accentuated the absolute requirement for strong supportive therapy, inclusive of school counsellors and medical professionals. Low plus spectacles were also prescribed, given the correlation with vergence and/or accommodative anomalies.^2,4 A clinical review was scheduled in 1 month.

Alternative therapies may provide supplementary support for patients with Streff syndrome. Together with basic mindfulness, positive visual imagery can be used to redirect attention away from negative emotions and regain individual control.^3,9 In addition, photonic stimulation of the autonomic nervous system has shown to increase communication between the retina and hypothalamus.¹ In this way, syntonic phototherapy may contribute to emotional stabilisation and improved visual-perceptual outcomes.

Conclusion

A female patient presented to the clinic with decreased vision and history of long-term spectacle wear, despite a minimal hyperopic prescription. Clinical examination revealed a discrepancy between subjective and objective clinical results. Further discussions revealed severe bullying at school, resulting in physical and emotional decline. Considering the clinical incongruencies in accordance with the underlying psychological trauma, the patient was diagnosed with Streff syndrome.

This case report highlights the importance of employing a holistic approach in clinical decision-making, with consideration given to social, environmental, and psychological stressors, rather than just biological. Furthermore, where clinical presentations demonstrate no significant visual issue, interdisciplinary collaboration with educators and healthcare professionals is important for recovery.

Disclosure statement

No potential conflict of interest was reported by the author(s).