Flicker pupil perimetry: In search of an objective visual field test for young or neurologically impaired patients
Authors:   , Portengen Brendan Lucas 
Published: February 2024

The assessment of the visual field (VF) is crucial in ophthalmological and neurological examinations, providing insights into potential damage along the visual pathway. VF tests are generally cost-effective and non-invasive, aiding clinicians in locating suspected damage sites. Timely diagnosis of VF loss in young and neurologically impaired individuals is pivotal for effective patient care, yet current VF tests are subjective and unreliable in this population.

This thesis aims to develop an objective and reliable VF assessment tool for young and neurologically impaired patients. Chapter 1 introduces VF assessment in these groups, discussing testing methods, visual and pupillary pathways, and the challenges in developing pupil perimetry. The chapter outlines the thesis's aims and structure.

Chapter 2 shares insights from testing children's VFs with neurological impairment. Standard automated perimetry (SAP), the gold standard, proved reliable in only 22-44%, while a behavioral VF test significantly improved time to diagnosis. The importance of accurate, reliable, and timely VF testing for better care in neurologically impaired children is emphasized.

Chapter 3 explores pupil perimetry as an objective alternative to SAP, comparing three techniques in healthy adults. Gaze-contingent flicker pupil perimetry (gcFPP) proves superior in discerning large simulated visual field defects.

Chapter 4 investigates gcFPP's capability to detect physiological aspects and upper versus lower VF differences in healthy adults. The method elicits strong pupil responses, emphasizing its potential. Recommendations include a gray background to reduce light scatter and an attention task to enhance responses, highlighting the cognitive component.

Chapter 5 delves into the trade-off between luminance and color contrast in human vision, emphasizing both factors' importance. Chapter 6 explores visual stimulus characteristics affecting gcFPP accuracy in neurologically impaired adults, revealing benefits from high luminance and color contrast.

Chapter 7 synthesizes previous findings into the gcFPP method. It evaluates conventional gcFPP and a virtual reality version (VRgcFPP) in neurologically impaired adults. Conventional gcFPP demonstrates high discriminative power and reliability, while VRgcFPP shows moderate accuracy compared to SAP.

Chapter 8 also explores VRgcFPP's feasibility in healthy children aged 3-11, indicating the technology's potential for objective VF assessments in pediatric populations. The head-mounted device is well-tolerated, evoking strong pupillary responses, and interactive fixation tasks ensure children maintain focus during the virtual reality-based test.

In summary, this thesis proposes gcFPP as a robust and objective tool for VF assessment in young and neurologically impaired patients. By advancing conventional gcFPP and exploring its application in virtual reality, the thesis underscores the technology's potential for pediatric populations, setting the stage for further development and research.