Clinical evaluation of eye-movement perimetry in glaucoma

Glaucoma is a chronic eye disease that eventually can lead to irreversible
blindness. Visual field (VF) testing is an important tool for detecting,
characterising and monitoring vision loss in glaucoma. The current gold
standard to measure the visual field is standard automated perimetry (SAP).
This technique requires prolonged focussed attention, understanding of the
test, and multi-tasking. These requirements exclude valid and reliable use of
SAP in very young and very old persons or persons with cognitive and/or motor
impairments, critically limiting the quality of vision care and rehabilitation
services such persons should receive. Eye-movement based techniques for
perimetry are a potential alternative to SAP as these do not require manual
responses and simplify the approach. In particular eye-movement based responses
can be used to detect glaucomatous visual field defects via slowed saccadic
reaction times to peripheral targets (Kadavath Meethal et al., 2018; Mazumdar
et al., 2014; McTrusty et al., 2017; Pel et al., 2013). The BulbiCAM (BulbiTech
AS, Trondheim, Norway) performs eye-movement perimetry by measuring saccadic
reaction times to peripherally presented targets. It uses a virtual reality
(VR) headset that measures both eyes separately as each eye looks at a
different screen. Recently, we took a distinctive approach towards eye movement
perimetry with the Eye-Movement Correlogram test (SONDA) in which we measure
eye-movement based tracking performance of a continuously moving stimulus,
shown on a regular display screen while the eyes are being tracked with a
remote eyetracker. In an earlier study (Study ID: NL70382.042.20; METc
2020/043) we have optimised this stimulus (Vrijling, de Boer et al 2023) and we
have shown that glaucomatous VF defects affect the tracking performance. The
results indicate that the SONDA can potentially be used as a fast and reliable
perimetric screening method for glaucoma in regular ophthalmic care. If proven
to be true, this could be an important development to improve vision care.
Therefore, to further this use of eye-movement based perimetry approaches in
clinical care, in this study, we aim to validate both the SONDA and the
BulbiCAM in a large, independent sample of glaucoma patients and age-matched
control participants in order to determine their diagnostic performance. And we
will determine the user friendliness for each perimetric technique with a
feedback questionnaire.

To determine the diagnostic performance (sensitivity, specificity, and area
under the ROC curve) of the current eye-movement based perimetry techniques,
SONDA and BulbiCAM, as potential screening instruments for glaucomatous VF
defects in ophthalmic practice.
To determine the userfriendliness of the perimetric techniques (feedback
questionnaire)

Observational case-control study.

The SONDA and the BulbiCAM tests themselves are very simple to perform; the
task for the participant consists of following a moving and jumping dot on a
screen with one*s eyes for the SONDA, and looking at appearing dots for the
BulbiCAM while the eye movements are tracked with an eyetracker. Total testing
takes at most 20 minutes (about 6-7 minutes per technique; for the SONDA we use
two versions: our experimental setup (SONDA-Eyelink) that was used to develop
the technique and a prototype of a version suitable for future clinical use;
SONDA-Neon). In addition, for control participants only, a short eye-health
check of approximately 20 minutes is performed to ensure eye-healthiness.

Participants will be made aware that they can refuse or end participation in
the study at any time. For all control participants: if any abnormal screening
results are obtained in the short eye-health check, they will be referred to
their GP. Detection of signs of an eye condition may come as an unexpected,
unpleasant surprise, however, an early diagnosis will allow treatments to be
initiated and therefore enable more preservation of visual functioning.

All participants will be asked to fill out a feedback questionnaire (see form
F1b), that will be used to qualitatively evaluate the user friendliness of each
perimetric technique.

Total test time and location:
- glaucoma patients: 20 minutes
- control participants: 40 minutes (including a short eye-health check of
approximately 20 minutes

The eye-health check will be conducted at the Ophthalmology Outpatient Clinic,
UMCG Groningen. The SONDA and the Bulbicam will be conducted at the Laboratory
for Experimental Ophthalmology, UMCG Groningen