Eye-tracking-based visual field analysis (EFA): a reliable and precise perimetric methodology for the assessment of visual field defects

Abstract

ObjectiveSeveral studies report evidence for training-related neuroplasticity in the visual cortex, while other studies suggest that improvements simply reflect inadequate eye fixation control during perimetric prediagnostics and postdiagnostics.Methods and analysisTo improve diagnostics, a new eye-tracking-based methodology for visual field analysis (eye-tracking-based visual field analysis (EFA)) was developed. The EFA is based on static automated perimetry and additionally takes individual eye movements in real time into account and compensates for them. In the present study, an evaluation of the EFA with the help of blind spots of 58 healthy participants and the individual visual field defects of 23 clinical patients is provided. With the help of the EFA, optical coherence tomography, Goldmann perimetry and a Humphrey field analyser, these natural and acquired scotomas were diagnosed and the results were compared accordingly.ResultsThe EFA provides a SE of measurement of 0.38° for the right eye (OD) and 0.50° for the left eye (OS), leading to 0.44° of visual angle for both eyes (OU). Based on participants’ individual results, the EFA provides disattenuated correlation (validity) of 1.00 for both OD and OS. Results from patients suffering from cortical lesions and glaucoma further indicate that the EFA is capable of diagnosing acquired scotoma validly and is applicable for clinical use.ConclusionOutcomes indicate that the EFA is highly reliable and precise in diagnosing individual shape and location of scotoma and capable of recording changes of visual field defects (after intervention) with unprecedented precision. Test duration is comparable to established instruments and due to the high customisability of the EFA, assessment duration can be shortened by adapting the diagnostic procedure to the patients’ individual visual field characteristics. Therefore, the saccade-compensating methodology enables researchers and healthcare professionals to rule out eye movements as a source of inaccuracies in pre-, post-, and follow-up assessments.

Visual field improvement in neglect after virtual reality intervention: a single-case study

“…To create the basic conditions for this we have developed two new tools in the field of diagnosis as well as in the field of rehabilitation. On the one hand, the perimetric tool "Eye tracking based visual field analysis" (EFA) helps us to obtain reliable and accurate assessment results on the patients' current visual field status as well as regarding potential changes after intervention (Leitner, Hutzler et al, 2021). On the other hand, the neuropsychological tool "Salzburg Visual Field Trainer" (SVFT) creates the virtual reality-based foundation for an accurate, controlled, and immersive rehabilitation situation (Leitner, Guetlin et al, 2021).…”

“…Against this background, we developed an eye tracking based-perimetric methodology for highly accurate pre-, post-, and follow-up assessments, i.e., "Eye Tracking Based Visual Field Analysis" (EFA) (Leitner, Hutzler et al, 2021). The EFA is based on static automated perimetry while additionally taking individual eye movements (with the help of an eye-tracker) in real time into account and compensating for them.…”

Salzburg Visual Field Trainer (SVFT): A virtual reality device for (the evaluation of) neuropsychological rehabilitation

“…This crucial factor is achieved as follows: In a first step the patients’ visual fields are diagnosed with the help of the EFA. Due to its eye-tracking-based adaptation process, highly accurate data regarding the patients’ perimetric status can be obtained [ 14 ]. Thus, this enables—in a second step—individually custom-tailored positioning of test stimuli in the SVFT, based on every patients’ respective visual field properties and the resulting individual characteristics of the border area between intact and defect visual field.…”

“…Using the blind spot as a marker of visual field measurement has a tradition in visual field research [ 20 ] and the German Ophthalmological Society (DOG) states that the blind spot should serve as a referential scotoma in every perimetric examination [ 21 ]. We already used this experimental paradigm successfully to investigate and show the high accuracy of the EFA [ 14 ].…”

“…To achieve robust and credible evidence for the effects of interventions based on the principles of VRT and for the issue of training-related neuroplasticity within the human visual cortex, we developed an eye-tracking based perimetric methodology (“Eye Tracking Based Visual Field Analysis” [EFA]) [ 14 ]. The EFA is based on static automated perimetry and additionally compensates individual eye movements during diagnosis in real time while providing a standard error of measurement of 0.44° of visual angle.…”