Pictorializing what people with glaucoma perceive in regions of visual field loss: Results from a novel iPad app

Abstract

Purpose : Glaucoma patients with peripheral vision loss subjectively describe their field loss as “blurred/missing parts” or “no vision compromise”. We developed an iPad app for patients to self-characterize perception within areas of glaucomatous visual field loss. We correlated subjective responses with parameters on the Humphrey visual fields (HVF).

Methods : Glaucoma patients with visual acuity ≥20/40 in each eye and stable and reliable HVF over 2 years were enrolled. An iPad app was designed to allow subjects to modify “blur”, or “dimness” on a sliding scale (Figure). Subjects were instructed to fixate centrally on a 2mx2m wall mounted scene (45°of field from center at 1m) and compare each area of the poster to the image on the iPad at 33 cm (central preserved field). Subjects then modified the iPad image to match their perception of the wall poster. Subjects were tested monocularly and binocularly. Monocular HVF were used to calculate an integrated binocular visual field index (VFI). iPad output was degree of blur/dim: normal, mild (0-5) and severe (5-10) noted on the iPad image at the 54 retinal loci tested by the HVF 24-2. This was compared to the corresponding threshold sensitivity values on the HVF 24-2. Right eye (OD), left eye (OS) and binocular (OU) data sets were analyzed separately.

Results : 36 HVF and iPad responses from 12 subjects (mean age 70± 8 years) were analyzed. The mean HVF-VFI was 77±21 OD, 76±21 OS, 83± 15 OU. The iPad responses at the retinal loci tested were categorized as normal (75% OD, 80% OS, 90% OU), mild blur (14% OD, 8% OS and 4% OU) and severe blur (12% OD, 12% OS and 6% OU). No subject reported dim or blackening response. For retinal loci with ≤ 10 db on HVF- most subjects reported blur (64% OD, 61% OS, 51% OU). For retinal loci with > 20 db on HVF, most subjects reported normal vision (87%OD, 91% OS, 96% OU). ROC curve analysis determined that the optimal cut-off HVF retinal sensitivity threshold value at which subjects reported blur in their visual field was 23 db (OD), 23.4db (OS) and 23.3 db (OU).

Conclusions : Glaucoma subjects pictorialized their field defects as blur; never dim or black as depicted in glaucoma simulations. A threshold value of 23 dB or lower resulted in visual blur. Our innovation allows translation of HVF data to real life visual experiences of patients with glaucomatous field defects.

This is a 2020 ARVO Annual Meeting abstract.