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To better understand what patients with peripheral vision loss due to glaucoma see, researchers developed an iPad application that enables patients to select images that illustrate their visual field defects. Findings of their study have been published in the British Journal of Ophthalmology.
In previous research, patients with glaucoma have described their vision symptoms as “missing,” “blur,” or “needing more light,” and their scotomas as blurred, missing, grey or normal, according to investigators. The objectives of this study were to develop an iPad app for patients with glaucoma to illustrate their visual field loss and validate the application by correlating subjective responses with parameters obtained via automated perimetry.
To accomplish this, the research team enrolled 12 glaucoma patients with visual acuity 20/40 or worse in each eye, stable and reliable Humphrey Visual Field (HVF) for longer than 2 years in the study. An iPad app held at 33 cm allowed patients to modify “blur” or “dimness” to match their perception of a 2×2 m wall-mounted poster at 1 m distance. Participants fixated at the center of the poster (spanning 45° of the field from the center). The degree of blur/dim (normal, mild, or severe) was noted on the iPad image at the 54 retinal loci and was compared with threshold sensitivity values at these loci. Monocular HVF responses were used to calculate an integrated binocular visual field index (VFI).
In total, 36 HVF and iPad responses from 12 study participants (mean age 71 years ± 8.2 years) were analyzed separately. The mean VFI was 77% OD, 76% OS, and 83% OU. The most common iPad response reported was “normal,” followed by “blur.” None of the participants in this study reported “dim” or “black” as a characteristic of their vision loss. The mean HVF sensitivity threshold was significantly associated with the iPad response at the corresponding retinal loci (For OD, OS and OU, respectively (dB): normal: 23, 25, 27; mild blur: 18, 16, 22; severe blur: 9, 9, 11). On receiver operative characteristic (ROC) curve analysis, the HVF retinal sensitivity cut-off at which participants reported blur was 23.4 OD, 23 OS and 23.3 OU (dB).
The study says the team has successfully designed and tested the novel iPad app for patients with glaucoma to self-pictorialize their visual experience.”This innovation fills a gap in the translation of clinic-derived automated perimetry used to monitor and treat glaucoma and its real-world impact on patients.”
Researchers noted several limitations to this study’s findings, including that only participants with good central vision and preserved cognition (high MoCA scores and reliable visual fields) were included. Second, each participant performed the test once for each eye, so the investigators did not evaluate test-retest variability and the learning effect. Third, an eye tracker was not used. Lastly, the study did not examine changes in color, vision-related quality of life, awareness of field loss, and the emotional impact of disclosing the disability to the patients.
Reference
Gagrani M, Ndulue J, Anderson D, et al. What do patients with glaucoma see: a novel iPad app to improve glaucoma patient awareness of visual field loss. Br J Ophthalmol. Published Online: November 20, 2020. doi:10.1136/bjophthalmol-2020-317034.
