Tablet‐based 'ON/OFF' pathway test can distinguish between rod‐ and cone‐dominated diseases. (22nd November 2022)

• Record Type: Journal Article
• Authors: Hathibelagal, Amithavikram R.; Bhutia, Phuntsok; Das, Mritunjoy; Babu, Helna; Jalali, Subhadra; Takkar, Brijesh; Paremeswarappa, Deepika C.; Ballae Ganeshrao, Shonraj
• Is Part Of: Ophthalmic and physiological optics. Volume 43:Number 2(2023)
• Page Start: 231
• Page End: 238
• Publication Date: 2022-11-22
• Subjects: inherited retinal disease -- ON function -- retinitis pigmentosa -- rod photoreceptor -- Stargardt disease; Ophthalmology -- Periodicals; Physiological optics -- Periodicals; Optometry -- Periodicals; Optics -- Periodicals; Vision -- Periodicals; 617.75
• DOI: 10.1111/opo.13072
• Languages: English
• ISSNs: 0275-5408

Abstract

Abstract: Introduction: The photopic ON pathway defect is associated with nocturnal vision loss. However, the measurement of ON function to detect a rod‐dominated disease (rods affected more than cones) has not been explored. We evaluated whether the psychophysical evaluation of ON/OFF pathways can be used to distinguish cone‐dominated from rod‐dominated diseases. Methods: Thirty‐seven patients with inherited retinal diseases were tested using the 'EyeSpeed' [iOS application] on an iPad. The test displayed a random number (1–3) of light or dark targets on a black‐and‐white noise background. Participants responded on a touch screen indicating the correct number of targets displayed. The outcome variables—reaction time, accuracy and performance index (speed [1/reaction time] * accuracy) to both light and dark targets were assessed for diagnostic ability using standard receiver‐operating characteristic (ROC) analysis. Results: Mean ± standard deviation age and visual acuity for the cone‐ and rod‐dominated groups were 25.15 ± 11.74 years, 0.80 ± 0.25 logMAR and 28.3 ± 14.29 years, 0.48 ± 0.26 logMAR, respectively. The median reaction time to light targets in rod‐dominated disease [interquartile range] was 5.28 s [3.17], significantly greater than for patients with cone‐dominated disease (2.07 s [0.93]; Mann–Whitney U test, p < 0.001). Amongst all of the outcome variables evaluated, the reaction time to light targets (criterion of ≥2.98 s) exhibited the highest area under the ROC curve (area = 0.89 ± 0.11; p < 0.001), with a sensitivity and specificity of 82.4% and 85% respectively. Conclusions: Reaction time to light targets using the ON/OFF pathway paradigm is a valid marker to differentiate between rod‐ and cone‐dominated retinal dystrophies. ON pathway function measured using a tablet‐based test could act as a supplemental test in the diagnosis of challenging photoreceptor‐specific inherited retinal diseases.