First data of a prospective study comparing the impact of Retinitis Pigmentosa linked to Usher Syndrome 1B caused by MYO7A mutations and non-syndromic on daily living one year apart

Abstract

Purpose : To investigate the impact over time of reduced visual function on daily living in Usher Syndrome 1B (USH1B) patients compared to non-syndromic retinitis pigmentosa (RP) patients.

Methods : 9 fully-sighted controls (CO), 10 USH1B and 15 RP patients performed two tasks at t₀ and t_+1year in the same experimental conditions. The mobility task consisted of moving around avoiding obstacles under 500 and 7.5 lux in an artificial street (Streetlab platform). The visual search task aimed to look for and grasp target objects among 48 placed in a kitchen in an experimental apartment (Homelab platform) under 500 lux. Errors and time parameters were measured. We compared the data collected at t₀ and t_+1year, analyzing separately those from patients whose vision remained stable (USH1B_st; RP_st) and those from patients whose visual acuity (VA) has decreased by at least 0.1 logMAR and / or visual field area (VF) has been reduced by at least 30% (USH1B_det; RP_det).

Results : At t_+1year, 3 USH1B and 6 RP patients’ vision has deteriorated (VA: p=0.042; VF: p=0.031). As at t₀, RP and USH1B showed reduced Pourcentage of Preferred Walking Speed (PPWS) (p<0.001) and greater number of collisions than CO (p<0.05) at t_+1year during the mobility task. There was no significant difference in PPWS and collisions between t₀ and t_+1year among USH1B_st and RP_st patients, nor among CO. At 7.5 lux, PPWS of RP_st increased by 3.9% from t₀ to t_+1year, whereas PPWS of RP_det decreased by 4.1% (ΔPPWS_t0-PPWS_t+1year: p=0.043). Trajectory errors increased by 64.3% from t₀ to t_+1year in RP_det and by 57.1% in USH1B_det. At t_+1year as at t_0, visual search task showed that searching time (ST) in RP and USH1B was slower than in CO (p=0.0001) and USH1B made more identification errors than CO (p=0.031). No significant difference between t₀ and t_+1year was observed in CO, RP_st and USH1B_st. At t_+1year, identification time of USH1B_st decreased by 26% – so they were faster – and made less errors than at t₀, whereas the one of USH1B_det increased by 9.7% (ΔST_t0-ST_t+1year: p=0.017; ΔErrors_t0-Errors_t+1year: p<0.0001).

Conclusions : The subjects' performance have an opposite evolution depending on whether or not their vision deteriorates. Further data are expected before the summer 2019 to confirm the results observed.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.