Gait Patterns in Severe Peripheral Field Loss due to Retinitis Pigmentosa

Abstract

Purpose : Peripheral field loss (PFL) can adversely impact mobility. However, the effect of severe PFL on specific gait parameters has not been well-described. Gait parameters could serve as novel outcome measures for future studies to evaluate interventions for improving mobility in severe PFL. Using data from a pilot clinical trial, we sought to compare gait patterns in participants with severe PFL due to retinitis pigmentosa (RP) and controls.

Methods : Participants were recruited from the Kellogg Eye Center who had RP, presenting visual acuity >20/60 in both eyes, and a maximum horizontal extent of 20° on the III4e isopter of the Goldmann visual field (GVF). Controls had a normal eye exam and visual acuity ≥20/25 in both eyes and were matched to participants based on age and sex. Inertial measurement units (IMU; Actigraph GT9X) were fit to each foot and to a headband worn around the forehead while participants walked roundtrip down a 30.8-meter hallway free of obstacles. Gyroscope and accelerometer data from IMUs was used to recreate the 3-dimensional kinematic trajectories of the feet as participants moved down the hallway. From foot trajectories we calculated lateral and forward stride variability. The Student’s t-test was used for statistical analyses.

Results : We included data from 7 participants with RP (mean age 27.4 years, 29% female) and 7 controls. Among participants with RP, mean visual acuity was 0.2 logMAR and the GVF was 14.9 degrees in the better-seeing eye. Figure 1 illustrates the forward and lateral stride variability for one participant in the study. Figure 2 depicts stride variability comparing all RP and control participants. The mean lateral stride variability was 0.15 m and 0.12 m for RP and controls (p=0.09), respectively. The mean forward stride variability was 0.07 m and 0.05 m for RP and controls, respectively (p=0.16).

Conclusions : There was a statistically non-significant trend toward greater lateral and forward stride variability among participants with RP compared to controls. Future studies with larger samples and more challenging walking courses could reveal meaningful differences in gait parameters that could serve as novel outcomes for future clinical studies to improve mobility in severe PFL.

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

 

Stride variability for one participant in the study. The eclipse highlights the variability in this inidvidual's strides.

 

Stride variability comparing retinitis pigmentosa and controls.