Novel mobility test to assess functional vision in patients with inherited retinal dystrophies
Daniel C Chung, Sarah McCague, Zi-Fan Yu, Satha Thill, Julie DiStefano-Pappas, Jean Bennett, Dominique Cross, Kathleen Marshall, Jennifer Wellman, Katherine A High, Daniel C Chung, Sarah McCague, Zi-Fan Yu, Satha Thill, Julie DiStefano-Pappas, Jean Bennett, Dominique Cross, Kathleen Marshall, Jennifer Wellman, Katherine A High
Abstract
Importance: This novel endpoint tracks functional vision changes in patients with inherited retinal dystrophies (IRDs) over time.
Background: The aims of the study were to determine whether a multi-luminance mobility test (MLMT) can detect functional vision changes over time in subjects with IRDs and to assess natural history and potential effects of investigational agents.
Design: This is a prospective, observational study.
Participants: Sixty-two subjects were enrolled. Sixty (29 normal sighted and 31 visually impaired) were eligible; 54 (28 visually impaired and 26 normal-sighted) completed all testing visits.
Methods: Subjects navigated MLMT courses three times over 1 year. At each visit, subjects completed testing using individual eyes, and both eyes, at up to nine standardized, increasing luminance levels (range 1 to 400 lux). Accuracy and speed were evaluated and compared with visual acuity (VA), visual field (VF) and a visual function questionnaire.
Main outcome measures: Accuracy and speed of normal and visually impaired subjects on MLMT, and reliability and content validity of MLMT were the main outcome measures.
Results: MLMT distinguished normal-sighted from visually impaired subjects. All control subjects passed all MLMT attempts at all tested light levels. Visually impaired subjects' performance varied widely; some declined over 1 year. Performance declined markedly below certain VA and VF thresholds. Concordance on performance on two baseline visits was high: correlations for accuracy were 94% and 98% for lowest common and highest common lux levels.
Conclusions and relevance: MLMT differentiated visually impaired from control populations and, in visually impaired subjects, identified a range of performances; and tracked performance declines over time, consistent with these progressive conditions.
Keywords: functional vision; inherited retinal dystrophy; luminance; mobility test.
Conflict of interest statement
Competing/conflicts of interest: Spark authors (DCC, KAH and JW) are employees of Spark Therapeutics and hold equity in the company. The following authors are inventors on a submitted patent related to the MLMT: Daniel C. Chung, Jean Bennett, Jennifer Wellman, Sarah McCague and Katherine A. High. Zi-Fan Yu and Satha Thill provided statistical consulting to Children’s Hospital of Philadelphia (CHOP) and Spark Therapeutics through their employer, Statistics Collaborative, Inc. Julie DiStefano-Pappas provided data management services to CHOP and Spark Therapeutics through her employer, Westat, Inc. Jean Bennett and Kathleen Marshall are inventors on a copyright for the visual function questionnaire.
© 2017 Royal Australian and New Zealand College of Ophthalmologists.
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Source: PubMed