title: Physical activity restriction in age-related eye disease: a cross-sectional study exploring fear of falling as a potential mediator.
abstract: BACKGROUND
  Fear of falling (FoF) is predictive of decreased physical activity. This study sought to determine if FoF mediates the relationship between decreased vision and physical activity restriction in individuals with glaucoma and age-related macular degeneration (AMD).
  
  
  METHODS
  Accelerometers were used to measure physical activity over 1 week in 59 control, 83 glaucoma, and 58 AMD subjects. Subjects completed the University of Illinois at Chicago Fear of Falling Questionnaire, and the extent of FoF was estimated using Rasch analysis. In negative binomial models adjusting for demographic, health, and social factors, FoF was investigated as a potential mediator between the severity of visual field (VF) loss (in glaucoma patients) or the severity of contrast sensitivity (CS) loss (in AMD patients) and decreased engagement in physical activity, defined as minutes spent in moderate-to-vigorous physical activity (MVPA) per day.
  
  
  RESULTS
  In multivariate negative binomial regression models, 5-decibels worse VF mean deviation was associated with 26 % less engagement in MVPA [rate ratio (RR) = 0.74, p < 0.01] amongst glaucoma subjects. When FoF was added to the model, the RR increased from 0.74 to 0.78, and VF loss severity remained associated with less MVPA at a statistically significant level (p < 0.01). Likewise, 0.1 log units worse CS was associated with 11 % less daily MVPA (RR = 0.89, p < 0.01) amongst AMD subjects. When FoF was added to the model, the RR increased from 0.89 to 1.02, and CS loss was no longer associated with MVPA at a statistically significant level (p = 0.53).
  
  
  CONCLUSIONS
  FoF may mediate the relationship between vision loss and physical activity restriction amongst patients with AMD. Future work should determine optimal strategies for reducing FoF in individuals with vision loss in order to prevent the deleterious effects of physical activity restriction.
authors.affiliation: Wilmer Eye Institute, Johns Hopkins University, 600 North Wolfe Street, Maumenee B-110, Baltimore, MD, 21287, USA. anguye24@jhmi.edu.
authors.forename: Angeline M
authors.initials: AM
authors.lastname: Nguyen
authors.affiliation: Wilmer Eye Institute, Johns Hopkins University, 600 North Wolfe Street, Maumenee B-110, Baltimore, MD, 21287, USA. karora2@jhmi.edu.
authors.forename: Karun S
authors.initials: KS
authors.lastname: Arora
authors.affiliation: Wilmer Eye Institute, Johns Hopkins University, 600 North Wolfe Street, Maumenee B-110, Baltimore, MD, 21287, USA. bswenor@jhsph.edu.|Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. bswenor@jhsph.edu.|The Dana Center for Preventive Ophthalmology, Wilmer Eye Institute, 600 North Wolfe Street, Maumenee B-110, Baltimore, MD, 21287, USA. bswenor@jhsph.edu.
authors.forename: Bonnielin K
authors.initials: BK
authors.lastname: Swenor
authors.affiliation: Wilmer Eye Institute, Johns Hopkins University, 600 North Wolfe Street, Maumenee B-110, Baltimore, MD, 21287, USA. david.friedman@jhu.edu.|Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. david.friedman@jhu.edu.|The Dana Center for Preventive Ophthalmology, Wilmer Eye Institute, 600 North Wolfe Street, Maumenee B-110, Baltimore, MD, 21287, USA. david.friedman@jhu.edu.
authors.forename: David S
authors.initials: DS
authors.lastname: Friedman
authors.affiliation: Wilmer Eye Institute, Johns Hopkins University, 600 North Wolfe Street, Maumenee B-110, Baltimore, MD, 21287, USA. pramulu@jhmi.edu.|The Dana Center for Preventive Ophthalmology, Wilmer Eye Institute, 600 North Wolfe Street, Maumenee B-110, Baltimore, MD, 21287, USA. pramulu@jhmi.edu.
authors.forename: Pradeep Y
authors.initials: PY
authors.lastname: Ramulu
mesh_terms: D000058:Accidental Falls; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005239:Fear; D005260:Female; D005901:Glaucoma / Q000150:complications / Q000503:physiopathology / Q000523:psychology*; D006801:Humans; D008268:Macular Degeneration / Q000150:complications / Q000503:physiopathology / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D011795:Surveys and Questionnaires; D015354:Vision, Low / Q000209:etiology / Q000503:physiopathology / Q000523:psychology*