Blind Adults that willing to participate in the study will be tested with well-established measuring techniques of Balance control using force plate in the movement and Rehabilitation Laboratory at Ben-Gurion University. An automated algorithm will be used to extract standardized stabilogram-diffusion parameters from each of the COP data sets collected during quiet standing. These parameters include diffusion coefficients, critical displacement, critical time and scaling exponents for both lateral and anterior-posterior sway directions (Collins & De Luca, 1993). the subjects will be tested in 3 task conditions (eyes blindfolded, eyes blindfolded holding stick, eyes blindfolded holding a dog). Participants will be required to stand on the platform 10 times for 30 s For each trial, they will be instructed to sway as little as possible.

Inclusion Criteria:

• Blind persons
• Able to stand safely for 30 seconds
• Able to walk independently
• Hip OA prior THA

Exclusion Criteria:

• Stroke or other neurological diseases
• Orthopedic surgery at the past year

30 blind persons and 30 control