Table 4.

Internal Consistency of the 9-item National Eye Institute Visual Function Questionnaire (NEI VFQ-9) in Women Who Participated in the Study of Osteoporotic Fractures (SOF) Year-10 Clinic Visits.

NEI VFQ-9 item	NEI VFQ: Cronbach Alpha Coefficient
	Composite Score (9-item)* N=3,631	Composite Score (8-item)† N=5,311
Overall	0.83	0.84
Cronbach coefficient alpha for deleted NEI VFQ-9 item
General vision
6-level general vision	0.81	0.82
Near vision
6-level reading normal newsprint	0.80	0.80
6-level seeing well up close	0.80	0.80
6-level finding objects on crowded shelf	0.81	0.81
Distance vision
6-level going down stairs at night	0.82	0.81
Driving
6-level daylight familiar places	0.82	NA
Peripheral vision
6-level seeing objects off to side	0.82	0.82
Role limitation
5-level limited in endurance	0.82	0.83
Well-being/Mental health
5-level amount time: Worry	0.85	0.86

^*NEI VFQ-9 9 item composite score was calculated among women who had valid responses to all 9 items.

^†NEI VFQ-9 8 item composite score was calculated among women who had valid responses to all 8 items, except for the driving item.