Taken in clothing that you normally wear on a daily basis
Uniforms should not be worn in your photo, except religious clothing that is worn daily.
Do not wear a hat or head covering that obscures the hair or hairline, unless worn daily for a religious purpose.
Your full face must be visible, and the head covering must not cast any shadows on your face.
Headphones, wireless hands-free devices, or similar items are not acceptable in your photo.
If you normally wear glasses (without tinted lenses), a hearing device, or similar articles, they may be worn in your photo.
Dark glasses or glasses with tinted lenses are not acceptable.
Glare on glasses is not acceptable in your photo. Glare can be avoided with a slight downward tilt of the glasses or by removing the glasses or by turning off the camera flash.
http://travel.state.gov/visa/visaphotoreq/visaphotoreq_5334.html
وهاي نماذج للصور ومن موقع وزارة الخارجية الامريكية لاحظوا النساء هنا بدون حجاب بس ما ظاهرة اذنهم
http://travel.state.gov/visa/visaphotoreq/photoexamples/photoexamples_5331.html