Welch Allyn Spot Vision Screener VS100, Инструкция по применению, Страница: 44 / 68

Accommodation or dilation
If you experience difficulty screening a subject, verify that the subject is not having
issues with accommodation or dilation.
Accommodation
Accommodation is the automatic adjustment of the focus of the eye by flattening or
thickening of the lens. Accommodation occurs when the subject fixates on the vision
screener. This improves vision for hyperopia (farsighted) subjects.
To reduce the possibility for a subject to accommodate:
1. Once the subject is seated, have the subject close his or her eyes for 10 to 15
seconds to encourage dilation.
2. Position the vision screener on the same plane with the subject’s eyes.
3. Activate the screening seconds before the subject opens his or her eyes.
4. Ask the subject to open his or her eyes to obtain quick capture, prior to the subject’s
eyes readjusting to the lights.
Dilation
Dilation is the expansion of the pupils. The vision screener cannot screen the subject if
the pupils are not dilated adequately. The vision screener displays a “Pupils too small”
message if the following occurs:
•
The pupils are constricted below 4 mm.
• The subject has something impeding the vision screener’s infrared light source, such
as blindness in one eye, cataract, or media opacity.
To encourage dilation:
1. First attempt recommendation.
a. Once the subject is seated, have the subject close his or her eyes for 10-15
seconds.
b. Position the vision screener on an even axis with the subject’s eyes.
c. Activate the screening seconds before the subject opens his or her eyes.
Ask the subject to open his or her eyes, which allows for a quick capture before
the subject’s eyes readjusts to the lights.
2. Second attempt recommendation.
a. Have the subject use his or her hands to shield his or her eyes, or use a book or
magazine to shield his or her eyes.
3. Third attempt recommendation.
a. Have the subject wear non-prescription sunglasses to shield light, or use
sunglasses that wrap to block light from his or her eyes.
4. Final recommendation.
a. Try new, darker environment and repeat the above recommendations.
b. Turn the device out of view from the subject and reactivate the screen while
rotating the device back to the subject.
40 Troubleshooting Welch Allyn® Spot™ Vision Screener Model VS100