We should do this one eye at a time and with the patient covering the eye in the same way we use for visual acuity. Now, the best way to test visual fields is to have the patient look directly at you.
-“Look at me, sir.”
And if he looks at your nose or between your eyes, then you know the axis of his vision is right there. You know that the lower fields are below your eyes, and the upper fields are above your eyes. You know the left visual field is to the right of your nose and the right is to the left of your nose. There is no reason whatsoever to take your hands out here when doing visual fields. Stay in tight and it is much more accurate. Also, finger counting is the best way to do a screening for visual fields; and have the patient count fingers one, two or five. Do not use three or four fingers. Even normal people can sometimes have trouble differentiating three or four in their peripheral vision.
-“Okay, can you cover your left eye for me, sir?”
Look at my nose. Okay, and tell me how many fingers you see.
-“One, two, five, two.”
-“Excellent.”
That is normal visual fields in that eye.
-“Let’s test the other eye. Look at my nose. How many fingers?”
-“Five, two, one, two.”
=”Good.”
If the patient darts his eyes to the sides, you know you are not testing visual fields. Make sure the eyes look at you right between your eyes. Now, on the other hand, if the patient is lethargic and can’t pay attention and you see the eyes dart to any stimulus in the area, you actually have good evidence that they can see in that direction, and that is why the eyes darted there. So, it can be useful in the sleepy patient or the aphasic patient.