OM t of c.iii - Vision Research Coordinating Center - Washington ...

2/22/96 Chapter 6 Vision Assessment page 6-4
The testing begins in the right eye with the left eye occluded carefully, and when
needed, after refraction and placement of the proper lenses in the trial frame.
Instruct the patient to read each letter on the chart starting in the top left hand
corner with the first line, line by line, letter by letter, from left to right.
Advise the patient to read slowly and to keep his or her head as still as possible.
The pace should not be faster than about one letter per second, so as to achieve the best
identification of each letter. Demonstrate the desired pace by reciting, “A, B, C.” If the
patient at any point reads too quickly, s/he should be asked stop, go back to the
beginning of the line, and read more slowly.
S/he is not to go to the next letter until s/he has given a definite response. If the
patient reads a number, s/he should be reminded that the chart contains no numbers
and the Clinician or Technician should request a letter in lieu of a number.
When the patient says s/he cannot read a letter, s/he should be encouraged and
required to guess. A maximum effort should be made to identify each letter. If a patient
identifies a letter as one of two letters, s/he should be asked to choose one letter and, if
necessary, to guess. You can suggest that the patient fixate eccentrically or turn or shake
his or her head in any manner if this improves visual acuity. If the patient employs
these maneuvers, care must be taken to ensure that the fellow eye remains covered and
that the patient is not leaning forward. There are several reasons for encouraging
patients to guess:
(1) Patients’ statements that they cannot identify a letter are often unreliable.
(2) The procedure helps to maximize patient effort.
(3) It helps to assure uniformity of procedure.
(4) It may help to prevent patient bias.
The Clinician or Technician uses the CLEK Visual Acuity Form to record the
patient’s answers. Score each letter as right or wrong. Letters read correctly are marked
with a “slash” through them. Letters read incorrectly are circled. If all the letters on a
row are read correctly, draw a horizontal line through all the letters on that line, or slash
through each of the 5 letters on that row. Record a perfectly read
line by putting a checkmark or the number “5” in the right-hand column. (See example
at the end of this chapter.)
If the patient is unable to read all 5 letters correctly on the top line of the chart at
4 m, the testing distance is decreased to 1 meter test and the above protocol is
completed in the same manner. If the patient is unable to read any letters on the chart at
1 m, then vision is recorded as “count fingers” or “hand motion.” These designations
are not used for recording low contrast acuity.