II Optic Nerve - Visual Acuity
- each eye is tested separately.
- test best corrected vision using eyeglasses.
- any patient with uncorrected visual acuity of less
than 20/20 should be examined with a pinhole. Improvement
of vision through a pinhole indicates that the error
- test distant vision using a Snellen chart at 10
or 20 feet.
- or test near vision using a near vision card at
- the patient is instructed to read progressively
smaller lines of letters until they can go no further.
- most young healthy individuals have vision of 20/20,
i.e. at 20 feet, the patient reads a line that a normal
eye sees at 20 feet.
- record for each eye separately, right eye = OD,
left eye = OS.
Abnormal Response: (Examples)
20/30 2: The patient
missed two letters of the 20/30 line.
20/200: Legally blind.
At 20 feet the patient reads a line that a normal eye
could see at 200 feet.
CF: If a patient is unable
to read the top line, have him count fingers at maximal
HM: If a patient cannot
count fingers, ask them to determine direction of hand
LP: If a patient cannot
perceive hand motion, see if they can perceive a light.
NLP: No light perception