Ophthalmology Book


Visual Acuity

Aka: Visual Acuity, Vision Screening, Snellen Chart
  1. See Also
    1. Refractive Error
    2. Vision Loss
  2. Precautions
    1. Visual Acuity is THE Vital Sign of the eye
      1. Obtain Visual Acuity on all patients with eye complaints
  3. Exam: Distance Vision
    1. Vision with each eye individually and together
    2. Appropriate chart (usually 10 foot distance to chart)
      1. Snellen Letters (6 years and older, adults)
      2. Snellen Numbers (Non-english speaking or illiterate)
      3. Tumbling E (Children ages 3 to 5 years)
      4. HOTV (Children ages 3 to 5 years)
      5. Picture Tests (Childen ages 3 to 5 years)
    3. Myopia suggested if Vision improves with pinhole
      1. Vision testing through a small pinhole corrects for Refractive Errors
      2. Consider pinhole for vision testing in a patient who did not bring their glasses to evaluation
    4. If vision less than 20/200, assess best vision with:
      1. Finger Counting (CF) at 1 foot and at 6 inches
      2. Hand Movements (HM)
      3. Light perception (LP)
      4. No light perception (NLP): total blindness
  4. Interpretation: Normal Vision for children 2.5 to 6 years
    1. Month 30-35: 20/60 (or 6/20) or better
    2. Month 36-47: 20/50 (or 6/15) or better
    3. Month 48-59: 20/40 (or 6/12) or better
    4. Month 60-72: 20/30 (or 6/10) or better
    5. Pan (2009) Opto Vis Sci 86(6): 607-12 [PubMed]
  5. Evaluation: Indications for referral to eye care specialist
    1. Indications for adults
      1. See Preventive Eye Examination for screening guidelines (e.g. Glaucoma)
      2. Uncorrected vision <20/50 or
      3. One line difference (on Snellen Chart) between eyes
    2. Indications for children
      1. Age 4-5: Either eye worse than 10/20 or 20/40
      2. Age >5: Either eye worse than 10/15 or 20/30
      3. Two line difference between eyes
        1. Example: OD 20/25 and OS 20/40
      4. Reference
        1. (2003) Pediatrics 111:903 [PubMed]
  6. Exam: Near Vision
    1. Not generally screened
    2. Presbyopia occurs after age 40 years
  7. Exam: Refraction
    1. Performed by Optometry or Ophthalmology
    2. Measures optical error of eyes to prepare lenses

Visual Acuity (C0042812)

Definition (MSH) Clarity or sharpness of OCULAR VISION or the ability of the eye to see fine details. Visual acuity depends on the functions of RETINA, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast.
Definition (NCI) Sharpness of vision, the ability to discern fine detail.
Definition (PSY) The ability or capacity of an observer to perceive fine detail.
Concepts Clinical Attribute (T201)
MSH D014792
SnomedCT 83760008, 363983007
LNC MTHU013695
English Acuities, Visual, Acuity, Visual, Visual Acuities, visual acuity, acuity visual, Visual Acuity, Visual acuity, function (observable entity), Visual acuity (biological function), Visual acuity, Visual acuity (observable entity), Resolving power of eye, Visual acuity, NOS, Visual acuity (qualifier value), VA - Visual acuity
Swedish Synskärpa
Czech zraková ostrost
Finnish Näöntarkkuus
Italian Acutezza visiva, Acuità visiva, Visus
Polish Ostrość wzroku
Norwegian Synsskarphet, Visuell skarphet
Spanish agudeza de la visión, agudeza de la visión (entidad observable), Acuidad Visual, agudeza de la visión (calificador), agudeza visual (entidad observable), agudeza visual, poder de resolución del ojo, Agudeza Visual
French Acuité visuelle
German Visus, Sehschärfe
Dutch Gezichtsscherpte, Visus
Portuguese Acuidade Visual
Derived from the NIH UMLS (Unified Medical Language System)

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