Color Perception Test

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Color Perception Test

Synonym/acronym: Color blindness test, Ishihara color perception test, Ishihara pseudoisochromatic plate test.

Common use

To assist in the diagnosis of color blindness.

Area of application





Defects in color perception can be hereditary or acquired. The congenital defect for color blindness is carried by the female, who is generally unaffected, and is expressed dominantly in males. Color blindness occurs in 8% of males and 0.4% of females. It may be partial or complete. The partial form is the hereditary form, and in the majority of patients the color deficiency is in the red-green area of the spectrum. Acquired color blindness may occur as a result of diseases of the retina or optic nerve. Color perception tests are performed to determine the acuity of color discrimination. The most common test uses pseudoisochromic plates with numbers or letters buried in a maze of dots. Misreading the numbers or letters indicates a color perception deficiency and may indicate color blindness, a genetic dysfunction, or retinal pathology.

Color perception is important in some occupations and testing for color perception may be a requirement for employment, especially for health-care workers whose responsibilities include assessment and monitoring of symptoms or changes in patients’ conditions. Some common examples of color based assessments in a health-care environment include interpreting the results of color pads on blood or urine test strips, identifying changes in body color (e.g. pallor, cyanosis, jaundice), determining the presence of blood or bile in body fluids and feces, or evaluating pH test strips to verify correct placement of a nasopharyngeal tube.

This procedure is contraindicated for



  • Detect deficiencies in color perception
  • Evaluate because of family history of color visual defects
  • Investigate suspected retinal pathology affecting the cones

Potential diagnosis

Normal findings

  • Normal visual color discrimination; no difficulty in identification of color combinations

Abnormal findings related to

  • Identification of some but not all colors

Critical findings


Interfering factors

  • Inability of the patient to cooperate or remain still during the procedure because of age, significant pain, or mental status.
  • Inability of the patient to read.
  • Poor visual acuity or poor lighting.
  • Failure of the patient to wear corrective lenses (glasses or contact lenses).
  • Damaged or discolored test plates.

Nursing Implications and Procedure


  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient or parent/child this procedure can assist in detection of color vision impairment.
  • Obtain a history of the patient’s complaints, including a list of known allergens.
  • Obtain a history of the patient’s known or suspected vision loss; changes in visual acuity, including type and cause; use of glasses or contact lenses; eye conditions with treatment regimens; eye surgery; and other tests and procedures to assess and diagnose visual deficit.
  • Obtain a history of symptoms and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Ask the patient if he or she wears corrective lenses; also inquire about the importance of color discrimination in his or her work, as applicable. Address concerns about pain and explain that no discomfort will be experienced during the test. Inform the patient that a health-care provider (HCP) performs the test in a quiet, darkened room, and that to evaluate both eyes, the test can take 5 to 15 or up to 30 min, depending on the complexity of testing required.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.


  • Potential complications: N/A
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient.
  • Instruct the patient to cooperate fully and to follow directions.
  • Seat the patient comfortably. Occlude one eye and hold test booklet 12 to 14 in. in front of the exposed eye.
  • Ask the patient to identify the numbers or letters buried in the maze of dots or to trace the objects with a handheld pointed object.
  • Repeat on the other eye.


  • Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • Recognize anxiety related to test results and be supportive of impaired activity related to color vision loss. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate. Provide contact information regarding vision aids for people with impaired color perception, if desired: ABLEDATA (sponsored by the National Institute on Disability and Rehabilitation Research [NIDRR], available at
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include refraction and slit-lamp biomicroscopy.
  • Refer to the Ocular System table at the end of the book for related tests by body system.
Handbook of Laboratory and Diagnostic Tests, © 2013 Farlex and Partners