Farnsworth And Lanthony Test Instructions                                       View Shopping Cart

(The following directions are the current version shipped with each Farnsworth D15 and Lanthony desaturated Color Disk test:)

Rev 1.3 (02/03)

Introduction

Farnsworth D15 and Lanthony Dichotomous Tests

For Congenital and Acquired Color Vision Defects

16 Color Discs, developed in the 1940's

The D15 set is a modification of the well-known Farnsworth-Munsell 100 Hue Test. The D15 test is intended for classification instead of more time-consuming in-depth study of color vision defects using the 100-Hue test. Each D15 set contains a reference disc and fifteen numbered discs, which make up an incomplete color circle. Following an attempt to sequentially arrange the discs by the patient, evaluation determines color perception or defects in deutan, protan or tritan axis discrimination. Sometimes there are indeterminate defects in the cases of retinal toxicity.

The Farnsworth D-15 test is called 'dichotomous' because it was designed to separate subjects into one of two groups: 1.) Strongly/Medium color deficient or 2.) Mildly color deficient or color normal. This is accomplished by the arrangement of vivid (saturated) colored discs. This makes the test fairly easy and a non-perfect score is indicative of a strong color deficiency.

The Lanthony D-15 test was designed to separate patients into one of two groups: 1.) Mildly color deficient or 2.) Normal color perception. This is accomplished by the arrangement of faded (unsaturated) colored discs. This makes the test fairly difficult and a non-perfect score is indicative of a mild color deficiency. The Lanthony test is considered more appropriate for use in the detection of acquired color defects. This test is not appropriate for patients who have already failed the Farnsworth D15 test.

Note: The administration of the test and the score sheet template are identical for the Farnsworth D15 and the Lanthony D15 tests. The only difference between these items is the color saturation of the discs.

Contents

Each Richmond Products Farnsworth D-15 or Lanthony D15 set consists of:

Reference Disc (Blank underside)

Fifteen colored discs (numbered on the bottom)

Plexiglas® Case (with top)

Finger Tip Cots in small bag

Instructions

Score Sheet Template (laminated)

Storage

The Farnsworth and Lanthony tests should be stored in a cool dry place. Since exposure to light will affect the color discs, the set should be kept wrapped in the shipping container or other provision to protect from light.

Precautions

Each color disc is mounted without any protection of the color sample to insure correlation to other color tests. Consequently, it is very important to insure that no one touches the color sample to avoid the damage of fingerprints. This is the reason that it is very important that the examiner and the patient wear some sort of protection of the fingertips. 

Test Environment Lighting

The test is intended to be administered on a black background to prevent surroundings from affecting the color perception by the patient. Further, it is very important to administer these tests under consistent conditions so that each subsequent retest over time can be judged properly. The illumination should provide approximately 6700ยบ Kelvin at 25 foot-candles or greater (Illuminant C) or daylight. The Daylight Illuminator provides acceptable illumination. 

Pre-test Considerations

The examiner must determine if the test will be accomplished using binocular vision or separately for each eye. Monocular variations are very rare, however history of trauma or other considerations may warrant one method over the other. Testing for congenital color defects is usually accomplished binocularly. Testing for acquired defects (toxicity, trauma, retinal disease, etc.) is usually administered on each eye separately.

The score sheet should be marked accordingly. The examiner should also determine the approximate time the patient will be permitted for the test. Children over the age of 5 often can perform the test adequately.

For patients with limited dexterity, the procedure indicated where each color disc selection is placed in the

Plexiglas® box may be altered with the patient requested to give each selection to the examiner for 'line-up' on the table. It is important that the patient be able to view the 'line-up' as it builds for review.

The Farnsworth D-15 and Lanthony D15 tests are not sensitive to mild to moderate visual acuity loss. The tests are engineered to be conducted at a working distance of 19.5 inches (50 cm).

For low vision patients, there are two alternative selections which may help. The first is a Magnetic Farnsworth D15 Test which uses a sealed box to avoid contamination of the discs. Discs are moved as in a game by a magnetic wand. Another alternative is a Farnsworth D-15 set with color discs that are almost three times in size called the Large Farnsworth D15.

Testing Procedure

Remove the sliding top to the Plexiglas® box, tip one end of the box and carefully slide all of the color discs onto a black surface. The examiner then selects the reference cap (the color disc with blank notation underside) and places that cap into the Plexiglas® box to the end. The patient is then instructed to select the color disc, which most closely matches the reference cap and slide it into the Plexiglas® box next to the reference cap.

The patient then continues to select the next closest color disc and places each in sequence in the Plexiglas® box. The patient should be given a reasonable time to arrange the discs and may be permitted to alter the sequence prior to completion, however, the time should be about 2 minutes and should not be unlimited .

At the completion of the test, the examiner should slide the lid into place to secure the test chips.

Scoring

Scoring is accomplished by reading the color chip numbers on the reverse side through the clear Plexiglas® bottom and recording the sequence selected by the patient on a copy of the score sheet. A patient with a color vision deficiency will arrange the color discs in a different order than a person with normal color vision.

The patient's selection of the discs is diagramed on a copy of the score sheet template. For example, if the patient's selection order was Reference cap, 1,15,2,3,14,13,12,11,10,9,8,7,6,5,4 the scoring would look like Example A.

A line is then drawn from the starting point (Reference disc which is blank on the bottom) through the sequence determined by the patient. If the lines remain along the outside of the circle (few chips out of order) then the patient is deemed to be 'normal' or very mildly color deficient. If the sequence lines cross the center repeatedly, the patient has a medium or strong defect. The type of defect is determined by comparing these crossover lines to see if they are parallel to the protan, deutan or tritan color confusion axes (see below). Confusions occurring regularly in a certain direction across the score sheet reveal the type of color defect. See Figures 1- 6. 

Confusions among color discs that are close together are not considered significant. Some examiners consider that one or two crossings are normal. Some examiners consider confusion crossing from color disc # 7 to #15 to be insignificant as these are so close in hue; however, if the line from # 15 does not remain along the outside edge of the circle, a defect in the blue/yellow axis should be suspected.

With the Farnsworth test, the difference between mild and medium defect is not easily defined. The difference between medium and strong deficiency is often considered at 10 crossings.

Retesting

Any score achieved that is less than normal should trigger a rest for the patient. Then review the instructions with the patient again to be sure that the test procedure was fully understood. Record the retest on a second properly marked score sheet.

Interpretation

A 'confusion axis' is a localized area on a color plot where a patient with less than normal color perception cannot adequately determine one color from another.

Deuteranomaly is the most common type of color vision deficiency affecting especially the green receptors. A deuteromalous patient will have trouble distinguishing blue-green from gray and red-purple.

Protanomaly is a color vision deficiency affecting especially the red receptors. A protanomalous patient will have trouble distinguishing red-green and confuses red-orange with blue-green and gray.

Tritanomaly affects especially the blue receptors. He or she will confuse violet with gray and yellow-green. A tritanomaly is rarely inherited. Recent studies have shown increases in this type of defect due to adult acquired color deficiency, often from medications.

Deutan subjects exhibit a 'confusion axis' from green to purple. Protans have a 'confusion axis' from red to blue-green. Tritans show a 'confusion axis' from yellow to blue. These 'confusion axes' represents a region on a color wheel (similar in layout to the score sheet) where the patient has problems discriminating among closely related colors. These axes divide the color wheel into two sections. Since the Farnsworth test distinguishes between two groups; i.e. those with normal or mild deficiency vs those with medium or strong color deficiency, the test is called 'dichotomous'. The Lanthony desaturated test is often used for those who have passed the Farnsworth D15 to distinguish between mild color deficiency and normal. It is more difficult for the patient to perform accurately.

Consultation of a textbook on this subject is suggested for additional clarification.

4428B   Laminated Farnsworth / Lanthony Score Card .......... $10.00 Add To Cart

4432      Plexiglas® Replacement Box for D15 set ....................... $45.00 Add To Cart

4433R   Replacement Color Discs ................................................ $34.00 Add To Cart

                (Specify Farnsworth or Lanthony; D15 or 100 Hue and disc number or reference disc)

References:

  1. Birch, J Diagnosis of Defective Colour Vision. Oxford Medical Publications1993

  2. Farnsworth, D The Farnsworth Munsell 100-Hue and dichotomous tests for colour vision Journal Ophthalmology Society American 33:568,1943

  3. Fukami, K. Evaluation of the Farnsworth-Munsell 100-Hue Test Japanese Journal of Clinical Ophthalmology 30:27-31, 1976

  4. Greenstein V, Sarter B, Noble K, and Carr R. Investigative Ophthalmology & Visual Science Vol. 31, 1008-1014. Hue discrimination and S cone pathway sensitivity in early diabetic retinopathy.

  5. Hahn C, Evaluation of Hahn Double 15 Hue Test Poster Session 10th Japan-Korea Joint Meeting of Ophthalmology 9/21-23/2000

  6. Helve, J. A comparative study of several diagnostic tests of colour vision used for measuring types and degrees of congenital red-green defects. Acta Ophthalmology Supplement. 115:18, 1972

  7. Hyvarinen L. Quantitative Color Vision Test V-16 Manual P/N 2690 Available from Richmond Products Inc, Phone 561-994-2112 or FAX 561-994-2235 or www.RichmondProducts.com

    8. 7. Smith VC, Pokorny J. Large-field trichromacy in protanopes and deuteranopes Journal Opt Soc Am

    1977; 67:213-220.

  8. Tasman W, Jaeger E.A. Duane's Clinical Ophthalmology, Vol 3, Chapter 6, Lippincott Williams & Wilkins, 2000

  9. Verriest G, van Laethem J, Uvijel A. A new assessment of the normal ranges of the Farnsworth-Munsell 100 hue test scores American Journal of Ophthalmology 1982; 93:635-642

  10. Vingrys AJ and King-Smith PE Investigative Ophthalmology & Visual Science Vol. 29, 50-53 'A quantitative scoring technique for panel tests of color vision'.

  11. McIntyre, Donald Colour Blindness - Causes and Effects Dalton Publishing, 2002

 

Plaquenil Testing References:

  1. Bernstein HN. Ophthalmic considerations and testing patients receiving long-term antimalarial therapy. AM J Med 1983;75(18):25-34

  2. Muirden KD. The use of chloroquine and D-penicillamine in the treatment of rheumatoid arthritis. Med J Aus 1986;144(1)32-7.

  3. Cullen AP, Chou BR. Keratopathy with low dose chloroquine therapy. J Am Optom Assoc 1986;5(5):368-72

  4. Meischer PA. Treatment of systemic lupus erythematosus. Springer Sem Immunopathol 1986;9:271-82

  5. Bartlett JD, Jaanus SD. Ocular effects of systemic drugs. In: Bartlett JD, Jaanus SD, eds Clinical Ocular Pharmacology, 2nd ed. Boston: Butterworths, 1989: 901-42

  6. Finbloom DS, Silver K, Newsome DA, Gunkel R. Comparison of hydroxychloroquine and chloroquine use and the development of retinal toxicity. J Rheumatol 1985;12(4):692-4

  7. Johnson MW, Vine AK. Hydroxychloroquine therapy in massive total doses without retinal toxicity. 1987;140:139-44

  8. The Medical Letter on Drugs and Therapeutics. 1987;29(734):21-4

  9. Rynes RL. Ophthalmologic safety of long-term hydroxychloroquine sulfate treatment. Am J Med 1983:75(18):35-8

  10. Kastrup EK, et al., eds. Facts and Comparisons. St Louis. Lippincott, 1986:253e-g.

  11. Bowman KJ. A method for quantitative scoring of the Farnsworth Panel D-15. Acta Ophthalmologica (Copenh) 1982;60:907-16

  12. Bowman KJ, Collins MJ, Henry CJ. The effect of age on performance of the panel D-15 and desaturated D-15: a quantitative evaluation. In: Verriest G, ed. Colour Vision Deficiencies, VII. The Hague: Dr W Junk Publishers, 1984:227-31

Cyert L. Eye and Vision Conditions in the American Indian. Pueblo Publishing Goss and Edmonson 1990:137-147

Web References:

NZHTA Report 7 - New Zealand Health Technology Assessment (NZHTA) The Clearing House for Health Outcomes and Health Technology Assessment Department of Public Health and General Practice Christchurch School of Medicine Christchurch, N.Z. Colour vision screening

Revision History:

Rev 1.3 Added Plaquenil References. Deleted filter glasses

Disc Arrangement Tests Accessories

Farnsworth and Lanthony Color Vision Tests

 

Color Vision Test Index

 

All Products In Alphabetical Order

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