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VisCorD Instructions

It is recommended that visual field perimetry and at least two additional items from the VisCorD are performed for screening. If a patient has a homonymous visual field defect without an imaging finding to account for the visual field defect and fails one of the six items on the VisCorD, then referral to a behavioral neurologist and/or neuropsychologist is indicated.

However, the sensitivity and specificity of the six items are only known for the CPC-Q; thus, the false positive and false negative rate for the other five items are unknown and patients should be made aware of the limitations of screening tests.

Viewing distance: All tests should be performed at a comfortable viewing distance except for Crowding test, which has specific requirements.

The Six Items (approximate time for administration)Stimulus/StimuliInstructionsPass or Fail

Threshold visual field perimetry (5 minutes)

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Threshold visual field perimetry for each eye. The Humphrey Visual Field Analyzer 24-2 SITA FAST protocol or equivalent is recommended.As per machine protocol.The clinician must interpret the results as usual. The presence of a homonymous (quadrant or hemifield) visual field defect in the absence of brain imaging that accounts for the homonymous defect is suspicious for cortical visual dysfunction.
Poppelreuter-Ghent Overlapping Figures1
(1 minute)		Line drawings of four overlapping figures:
  1. Hand saw
  2. Umbrella
  3. Pear
  4. Coffee cup/mug
Ask the patient to name all items they see. If problems arise naming an item or items, ask the patient to describe the item or its use, which is acceptable.

Pass: To pass, the patient must accurately name or describe all four objects without errors of omission or commission.

Fail: If the patient is unable to name or describe all four objects or reports seeing objects or pieces of objects that are not in the drawing, they fail this test

Navon Figures2
(1 minute)

Navon figures are letters or shapes composed of a set of different smaller letters or shapes. The stimuli here consist of a letter "H" formed by multiple "S" letters and a “triangle” shape formed by multiple small “circles”.

Ask the patient to describe what they see.

Pass: To pass, the patient must describe both the local images (S and circles) and the global images (H and circles).

Fail: If the patient is unable to name or describe all four figures (H of multiple “S” letters and triangle of multiple circles), they fail this test.

Intersecting pentagons copy task3
(1 minute)		A line drawing of intersecting pentagons.

Ask the patient to copy the drawing (do not describe the drawing or name the shapes they are to copy) onto a blank piece of paper while viewing the drawing. They are not allowed to draw on top of a reproduced copy of the intersecting pentagons.

If you have a tablet, they can use a stylus to copy the pentagons, and you can download the image to your device.

Best used with a touch screen device or a blank piece of paper instead of a mouse.

Pass: To pass, the patient must copy the drawing with five sides to each figure with an overlap of one corner from each pentagon that creates a 4-sided figure.

Fail: If the patient is unable to copy the drawing appropriately after 2 attempts, they fail this test.

Reading two paragraphs: one in in cursive and one in non-cursive font4
(3 minutes)

Two paragraphs, with one in cursive font and the other in non-cursive font.

Note: The paragraphs are written at reading levels between the 3rd and 5th grade.

Present the patient with the non-cursive paragraph to read a loud and listen and record errors (by simply counting or recording the type of error). Present the patient with the cursive paragraph to read aloud and record the errors in the same manner.

Types of errors: struggling to track to the proper line of text, re-reading a word or words, backtracking, or otherwise struggling to read smoothly.

Pass: To pass, the patient must be able to read both paragraphs without errors. The patient should read both paragraphs smoothly.

Fail: If the patient makes errors while reading either paragraph they fail this reading screening test.

A visual crowding task5
(2-3 minutes)		The stimuli consist of four strings of 7 letters and digits. Two of the strings have minimal space between the letters and digits (crowded strings), and two strings have greater space between the letters and digits (uncrowded strings).

First, you must calibrate the viewing distance before starting. Calibration instructions are on the test page for crowding.

Each string is presented alone, and the patient is asked to read the string.

Count the errors made for each string. Errors include skipping or misreading a digit or letter.

Pass: The patient must read each string without errors for both the crowded and uncrowded conditions.

Fail: If the patient makes more total errors reading the crowded strings than reading the uncrowded strings.

Colorado Posterior Cortical Questionnaire (CPC-Q)6
(6-7 minutes)		Fifteen questions regarding visual dysfunction, and each question is answered using a Likert scale as follows: Never (0), Almost Never (1), Sometimes (2), Fairly Often (3), or Very Often (4).Ask the patient to fill out the questionnaire. However, if they have difficulty reading, the examiner should read the questions and the response choices to the patient and record responses. The total score is added from the individual responses.

Pass: To pass, the patient must have a total score of 6 or lower.

Fail: If the patient has a total score of 7 or greater, they fail this screening questionnaire.

References:

  1. Della Sala S, Laiacona M, Spinnler H, Trivelli C. Poppelreuter-Ghent's Overlapping Figures Test: its sensitivity to age, and its clinical use. Arch Clin Neuropsychol. Nov 1995;10(6):511-34. doi:10.1016/0887-6177(94)00049-v
  2. Navon D. Forest before trees: The precedence of global features in visual perception. Cogn Psychol. 1977;9:353-383.
  3. Folstein MF, Folstein SE, McHugh PR. "Mini-mental state". A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. Nov 1975;12(3):189-98.
  4. Pelak VS, Tang‐Wai DF, Boeve BF, Bouwman FH, Graff‐Radford J, Rabinovici G, Holden SK, Townley RA, Day GS, Whitwell J, Ossenkoppele R, Boon BDC, Putcha D, Onyike CU, Snyder H, Crutch S, Yong KXX. Consensus recommendations for clinical assessment tools for the diagnosis of posterior cortical atrophy syndrome from the Atypical AD PIA of ISTAART. Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring. 2023;15(3):e12474. doi:10.1002/dad2.12474
  5. Whitney D, Levi DM. Visual crowding: a fundamental limit on conscious perception and object recognition. Trends Cogn Sci. Apr 2011;15(4):160-8. doi:10.1016/j.tics.2011.02.005
  6. Holden SK, Pelak VS, Sooy T, Heffernan KS, McConnell BV, Pressman PS, Bettcher BM. Development of the Colorado posterior cortical questionnaire within an Alzheimer's disease study cohort. J Clin Exp Neuropsychol. Apr 2022;44(3):226-236. doi:10.1080/13803395.2022.2105820