C.8.25.12 Visual Acuity Measurements Module
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#### C.8.25.12 Visual Acuity Measurements Module

Table C.8.25.12-1 defines the Attributes used to represent the subjective measurements of a patient's visual acuity. Usually each eye is measured individually, but sometimes only one eye is measured; sometimes the visual acuity of both eyes working together is measured. The visual acuity may be measured uncorrected, or with various refractive corrections, such as best corrected distance, pinhole, habitual near, etc

Table C.8.25.12-1. Visual Acuity Measurements Module Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Viewing Distance Type | (0046,0125) | 1 | The viewing distance conditions under which a patient's vision was measured. Enumerated Values: DISTANCE NEAR INTERMEDIATE OTHER
Visual Acuity Type Code Sequence | (0046,0121) | 1 | A sequence that specifies the conditions under which a patient's vision was measured. Only a single Item shall be included in this Sequence.
>Include Table 8.8-1 “Code Sequence Macro Attributes”. Defined CID 4216 “Ophthalmic Visual Acuity Type”. |
Background Color | (0046,0092) | 1 | The color of the background upon which optotypes are displayed for measurements of visual acuity. Defined Terms: RED GREEN WHITE REDGREENSPLIT
Optotype | (0046,0094) | 1 | The standardized test type (standard object of regard) used in measurements of visual acuity. Defined Terms: LETTERS NUMBERS PICTURES TUMBLING E LANDOLT C
Optotype Detailed Definition | (0046,0139) | 1C | Required if the Optotype (0046,0094) Attribute value is LETTERS or NUMBERS or PICTURES. Provides additional information to define what optotype was used. ### Note Letters, numbers, and pictures are commonly used but poorly standardized. The tumbling E and Landolt C are well defined.
Optotype Presentation | (0046,0095) | 1 | Specifies whether single or multiple optotypes were presented. Enumerated Values: SINGLE MULTIPLE
Visual Acuity Right Eye Sequence | (0046,0122) | 1C | A sequence that specifies the subjective measurement of a patient's visual acuity for the right eye. Only a single Item shall be included in this Sequence. Required if the right eye is measured. ### Note If Visual Acuity Right Eye Sequence (0046,0122) is present, Measurement Laterality (0024,0113), if present, will have a value of R or B as appropriate.
>Include Table C.8.25.12-2 “Visual Acuity Measurements Macro Attributes” |
Visual Acuity Left Eye Sequence | (0046,0123) | 1C | A sequence that specifies the subjective measurements of a patient's visual acuity for the left eye. Only a single Item shall be included in this Sequence. Required if the left eye is measured. ### Note If Visual Acuity Left Eye Sequence (0046,0123) is present, Measurement Laterality (0024,0113), if present, will have a value of L or B as appropriate.
>Include Table C.8.25.12-2 “Visual Acuity Measurements Macro Attributes” |
Visual Acuity Both Eyes Open Sequence | (0046,0124) | 3 | A sequence that specifies a patient's subjective visual acuity measurements with both eyes open. Only a single item is permitted in this Sequence. ### Note If Visual Acuity Both Eyes Open Sequence (0046,0124) is present, Measurement Laterality (0024,0113), if present, will have a value of B.
>Include Table C.8.25.12-2 “Visual Acuity Measurements Macro Attributes” |

Table C.8.25.12-2 describes the attributes for the Visual Acuity Measurements Macro.

Table C.8.25.12-2. Visual Acuity Measurements Macro Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Decimal Visual Acuity | (0046,0137) | 1 | A patient's visual acuity specified in decimal. The value is derived from two values in a fraction where the numerator of the fraction is the nominal distance to the chart that the patient is reading. The denominator represents the line of smallest optotypes of which the patient can see more than half. ### Note Typical examples: reference standard is 1, severe vision loss is 0.1 See Annex RR “Ophthalmic Refractive Reports Use Cases (Informative)” in PS3.17 for guidance in converting Decimal Visual Acuity to other customarily used display notation such as 20/20 in the US and 6/6 in Britain.
Visual Acuity Modifiers | (0046,0135) | 3 | The first value is a positive or negative integer numeric value such as +1, +2, +3, 0, -1, -2, or -3 used to indicate that the patient missed letters on the line referenced, or saw additional letters on the next smaller line. The second value is a positive or negative integer numeric value such as +1, +2, +3, 0, -1, -2, or -3, which in combination with the first value indicates that the patient both saw additional letters on the next smaller line and missed letters on the line referenced. ### Note When the modifier values are zero, the values are not typically displayed to the user. See Annex RR “Ophthalmic Refractive Reports Use Cases (Informative)” in PS3.17 for guidance regarding significance of modifiers.

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