Table of Contents

Locator Record

Title: Vision (VIX_C )
Contact Number: 1-866-441-NCHS
Years of Content: 2003 - 2004
First Published: December, 2005
Revised: NA
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:Vision
Record Source: NHANES 2003 - 2004
Survey Methodology: NHANES 2003 - 2004 is a stratified multistage probability sample of the civilian non-institutionalized population of the U.S.
Medium: NHANES Web site; SAS transport files

Component Description

The NHANES Vision Examination data will be used to:

  1. measure the prevalence of visual acuity impairment (visual acuity worse than 20/40) in the U.S. population;
  2. measure the distribution of refractive error in the U.S. population; and
  3. evaluate functional impairment related to vision.

The NHANES 2003–2004 Vision Examination consisted of three parts:

Eye Glasses Prescription Determination – For persons 12 years of age and older, eye glass prescriptions are measured when eye glasses for viewing distant objects are available.

Distance Visual Acuity and Objective Refraction/Keratometric Evaluation – For all persons 12 years and older, distance vision is assessed regardless of whether they wear eyeglasses or contacts; the refraction test measures the person’s refractive error and corneal curvature.

Vision Near Card Test – For persons 50 years and over, visual acuity at near was assessed.

Eligible Sample

All sample persons aged 12 years and older are eligible to participate in (1) automated determination of prescription for eye glasses used to view distant objects, (2) distance visual acuity assessment and (3) automated objective refraction/keratometric evaluation. Sample persons aged 50 years and older are also eligible for the Near Card visual acuity test.

Participants were excluded from the Vision Exam if they were determined to be completely blind or unable to see in both eyes based on the following question asked in the Sample Person Household Interview: “With both eyes open, can you see light?” Participants were also excluded from the exam if they had a severe eye infection (i.e., purulent discharge with redness and inflammation) in one or both eyes. A participant wearing an eye patch would not be excluded; however, the exam would not be conducted on the affected eye.

Protocol and Procedure

The vision exam included measurements of: 1) eyeglass prescription for glasses used to view distant objects; 2) presenting visual acuity with current correction; 3) visual acuity incorporating objective refraction; and 4) near-vision acuity.

Health technicians completed screening questions that involved observation of the subject to determine if the medical exclusion criteria applied. The sample person was then asked additional screening questions (e.g. do they wear any distance correction) to determine which measurements in the examination protocol were relevant.

If the sample person wore eyeglasses to see distant objects, their current eyeglass prescription was determined by using the Nidek Auto Lensmeter Model LM-990A. The Nidek Auto Refractor Model ARK-760 instrument was used to assess visual acuity. Presenting visual acuity was tested with whatever distance correction the participant usually wears, if any. If the participant’s visual acuity with their usual correction was 20/30 or worse, visual acuity was further assessed using the objective refraction measurements as the “correction factor” for the participant.

For sample persons aged 50 years and older, near vision was tested with a near vision card, and usual reading distance was recorded prior to measuring their presenting distance visual acuity.
The Nidek Auto Lensmeter Model LM-990A and the Nidek Auto Refractor Model ARK-760 instruments have been used since 1999.

The Vision Examination Protocol is discussed in detail in the NHANES Vision Procedures Manual.

Quality Assurance & Quality Control

A variety of quality control procedures were used to ensure the accurate and reliable collection of these data. Calibrations of the lensmeter and the autorefractor were performed prior to conducting examinations at each survey location, and weekly thereafter. At regular intervals, NCHS and contractor staff observed vision examinations conducted in the MEC to evaluate whether appropriate procedures and techniques were being followed. Retraining sessions were conducted with all MEC health technicians to review data collection procedures.

The MEC health technicians conducted the vision examination. These technicians received 8 weeks of training initially, and subsequently underwent updates and remedial training as needed. Technicians referred to the Vision Procedures Manual for specific instructions for the administration of this component.
For details on the QA/QC process for this component, please refer to the NHANES Vision Procedures Manual.

References

Codebook and Frequencies

SEQN - Respondent sequence number

Variable Name:
SEQN
SAS Label:
Respondent sequence number
English Text:
Respondent sequence number
Target:
Both males and females 12 YEARS - 150 YEARS

VIQ110 - SP has a severe eye infection?

Variable Name:
VIQ110
SAS Label:
SP has a severe eye infection?
English Text:
Does SP appear to have a severe eye infection in one or both eyes?
English Instructions:
The examiner observes the examinee's eyes for possible infection. If either eye has a sign of infection, the examinee is excluded from the vision component.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 3 3
2 No 6527 6530 VIQ130
. Missing 460 6990

VIQ121 - Which eye(s) infected?

Variable Name:
VIQ121
SAS Label:
Which eye(s) infected?
English Text:
if VIQ110 = "Yes" record which eye(s) is/are affected.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Right 1 1 End of Section
2 Left 0 1 End of Section
3 Both 2 3 End of Section
. Missing 6987 6990

VIQ130 - Is SP wearing an eye patch?

Variable Name:
VIQ130
SAS Label:
Is SP wearing an eye patch?
English Text:
Is SP wearing an eye patch?
English Instructions:
Although the SP is not excluded from the vision examination because he/she wears an eye patch, the examiner will not conduct the examination on the affected eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 1 1
2 No 6526 6527 VIQ150
. Missing 463 6990

VIQ141 - Which eye has eye patch?

Variable Name:
VIQ141
SAS Label:
Which eye has eye patch?
English Text:
If VIQ130 = "Yes" record which eye(s) is/are affected.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Right 0 0
2 Left 1 1
3 Both 0 1
. Missing 6989 6990

VIQ150 - Glasses/contact lenses for near work?

Variable Name:
VIQ150
SAS Label:
Glasses/contact lenses for near work?
English Text:
Do you wear glasses or contact lenses for reading or near work?
Target:
Both males and females 50 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 1870 1870
2 No 268 2138 VIXNC1
9 Don't know 2 2140
. Missing 4850 6990

VIQ160 - Glasses/contact lenses available?

Variable Name:
VIQ160
SAS Label:
Glasses/contact lenses available?
English Text:
If VIQ150 = "Yes", record if the examinee brought their near work glasses, contacts, or a combination of glasses and/or contacts to the testing facility.
Target:
Both males and females 50 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 1617 1617
2 No 253 1870 VIXNC1
. Missing 5120 6990

VIQ170 - Glasses or contacts worn for near test?

Variable Name:
VIQ170
SAS Label:
Glasses or contacts worn for near test?
English Text:
If VIQ160 = "Yes", record whether the examinee wore glasses, contacts, or a combination of glasses and/or contacts for test of near vision.
Target:
Both males and females 50 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Glasses 1587 1587
2 Contacts 24 1611
3 Both glasses and contact lenses 6 1617
. Missing 5373 6990

VIXNC1 - Line read on near card

Variable Name:
VIXNC1
SAS Label:
Line read on near card
English Text:
The number of the last line the examinee read with one or fewer misses, that is the number of the last line where the examinee read at least four out of the five characters correctly. Line 1 has the largest print: line 5 has the smallest print.
Target:
Both males and females 50 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 5 Range of Values 2133 2133
8 Could not obtain 7 2140
. Missing 4850 6990

VIXNC2 - Testing distance of near card

Variable Name:
VIXNC2
SAS Label:
Testing distance of near card
English Text:
Record to the nearest inch the distance from the center of the card to the examinee's brow.
English Instructions:
A measuring tape is used to determine the distance. (Rounding rule: Numbers less than 0.5, round down (example 16 1/4 = 16) and numbers equal to or greater than 0.5, round up (13 1/2 = 14, 21 3/4 = 22).)
Target:
Both males and females 50 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
5 to 31 Range of Values 2133 2133
88 Could not obtain 7 2140
. Missing 4850 6990

VIQ180 - Eye surgery for near sightedness?

Variable Name:
VIQ180
SAS Label:
Eye surgery for near sightedness?
English Text:
Have you ever had eye surgery to treat or prevent nearsightedness or myopia?
English Instructions:
The interest is in laser or radial keratotomy (RK) surgeries used to improve nearsightedness. Some other terms to describe this surgery include: PRK, RK, Lasik, Eximer, or Refractive Surgery.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 58 58
2 No 6463 6521 VIQ200
9 Don't know 5 6526 VIQ200
. Missing 464 6990

VIQ191 - Which eye(s) surgery - near-sightedness?

Variable Name:
VIQ191
SAS Label:
Which eye(s) surgery - near-sightedness?
English Text:
If VIQ180 = "Yes", record which eye(s) was/were operated on.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Right 5 5
2 Left 3 8
3 Both 50 58
. Missing 6932 6990

VIQ200 - Eye surgery for cataracts?

Variable Name:
VIQ200
SAS Label:
Eye surgery for cataracts?
English Text:
Have you ever had eye surgery to treat cataracts?
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 425 425
2 No 6092 6517 VIQ220
9 Don't know 9 6526 VIQ220
. Missing 464 6990

VIQ211 - Which eye(s) cataract surgery?

Variable Name:
VIQ211
SAS Label:
Which eye(s) cataract surgery?
English Text:
if VIQ200 = "Yes", record which eye(s) was/were operated on for cataracts.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Right 74 74
2 Left 50 124
3 Both 300 424
9 Don't know 1 425
. Missing 6565 6990

VIQ220 - Glasses/contact lenses worn for distance

Variable Name:
VIQ220
SAS Label:
Glasses/contact lenses worn for distance
English Text:
Do you wear glasses or contact lenses for distance vision, such as when you watch television?
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 2819 2819
2 No 3702 6521 VIXOCMT
9 Don't know 5 6526
. Missing 464 6990

VIQ230 - Is distance correction available?

Variable Name:
VIQ230
SAS Label:
Is distance correction available?
English Text:
If VIQ220 = "Yes", record if examinee brought their distance correction to the testing center.
English Instructions:
The SP could be wearing the correction or brought it with them.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 2413 2413
2 No 406 2819
. Missing 4171 6990

VIQ240 - Which type? Glasses or contacts?

Variable Name:
VIQ240
SAS Label:
Which type? Glasses or contacts?
English Text:
If VIQ230 = "Yes", record the type of correction (glasses, contacts, or a combination of glasses and contacts) the SP has with them.
English Instructions:
This specifies the type of correction worn by the SP for the presenting VA tests (VIDRVA and VIDLVA).
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Glasses 2010 2010
2 Contacts 350 2360 VIXOCMT
3 Both glasses and contact lenses 53 2413
. Missing 4577 6990

VIQ250 - Was prescription obtained?

Variable Name:
VIQ250
SAS Label:
Was prescription obtained?
English Text:
Did the examiner capture the prescription of the examinee's lens?
English Instructions:
This pertains to the lens prescription used for viewing distant objects.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 2057 2057
2 No 1 2058
. Missing 4932 6990

VIXPRS - Prescription, right sphere

Variable Name:
VIXPRS
SAS Label:
Prescription, right sphere
English Text:
The prescription of the sphere in the right lens used for distance correction.
English Instructions:
For distance eyeglasses only.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
-15 to 6.5 Range of Values 1989 1989
88 Could not obtain 69 2058
. Missing 4932 6990

VIXPRC - Prescription, right cylinder

Variable Name:
VIXPRC
SAS Label:
Prescription, right cylinder
English Text:
Prescription of the cylinder in the right lens used for distance correction
English Instructions:
For distance eyeglasses only
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 7.75 Range of Values 1989 1989
88 Could not obtain 69 2058
. Missing 4932 6990

VIXPRA - Prescription, right axis

Variable Name:
VIXPRA
SAS Label:
Prescription, right axis
English Text:
Prescription of the axis in the right lens used for distance correction
English Instructions:
For distance eyeglasses only.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 180 Range of Values 1989 1989
888 Could not obtain 69 2058
. Missing 4932 6990

VIXPLS - Prescription, left sphere

Variable Name:
VIXPLS
SAS Label:
Prescription, left sphere
English Text:
Prescription of the sphere in the left lens used for distance correction.
English Instructions:
For distance eyeglasses only.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
-14 to 8 Range of Values 1988 1988
88 Could not obtain 70 2058
. Missing 4932 6990

VIXPLC - Prescription, left cylinder

Variable Name:
VIXPLC
SAS Label:
Prescription, left cylinder
English Text:
Prescription of the cylinder in the left lens used for distance correction.
English Instructions:
For distance eyeglasses only.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 8.75 Range of Values 1988 1988
88 Could not obtain 70 2058
. Missing 4932 6990

VIXPLA - Prescription, left axis

Variable Name:
VIXPLA
SAS Label:
Prescription, left axis
English Text:
Prescription of the axis in the left lens used for distance correction.
English Instructions:
For distance eyeglasses only
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 180 Range of Values 1988 1988
888 Could not obtain 70 2058
. Missing 4932 6990

VIXOCMT - Visual Acuity Comments

Variable Name:
VIXOCMT
SAS Label:
Visual Acuity Comments
English Text:
The examiner can note special circumstances related to a visual acuity test.
English Instructions:
These apply to distance vision tests.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Monovision glasses/contacts worn for visual acuity 9 9
2 Cataract contact lenses worn for objective refraction 2 11
3 Contacts worn for objective refraction 9 20
4 Artificial eye 7 27
5 Monovision contacts worn for objective refraction 2 29
6 Contact in right eye only for presenting visual acuity 2 31
7 Contact in left eye only for presenting visual acuity 2 33
. Missing 6957 6990

VIXORSM - OR right sphere, median

Variable Name:
VIXORSM
SAS Label:
OR right sphere, median
English Text:
Spherical dioptric power (median value of three objective refractions) of the examinee's right eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
-21.75 to 6.75 Range of Values 6296 6296
88 Could not obtain 197 6493
. Missing 497 6990

VIXORCM - OR right cylinder, median

Variable Name:
VIXORCM
SAS Label:
OR right cylinder, median
English Text:
Cylindrical dioptric power (median value of three objective refractions) of the examinee's right eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 8.25 Range of Values 6296 6296
88 Could not obtain 197 6493
. Missing 497 6990

VIXORAM - OR right axis, median

Variable Name:
VIXORAM
SAS Label:
OR right axis, median
English Text:
Axis of refractive astigmatism (median value of three objective refractions) of the examinee's right eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 180 Range of Values 6296 6296
888 Could not obtain 197 6493
. Missing 497 6990

VIDORFM - OR right confidence level reading

Variable Name:
VIDORFM
SAS Label:
OR right confidence level reading
English Text:
The confidence level of the objective refraction reading for the right eye (mean of three measures).
English Instructions:
Lower values equate to less confidence in the objective refraction values.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
5 to 9 Range of Values 6322 6322
. Missing 668 6990

VIXOLSM - OR left sphere, median

Variable Name:
VIXOLSM
SAS Label:
OR left sphere, median
English Text:
Spherical dioptric power (median value of three objective refractions) of the examinee's left eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
-19.75 to 11 Range of Values 6264 6264
88 Could not obtain 229 6493
. Missing 497 6990

VIXOLCM - OR left cylinder, median

Variable Name:
VIXOLCM
SAS Label:
OR left cylinder, median
English Text:
Cylindrical dioptric power (median value of three objective refractions) of the examinee's left eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 7.75 Range of Values 6264 6264
88 Could not obtain 229 6493
. Missing 497 6990

VIXOLAM - OR left axis, median

Variable Name:
VIXOLAM
SAS Label:
OR left axis, median
English Text:
Axis of refractive astigmatism (median value of three objective refractions) of the examinee's left eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 180 Range of Values 6264 6264
888 Could not obtain 229 6493
. Missing 497 6990

VIDOLFM - OR left confidence level reading

Variable Name:
VIDOLFM
SAS Label:
OR left confidence level reading
English Text:
The confidence level of the objective refraction reading of the left eye (mean of three measures).
English Instructions:
Lower values equate to less confidence in the objective refraction values.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
5 to 9 Range of Values 6352 6352
. Missing 638 6990

VIXKRM1 - Right keratometry radius flat curve (mm)

Variable Name:
VIXKRM1
SAS Label:
Right keratometry radius flat curve (mm)
English Text:
Keratometric measure. Radius of corneal curvature (in mm) in the least power meridian of the examinee's right eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
5.96 to 9.91 Range of Values 6442 6442
88 Could not obtain 51 6493
. Missing 497 6990

VIXKRD1 - Right keratometry power flat curve (D)

Variable Name:
VIXKRD1
SAS Label:
Right keratometry power flat curve (D)
English Text:
Keratometric measure. Dioptric power in the least power meridian of the cornea in the examinee's right eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
34 to 56.75 Range of Values 6442 6442
88 Could not obtain 51 6493
. Missing 497 6990

VIXKRG1 - Right keratometry axis flat curve (deg)

Variable Name:
VIXKRG1
SAS Label:
Right keratometry axis flat curve (deg)
English Text:
Keratometric measure. Axis of corneal astigmatism (in degrees) in the least power meridian of the examinee's right eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 180 Range of Values 6441 6441
888 Could not obtain 51 6492
. Missing 498 6990

VIXKRM2 - Right keratometry radius steep curve(mm)

Variable Name:
VIXKRM2
SAS Label:
Right keratometry radius steep curve(mm)
English Text:
Keratometric measure. Radius of corneal curvature (in mm) in the greatest power meridian of the examinee's right eye
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
4.94 to 9.04 Range of Values 6442 6442
88 Could not obtain 51 6493
. Missing 497 6990

VIXKRD2 - Right keratometry power steep curve (D)

Variable Name:
VIXKRD2
SAS Label:
Right keratometry power steep curve (D)
English Text:
Keratometric measure. Dioptric power in the meridian of the cornea with the greatest power in the examinee's right eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
37.25 to 68.25 Range of Values 6442 6442
88 Could not obtain 51 6493
. Missing 497 6990

VIXKRG2 - Right keratometry axis steep curve (deg)

Variable Name:
VIXKRG2
SAS Label:
Right keratometry axis steep curve (deg)
English Text:
Keratometric measure. Axis of corneal astigmatism (in degrees) in the greatest power meridian of the examinee's right eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 179 Range of Values 6441 6441
888 Could not obtain 51 6492
. Missing 498 6990

VIXKRMM - Right keratometry radius, average (mm)

Variable Name:
VIXKRMM
SAS Label:
Right keratometry radius, average (mm)
English Text:
Keratometric measure. Radius of corneal curvature (in mm) averaged across meridians in the examinee's right eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
5.81 to 9.09 Range of Values 6442 6442
88 Could not obtain 51 6493
. Missing 497 6990

VIXKRDM - Right keratometry power, average (D)

Variable Name:
VIXKRDM
SAS Label:
Right keratometry power, average (D)
English Text:
Keratometric measure. Dioptric power of the cornea averaged across meridians in the examinee's right eye
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
37.25 to 58 Range of Values 6442 6442
88 Could not obtain 51 6493
. Missing 497 6990

VIXKRCD - Right keratometry cylinder

Variable Name:
VIXKRCD
SAS Label:
Right keratometry cylinder
English Text:
Keratometric measure. Difference in dioptric power between meridians of the cornea in the examinee's right eye
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 32.75 Range of Values 6442 6442
88 Could not obtain 51 6493
. Missing 497 6990

VIXKRCG - Right keratometry axis (deg)

Variable Name:
VIXKRCG
SAS Label:
Right keratometry axis (deg)
English Text:
Keratometric measure. Axis of corneal astigmatism (in degrees) in the steepest meridian of the cornea in the examinee's right eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 179 Range of Values 6441 6441
888 Could not obtain 51 6492
. Missing 498 6990

VIXKLM1 - Left keratometry radius flat curve (mm)

Variable Name:
VIXKLM1
SAS Label:
Left keratometry radius flat curve (mm)
English Text:
Keratometric measure. Radius of corneal curvature (in mm) in the least power meridian of the examinee's left eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
6.13 to 10 Range of Values 6451 6451
88 Could not obtain 42 6493
. Missing 497 6990

VIXKLD1 - Left keratometry power flat curve (D)

Variable Name:
VIXKLD1
SAS Label:
Left keratometry power flat curve (D)
English Text:
Keratometric measure. Dioptric power in the least power meridian of the cornea in the examinee's left eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
33.75 to 55 Range of Values 6451 6451
88 Could not obtain 42 6493
. Missing 497 6990

VIXKLG1 - Left keratometry axis flat curve (deg)

Variable Name:
VIXKLG1
SAS Label:
Left keratometry axis flat curve (deg)
English Text:
Keratometric measure. Axis of corneal astigmatism (in degrees) in the least power median of the examinee's left eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 180 Range of Values 6451 6451
888 Could not obtain 42 6493
. Missing 497 6990

VIXKLM2 - Left keratometry radius steep curve (mm)

Variable Name:
VIXKLM2
SAS Label:
Left keratometry radius steep curve (mm)
English Text:
Keratometric measure. Radius of corneal curvature (in mm) in the greatest power meridian of the examinee's left eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
5.55 to 8.98 Range of Values 6451 6451
88 Could not obtain 42 6493
. Missing 497 6990

VIXKLD2 - Left keratometry power steep curve (D)

Variable Name:
VIXKLD2
SAS Label:
Left keratometry power steep curve (D)
English Text:
Keratometric measure. Dioptric power in the meridian of the cornea with the greatest power in the examinee's left eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
37.5 to 60.75 Range of Values 6451 6451
88 Could not obtain 42 6493
. Missing 497 6990

VIXKLG2 - Left keratometry axis steep curve (deg)

Variable Name:
VIXKLG2
SAS Label:
Left keratometry axis steep curve (deg)
English Text:
Keratometric measure. Axis of corneal astigmatism (in degrees) in the greatest power meridian of the examinee's left eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 180 Range of Values 6451 6451
888 Could not obtain 42 6493
. Missing 497 6990

VIXKLMM - Left keratometry radius, average (mm)

Variable Name:
VIXKLMM
SAS Label:
Left keratometry radius, average (mm)
English Text:
Keratometric measure. Radius of corneal curvature (in mm) averaged across meridians in the examinee's left eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
5.85 to 9.09 Range of Values 6451 6451
88 Could not obtain 42 6493
. Missing 497 6990

VIXKLDM - Left keratometry power, average (D)

Variable Name:
VIXKLDM
SAS Label:
Left keratometry power, average (D)
English Text:
Keratometric measure. Dioptric power of the cornea averaged across meridians in the examinee's left eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
37.25 to 57.75 Range of Values 6451 6451
88 Could not obtain 42 6493
. Missing 497 6990

VIXKLCD - Left keratometry cylinder

Variable Name:
VIXKLCD
SAS Label:
Left keratometry cylinder
English Text:
Keratometric measure. Difference in dioptric power between meridians of the cornea in the examinee's left eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 18.5 Range of Values 6451 6451
88 Could not obtain 42 6493
. Missing 497 6990

VIXKLCG - Left keratometry axis (deg)

Variable Name:
VIXKLCG
SAS Label:
Left keratometry axis (deg)
English Text:
Keratometric measure. Axis of corneal astigmatism (in degrees) in the steepest meridian of the cornea in the examinee's left eye.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 180 Range of Values 6451 6451
888 Could not obtain 42 6493
. Missing 497 6990

VIDRVA - Right visual acuity, presenting

Variable Name:
VIDRVA
SAS Label:
Right visual acuity, presenting
English Text:
The presenting visual acuity of the right eye with usual correction.
English Instructions:
Usual correction could be: eyeglasses, contacts, eyeglasses and contacts, or no correction depending on what the SP wore (or brought with them) to view distant objects on the day they visited the MEC (see VIQ230 and VIQ240).
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
20 20/20 2776 2776
25 20/25 1638 4414
30 20/30 613 5027
40 20/40 320 5347
50 20/50 666 6013
60 20/60 104 6117
80 20/80 85 6202
200 20/200 161 6363
666 20/200+ 85 6448
. Missing 542 6990

VIDLVA - Left visual acuity, presenting

Variable Name:
VIDLVA
SAS Label:
Left visual acuity, presenting
English Text:
The presenting visual acuity of the left eye with usual correction.
English Instructions:
Usual correction could be: eyeglasses, contacts, eyeglasses and contacts, or no correction depending on what the SP wore (or brought with them) to view distant objects on the day they visited the MEC (see VIQ230 and VIQ240).
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
20 20/20 2818 2818
25 20/25 1566 4384
30 20/30 643 5027
40 20/40 312 5339
50 20/50 685 6024
60 20/60 78 6102
80 20/80 81 6183
200 20/200 160 6343
666 20/200+ 104 6447
. Missing 543 6990

VIDROVA - Right visual acuity, w/ obj. refraction

Variable Name:
VIDROVA
SAS Label:
Right visual acuity, w/ obj. refraction
English Text:
The visual acuity with objective refraction of the right eye.
English Instructions:
This is the visual acuity reported by the SP after the autorefractor inserted what it deemed, based on the objective refraction, to be the most appropriate lens (if any) to allow the eye to see 20/25 or better. This test was only performed on eyes whose presenting visual acuity was 20/30 or worse.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
25 20/25 1356 1356
30 20/30 122 1478
40 20/40 120 1598
50 20/50 221 1819
60 20/60 15 1834
80 20/80 28 1862
200 20/200 42 1904
666 20/200+ 31 1935
. Missing 5055 6990

VIDLOVA - Left visual acuity, w/ obj. refraction

Variable Name:
VIDLOVA
SAS Label:
Left visual acuity, w/ obj. refraction
English Text:
The visual acuity with objective refraction of the left eye.
English Instructions:
This is the visual acuity reported by the SP after the autorefractor inserted what it deemed, based on the objective refraction, to be the most appropriate lens (if any) to allow the eye to see 20/25 or better. This test was only performed on eyes whose presenting visual acuity was 20/30 or worse.
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
25 20/25 1396 1396
30 20/30 142 1538
40 20/40 95 1633
50 20/50 197 1830
60 20/60 21 1851
80 20/80 38 1889
200 20/200 39 1928
666 20/200+ 51 1979
. Missing 5011 6990