Codes and Frequencies
GLASSLENS indicates whether the respondent, or anyone in the respondent's family (for surveys prior to 1982), wore eyeglasses or contacts at the time of the interview.
The 1973 and 1982 Field Representative's Manuals, instructed interviewers to mark "yes" if the respondent volunteers that although they have eyeglasses or contact lenses, they do not use them. The 1982 Manual also defined contact lenses as "Lenses worn over the cornea to aid defective vision."
In 2019, functioning and disability measures included on the NHIS questionnaire were modified to align with validated, internationally-comparable disability measures developed by the Washington Group on Disability Statistics (WG). For more information about the WG initiative, other WG functioning and disability measures included on the NHIS questionnaire, and guidance for researchers about how to use the WG measures in analyses, please see our user note on the Washington Group Disability Measures.
The comparability of this variable over time is partly limited by the change in definition of "glasses" over time. The Field Representative's Manuals and survey texts for 1973 and 1979, did not provide specific definitions or criteria for eyeglasses. In 1980, 1981, 1982, and 1988, the Manuals state that "eyeglasses" referred to glasses which corrected or improved vision: sunglasses or safety glasses were not to be counted, unless they also had corrective lenses. In 1980, interviewers were specifically instructed not to probe but also not to assume if the respondent was wearing glasses, that these were corrective lenses. The Manuals for 2008 forward, did not provide criteria for the definition of eyeglasses (or contact lenses).
In the 1981 and 1988, this question only appeared in the child health questionnaire. The Manuals included special instructions that indicated that interviewers should mark "yes" for this variable for children who wear special glasses with one lens blacked out (instead of an eye patch, to correct for a "lazy eye"), regardless of corrective properties.
There was also a change in the variable universe, with persons age 3 and over included for 1973 and 1982; all sample persons in 1977, 1979 and 1980; only sample children age 3 to 17 in 1981 and 1988; sample adults and sample children age 6 to 17 (who weren't blind ) in 2008, 2016, 2017; and sample adults and sample children age 2 to 17 in 2019.
In 1973, 1977, 1979, and 1980, a respondent representing the family (a proxy) could answer the question for GLASSLENS for other adult family members. For all sample children, adult respondents reported for the child, though this is not considered proxy reporting. In 1982 and 2008 forward, except in rare cases where disability precluded self-reporting, sample adults answered the question themselves. Although self-reporting is likely to be more accurate than proxy reporting, the visibility of eyeglasses or contact lens to other family members would increase the accuracy of proxy report for GLASSLENS.
Lastly, there were very slight changes in the question wording which would probably not affect comparability. In 1973, the question asked if anyone had eyeglasses or contacts; in 1979 and 1980, and 1982, the question asked if anyone used eyeglasses or contacts. In 1981, 1988 and 2008 forward, the question asked if the child or sample adult (2008) wore glasses or contact lenses. While having and using are two different verbs, interviewers were instructed to mark "yes" even if the respondent reported having but not wearing the lenses.
The NHIS questionnaire was substantially redesigned in 2019 to introduce a different data collection structure and new content. For more information on changes in terminology, universes, and data collection methods beginning in 2019, please see the user note.
- 1973 1982: Persons age 3+.
- 1977: All persons.
- 1979-1980: All persons.
- 1981, 1988: Sample persons age 3 to 17.
- 2008, 2016 2017: Sample adults age 18+ and sample children age 6 to 17 who are not blind.
- 2019-2021: Sample adults age 18+ and sample children age 2 to 17.
- 1973, 1977, 1979-1982, 1988, 2008, 2016-2017, 2019-2021