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Vision-targeted health related quality of life in older adults: patient-reported visibility problems in low luminance activities are more likely to decline than daytime activities
© The Author(s). 2016
Received: 26 January 2016
Accepted: 23 June 2016
Published: 7 July 2016
Commonly used vision-targeted health-related quality of life questionnaires almost exclusively focus items on vision under daytime conditions. Older adults even when in good eye health frequently report experiencing vision problems at night and under low environmental light levels, and psychophysical studies also document these visibility problems. Here we compare the progression of self-reported low luminance visibility problems and self-reported visibility problems under daytime conditions in older adults.
Trained interviewers administered two questionnaires to older adults in normal eye health: the National Eye Institute Visual Function Questionnaire – 25 (NEI VFQ-25) where items are almost entirely focused on difficulties in daytime activities, and the Low Luminance Questionnaire (LLQ) where items are focused on difficulties seeing at night and under low luminance conditions. The following visual functions were also measured: visual acuity, low luminance visual acuity, low luminance deficit, contrast sensitivity, light sensitivity in the macula, and rod-mediated dark adaptation. The protocol was repeated 3 years later.
Scores on the NEI VFQ-25 composite and its subscales were unchanged between baseline and 3-year follow-up, whereas scores on the LLQ composite and 5 of 6 subscales significantly decreased (corresponding to less functionality) at the 3-year follow-up. Participants were more likely to display a ≥ 5 point decrease on the LLQ composite than on the NEI VFQ-25 over 3 years. Visual functional tests were largely unrelated to changes in NEI VFQ-25 and LLQ scores from baseline to follow-up.
Older adults’ vision-targeted quality of life as measured by questionnaire is more likely to exhibit a practically significant decrease over 3 years using a questionnaire that focused on low luminance activities (LLQ) than one focused on daytime activities (NEI VFQ-25). That the results of visual functional testing did not correspond to older adults’ decline in self-reported problems in low luminance activities emphasizes the importance of questionnaires in understanding visual difficulties from the patients’ own perspective.
Older adults experience aging-related challenges in the visual activities of daily living, even in the absence of the common eye conditions and diseases of later adulthood (e.g., cataract, age-related macular degeneration (AMD), glaucoma, diabetic retinopathy). They frequently report experiencing vision problems at night and under low environmental light levels. For example, they cite difficulty with night driving and often avoid it [1–3] and report task difficulties under low illumination (e.g., reading a menu in a dimly lit restaurant) . Psychophysical studies confirm that older adults, even when free of significant ocular conditions, tend to exhibit decreased scotopic and mesopic light sensitivity, contrast sensitivity, and acuity, as compared to younger adults [5–10].
It is thus concerning that commonly used vision-targeted health-related quality of life questionnaire instruments designed for use in the older adult population almost exclusively focus items on vision under photopic (day-time) conditions, such as the National Eye Institute Visual Function Questionnaire (NEI VFQ-25,)  among others [12, 13]. Thus, these questionnaire instruments do not adequately address one of the major vision problem areas cited by older adults, activities at lower ambient light levels. In response to a need for a questionnaire focused on low luminance content, a questionnaire was recently developed specifically targeted at this content; the Low Luminance Questionnaire (LLQ) is a 32-item questionnaire designed for use with older adults and has established content and construct validity and test-retest reliability [14, 15] The LLQ is accessible at http://www.uab.edu/medicine/ophthalmology/images/Research/Low%20Luminance.pdf). It has six subscales: driving, extreme lighting, mobility, emotional distress, general dim lighting, peripheral vision.
Even though considerable research has shown that older adults’ vision problems are exacerbated under low luminance as measured psychophysically and by self-report, it remains to be determined whether self-reported low luminance visibility problems progress more rapidly over time in older adults as they age as compared to visibility issues they cite under daytime conditions. Here we examine whether responses on the LLQ display larger decreases over 3 years in older adults free of significant ocular conditions, as compared to responses on the NEI VFQ-25, which is largely focused on daytime activities. We also examined whether decreases in questionnaire scores were related to visual function at baseline and change in visual function over a 3-year period of follow-up.
The protocol (#F080205001) was approved by the Institutional Review Board of the University of Alabama at Birmingham (UAB) and followed the tenants of the Declaration of Helsinki. Informed consent was obtained from all participants after the nature and purpose of the study was described. This study made use of the sample assembled for the Alabama Study on Early Age-Related Macular Degeneration (ALSTAR), a prospective study of older adults in normal macular health at baseline [16, 17]. As described previously, participants were recruited from two primary care ophthalmology practices in the Callahan Eye Hospital at UAB. Eligibility criteria were as follows: (1) age ≥ 60 years old; (2) normal macular health in both eyes as determined by 3-field digital stereo-fundus photos (Carl Zeiss Meditec 450 Plus camera, Dublin, CA) evaluated by an experienced grader masked to other study variables. Each eye’s grade had to be 1 in the Age-Related Eye Disease Study (AREDS) 9-step classification system , indicating normal macular health. (3) No previous diagnoses of glaucoma, other retinal conditions, optic nerve conditions, corneal disease, diabetes, Alzheimer’s disease, Parkinson’s disease, brain injury, other neurological or psychiatric conditions as revealed by the medical record or by self-report.
A baseline visit consisted of the following. Participants provided information on demographic characteristics (age, gender, race/ethnicity). The NEI VFQ-25 and the LLQ were interviewer administered. Both of these instruments were developed using classical test theory,  and we elected to score each instrument using recommended scoring instructions by their developers [11, 14] The NEI VFQ-25 and the LLQ composite and subscale scores are computed using the same method, that is, by scaling individual item responses from 0 to 100, where 100 represents the highest functional level and 0 the lowest, and then averaging the individual items. Other options for scoring these types of questionnaires include a collection of measurement models referred to as item response theory . General cognitive status was estimated by the Mini-Mental State Examination (MMSE) ; scores less than 24 indicated cognitive impairment.
Several visual function tests were also administered; tests were administered for each eye unless otherwise noted. The eye with better visual function was used in analyses. Best-corrected visual acuity for each eye was assessed via the Electronic Visual Acuity tester  (EVA; JAEB Center, Tampa FL) under photopic conditions (100 cd/m2) and expressed as the logarithm of the minimum angle resolvable (logMAR). The EVA was also used to assess low luminance visual acuity for each eye, with participants viewing letters through a 1.5 log unit neutral density filter . The filter reduced background luminance to 3.1 cd/m2. To determine how much logMAR decreased under conditions of the lower light level as compared to the photopic (100 cd/m2) assessment, we defined a decrease in visual acuity under low luminance by the increase in logMAR (referred to as the “low luminance deficit” ). Contrast sensitivity for each eye was estimated by the Pelli-Robson chart  (Precision Vision, La Salle, IL) with mean luminance of 100 cd/m2, the letter-by-letter scoring method , and expressed as logarithm of sensitivity. Macular light sensitivity for each eye was assessed using the Humphrey Field Analyzer (Carl Zeiss Meditec, Dublin, CA) and the 24-2 SITA standard protocol, as previously described . Sensitivities for 16 test targets within a 9° × 9° macular region were averaged, and expressed as decibels (dB). Rod-mediated dark adaptation was measured using a computerized dark adaptometer as described previously [16, 17]. Test targets with a diameter of 2° were positioned at 5° on the inferior vertical meridian (superior to the fovea on the retina). Following a photobleach exposure (equivalent ~83 % bleach), sensitivity was measured at 30-s intervals for 20 min following bleach offset. Dark adaptation time was defined by the rod intercept, the time in minutes needed by the participant to reach a criterion sensitivity value in the latter half of the second component of rod recovery. Due to time constraints in the protocol visit, dark adaptation was measured in one eye only.
Administration of the NEI VFQ-25, LLQ, and visual function testing was repeated 3 years after the baseline visit. The only exception was measurement of macular light sensitivity, which was not repeated at the 3-year follow-up due to time constraints in the study protocol. The eye with better visual function was used in analyses.
Baseline and 3-year follow-up NEI-VFQ and LLQ composite and subscale scores were compared using paired t-tests. Unpaired t-tests were used to compare participants whose LLQ composite did and did not decrease by five or more points with respect to visual function variables. A similar analysis was conducted for the NEI-VFQ composite. P-values less than 0.05 (two-tailed) were considered statistically significant.
Demographic and cognitive status characteristics of the sample, N = 365
Age, years, n (%)
Gender, n (%)
Cognitive status, MMSE score
NEI-VFQ Composite and Subscales scores at baseline and follow-up for participants in normal macular health group and the change in scores over this 3-year period (N = 365)
Normal macular health at baseline a
3-year follow-up score
LLQ Composite and Subscales scores at baseline and follow-up for participants in normal macular health group and the change in scores over this 3-year period (N = 365)
Normal macular health at baseline a
3-year follow-up score
Extreme lighting conditions
Percentage of participants having a ≥ 5 point decrease in the NEI VFQ-25 composite as compared to the LLQ composite over 3 years
Composite decreased by ≥ 5 points
Composite did not decrease by ≥ 5 points
Vision variables stratified by participants with a ≥ 5 point decrease in the LLQ composite from baseline to 3-year follow-up versus those whose scores did not decrease by ≥ 5 points
LLQ composite decreased by ≥ 5 points
N = 85
LLQ composite did not decrease by ≥ 5 points
N = 280
NEI VFQ-25 composite decreased by ≥ 5 points
NEI VFQ-25 composite did not decrease by ≥ 5 points
Mean (standard deviation) unless otherwise noted
Visual acuity at baseline (logMAR)
Change in visual acuty a
Contrast sensitivity, log sensitivity
Change in contrast sensitivity
Light sensitivity, dB b
Low luminance deficit
Change in low luminance deficit
Rod-mediated dark adaptation, rod intercept (minutes)
Change in rod-mediated dark adaptation
Our results suggest that a vision-targeted health-related quality of life questionnaire whose content is focused on night-time and low luminance visual activities is more likely to show a decline over time in older adults than a questionnaire that focuses on daytime activities. Older adults’ composite scores were more likely to have a practically significant decrease over 3 years using a questionnaire that focused on low luminance activities (LLQ) than one focused on daytime activities (NEI VFQ-25). In addition, scores on five of six subscales of the LLQ significantly declined 3 years later, however none of the twelve subscales of NEI VFQ-25 declined over the same period. Our results imply that the use of questionnaires in clinical vision research on older adults that exclusively target daytime visual activities are likely to miss certain types and the extent of visibility problems older adults experience in daily life. It is noteworthy that this pattern of results emerged even in older adults in normal eye health, free of the common eye conditions of aging. Common ageing-related eye conditions such as AMD and glaucoma are associated with visual deficits under mesopic and scotopic conditions, which are more severe than what would be expected through aging alone [14, 27–29]. It remains to be determined whether changes in the LLQ are associated with patients’ perceptions about the worsening of low luminance vision in these conditions, as they progress.
This greater tendency for older adults’ self-report activity problems under low luminance than in photopic conditions is consistent with psychophysical reports that older adults’ visibility problems are accentuated under mesopic and scotopic conditions, as compared to younger adults [7–9, 30]. However, in this study there was no association between psychophysically measured deficits and self-reported deficits as reported on the LLQ. Those persons who had worse visual function at baseline or had more visual decrease over 3 years, were not more likely to be those who had larger decreases on the LLQ over the 3 year period. This study focused on older adults in normal health, and it is possible that psychophysical testing is not sensitive enough to quantitate the low luminance difficulties in everyday life older adults in good eye health experience subjectively.
How patients view their own visual task difficulties and the emotional consequences these challenges present is an appropriate part of understanding the impact of eye conditions and aging on everyday life. Patient reported outcomes, such as questionnaires on vision-targeted health-related quality of life, are an essential part of evaluating the impact of ophthalmic interventions to slow the progression of age-related eye conditions such as AMD, glaucoma, and diabetic retinopathy. Yet also part of understanding the role of patient reported outcomes is the transition of aging-associated conditions from normal eye health to their earliest incident emergence. Thus, it is important to recognize, that even in aging, low luminance activities already play a significant role in reducing vision-targeted health related quality of life, and a health-related quality of life questionnaire reflects this trend.
AMD, age-related macular degeneration; ALSTAR, Alabama Study on Early Age-Related Macular Degeneration; AREDS, Age-Related Eye Disease Study; dB, decibels; LLQ, Low Luminance Questionnaire; logMAR, logarithm of the minimum angle of resolution; MMSE,, Mini-mental State Examination; NEI VFQ-25, National Eye Institute Visual Functioning Questionnaire (25-item version); UAB, University of Alabama at Birmingham
This research was supported by grants from the National Institute on Aging (R01AG04212), Research to Prevent Blindness, and the EyeSight Foundation of Alabama.
Availability of data and materials
The data have not yet been placed in a publicly available repository since the investigators are still in the process of analyzing and publishing the ALSTAR study findings.
CO designed the study, oversaw data collection, interpreted the data, and drafted the manuscript. GMGJ designed the study, designed the statistical analyses of the data, interpreted the data, and drafted the manuscript. Both authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
No personal data or clinical data associated with personal data are presented in this manuscript.
Ethics approval and consent to participate
The protocol (#F080205001) was approved by the Institutional Review Board of the University of Alabama at Birmingham (UAB) and followed the tenants of the Declaration of Helsinki. Informed consent was obtained from all participants after the nature and purpose of the study was described.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
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