Repeatability of Rod-Mediated Dark Adaptation Testing in Normal Aging and Early and Intermediate Age-Related Macular Degeneration

Abstract

Purpose:
The vulnerability of rod photoreceptors in aging and early and intermediate age-related macular degeneration (AMD) has been well documented. Rod-mediated dark adaptation (RMDA) is a measure of the recovery of light sensitivity in rod photoreceptors following a bright light. Delays in RMDA during early and intermediate AMD have been widely reported. For RMDA's promise as an outcome for trials targeted at early and intermediate AMD to be realized, excellent test-retest reliability, its repeatability, must be established.

Methods:
Test-retest performance in a commonly used RMDA test based on the rod intercept time metric (RIT) was evaluated in participants with early and intermediate AMD and with normal retinal aging with testing approximately 2 weeks apart. The test target was placed at 5° eccentricity superior to the foveal center, an area with maximal rod loss in aging and AMD. Disease severity was identified by a trained and masked grader of fundus photographs using both the AREDS 9-step and Beckman classification systems. Bland-Altman plots and intra-class correlation coefficients (ICC) evaluated repeatability.

Results:
The analysis sample consisted of 37 older adults (mean age 76 years, standard deviation 5), with approximately one-third of the sample in each of three groups - normal aging, early AMD, and intermediate AMD. For the total sample, the ICC was 0.98. For individual AMD groups for both AREDS 9-step and Beckman classifications, the ICCs were also very high ranging from 0.82 to 0.99.

Conclusion:
We demonstrated that RMDA testing using the RIT metric has excellent repeatability when target location is at 5° in studying older adults from normal aging to intermediate AMD, suggesting the reliable use of this functional measure in trials.

Full text

Full Terms & Conditions of access and use can be found at
https://www.tandfonline.com/action/journalInformation?journalCode=icey20
Current Eye Research
ISSN: (Print) (Online) Journal homepage: www.tandfonline.com/journals/icey20
Repeatability of Rod-Mediated Dark Adaptation
Testing in Normal Aging and Early and
Intermediate Age-Related Macular Degeneration
Cynthia Owsley, Thomas A. Swain, Gerald McGwin Jr., Mary Margaret
Bernard, Mark E. Clark & Christine A. Curcio
To cite this article: Cynthia Owsley, Thomas A. Swain, Gerald McGwin Jr., Mary Margaret
Bernard, Mark E. Clark & Christine A. Curcio (04 Mar 2024): Repeatability of Rod-Mediated
Dark Adaptation Testing in Normal Aging and Early and Intermediate Age-Related Macular
Degeneration, Current Eye Research, DOI: 10.1080/02713683.2024.2326077
To link to this article: https://doi.org/10.1080/02713683.2024.2326077
Published online: 04 Mar 2024.
Submit your article to this journal
View related articles
View Crossmark data

CURRENT EYE RESEARCH
Repeatability of Rod-Mediated Dark Adaptation Testing in Normal Aging and
Early and Intermediate Age-Related Macular Degeneration
Cynthia Owsleya, Thomas A. Swaina,b, Gerald McGwin Jr.a,b, Mary Margaret Bernarda, Mark E. Clarka and
Christine A. Curcioa
aDepartment of Ophthalmology & Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA;
bDepartment of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA
ABSTRACT
Purpose: The vulnerability of rod photoreceptors in aging and early and intermediate age-related
macular degeneration (AMD) has been well documented. Rod-mediated dark adaptation (RMDA) is
a measure of the recovery of light sensitivity in rod photoreceptors following a bright light. Delays
in RMDA during early and intermediate AMD have been widely reported. For RMDA’s promise as an
outcome for trials targeted at early and intermediate AMD to be realized, excellent test-retest
reliability, its repeatability, must be established.
Methods: Test-retest performance in a commonly used RMDA test based on the rod intercept time
metric (RIT) was evaluated in participants with early and intermediate AMD and with normal retinal
aging with testing approximately 2 weeks apart. The test target was placed at 5° eccentricity superior
to the foveal center, an area with maximal rod loss in aging and AMD. Disease severity was identified
by a trained and masked grader of fundus photographs using both the AREDS 9-step and Beckman
classification systems. Bland-Altman plots and intra-class correlation coefficients (ICC) evaluated
repeatability.
Results: The analysis sample consisted of 37 older adults (mean age 76 years, standard deviation 5),
with approximately one-third of the sample in each of three groups – normal aging, early AMD, and
intermediate AMD. For the total sample, the ICC was 0.98. For individual AMD groups for both
AREDS 9-step and Beckman classifications, the ICCs were also very high ranging from 0.82 to 0.99.
Conclusion: We demonstrated that RMDA testing using the RIT metric has excellent repeatability
when target location is at 5° in studying older adults from normal aging to intermediate AMD,
suggesting the reliable use of this functional measure in trials.
Introduction
Current AMD interventions are focused on slowing advanced
age-related macular degeneration (AMD) through treating
neovascularization or pre-existing atrophy.1–3 Yet there has
been growing interest from researchers and pharma in
arresting AMD progression in the early stages of AMD
before foveal cone photoreceptors degenerate and die.4 Loss
of cone photoreceptors in advanced AMD5 engenders irre-
versible central vision impairment.6 Thus, arresting AMD
before severe cone dysfunction and even early degeneration
emerge is a potentially effective strategy for preventing
end-stage AMD.
Research over the past 25 years has indicated that
rod-mediated dark adaptation (RMDA), a dynamic measure
of scotopic vision measured close to the fovea, has promise
as a functional outcome measure for interventions designed
to arrest early AMD progression or to prevent AMD.7–11
RMDA refers to rod photoreceptors’ recovery of light sensi-
tivity in the dark after exposure to very bright light.12 Rod
intercept time (RIT) is a metric for measuring the rate of
RMDA recovery and is defined as the duration in minutes
required for sensitivity to recover to a criterion value of 3
log sensitivity, which is located in the latter one-half of the
second component of rod-mediated recovery.13
Cross-sectional data suggest that the largest decline in
vision from normal aging to intermediate AMD is for
RMDA at 5° eccentricity exactly within a region of rod loss
in aging and AMD,5,14 as compared to other photopic and
mesopic visual functions.11 Delayed RMDA is the first iden-
tified functional biomarker for incident early AMD,10 and it
is also associated with the presence of the two strongest risk
alleles for AMD, ARMS2 and CFH.15 Structural changes in
AMD are associated with delayed RMDA. With increasing
AMD severity from normal aging to intermediate AMD,
RMDA delays worsen.9,11 A deep learning analysis of optical
coherence tomography (OCT) found a relationship of RMDA
slowing with outer retinal reflective bands in central retina,
suggesting a structural basis for RMDA.16 Slowing in RMDA
is exacerbated by the presence of subretinal drusenoid
© 2024 Taylor & Francis Group, LLC
CONTACT Cynthia Owsley cynthiaowsley@uabmc.edu Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of
Alabama at Birmingham, Birmingham, AL, USA
https://doi.org/10.1080/02713683.2024.2326077
ARTICLE HISTORY
Received 8 November 2023
Accepted 26 February 2024

2 C. OWSLEY ETAL.
deposits (SDD) (i.e. reticular pseudodrusen),17–19 which
increase the risk of developing advanced AMD.20,21
Hyperreflective foci,22 circumscribed lesions in the neurosen-
sory retina that increase risk for advanced AMD,23–25 are
also associated with slower RMDA.26,27 Choriocapillaris flow
signal deficits as revealed by OCT angiography (OCTA) in
normal aging and early and intermediate AMD are associ-
ated with delayed RMDA.28
For RMDA to be an acceptable outcome for clinical trials
in normal aging to intermediate AMD, the test-retest reli-
ability, or the repeatability, of RMDA testing must be estab-
lished for this population. Herein we perform a study
examining the repeatability of a paradigm that has been fre-
quently utilized in the literature in studies on RMDA in this
population.4,10,11,29–32
Methods
This study was approved by the Institutional Review Board
of the University of Alabama at Birmingham (UAB). Written
informed consent was provided by participants after the
nature and purpose of the study were described. The study
followed the tenants of the Declaration of Helsinki and the
Health Insurance Portability and Accountability Act of 1996.
The study design was a single-site longitudinal cohort
examining RMDA performance at baseline and at a second
visit 1-2 weeks later. Enrollment was largely modeled after
the enrollment and eligibility requirements of the Alabama
Study on Early Age-Related Macular Degeneration 2
(ALSTAR2).33 Persons aged 70 years old and over were
recruited from the Callahan Eye Clinics, the clinical service
of the UAB Department of Ophthalmology and Visual
Sciences. We recruited three groups of participants – those
with early AMD, intermediate AMD and those with normal
aging. The clinic’s electronic medical record was used to
search for patients with early or intermediate AMD using
the International Classification of Diseases 10th edition
(ICD-10) codes for these conditions (H35.30*; H35.31*;
H35.36*). Exclusion criteria, described previously,11 were
extensive and included eye or brain conditions that could
impair vision (except for early cataract), diabetes, psychiatric
or neurological disorders that could impair the ability to fol-
low instructions, and any medical condition that caused
frailty or was thought to be terminal. Persons exhibiting
normal aging had the same eligibility criteria as those with
early and intermediate AMD except they did not have
ICD-10 codes for early and intermediate AMD.
One eye was tested in each participant, selected as the
eye with better visual acuity; if the eyes had the same acuity,
an eye was randomly selected. Classification into the three
groups was defined by a trained grader’s evaluation of color
fundus photographs taken with a digital camera (Model
450+, Carl Zeiss Meditec, Dublin CA) after pharmacologic
mydriasis with 1% tropicamide and 2.5% phenylephrine
hydrochloride. The Age-Related Eye Disease Study (AREDS)
9-step classification system34 was used by the grader to iden-
tify the presence and severity of AMD in the eye. Those
eyes with normal aging had AREDS grade 1, early AMD
with grades of 2–4, and intermediate AMD with grades of
5–8. The grader was masked to all other participant charac-
teristics. As described previously,26 intra-grader agreement
was K = 0.88; inter-grader agreement with a second grader
was K = 0.75. We also implemented the Beckman classifica-
tion system35 for identifying AMD. Normal aging in this
system was defined as grades 1 to 2, early AMD as grade 3,
and intermediate AMD as grade 4.
At Visit 1, a self-administered questionnaire collected
information on birthdate, gender, and race/ethnicity. Best
corrected visual acuity was measured for the study eye with
the Electronic Visual Acuity Tester36 (M&S Technologies,
Niles IL) under photopic conditions (100 cd/m2) and
expressed as logarithm10 of the minimum angle of resolution
(logMAR). After pupillary dilation (as described above),
pupils had diameters of ≥ 6 mm. RMDA was measured for
the study eye using the AdaptDx (LumaThera, Poulsbo WA).
The target was positioned at 5° on the superior vertical
meridian of the retina, since rod loss is proportionately
maximal in aging and AMD at 5°, yet rod spatial density
(cells/mm2) is less than its peak at 10.4–17.4° (3–5 mm)
along the same meridian.5,14 Participants wore their best
refractive correction for the test distance of 30 cm. As previ-
ously described,11 the procedure began with a brief
photo-bleach flash (equivalent ~83% bleach of 50 ms dura-
tion, 58,000 scotopic cd/m2 s intensity37) of 6° diameter cen-
tered at the test target location, while the participant focused
on the fixation light. Threshold measurement for a 2° diam-
eter, 500 nm circular target began 15 s after bleach offset.
Log thresholds were expressed as sensitivity in decibel units
as a function of time since bleach offset. Threshold mea-
surement continued until the RIT was reached, where RIT is
the duration in minutes required for sensitivity to recover to
a criterion value of 5.0 x 10−3 scotopic cs/m2,10,13 located in
the latter half of the second component of rod-mediated
recovery.12,38 This corresponds to a decibel reading on the
ordinate of a log sensitivity 3. Participants with fixation
errors > 30% were excluded from the analysis sample. At
Visit 2, one to two weeks later, RMDA testing was repeated
on the same eye using the same methods as described for
Visit 1.
Statistical analysis
Continuous and categorical data were summarized using
mean (standard deviation, SD) or number (percent) for con-
tinuous and categorical data, respectively. The Shrout-Fleiss
reliability random set (two-way random effects) was used to
calculate the intraclass correlation coefficient (ICC) and
associated 95% confidence intervals (95% CIs).39 This mea-
sure of reliability is appropriate given there is a single RMDA
test completed by all participants, and the objective is to
generalize test-retest results to all older persons in normal
macular health or with early or intermediate AMD.40 A
Bland-Altman plot was used to illustrate the mean RIT of
the two tests for each participant versus the difference
between RITs.41 Analyses were conducted in SAS Version 9.4
(SAS Institute, Cary, NC) or R Version 4.1.1.

CURRENT EYE RESEARCH 3
Results
A total of 44 persons enrolled and completed Visit 1. There
were two participants with >30% fixation errors and there-
fore not scheduled for the follow-up visit. At the second
visit, one person had fixation errors >30% and another could
not complete RMDA testing. After removing these four sub-
jects, an additional three persons were removed as they were
graded as having advanced AMD in the study eye (which
did not meet the inclusion criteria). The final analysis sam-
ple had 37 participants. With this sample size, we had over
90% statistical power to examine the ICC per Table 1a in
this reference.42 Visit 2 followed Visit 1 on average by 8 days
(SD = 4). Demographic characteristics are listed in Table 1.
The mean age was 76 years with approximately ¾ women
and 89% white with the balance African American. In terms
of AMD presence and severity per the AREDS 9-step sys-
tem, 13 had normal aging, 11 with early AMD and 13 with
intermediate AMD. With the Beckman system, 9 had nor-
mal aging, 11 with early AMD and 17 with intermediate
AMD. The average visual acuity was 0.03 logMAR (SD 0.12)
in the overall sample; by AREDS AMD categories, acuity
ranged from -0.03 logMAR (SD 0.12) among those with
early AMD to 0.07 logMAR (0.13) among those with inter-
mediate AMD.
The Bland-Alman plot (Figure 1) illustrates the repeat-
ability of RIT between the two visits. The bias between the
two tests, or mean difference, is -14 s (SD 2.4 min). The 95%
confidence intervals of the mean difference are less than ±
5 min. As RIT increased, mean differences did not also
increase, indicating that test-retest reliability is independent
of AMD severity among those without advanced AMD.
Intra-class correlation coefficients (ICCs) were computed
for the overall sample and for each AMD severity group, for
both the AREDS 9-step system and the Beckman system
(Table 2). For the total sample, the ICC was 0.98. For the
individual groups for both AREDS 9-step and Beckman clas-
sifications, the ICCs were also very high ranging from 0.82
to 0.99. Figure 2 displays representational examples of
RMDA test-retest results in participants with normal aging,
early AMD, and intermediate AMD.
Discussion
Test-retest reliability for RIT from RMDA testing as assessed
by the ICC in persons with normal aging, early AMD, and
intermediate AMD was excellent, with a coefficient of 0.98.43
Repeatability was excellent within each group and also when
we used two different AMD classification systems, AREDS
9-step and Beckman. Our results are similar to RIT repeat-
ability in one study reported by both Flamendorf et al.17 and
Hess et al.44 also studying persons from normal aging to
intermediate AMD; they reported an ICC of 0.89. Both our
study and that reported by Flamendorf/Hess measured
RMDA with a target located at 5° on the upper vertical ret-
inal meridian. At this retinal location, rod photoreceptors
have their greatest proportional loss during aging and also
in early and intermediate AMD, compared to other retinal
areas.5,14 Thus, because of this accentuated rod vulnerability,
this retinal region is particularly appropriate for probing rod
function as an outcome measure in aging and the early
phases of AMD. Measuring RMDA at greater eccentricities
Table 1. Demographic characteristics of the sample.
Mean Standard deviation
Age 76 5
n%
Gender
Men 10 27
Women 27 73
Racea
African American 4 11
White 33 89
AMD (AREDS 9-step)
Normal aging 13 35
Early AMD 11 30
Intermediate AMD 13 35
AMD (Beckman)
Normal aging 9 24
Early AMD 11 30
Intermediate AMD 17 46
aAll participants were of non-Hispanic descent.
Figure 1. This Bland-Altman plot shows the average RIT of each participant from both tests (x-axis) and the dierence for each participant between tests (y-axis).
The line of equality, where the dierence equals zero, is the solid black line. The dashed line directly below the line of equality is the mean dierence, or bias,
of all participants with a value of -14 s (SD of 2.4 min). The outermost dashed lines represent the 95% condence interval between which 95% of the dierences
exist.

4 C. OWSLEY ETAL.
in AMD, such as at or near the edge of the central area
(10–12°) leads to shorter RIT, meaning smaller delays in
RMDA when comparing intermediate AMD to normal
aging.31,45–48 This smaller delay in RMDA at 12° does not
necessarily lead to a faster duration for the time course of a
clinical trial, because the effect size is smaller.31
MACUSTAR, a prospective study on AMD,49 also evalu-
ated test-retest repeatability of RIT in participants with inter-
mediate AMD. Their ICC was lower, at 0.67, which they
described as “adequate.”50 Possible reasons for their decreased
repeatability compared to the current study and the
Flamendorf/Hess study are unknown. Unlike the Flamendorf/
Hess study and ours, where RMDA was measured with the
test target positioned at 5°, the MACUSTAR target was located
at 12°.50 Observer responses for non-foveal targets can involve
greater fixation errors when a more eccentric target (at 12°) is
used compared to a less eccentric target (at 5°), which may
have contributed to noisier responses for MACUSTAR’s 12°
protocol.51,52 In the MACUSTAR study fixation errors could
be as high as 40% whereas in the current study and the
Flamendorf/Hess study fixation errors could not exceed 30%.
Despite standardized procedures across sites, MACUSTAR
data loss was high with 36.4% of the RMDA data from par-
ticipants excluded due to error which included general site
procedural errors (9%), insufficient bleach (13.7%), and fixa-
tion loss (13.7%). In contrast, the current study excluded only
7% of persons due to fixation error exceeding 30% and no
data were removed due to insufficient bleach or other proce-
dural errors. Both MACUSTAR and this study had around 2%
of persons unable to perform the test.
Strengths of this study are the use of both the AREDS
9-step and Beckman AMD classification systems since
different research groups prefer the use of one classification
scheme over the other. A limitation is the relatively small
sample size. However, despite this sample size we found
excellent agreement between visit 1 and 2 testing.
In summary, we have shown that RMDA testing using
the RIT metric has excellent repeatability when target loca-
tion is at 5° when studying older adults from normal aging
to intermediate AMD. This is the case regardless of whether
one uses the AREDS 9-step or the Beckman AMD classifi-
cation systems. Our finding of excellent repeatability has
also been reported in a previous study by both Flamendorf
et al.17 and Hess et al.44 who studied a similar population.
With this high level of repeatability and the growing number
of structural validations of RMDA emerging in the literature
on early and intermediate AMD,9,11,16–19,26–28 RMDA is an
excellent candidate as a functional outcome for early to
intermediate AMD trials, even in prevention trials when
they arise.53
Authors’ contribution
Cynthia Owsley is an inventor on the device used to measure
rod-mediated dark adaptation in this study. Chirstine Curcio receives
research support from Genentech/Homan La Roche, Heidelberg
Engineering, and Novartis, and is a consultant for Apellis, Astellas,
Genentech, Boehringer Ingelheim, Osanni, Character Biosciences, and
Annexon.
Disclosure statement
No potential conict of interest was reported by the author(s).
Funding
is research was funded by National Institutes of Health grants
R01EY029595, R01EY029595-S1, P30EY03039, Dorsett Davis Discovery
Fund, Alfreda J. Schueler Trust, EyeSight Foundation of Alabama, and
Research to Prevent Blindness
ORCID
Christine A. Curcio http://orcid.org/0000-0001-9769-1538
Table 2. Intra-class correlation coecients (ICC) for repeatability of RIT for visit
1 and visit 2, presented for both AREDS 9-step system and Beckman system.
AREDS 9-step Beckman
ICC 95% CI ICC 95% CI
Normal aging 0.92 0.74 – 0.97 0.82 0.38 – 0.96
Early AMD 0.82 0.48 – 0.95 0.97 0.89 – 0.99
Intermediate AMD 0.99 0.95 – 0.99 0.99 0.96 – 0.99
Total sample ICC 0.98 95% CI 0.96 – 0.99
CI: condence interval
Figure 2. Examples of test-retest results for each group: A: normal aging; B: early AMD; C: intermediate AMD. RIT is indicated by the arrow to the abscissa.

CURRENT EYE RESEARCH 5
Data availability statement
Data are available on request from the authors.
References
1. Tan CS, K NW, Chay IW, Ting DS, Sadda SR. Current AMD
interventions are focused on slowing advanced age-related mac-
ular degeneration (nAMD): a review of emerging treatment op-
tions. Clin Ophthalmol. 2022;16:917–933. doi: 10.2147/OPTH.
S231913.
2. Heier JS, Lad EM, Holz FG, Rosenfeld PJ, Guymer RH, Boyer D,
Grossi F, Baumal CR, Korobelnik JF, Slakter JS, et al.
Pegcetacoplan for the treatment of geographic atrophy second-
ary to age-related macular degeneration (OAKS and DERBY):
two multicentre, randomised, double-masked, sham-controlled,
phase 3 trials. Lancet. 2023;402(10411):1434–1448. doi: 10.1016/
S0140-6736(23)01520-9.
3. Kang C. Avacincaptad pegol: rst approval. Drugs.
2023;83(15):1447–1453. doi: 10.1007/s40265-023-01948-8.
4. Lad EM, Fang V, Tessier M, Rautanen A, Gayan J, Stinnett SS,
Luhmann UFO. Longitudinal evaluation of visual function im-
pairments in early and intermediate age-related macular degener-
ation patients. Ophthalmol Sci. 2022;2(3):100173. doi: 10.1016
/j.xops.2022.100173.
5. Curcio CA, Medeiros NE, Millican CL. Photoreceptor loss in
age-related macular degeneration. Invest Ophthalmol Vis Sci.
1996;37(7):1236–1249.
6. Razavi H, Walton R, Gillies M, Guymer R,. Seven-year trends in
visual acuity at rst presentation in patients with neovascular
AMD. Ophthalmology. 2017;124(2):270–272. doi: 10.1016/j.oph-
tha.2016.08.013.
7. Steinmetz RL, Haimovici R, Jubb C, Fitzke FW, Bird AC.
Symptomatic abnormalities of dark adaptation in patients with
age-related Bruch’s membrane change. Br J Ophthalmol.
1993;77(9):549–554. doi: 10.1136/bjo.77.9.549.
8. Owsley C, Jackson GR, White MF, Feist R, Edwards D. Delays
in rod-mediated dark adaptation in early age-related maculopa-
thy. Ophthalmology. 2001;108(7):1196–1202. doi: 10.1016/
s0161-6420(01)00580-2.
9. Owsley C, McGwin G, Jackson G, Kallies K, Clark M. Cone- and
rod-mediated dark adaptation impairment in age-related macu-
lopathy. Ophthalmology. 2007;114(9):1728–1735. doi: 10.1016/j.
ophtha.2006.12.023.
10. Owsley C, McGwin GJ, Clark ME, Jackson GR, Callahan
MA, Kline LB, Witherspoon CD, Curcio CA. Delayed
rod-mediated dark adaptation is a functional biomarker for in-
cident early age-related macular degeneration. Ophthalmology.
2016;123(2):344–351. doi: 10.1016/j.ophtha.2015.09.041.
11. Owsley C, Swain TA, McGwin G, Clark ME, Kar D, Crosson JN,
Curcio C. How vision is impaired from aging to early and inter-
mediate age-related macular degeneration: insights from ALSTAR2
baseline. Transl Vis Sci Technol. 2022;11(7):17. doi: 10.1167/
tvst.11.7.17.
12. Lamb TD, Pugh ENJ. Dark adaptation and the retinoid cycle of
vision. Prog Retin Eye Res. 2004;23(3):307–380. doi: 10.1016/
j.preteyeres.2004.03.001.
13. Jackson GR, Edwards JG. A short-duration dark adaptation pro-
tocol for assessment of age-related maculopathy. J Ocul Biol Dis
Infor. 2008;1(1):7–11. doi: 10.1007/s12177-008-9002-6.
14. Curcio CA, Millican CL, Allen KA, Kalina RE. Aging of the hu-
man photoreceptor mosaic: evidence for selective vulnerability of
rods in central retina. Invest Ophthalmol Vis Sci. 1993;34(12):3278–
3296.
15. Mullins RF, McGwin GJ, Searcey K, Clark ME, Kennedy EL, Curcio
CA, Stone EM, Owsley C. e ARMS2 A69S polymorphism is as-
sociated with delayed rod-mediated dark adaptation in eyes at risk
for incident age-related macular degeneration. Ophthalmology.
2018;126(4):591–600. doi: 10.1016/j.ophtha.2018.10.037.
16. Lee AY, Lee CS, Blazes MS, Owen JP, Bagdasarova Y, Wu Y,
Spaide T, Yanagihara RT, Kihara Y, Clark ME, etal. Exploring a
structural basis for delayed rod-mediated dark adaptation in
age-related macular degeneration via deep learning. Transl Vis
Sci Technol. 2020;9(2):62. doi: 10.1167/tvst.9.2.62.
17. Flamendorf J, Agrón E, Wong WT, ompson D, Wiley HE,
Doss EL, Al-Holou S, Ferris FL, Chew EY, Cukras C. Impairments
in dark adaptation are associated with age-related macular degen-
eration severity and reticular pseudodrusen. Ophthalmology.
2015;122(10):2053–2062. doi: 10.1016/j.ophtha.2015.06.023.
18. Sevilla MB, McGwin GJ, Lad EM, Clark M, Yuan EL, Farsiu S,
Curcio CA, Owsley C, Toth CA. Relating retinal morphology and
function in aging and early to intermediate age-related macular
degeneration subjects. Am J Ophthalmol. 2016;165:65–77. doi:
10.1016/j.ajo.2016.02.021.
19. Laíns I, Miller JB, Park DH, Tsikata E, Davoudi S, Rahmani S,
Pierce J, Silva R, Chen TC, Kim IK, etal. Structural changes as-
sociated with delayed dark adaptation in age-related macular de-
generation. Ophthalmology. 2017;124(9):1340–1352. doi: 10.1016/j.
ophtha.2017.03.061.
20. Agrón E, Domalpally A, Cukras CA, Clemons TE, Chen Q, Lu
Z, Chew EY, Keenan TDL, Reticular pseudodrusen: the third
macular risk feature for progression to late age-related macular
degeneration. Age-related eye disease Study 2 Report 30.
Ophthalmology. 2022;129(10):1107–1119. doi: 10.1016/j.oph-
tha.2022.05.021.
21. Agrón E, Domalpally A, Cukras CA, Clemons TE, Chen Q,
Swaroop A, Lu Z, Chew EY, Keenan TDL. Reticular pseudodrusen
status, ARMS2/HTRA1 genotype, and geographic atrophy enlarge-
ment. Age-related eye disease Study 2 Report 32. Ophthalmology.
2023;130(5):488–500. doi: 10.1016/j.ophtha.2022.11.026.
22. Zacks DN, Johnson MW. Transretinal pigment migration: an op-
tical coherence tomographic study. Arch Ophthalmol.
2004;122(3):406–408. doi: 10.1001/archopht.122.3.406.
23. Christenbury JG, Folgar FA, O’Connell RV, Chiu SJ, Farsiu S,
Toth CA. Progression of intermediate age-related macular degen-
eration with proliferation and iner retinal migration of hyperre-
ective foci. Ophthalmology. 2013;120(5):1038–1045. doi:
10.1016/j.ophtha.2012.10.018.
24. Ouyang Y, Heussen FM, Hariri A, Keane PA, Sadda SR. Optical
coherence tomography-based observation of the natural history
of drusenoid lesion in eyes with dry age-related macular degen-
eration. Ophthalmology. 2013;120(12):2656–2665. doi: 10.1016/j.
ophtha.2013.05.029.
25. Sleiman K, Veerappan M, Winter KP, McCall MN, Yiu G, Farsiu
S, Chew EY, Clemons T, Toth CA. Optical coherence tomography
predictors of risk for progression to non-neovascular atrophic
age-related macular degeneration. Ophthalmology.
2017;124(12):1764–1777. doi: 10.1016/j.ophtha.2017.06.032.
26. Echols BS, Clark ME, Swain TA, Chen L, Kar D, Zhang Y,
Sloan KR, McGwin G, Singireddy R, Mays C, et al.
Hyperreective foci and specks are associated with delayed
rod-mediated dark adaptation in nonneovascular age-related
macular degeneration. Ophthalmol Retina. 2020;4(11):1059–
1068. doi: 10.1016/j.oret.2020.05.001.
27. Duic C, Pfau K, Keenan TDL, Wiley H, avikulwat A, Chew
EY, Cukras C. Hyperreective foci in age-related macular degen-
eration are associated with disease severity and functional im-
pairment. Ophthalmol Retina. 2022;7(4):307–317. doi: 10.1016/
j.oret.2022.11.006.
28. Kar D, Corradetti G, Swain TA, Clark ME, McGwin GJ, Owsley
C, Sadda SR, Curcio C. Choriocapillaris impairment is associated
with delayed rod-mediated dark adaptation in age-related macu-
lar degeneration. Invest Ophthalmol Vis Sci. 2023;64(12):41. doi:
10.1167/iovs.64.12.41.
29. Owsley C, Huisingh C, Clark ME, Jackson GR, McGwin GJ.
Comparison of visual function in older eyes in the earliest stages
of age-related macular degeneration to those in normal macular
health. Curr Eye Res. 2016;41(2):266–272. doi: 10.3109/02713683.
2015.1011282.

6 C. OWSLEY ETAL.
30. Cocce KJ, Stinnett SS, Luhmann UFO, Vajzovic L, Horne A,
Schuman SG, Toth CA, Cousins SW, Lad EM. Visual function
metrics in early and intermediate dry age-related macular degen-
eration for use as clinical trial endpoints. Am J Ophthalmol.
2018;189:127–138. doi: 10.1016/j.ajo.2018.02.012.
31. Owsley C, Swain TA, McGwin GJ, Clark ME, Kar D, Curcio CA.
Biologically guided optimization of test target location for
rod-mediated dark adaptation in age-related macular degenera-
tion. Ophthalmol Sci. 2023;3(2):100274. doi: 10.1016/j.xops.2023.
100274.
32. Tanaya T, Swain TA, Clark ME, Swanner JC, Lolley VR, Callahan
MA, McGwin GJ, Owsley C. Comparing rod-mediated dark ad-
aptation in older adults before and aer cataract surgery. Curr
Eye Res. 2023;48(5):512–517. doi: 10.1080/02713683.2023.2171438.
33. Curcio CA, McGwin G, JrSadda SR, Hu Z, Clark ME, Sloan KR,
Swain T, Crosson JN, Owsley C. Functionally validated imaging
endpoints in the Alabama study on early age-related macular de-
generation 2 (ALSTAR2): design and methods. BMC Ophthalmol.
2020;20(1):196. doi: 10.1186/s12886-020-01467-0.
34. Age-Related Eye Disease Study Research Group. e age-related
eye disease study severity scale for age-related macular degenera-
tion. AREDS Report No. 17. Arch Ophthalmol. 2005;123:1484–
1498.
35. Ferris FLI, Wilkinson CP, Bird A, Chakravarthy U, Chew E,
Csaky K, Sadda SR, Clinical classication of age-related macular
degeneration. Ophthalmology. 2013;120(4):844–851. doi: 10.1016/j.
ophtha.2012.10.036.
36. Beck RW, Moke PS, Turpin AH, Ferris FL, SanGiovanni JP,
Johnson CA, Birch EE, Chandler DL, Cox TA, Blair RC, et al.
A computerized method of visual acuity testing: adaptation of
the early treatment of diabetic retinopathy study testing proto-
col. Am J Ophthalmol. 2003;135(2):194–205. doi: 10.1016/
s0002-9394(02)01825-1.
37. Pugh ENJ. Rushton’s paradox: rod dark adaptation aer ash
photolysis. J Physiol. 1975;248(2):413–431. doi: 10.1113/jphysi-
ol.1975.sp010982.
38. Leibrock CS, Reuter T, Lamb TD. Molecular basis of dark adap-
tation in rod photoreceptors. Eye . 1998;12 (Pt 3b)(3):511–520.
:doi: 10.1038/eye.1998.139.
39. Shrout PE, Fleiss JL. Intraclass correlations: uses in assessing rat-
er reliability. Psychol Bull. 1979;86(2):420–428. doi: 10.1037/0033-
2909.86.2.420.
40. Koo TK, Li MY. A guideline of selecting and reporting intraclass
correlation coecients for reliability research. J Chiropr Med.
2016;15(2):155–163. doi: 10.1016/j.jcm.2016.02.012.
41. Bland JM, Altman DG. Statistical methods for assessing agree-
ment between two methods of clinical measurement. Lancet.
1986;327(8476):307–310. doi: 10.1016/S0140-6736(86)90837-8.
42. Bujang MA, Baharum N. A simplied guide to determinination of
sample size requirements for estimating the value of intraclass cor-
relation coecient: a review. Arch Orofac Sci. 2017;12(1):1–11.
43. Cicchetti DV. Guidelines, criteria, and rules of thumb for evaluat-
ing normed and standardized assessment instruments in psycholo-
gy. Psychol Assess. 1994;6(4):284–290. doi: 10.1037/1040-3590.6.4.284.
44. Hess K, de Silva T, Grisso P, Wiley H, avikulwat AT, Keenan
TDL, Chew EY, Cukras C. Evaluation of cone- and rod-mediated
parameters of dark adaptation testing as outcome measures in
age-related macular degeneration. Ophthalmol Retina.
2022;6(12):1173–1184. doi: 10.1016/j.oret.2022.05.018.
45. Tahir HJ, Rodrigo-Diaz E, Parry NRA, Kelly JMF, Carden D,
Aslam TM, Murray IJ. Slowed dark adaptation in early AMD:
dual stimulus reveals scotopic and photopic abnormalities. Invest
Ophthalmol Vis Sci. 2018;59(4):AMD202–AMD210. doi: 10.1167/
iovs.18-24227.
46. Tan RS, Guymer RH, Aung K-Z, Caruso E, Luu CD. Longitudinal
assessment of rod function in intermediate age-related macular
degeneration with and without reticular pseudodrusen. Invest
Ophthalmol Vis Sci. 2019;60(5):1511–1518. doi: 10.1167/iovs.
18-26385.
47. Flynn OJ, Jerey BG, Cukras CA. Characterization of rod function
phenotypes across a range of age-related macular degeneration se-
verities and subretinal drusenoid deposits. Invest Ophthalmol Vis
Sci. 2018;59(6):2411–2421. doi: 10.1167/iovs.17-22874.
48. Binns AM, Taylor DJ, Edwards LA, Crabb DP. Determining opti-
mal test parameters for assessing dark adaptation in people with
intermediate age-related macular degeneration. Invest Ophthalmol
Vis Sci. 2018;59(4):AMD114–AMD121. doi: 10.1167/iovs.18-24211.
49. Finger RP, Schmitz-Valckenberg S, Schmid M, Rubin GS, Dunbar
H, Tufail A, Crabb DP, Binns A, Sánchez CI, Margaron P., et al.
MACUSTAR: development and clinical validation of function,
structural, and patient-reported endpoings in intermediate
age-related macular degeneration. Ophthalmologica. 2019;241(2):61–
72. doi: 10.1159/000491402.
50. Higgins BE, Montesano G, Dunbar HMP, Binns AM, Taylor DJ,
Behning C, Abdirahman A, Schmid MC, Terheyden JH, Zakaria
N, et al. Test-retest variability and discriminatory power of mea-
surements from microperimetry and dark adaptation assessment
in people with intermediate age-related macular degeneration—A
MACUSTAR Study Report. Transl Vis Sci Technol. 2023;12(7):19.
doi: 10.1167/tvst.12.7.19.
51. Carrasco M, Evert DL, Chang I, Katz SM. e eccentricity eect:
target eccentricity aects performance on conjunction searches.
Percept Psychophys. 1995;57(8):1241–1261. doi: 10.3758/
bf03208380.
52. Wall M, Johnson CA. Morphology and repeatabiity of automated
perimetry using stimulus sizes III, V, and VI. Med Res Arch.
2020;9:1–15.
53. de Koning-Backus APM, Kiee-de Jong JC, van Rooij JGJ,
Uitterlinden AG, Voortman TG, Meester-Smoor MA, Klaver
CCW.. Lifestyle intervention randomized controlled trial for
age-related macular degeneration (AMD-Life): study design.
Nutrients. 2023;15(3):602. doi: 10.3390/nu15030602.