Abstract
Background
Myopia is a major global public health concern, and near work has been identified as a key risk factor for its onset and progression. This study aimed to evaluate short-term retinal and choroidal vascular and structural responses to near work and subsequent eye-closure rest in young adults.
Methods
Thirty medical students (aged 18–24 years) underwent wide-field swept-source OCTA at baseline, after 20, 40, and 60 min of near work, and after 10, 20, and 30 min of eye-closure rest. Vascular parameters of the nerve fiber layer vascular plexus (NFLVP), superficial vascular complex (SVC), deep vascular complex (DVC), choriocapillaris, and choroid were analyzed.
Results
During near work, NFLVP vessel density (VD) and vessel diameter index increased in the temporal 1–3 mm and 6–9 mm sectors; the 6–9 mm temporal sector remained elevated above baseline throughout rest (all p < 0.05). SVC VD, small vessel density, and vessel length density in the superior 3–6 mm sector fell below baseline during rest (all p < 0.05). Choroidal perfusion area, thickness, and stromal volume declined significantly relative to pre-rest values at 20 min of rest (all p < 0.05).
Conclusions
NFLVP perfusion in the temporal 6–9 mm sector increased during near work and remained elevated above baseline throughout the rest period; SVC perfusion in the same sector likewise remained above baseline during rest, while SVC perfusion in the superior 3–6 mm sector fell below baseline. These alterations may provide important insights into the vascular regulatory mechanisms underlying myopia development.
Keywords: Retina, Choroid, Near work, Optical coherence tomography angiography, Medical student
Introduction
Myopia has become a major global public health concern, with prevalence reaching 80–90% among young people in East and Southeast Asia and imposing an economic burden of several billion dollars worldwide due to medical costs and productivity loss [1, 2]. While myopia was once thought to stabilize in adulthood, recent studies indicate that progression does not cease after maturity but continues throughout life [3, 4]. Longitudinal studies in both university students and the general population have shown that myopia may begin and continue to progress during young adulthood [3, 5]. Evidence from numerous pediatric studies consistently identifies near work as a major risk factor for the onset and progression of myopia [6, 7]. In modern society, young adults—particularly medical students—are exposed to an increasing burden of near work activities such as writing, reading, and prolonged use of digital screens [8], which may contribute to ongoing myopic progression [9].
With advances in optical coherence tomography angiography (OCTA), retinal and choroidal microvascular structures can now be assessed in greater detail, with higher accuracy, and over wider fields. This technology enables comprehensive evaluation of blood flow and structural changes in the retina and choroid, offering new insights into the pathophysiology of myopia [10, 11]. Our previous work demonstrated reduced perfusion in retinal and choroidal capillaries among myopic eyes, and accumulating evidence further suggests that the choroid plays a critical role in ocular growth regulation and myopia development through a vision-driven retina–choroid–sclera signaling cascade [12–14]. Experimental studies in children and young adults have further reported that short-term near work (40–60 min) induces choroidal thinning and reduced choroidal perfusion [15, 16].
These prior studies have been limited to a narrow macular field—typically within the central 6 mm—a single post-task time point, and isolated choroidal or choriocapillaris parameters, leaving peripheral retinal and choroidal responses beyond this range uncharacterized. In contrast, wide-field swept-source OCTA enables imaging of both macular and peripheral regions extending to 12 mm eccentricity, capturing spatially heterogeneous vascular response patterns in peripheral regions that would otherwise be undetectable with narrower macular-confined scanning fields. Consequently, the spatiotemporal dynamics of the full retinal vascular hierarchy remain incompletely characterized, and the dynamic changes in ocular blood flow during eye-closure rest have yet to be fully explored.
In this study, we examined wide-field retinal and choroidal blood flow and thickness responses to near work in young adults (medical students). Our findings contribute to a better understanding of the role of retinal and choroidal circulation in near–work–induced myopia progression and provide new perspectives for future research and potential interventions aimed at mitigating myopia in populations with sustained near-work demands.
Methods
Study design and participants
From December 2024 to January 2025, a total of 32 university students aged 18 to 24 years were recruited for this study. All participants were in good general health and met the following inclusion criteria: (1) spherical equivalent refraction (SER) greater than − 6.00 diopters (D); (2) astigmatism less than 1.00 D; (3) best-corrected visual acuity (BCVA) better than 0.0 logMAR; (4) intraocular pressure (IOP) below 21 mmHg; (5) all repeated acquisitions were required to achieve an image quality score of ≥ 7. Exclusion criteria were as follows: (1) a history of ocular trauma, disease, or surgery; (2) current use of ophthalmic prescription medications; and (3) the presence of any major systemic diseases. All participants provided written informed consent prior to enrollment. For participants in whom both eyes met the inclusion criteria, one eye was randomly selected for inclusion. All participants provided written informed consent. The study was approved by the Ethics Committee of Renmin Hospital of Wuhan University (WDRY2024-K187) and conducted in accordance with the principles of the Declaration of Helsinki. A flowchart illustrating the study design is provided in Fig. 1.
Fig. 1.
Flow chart of the study design. Of 35 subjects screened, 3 with high myopia, 2 with prior ocular surgery were excluded, leaving 30 subjects (30 eyes). Retinal and choroidal blood flow and perfusion (BFP) were measured at baseline, after 20, 40, and 60 min of near work, and after 10, 20, and 30 min of subsequent eye-closure rest
Ophthalmic examination
All participants underwent comprehensive ophthalmic examinations, including BCVA assessment, slit-lamp biomicroscopy of the anterior and posterior segments, subjective refraction (performed using RT-5100; NEDEK, Gamagori, Japan), axial length measurement (IOL Master 700; Carl Zeiss, Germany), IOP measurement (FT100 TOMEY; Nagoya, Japan), and OCTA (VG200C, SVision Imaging, China). Spherical equivalent was calculated as the sphere plus half of the cylinder.
Participants were instructed to abstain from alcohol and caffeine for at least 24 h prior to their visit. To eliminate any effects of prior visual tasks, each participant first performed at least 15 min of distance viewing (at 6 m) while wearing full refractive correction with trial lenses. OCTA imaging was then performed at baseline. This was followed by a near work task, during which all participants, under the investigator’s supervision, read the same printed English literature at a distance of 33 cm, with reading distance checked every 5 min. The reading material consisted of reading printed copies of two published English-language ophthalmology research articles, and the text was printed in a standardized format: Times New Roman, 10 pt, single-spaced, black text on white paper. Participants were required to answer relevant questions to ensure active reading. After each 20-minute reading session, participants were moved to the OCTA device for imaging. The indoor lighting was maintained at 200 to 300 lx. After completing a total of 60 min of reading, participants were asked to rest with their eyes closed, and OCTA scans were performed every 10 min during the resting period. During the rest periods, all participants remained seated, silent, and awake. The near-work durations (20, 40, and 60 min) were chosen to align with prior studies examining choroidal and retinal responses to near work [15, 16]. The subsequent eye-closure rest was monitored at 10-minute intervals (10, 20, and 30 min) to track the temporal dynamics of vascular recovery following near work.
OCTA
A swept-source OCT (SS-OCT) devicewith a central wavelength of 1050 nm was used for OCT imaging. The scanning speed was 400,000 A-scans per second. The axial optical resolution was 3.8 μm, and the axial digital resolution was 2.0 μm. The maximum scanning depth of the posterior segment was 9 mm. For each eye of every participant, a 12 mm × 15 mm macular OCTA scan centered on the fovea were obtained. The first scan was acquired in follow-up mode, and all subsequent scans used follow-up mode to ensure consistency in the scanned regions. Segmentation of each vascular layer was performed automatically by the device’s built-in software (Fig. 2). Automated segmentation of vascular layers was performed by the built-in software, including the nerve fiber layer vascular plexus (NFLVP), superficial vascular complex (SVC), deep vascular complex (DVC), choriocapillaris (CC), and choroid. Quantitative blood flow parameters were also automatically provided by the system, including vessel density (VD), small vessel density (SVD), vessel diameter index (VDI), vessel length density (VLD), perfusion area (PA), choroidal vascular volume (CVV), and choroidal stromal volume (CSV). All scans were performed between 14:30 and 17:30 each day to minimize the potential influence of diurnal variations in the choroid. All OCTA segmentation results were manually reviewed by two trained investigators and corrected where necessary.
Fig. 2.
OCTA scan and regional segmentation map. Representative wide-field OCTA image of the macula with concentric rings divided into five rings (0–1 mm, 1–3 mm, 3–6 mm, 6–9 mm, and 9–12 mm). Each ring was further segmented into superior (S), inferior (I), nasal (N), and temporal (T) quadrants
Statistical analysis
All statistical analyses were performed using Python (version 3.9.6). Results are presented as mean ± standard deviation (SD) or as median values, as appropriate. Categorical variables were summarized as frequencies. The Shapiro-Wilk test was used to assess normality for each dataset. For each parameter, changes between two time points were evaluated using the paired Wilcoxon signed-rank test, applied where the distribution of within-subject paired differences violated the normality assumption. Each eye was treated as an independent sample, and paired comparisons were performed across different time points. Additionally, Cliff’s delta was calculated for each comparison to quantify the probability of distributional differences between two time points. To control for multiple comparisons, Benjamini–Hochberg false discovery rate (FDR) correction was applied within each parameter–region combination across the six pairwise comparisons. All reported p-values are FDR-adjusted, with significance defined as p < 0.05.
Few studies have reported wide-field retinal and choroidal perfusion and thickness changes during near work. Referring to similar studies [17], we assumed a significance level of 0.05, an expected statistical power of 90%, a minimum meaningful difference of 1.5%, and an intra-group standard deviation of 1.5%. Using the paired t-test, the preliminary estimated required sample size was 12 cases. Considering that the current study utilized the nonparametric Wilcoxon signed-rank test, the sample size was conservatively increased to at least 15 cases. In this study, 30 participants were finally included, meeting these requirements.
Results
A total of 30 participants (30 eyes) were included in the study, comprising 19 females and 11 males, with a mean age of 21.1 ± 1.7 years. The mean axial length was 25.20 ± 0.96 mm, the mean SER was − 3.36 ± 1.89 D, and the mean IOP was 1 15.75 ± 2.66 mm Hg, and the median SER was − 3.75 D (IQR: −4.94 to − 2.75 D).
Tables 1 and 2 show NFLVP perfusion changes during near work and rest. During near work, VD and SVD increased significantly in sectors 1T and 6T (all p < 0.05), and VDI increased in 6T (all p < 0.05); VD also increased in 9S at 20 min of near work (p = 0.046). During rest, VD and SVD declined relative to pre-rest values in sectors 1T and 6S (all p < 0.05), and VLD decreased in the temporal sectors of the 1–6 mm rings and in sectors 3I and 3S (all p < 0.05). At the end of the rest period, VD and VDI in sector 6T remained significantly elevated above baseline (p = 0.033, 0.044).
Table 1.
Median values of NFLVP vessel density (VD, %) and small vessel density (SVD, %) across time points
| Variable | Baseline | Read20min | Read40min | Read60min | Rest10min | Rest20min | Rest30min |
|---|---|---|---|---|---|---|---|
| NFLVPVDfoveal | 0.046 | 0.029 | 0.041 | 0.058 | 0.058 | 0.020 | 0.018 |
| NFLVPVD1I | 5.760 | 5.404 | 6.810 | 6.284 | 6.042 | 6.001 | 5.668 |
| NFLVPVD1N | 3.435 | 3.180 | 3.386 | 3.417 | 3.157 | 3.099 | 3.469 |
| NFLVPVD1S | 7.712 | 6.552 | 6.922 | 7.460 | 7.416 | 7.012 | 6.410 |
| NFLVPVD1T | 1.967 | 2.738* | 2.341* | 2.621* | 2.154# | 2.055# | 2.413 |
| NFLVPVD3I | 26.506 | 24.300 | 26.512 | 27.331 | 24.901 | 25.682# | 25.857 |
| NFLVPVD3N | 35.496 | 32.787 | 36.753 | 35.743 | 33.337 | 34.086 | 35.395 |
| NFLVPVD3S | 25.354 | 24.698 | 25.812 | 24.982 | 21.873 | 22.802 | 23.500 |
| NFLVPVD3T | 9.495 | 9.343 | 9.217 | 10.078 | 9.458 | 9.415 | 9.402 |
| NFLVPVD6I | 37.145 | 36.622 | 36.560 | 39.321 | 38.464 | 36.285 | 37.003 |
| NFLVPVD6N | 80.088 | 78.592 | 80.532 | 80.930 | 79.902 | 78.869 | 79.704 |
| NFLVPVD6S | 34.029 | 34.592 | 33.441 | 34.822 | 33.089 | 32.444 | 33.497 |
| NFLVPVD6T | 12.545 | 12.728 | 13.048* | 12.838* | 13.416 | 13.115* | 13.484* |
| NFLVPVD9I | 15.385 | 15.916 | 15.992 | 17.124 | 15.570 | 16.285 | 17.095 |
| NFLVPVD9N | 54.538 | 55.496 | 56.402 | 56.615 | 56.948 | 55.084 | 56.581 |
| NFLVPVD9S | 21.069 | 21.820* | 23.360 | 22.305 | 22.189 | 22.258 | 22.188 |
| NFLVPVD9T | 13.611 | 13.250 | 13.770 | 13.668 | 13.662 | 14.073 | 14.005 |
| NFLVPSVDfoveal | 0.046 | 0.036 | 0.041 | 0.058 | 0.058 | 0.020 | 0.018 |
| NFLVPSVD1I | 3.173 | 3.346 | 3.473 | 3.236 | 3.504 | 3.086 | 3.276 |
| NFLVPSVD1N | 2.719 | 2.593 | 2.404 | 2.790 | 2.403 | 2.474 | 2.718 |
| NFLVPSVD1S | 4.378 | 4.055 | 3.551 | 4.806 | 3.930 | 3.938 | 4.238 |
| NFLVPSVD1T | 1.647 | 2.364* | 2.010 | 2.319* | 1.685# | 1.717# | 1.713# |
| NFLVPSVD3I | 11.850 | 10.739 | 11.341 | 11.992 | 12.023 | 10.866 | 10.239 |
| NFLVPSVD3N | 21.054 | 21.314 | 21.135 | 20.892 | 20.679 | 19.512 | 20.091 |
| NFLVPSVD3S | 12.948 | 12.438 | 12.312 | 11.889 | 10.775 | 10.923 | 10.830 |
| NFLVPSVD3T | 4.828 | 4.772 | 4.638 | 4.802 | 4.765 | 4.868 | 5.099 |
| NFLVPSVD6I | 15.277 | 15.483 | 14.630 | 16.500 | 15.144 | 14.710 | 15.266 |
| NFLVPSVD6N | 20.131 | 20.138 | 20.504 | 21.709 | 20.495 | 20.493 | 21.000 |
| NFLVPSVD6S | 14.846 | 15.076 | 14.336 | 14.805 | 14.006# | 14.257# | 13.980# |
| NFLVPSVD6T | 5.280 | 5.582 | 5.512 | 5.509* | 5.612 | 5.498 | 5.431 |
| NFLVPSVD9I | 5.609 | 5.364 | 5.152 | 5.577 | 4.912 | 5.117 | 5.721 |
| NFLVPSVD9N | 16.363 | 16.615 | 16.626 | 16.250 | 16.153 | 16.031 | 17.119 |
| NFLVPSVD9S | 7.330 | 8.215 | 7.414 | 7.368 | 7.008 | 7.578 | 8.325 |
| NFLVPSVD9T | 4.903 | 4.776 | 4.849 | 4.735 | 4.616 | 4.845 | 4.803 |
Abbreviations: nerve fiber layer vascular plexus (NFLVP), vessel density (VD), small vessel density (SVD),*: Statistically significant difference compared with baseline (p < 0.05)#: Statistically significant difference compared with read 60 min (p < 0.05)
Table 2.
Median values of NFLVP vessel diameter index (VDI) and vessel length density (VLD, mm/mm²) across time points
| Variable | Baseline | Read20min | Read40min | Read60min | Rest10min | Rest20min | Rest30min |
|---|---|---|---|---|---|---|---|
| NFLVPVDIfoveal | 1.000 | 1.000 | 1.000 | 1.000 | 1.000 | 1.000 | 1.000 |
| NFLVPVDI1I | 1.171 | 1.195 | 1.204 | 1.187 | 1.185 | 1.170 | 1.167 |
| NFLVPVDI1N | 1.126 | 1.133 | 1.151 | 1.134 | 1.137 | 1.137 | 1.127 |
| NFLVPVDI1S | 1.204 | 1.185 | 1.204 | 1.223 | 1.208 | 1.217 | 1.211 |
| NFLVPVDI1T | 1.070 | 1.105 | 1.113 | 1.121 | 1.087 | 1.129 | 1.081 |
| NFLVPVDI3I | 1.444 | 1.466 | 1.443 | 1.427 | 1.444 | 1.444 | 1.434 |
| NFLVPVDI3N | 1.372 | 1.382 | 1.380 | 1.368 | 1.382 | 1.377 | 1.363 |
| NFLVPVDI3S | 1.384 | 1.404 | 1.407 | 1.417 | 1.423 | 1.407 | 1.399 |
| NFLVPVDI3T | 1.236 | 1.259 | 1.252 | 1.261 | 1.246 | 1.277 | 1.258 |
| NFLVPVDI6I | 1.687 | 1.725 | 1.696 | 1.706 | 1.717 | 1.714 | 1.711 |
| NFLVPVDI6N | 1.748 | 1.731 | 1.736 | 1.755 | 1.730 | 1.718 | 1.712 |
| NFLVPVDI6S | 1.631 | 1.640 | 1.637 | 1.635 | 1.705 | 1.637 | 1.639 |
| NFLVPVDI6T | 1.306 | 1.330* | 1.346* | 1.318 | 1.333* | 1.337* | 1.346* |
| NFLVPVDI9I | 1.545 | 1.596 | 1.566 | 1.598 | 1.552 | 1.592 | 1.562 |
| NFLVPVDI9N | 1.817 | 1.840 | 1.890 | 1.833 | 1.837 | 1.836 | 1.818 |
| NFLVPVDI9S | 1.567 | 1.591 | 1.583 | 1.582 | 1.602* | 1.594 | 1.568 |
| NFLVPVDI9T | 1.408 | 1.421 | 1.422 | 1.429 | 1.439* | 1.433 | 1.431 |
| NFLVPVLDfoveal | 0.315 | 0.105 | 0.209 | 0.209 | 0.070 | 0.070 | 0.174 |
| NFLVPVLD1I | 5.042 | 5.122 | 5.979 | 5.066 | 5.056 | 5.574 | 4.940 |
| NFLVPVLD1N | 2.903 | 3.135 | 2.545 | 2.926 | 2.484 | 2.825 | 2.803 |
| NFLVPVLD1S | 6.481 | 5.188 | 5.754 | 5.818 | 5.700 | 6.053 | 5.651 |
| NFLVPVLD1T | 1.703 | 1.844 | 1.934 | 2.278 | 1.535# | 1.612# | 1.625# |
| NFLVPVLD3I | 15.307 | 14.525 | 14.989 | 15.121 | 14.557 | 14.416# | 14.642 |
| NFLVPVLD3N | 19.099 | 18.467 | 19.417 | 19.953 | 18.943 | 19.061 | 19.354 |
| NFLVPVLD3S | 15.029 | 14.697 | 15.127 | 15.023 | 13.596# | 14.382# | 14.615 |
| NFLVPVLD3T | 7.018 | 7.179 | 7.123 | 7.450 | 7.142# | 6.844# | 7.223 |
| NFLVPVLD6I | 19.611 | 19.296 | 19.389 | 20.106 | 19.770 | 19.650 | 19.945 |
| NFLVPVLD6N | 31.005 | 31.161 | 31.265 | 31.336 | 31.429 | 31.255 | 31.696 |
| NFLVPVLD6S | 18.706 | 18.529 | 18.769 | 19.233 | 17.769 | 18.079 | 18.256 |
| NFLVPVLD6T | 10.509 | 10.308 | 10.650 | 10.800 | 10.255# | 10.227 | 10.916 |
| NFLVPVLD9I | 14.245 | 14.369 | 13.832 | 14.715 | 13.652 | 14.271 | 14.866 |
| NFLVPVLD9N | 25.862 | 25.880 | 26.174 | 26.379 | 26.563 | 26.177 | 26.627 |
| NFLVPVLD9S | 16.696 | 16.562 | 16.957 | 17.374 | 16.182 | 16.558 | 17.637 |
| NFLVPVLD9T | 12.463 | 11.597 | 12.615 | 12.289 | 12.132 | 12.333 | 12.313 |
*: Statistically significant difference compared with baseline (p < 0.05)
#: Statistically significant difference compared with read 60 min (p < 0.05)
Tables 3 and 4 present SVC and DVC perfusion changes. During near work, SVC VDI increased significantly across multiple sectors of the 1–9 mm rings (all p < 0.05). During rest, SVC VD, SVD, and VLD declined relative to pre-rest values across the 1–6 mm rings and in sector 6S (all p < 0.05). At the end of the rest period, VD, SVD, and VLD in sector 3S remained significantly below baseline (all p < 0.05), while VD and VDI in sector 6T and VD in sector 9T remained above baseline (all p < 0.05). DVC VDI increased significantly in sectors 3T, 6T, and 9T during near work (all p < 0.05).
Table 3.
Median values of SVC and DVC vessel density (VD, %) and small vessel density (SVD, %) across time points
| Variable | Baseline | Read20min | Read40min | Read60min | Rest10min | Rest20min | Rest30min |
|---|---|---|---|---|---|---|---|
| SVCSVDfoveal | 10.524 | 9.808 | 10.032 | 11.093 | 9.112 | 9.926 | 9.105 |
| SVCSVD1I | 25.991 | 23.926 | 25.185 | 27.256 | 25.450# | 25.286# | 25.690 |
| SVCSVD1N | 27.542 | 25.915 | 25.939 | 27.838 | 23.879# | 26.054# | 26.769 |
| SVCSVD1S | 27.000 | 26.216 | 27.219 | 27.513 | 26.448# | 24.462# | 27.540 |
| SVCSVD1T | 23.154 | 21.620 | 23.316 | 23.723 | 22.019 | 20.375# | 22.410 |
| SVCSVD3I | 26.209 | 24.762 | 24.352 | 25.730 | 25.990 | 22.984 | 24.977 |
| SVCSVD3N | 33.350 | 32.991 | 33.720 | 33.463 | 33.024 | 32.549 | 33.818 |
| SVCSVD3S | 26.372 | 24.192 | 24.730 | 26.169 | 24.567# | 23.313*# | 24.590* |
| SVCSVD3T | 14.367 | 12.703 | 14.519 | 14.131 | 13.507# | 13.005# | 14.173 |
| SVCSVD6I | 20.219 | 19.747 | 20.095 | 22.068 | 21.213 | 21.125 | 21.841 |
| SVCSVD6N | 20.938 | 21.365 | 21.998 | 22.776 | 20.845 | 21.323 | 22.427 |
| SVCSVD6S | 21.555 | 21.500 | 21.207 | 22.132 | 20.388 | 20.903# | 21.290 |
| SVCSVD6T | 8.735 | 8.344 | 8.642 | 9.043 | 9.027 | 9.275 | 8.812 |
| SVCSVD9I | 8.417 | 8.695 | 7.191 | 9.188 | 8.176 | 8.242 | 8.786 |
| SVCSVD9N | 19.455 | 19.879 | 19.189 | 20.103 | 19.519 | 19.340 | 20.111* |
| SVCSVD9S | 13.313 | 14.224 | 13.908 | 14.148 | 11.812 | 14.237 | 14.011 |
| SVCSVD9T | 6.369 | 6.403 | 6.651 | 6.438 | 6.349 | 6.732 | 6.922 |
| SVCVDfoveal | 11.919 | 11.583 | 11.897 | 13.409 | 11.361 | 12.141 | 11.086 |
| SVCVD1I | 43.070 | 41.797 | 44.595 | 45.916 | 39.947# | 42.042# | 42.229 |
| SVCVD1N | 39.847 | 38.970 | 39.422 | 40.956 | 35.342# | 37.463# | 38.805 |
| SVCVD1S | 46.905 | 42.670 | 44.800 | 45.772 | 43.500# | 44.614# | 43.537 |
| SVCVD1T | 33.472 | 31.955 | 35.389 | 34.996 | 33.130 | 30.668# | 32.943 |
| SVCVD3I | 47.325 | 44.746 | 45.087 | 46.441 | 47.560 | 44.607 | 45.694 |
| SVCVD3N | 60.293 | 59.403 | 60.406 | 60.772 | 59.274# | 59.862# | 60.372 |
| SVCVD3S | 47.074 | 45.583 | 46.978 | 47.785 | 44.164# | 42.981*# | 44.570*# |
| SVCVD3T | 27.776 | 24.623 | 27.468 | 28.603 | 28.271 | 26.389 | 27.802 |
| SVCVD6I | 45.452 | 43.815 | 44.115 | 47.754 | 47.324 | 44.479 | 45.285 |
| SVCVD6N | 82.979 | 81.745 | 82.797 | 83.603 | 81.909 | 82.380 | 82.706 |
| SVCVD6S | 45.054 | 43.750 | 43.824 | 45.485 | 43.623 | 43.018# | 43.489 |
| SVCVD6T | 18.837 | 18.544 | 19.481 | 19.578 | 19.794* | 19.973* | 19.945* |
| SVCVD9I | 20.121 | 21.255 | 19.883 | 22.334 | 20.893 | 21.493 | 22.136 |
| SVCVD9N | 58.829 | 60.669 | 59.871 | 61.660 | 60.967 | 60.586 | 61.778 |
| SVCVD9S | 29.156 | 29.254 | 31.603 | 30.362 | 30.923 | 30.670 | 30.849 |
| SVCVD9T | 16.815 | 17.011 | 17.509 | 17.497 | 17.556 | 17.756 | 18.569* |
| DVCVDfoveal | 30.610 | 29.711 | 30.863 | 30.705 | 29.225 | 27.680# | 27.876 |
| DVCVD1I | 54.212 | 52.644 | 52.722 | 53.781 | 52.325 | 52.052# | 53.023 |
| DVCVD1N | 55.908 | 55.754 | 54.500 | 56.847 | 55.684 | 55.372 | 55.236 |
| DVCVD1S | 54.897 | 54.028 | 55.026 | 54.622 | 54.122 | 52.700# | 54.986 |
| DVCVD1T | 57.687 | 56.323 | 56.489 | 55.248 | 56.114 | 54.049*# | 53.599 |
| DVCVD3I | 47.224 | 43.410 | 45.617 | 47.056 | 45.880 | 45.955 | 45.922 |
| DVCVD3N | 42.892 | 43.344 | 43.766 | 44.663 | 43.523 | 42.532 | 45.238 |
| DVCVD3S | 48.527 | 46.749 | 48.521 | 49.323 | 48.932 | 46.933# | 49.567 |
| DVCVD3T | 55.952 | 53.462 | 55.800 | 55.873 | 54.317 | 53.893 | 54.557 |
| DVCVD6I | 30.745 | 27.284 | 26.447 | 29.603 | 28.980 | 29.597 | 29.665 |
| DVCVD6N | 14.181 | 14.222 | 14.344 | 15.343 | 15.046 | 15.061 | 15.698 |
| DVCVD6S | 36.788 | 35.764 | 34.669 | 35.989 | 35.272 | 32.074 | 37.138 |
| DVCVD6T | 47.387 | 45.837 | 46.934 | 48.051 | 47.557 | 46.889 | 47.255 |
| DVCVD9I | 33.191 | 33.204 | 31.078 | 34.382 | 33.450 | 34.531 | 34.729 |
| DVCVD9N | 16.421 | 17.880 | 16.135 | 14.663 | 20.482# | 18.864 | 19.821# |
| DVCVD9S | 41.524 | 43.465 | 42.657 | 43.003 | 41.333 | 41.138 | 44.099 |
| DVCVD9T | 32.037 | 33.020 | 33.835 | 35.668 | 32.909 | 34.918 | 35.252 |
Abbreviations: superficial vascular complex (SVC), deep vascular complex (DVC), vessel density (VD)
*: Statistically significant difference compared with baseline (p < 0.05)
#: Statistically significant difference compared with read 60 min (p < 0.05)
Table 4.
Median values of SVC and DVC vessel diameter index (VDI) and vessel length density (VLD, mm/mm²) across time points
| Variable | Baseline | Read20min | Read40min | Read60min | Rest10min | Rest20min | Rest30min |
|---|---|---|---|---|---|---|---|
| SVCVDIfoveal | 1.153 | 1.151 | 1.165 | 1.156 | 1.186 | 1.158 | 1.137 |
| SVCVDI1I | 1.274 | 1.281* | 1.286 | 1.271 | 1.277* | 1.283 | 1.259 |
| SVCVDI1N | 1.251 | 1.256 | 1.252 | 1.257 | 1.265 | 1.253 | 1.236 |
| SVCVDI1S | 1.283 | 1.299 | 1.306 | 1.313 | 1.306 | 1.296 | 1.289 |
| SVCVDI1T | 1.227 | 1.243 | 1.242 | 1.214 | 1.232 | 1.226 | 1.219 |
| SVCVDI3I | 1.438 | 1.444* | 1.427 | 1.435 | 1.453* | 1.447 | 1.410 |
| SVCVDI3N | 1.374 | 1.385 | 1.386 | 1.370 | 1.389* | 1.385 | 1.359 |
| SVCVDI3S | 1.380 | 1.397* | 1.406* | 1.420 | 1.423* | 1.402* | 1.398 |
| SVCVDI3T | 1.285 | 1.294 | 1.304 | 1.289 | 1.330*# | 1.311 | 1.301* |
| SVCVDI6I | 1.640 | 1.633 | 1.618 | 1.646 | 1.650 | 1.649 | 1.663 |
| SVCVDI6N | 1.720 | 1.709 | 1.714 | 1.727 | 1.706 | 1.717 | 1.683 |
| SVCVDI6S | 1.549 | 1.573* | 1.562 | 1.573 | 1.588 | 1.551 | 1.553 |
| SVCVDI6T | 1.331 | 1.363* | 1.354* | 1.342 | 1.359* | 1.361* | 1.348* |
| SVCVDI9I | 1.536 | 1.541 | 1.548 | 1.548 | 1.550 | 1.560 | 1.536 |
| SVCVDI9N | 1.784 | 1.796 | 1.840 | 1.806 | 1.805 | 1.801 | 1.784 |
| SVCVDI9S | 1.515 | 1.532 | 1.550 | 1.532 | 1.571* | 1.539 | 1.526 |
| SVCVDI9T | 1.408 | 1.432 | 1.428 | 1.435 | 1.438* | 1.447 | 1.443 |
| SVCVLDfoveal | 8.144 | 7.606 | 8.039 | 8.494 | 7.131 | 8.508 | 7.865 |
| SVCVLD1I | 25.399 | 24.582 | 25.591 | 26.814 | 25.660# | 24.511# | 25.799 |
| SVCVLD1N | 25.140 | 23.909 | 24.162 | 25.167 | 22.224# | 23.104# | 24.220 |
| SVCVLD1S | 27.173 | 25.260 | 26.432 | 25.926 | 24.794# | 24.756 | 26.096 |
| SVCVLD1T | 22.955 | 22.415 | 23.267 | 23.459 | 21.371# | 21.564# | 21.793 |
| SVCVLD3I | 24.074 | 23.460 | 23.897 | 24.203 | 23.947 | 22.523 | 23.828 |
| SVCVLD3N | 30.247 | 28.852 | 30.133 | 30.914 | 29.561# | 29.909 | 30.475 |
| SVCVLD3S | 24.917 | 23.656* | 23.902 | 24.793 | 22.670*# | 23.220*# | 24.402* |
| SVCVLD3T | 18.384 | 17.707 | 18.225 | 18.634 | 17.140# | 17.824# | 18.169 |
| SVCVLD6I | 24.011 | 23.741 | 23.482 | 24.716 | 24.194 | 24.421 | 24.711 |
| SVCVLD6N | 32.303 | 32.562 | 32.662 | 32.756 | 32.995 | 32.853 | 33.492 |
| SVCVLD6S | 24.682 | 24.215 | 24.177 | 24.561 | 23.586 | 24.146 | 24.309 |
| SVCVLD6T | 15.834 | 15.004 | 16.011 | 16.267 | 16.238# | 16.156 | 16.404 |
| SVCVLD9I | 19.345 | 19.340 | 18.525 | 19.509 | 19.085 | 19.140 | 19.461 |
| SVCVLD9N | 28.387 | 28.194 | 28.406 | 28.257 | 28.556 | 28.559 | 29.173# |
| SVCVLD9S | 23.211 | 23.187 | 23.551 | 23.929 | 23.015 | 23.734 | 24.445 |
| SVCVLD9T | 16.643 | 16.219 | 17.110 | 17.223 | 17.097 | 17.063 | 17.137 |
| DVCVDIfoveal | 1.249 | 1.258 | 1.241 | 1.279 | 1.228 | 1.267 | 1.274 |
| DVCVDI1I | 1.295 | 1.314 | 1.299 | 1.299 | 1.305 | 1.310 | 1.294 |
| DVCVDI1N | 1.293 | 1.300 | 1.301 | 1.304 | 1.309 | 1.296 | 1.303 |
| DVCVDI1S | 1.291 | 1.302 | 1.307 | 1.301 | 1.324 | 1.306 | 1.318 |
| DVCVDI1T | 1.289 | 1.296 | 1.306 | 1.295 | 1.304 | 1.298 | 1.295 |
| DVCVDI3I | 1.305 | 1.304 | 1.306 | 1.298 | 1.307 | 1.310 | 1.298 |
| DVCVDI3N | 1.305 | 1.305 | 1.309 | 1.309 | 1.318 | 1.303 | 1.307 |
| DVCVDI3S | 1.306 | 1.315 | 1.307 | 1.306 | 1.301 | 1.295 | 1.298 |
| DVCVDI3T | 1.292 | 1.301* | 1.300* | 1.295 | 1.296* | 1.305* | 1.293 |
| DVCVDI6I | 1.308 | 1.308 | 1.312 | 1.302 | 1.307 | 1.304 | 1.309 |
| DVCVDI6N | 1.312 | 1.321 | 1.328 | 1.319 | 1.321 | 1.311 | 1.316 |
| DVCVDI6S | 1.296 | 1.305 | 1.297 | 1.302 | 1.307* | 1.299 | 1.305 |
| DVCVDI6T | 1.292 | 1.307* | 1.304* | 1.299 | 1.301* | 1.295 | 1.295 |
| DVCVDI9I | 1.317 | 1.312 | 1.326 | 1.328 | 1.313 | 1.317 | 1.318 |
| DVCVDI9N | 1.316 | 1.320 | 1.316 | 1.323 | 1.323 | 1.318 | 1.319 |
| DVCVDI9S | 1.307 | 1.312 | 1.311* | 1.315 | 1.320 | 1.307 | 1.307 |
| DVCVDI9T | 1.300 | 1.310* | 1.309 | 1.306 | 1.311 | 1.306 | 1.296 |
| DVCVLDfoveal | 11.709 | 10.835 | 11.340* | 12.478 | 11.011 | 11.185* | 10.905 |
| DVCVLD1I | 29.712 | 28.256 | 28.127 | 29.805 | 28.061# | 27.934# | 27.751 |
| DVCVLD1N | 29.846 | 29.048 | 27.986 | 29.617 | 28.561# | 29.146 | 29.442 |
| DVCVLD1S | 29.851 | 28.752 | 29.518 | 29.822 | 28.297# | 28.355*# | 28.675 |
| DVCVLD1T | 30.299 | 29.408 | 29.260 | 29.420 | 29.352 | 28.296# | 28.797 |
| DVCVLD3I | 24.583 | 23.034 | 23.157 | 24.633 | 24.183 | 24.381 | 25.174 |
| DVCVLD3N | 24.362 | 24.573 | 23.799 | 24.543 | 23.718 | 24.275 | 25.905 |
| DVCVLD3S | 24.959 | 24.828 | 25.434 | 25.276 | 24.707 | 24.341 | 27.112 |
| DVCVLD3T | 28.398 | 27.369* | 27.786 | 27.451 | 26.694* | 27.082 | 28.065 |
| DVCVLD6I | 20.517 | 19.404 | 18.739 | 20.785 | 20.565 | 20.471 | 20.826 |
| DVCVLD6N | 13.314 | 13.732 | 12.707 | 13.724 | 14.013 | 14.129 | 14.927 |
| DVCVLD6S | 22.873 | 21.863 | 20.635 | 22.478 | 22.436 | 21.532 | 22.058 |
| DVCVLD6T | 26.804 | 25.804 | 26.995 | 26.903 | 25.977 | 27.043 | 27.894 |
| DVCVLD9I | 26.304 | 25.795 | 23.818 | 26.641 | 25.303 | 26.332 | 27.235 |
| DVCVLD9N | 17.413 | 19.410 | 17.375 | 16.888 | 17.605 | 18.641 | 19.058# |
| DVCVLD9S | 29.546 | 28.674 | 27.888 | 29.635 | 28.208 | 29.007 | 29.878 |
| DVCVLD9T | 26.379 | 26.891 | 27.547 | 28.040 | 26.659 | 27.864 | 29.222 |
Abbreviations: superficial vascular complex (SVC), deep vascular complex (DVC), vessel diameter index (VDI), vessel length density (VLD)
*: Statistically significant difference compared with baseline (p < 0.05)
#: Statistically significant difference compared with read 60 min (p < 0.05)
Tables 5 and 6 display choroidal changes. CC VD in sector 1T was significantly elevated above baseline at 10 min of rest (5p = 0.030). Choroidal PA increased significantly in sector 6N during near work (all p < 0.05). At 20 min of rest, choroidal PA, CT, and CSV declined significantly relative to pre-rest values across multiple regions (all p < 0.05).
Table 5.
Median values of choriocapillaris vessel density (CC VD, %) and choroidal perfusion area (PA, mm²) and thickness (µm) across time points
| Variable | Baseline | Read20min | Read40min | Read60min | Rest10min | Rest20min | Rest30min |
|---|---|---|---|---|---|---|---|
| CCVDfoveal | 72.826 | 73.130 | 74.230 | 74.694 | 76.631 | 73.895 | 75.002 |
| CCVD1I | 78.768 | 78.883 | 78.885 | 79.383 | 77.061 | 79.054 | 79.957 |
| CCVD1N | 74.467 | 75.935 | 78.195 | 76.917 | 77.339 | 75.476 | 76.019 |
| CCVD1S | 77.143 | 77.004 | 79.424 | 77.801 | 78.667 | 78.675 | 78.780 |
| CCVD1T | 73.567 | 73.348 | 74.959 | 72.608 | 74.576* | 73.491 | 75.230 |
| CCVD3I | 77.332 | 77.474 | 76.645 | 77.631 | 78.275 | 76.586 | 76.015 |
| CCVD3N | 78.874 | 78.883 | 79.954 | 79.766 | 77.747 | 78.172 | 79.116 |
| CCVD3S | 78.489 | 78.617 | 79.001 | 79.164 | 79.283 | 78.420 | 79.506 |
| CCVD3T | 77.792 | 75.918 | 77.101 | 78.711 | 79.637 | 76.743 | 79.393 |
| CCVD6I | 77.175 | 75.464 | 76.098 | 76.927 | 77.840 | 76.534 | 77.262 |
| CCVD6N | 73.602 | 74.057 | 74.953 | 74.742 | 73.675 | 72.156 | 73.571 |
| CCVD6S | 79.434 | 79.252 | 80.478 | 80.366 | 80.521 | 79.051 | 79.602 |
| CCVD6T | 78.646 | 79.566 | 74.845 | 78.892 | 78.523 | 78.041 | 78.298 |
| CCVD9I | 72.563 | 70.953 | 70.520 | 72.309 | 70.699 | 72.583 | 72.547 |
| CCVD9N | 68.817 | 70.343 | 70.053 | 70.386 | 67.853 | 66.890 | 69.085 |
| CCVD9S | 77.896 | 76.522 | 78.259 | 77.865 | 78.005 | 77.003 | 77.447 |
| CCVD9T | 78.301 | 77.487 | 78.037 | 78.503 | 75.833 | 72.828 | 77.518 |
| ChoroidPAfoveal | 0.763 | 0.764 | 0.769 | 0.769 | 0.764 | 0.746# | 0.762 |
| ChoroidPA1I | 1.514 | 1.516 | 1.540 | 1.523 | 1.516 | 1.507 | 1.528 |
| ChoroidPA1N | 1.501 | 1.496 | 1.523 | 1.526 | 1.488 | 1.490# | 1.503 |
| ChoroidPA1S | 1.509 | 1.484 | 1.517 | 1.523 | 1.530 | 1.490 | 1.514 |
| ChoroidPA1T | 1.484 | 1.485 | 1.532 | 1.504 | 1.509 | 1.472 | 1.492 |
| ChoroidPA3I | 5.000 | 5.000 | 5.183 | 5.074 | 5.000 | 5.000# | 5.000 |
| ChoroidPA3N | 5.000 | 5.000 | 5.132 | 5.064 | 5.000 | 5.000# | 5.000 |
| ChoroidPA3S | 5.133 | 5.126 | 5.160 | 5.165 | 5.187 | 5.000# | 5.119 |
| ChoroidPA3T | 5.056 | 5.125 | 5.159 | 5.183 | 5.120 | 5.057 | 5.130 |
| ChoroidPA6I | 8.313 | 8.304 | 8.398 | 8.371 | 8.332 | 8.147 | 8.316 |
| ChoroidPA6N | 7.093 | 7.369 | 7.453* | 7.499* | 7.437 | 7.197 | 7.320 |
| ChoroidPA6S | 8.509 | 8.485 | 8.555 | 8.542 | 8.522 | 8.302# | 8.525 |
| ChoroidPA6T | 8.529 | 8.603 | 8.639 | 8.653 | 8.537 | 8.572 | 8.547 |
| ChoroidPA9I | 11.183 | 10.922 | 10.721 | 11.277 | 11.075 | 11.097 | 11.034 |
| ChoroidPA9N | 10.253 | 10.448 | 10.556 | 10.359 | 10.384 | 10.270 | 10.307 |
| ChoroidPA9S | 11.953 | 12.000 | 11.840 | 11.884 | 11.895 | 11.670 | 11.962 |
| ChoroidPA9T | 11.871 | 11.880 | 12.000 | 11.982 | 11.998 | 11.964 | 11.952 |
| ChoroidThicknessfoveal | 268.484 | 276.649 | 279.534 | 278.779 | 277.237 | 281.815# | 289.344 |
| ChoroidThickness1I | 277.852 | 280.151 | 283.300 | 287.814 | 283.003 | 287.808 | 295.205 |
| ChoroidThickness1N | 240.887 | 245.272 | 245.089 | 242.492 | 238.684 | 240.004# | 245.778 |
| ChoroidThickness1S | 286.410 | 295.241 | 300.403 | 298.149 | 296.148# | 293.824 | 303.787 |
| ChoroidThickness1T | 291.978 | 297.452 | 301.547 | 305.334 | 306.503 | 310.902# | 316.964 |
| ChoroidThickness3I | 283.411 | 291.223 | 291.207 | 292.156 | 295.077# | 291.157# | 299.717 |
| ChoroidThickness3N | 209.652 | 211.578 | 208.916 | 207.990 | 208.033# | 208.343# | 216.324 |
| ChoroidThickness3S | 299.979 | 312.226 | 317.087 | 313.344 | 317.132 | 315.820 | 333.286 |
| ChoroidThickness3T | 313.365 | 315.069 | 315.526 | 322.070 | 320.964 | 319.505# | 327.271 |
| ChoroidThickness6I | 268.248 | 275.745 | 276.285 | 277.221 | 273.570 | 276.081# | 280.264 |
| ChoroidThickness6N | 165.171 | 167.894 | 167.260 | 172.910 | 168.931 | 167.007# | 174.209 |
| ChoroidThickness6S | 316.807 | 323.674 | 324.918 | 322.169 | 322.338 | 322.385 | 332.132 |
| ChoroidThickness6T | 315.976 | 316.960 | 322.867 | 321.353 | 326.601 | 324.992# | 326.730 |
| ChoroidThickness9I | 232.778 | 235.637 | 247.111 | 237.440 | 236.376 | 237.331# | 246.216 |
| ChoroidThickness9N | 192.186 | 199.356 | 193.116 | 205.163 | 198.027 | 197.452 | 206.043 |
| ChoroidThickness9S | 304.029 | 307.405 | 306.225 | 319.442 | 306.050 | 307.296 | 304.051 |
| ChoroidThickness9T | 302.484 | 301.077 | 308.112 | 308.080 | 307.784 | 306.790# | 313.655 |
Abbreviations: choriocapillaris (CC), perfusion area (PA)
*: Statistically significant difference compared with baseline (p < 0.05)
#: Statistically significant difference compared with read 60 min (p < 0.05)
Table 6.
Median values of choroidal stromal volume (CSV, mm³) and choroidal vascular volume (CVV, mm³) across time points
| Variable | Baseline | Read20min | Read40min | Read60min | Rest10min | Rest20min | Rest30min |
|---|---|---|---|---|---|---|---|
| CSVfoveal | 0.100 | 0.110 | 0.111 | 0.108 | 0.107 | 0.108 | 0.114 |
| CSV1I | 0.209 | 0.214 | 0.220 | 0.224 | 0.226 | 0.224# | 0.225 |
| CSV1N | 0.174 | 0.177 | 0.175 | 0.177 | 0.177 | 0.176 | 0.189 |
| CSV1S | 0.222 | 0.225 | 0.232 | 0.229 | 0.230 | 0.228 | 0.234 |
| CSV1T | 0.225 | 0.237 | 0.239 | 0.248 | 0.246 | 0.238# | 0.251 |
| CSV3I | 0.761 | 0.770 | 0.780 | 0.783 | 0.792 | 0.773# | 0.790 |
| CSV3N | 0.472 | 0.480 | 0.480 | 0.487 | 0.493 | 0.486 | 0.530 |
| CSV3S | 0.811 | 0.833 | 0.857 | 0.805 | 0.856 | 0.854 | 0.926 |
| CSV3T | 0.847 | 0.851 | 0.892 | 0.890 | 0.932 | 0.887# | 0.919 |
| CSV6I | 1.153 | 1.194 | 1.216 | 1.219 | 1.176 | 1.177# | 1.216 |
| CSV6N | 0.647 | 0.716 | 0.658 | 0.714 | 0.668 | 0.657 | 0.711 |
| CSV6S | 1.472 | 1.490 | 1.547 | 1.520 | 1.528 | 1.523 | 1.572 |
| CSV6T | 1.453 | 1.451 | 1.498 | 1.473 | 1.470 | 1.470# | 1.500 |
| CSV9I | 1.319 | 1.333 | 1.428 | 1.363 | 1.384 | 1.329# | 1.386 |
| CSV9N | 1.038 | 1.153 | 1.044 | 1.158 | 1.109 | 1.097 | 1.213 |
| CSV9S | 1.951 | 2.019 | 2.098 | 2.074 | 2.051 | 2.014# | 2.048 |
| CSV9T | 1.922 | 1.916 | 1.944 | 1.988 | 1.965 | 1.948# | 2.018 |
| CVVfoveal | 0.077 | 0.077 | 0.078 | 0.079 | 0.077 | 0.078# | 0.077 |
| CVV1I | 0.150 | 0.154 | 0.148 | 0.148 | 0.151 | 0.154 | 0.157 |
| CVV1N | 0.124 | 0.130 | 0.129 | 0.129 | 0.127 | 0.131 | 0.133 |
| CVV1S | 0.157 | 0.156 | 0.154 | 0.151 | 0.149 | 0.151 | 0.151 |
| CVV1T | 0.154 | 0.152 | 0.156 | 0.160 | 0.158 | 0.160 | 0.159 |
| CVV3I | 0.506 | 0.513 | 0.515 | 0.519 | 0.505 | 0.523 | 0.530 |
| CVV3N | 0.351 | 0.354 | 0.366 | 0.364 | 0.343# | 0.358 | 0.361 |
| CVV3S | 0.519 | 0.538 | 0.517 | 0.512 | 0.502 | 0.516 | 0.535 |
| CVV3T | 0.558 | 0.553 | 0.550 | 0.556 | 0.552 | 0.550 | 0.561 |
| CVV6I | 0.808 | 0.811 | 0.806 | 0.803 | 0.784 | 0.803 | 0.807 |
| CVV6N | 0.425 | 0.448 | 0.424 | 0.455 | 0.422 | 0.433 | 0.448 |
| CVV6S | 0.887 | 0.900 | 0.884 | 0.904 | 0.907 | 0.913 | 0.913 |
| CVV6T | 0.916 | 0.902 | 0.875 | 0.886 | 0.871 | 0.907 | 0.919 |
| CVV9I | 0.904 | 0.949 | 0.944 | 0.914 | 0.938 | 0.957 | 0.948 |
| CVV9N | 0.712 | 0.723 | 0.712 | 0.718 | 0.721 | 0.720 | 0.753 |
| CVV9S | 1.219 | 1.214 | 1.184 | 1.224 | 1.224 | 1.219 | 1.220 |
| CVV9T | 1.186 | 1.180 | 1.137 | 1.195 | 1.149 | 1.178 | 1.257 |
Abbreviations: choroidal vascular volume (CVV), and choroidal stromal volume (CSV)
*: Statistically significant difference compared with baseline (p < 0.05)
#: Statistically significant difference compared with read 60 min (p < 0.05)
The temporal dynamics of all parameters across retinal layers and choroidal sectors are summarized in Fig. 3, providing an overview of directional changes and FDR-corrected significant findings reported above.
Fig. 3.
Median trends of retinal and choroidal vascular parameters across seven time points during near work and eye-closure rest. Abbreviations: nerve fiber layer vascular plexus (NFLVP), superficial vascular complex (SVC), deep vascular complex (DVC), choriocapillaris (CC), vessel density (VD), small vessel density (SVD), vessel diameter index (VDI), vessel length density (VLD), perfusion area (PA), choroidal vascular volume (CVV), and choroidal stromal volume (CSV). T1, baseline; T2, reading 20 min; T3, reading 40 min; T4, reading 60 min; T5, rest 10 min; T6, rest 20 min; T7, rest 30 min. * (above line) p < 0.05 vs. T1 (baseline) * (below line) p < 0.05 vs. T4 (reading 60 min) (paired Wilcoxon signed-rank test)
Discussion
We used wide-field OCTA to dynamically evaluate changes in retinal and choroidal blood flow and thickness in young healthy adults during near work and subsequent eye-closure rest. NFLVP perfusion in the temporal 6–9 mm sector increased during near work and remained elevated above baseline throughout the rest period, while SVC perfusion in the same sector likewise remained above baseline; in contrast, SVC perfusion in the superior 3–6 mm sector fell below baseline during rest. These alterations represent acute physiological responses to visual demand. Whether such transient hemodynamic changes bear any relationship to the chronic vascular remodeling associated with myopia progression remains to be established in longitudinal studies.
Unlike the radial peripapillary capillaries (RPC) described in previous studies, the NFLVP extends into the parafoveal region, serving as a microvascular network supplying the RNFL that is highly sensitive to ischemia [18, 19]. Histological evidence has confirmed that NFLVP runs in a radial pattern, aligned with the direction of RGC axons [20]. In this study, NFLVP perfusion showed an increasing trend during near work, most prominently in the temporal region. VDI changes corresponded with perfusion increases, which may indicate that perfusion enhancement near the macula is mediated by vascular dilation [21]. During the eye-closure rest phase, NFLVP perfusion declined overall compared with pre-rest period. Notably, VD and VDI in the superior temporal 6–9 mm sector remained significantly elevated above baseline at the end of the rest period in both the NFLVP and SVC. Previous OCTA studies have not reported significant increases in retinal perfusion following near work, likely because their scanning areas were confined to within 6 mm of the fovea, leaving peripheral vascular responses beyond this range unexplored [17]. The observed elevation in VDI suggests that vascular dilation is the primary mechanism of short-term perfusion enhancement in this outer region. Compared with the macular center, the region farther from the fovea has a sparser capillary network and a higher proportion of large vessels [22, 23], enabling vascular dilation to induce a more pronounced increase in blood flow, which may explain the outer ring perfusion enhancement observed in this study.
Notably, in the 3 S sector, VD, SVD, and VLD of the SVC were all reduced below baseline levels during rest, most prominently at 20 min of rest. During eye-closure rest, the withdrawal of photic input — which serves as a key driver of tonic inner retinal perfusion — combined with the intrinsically higher vascular resistance of superior retinal vessels [24], likely accounts for the more pronounced below-baseline hypoperfusion in this sector, reflecting regional heterogeneity in neurovascular coupling [25, 26]. Retinal metabolic activity, particularly in the photoreceptor layer, decreases significantly during eye closure — due to suspended visual signal processing, reduced neuronal excitability, and lower oxygen and glucose consumption [27] — further driving the perfusion decline observed across the rest period. These cyclic fluctuations—characterized by increased ocular perfusion during near work and decreased perfusion during rest—constitute acute physiological responses to visual demand. However, it remains unclear whether repeated or prolonged exposure to such hemodynamic stressors induces chronic vascular remodeling or endothelial dysfunction [28]. Moreover, the potential mechanistic link between these transient perfusion changes and the progressive decline in ocular perfusion previously observed in myopic eyes warrants further investigation [12, 13].
DVC vessel density showed no significant changes relative to baseline at nearly all time points and regions. Regional differences in perfusion responses are also closely linked to the metabolic activity and vascular architecture of retinal layers [26]. SVC vessels are mainly derived from arterioles, serving as the primary channels of retinal arterial inflow, whereas the DVC lies beneath, vertically connected to the SVC through capillaries and primarily responsible for venous outflow [19, 29]. Functional hyperemia in the retina, triggered by neuronal activity under light stimulation, is driven principally by active arteriolar dilation [22, 27]. Therefore, compared with the SVC, the DVC exhibited smaller perfusion changes during near work.
Unlike retinal perfusion, which is driven primarily by local neurovascular coupling in response to neuronal metabolic demand [27], choroidal blood flow is governed predominantly by autonomic control [30]. Although distinct in their regulatory origins, these two systems respond in a complementary fashion to jointly maintain posterior ocular homeostasis under varying visual demands. At 20 min of rest, choroidal PA, CT, and CSV declined significantly relative to pre-rest values across multiple regions. Unlike the retina, the choroid lacks direct metabolic autoregulation; its blood flow is governed primarily by central autonomic circuits, with parasympathetic fibers from the pterygopalatine ganglion mediating vasodilation and sympathetic fibers from the superior cervical ganglion mediating vasoconstriction [30]. Notably, the decline in CT was more consistent with the reduction in CSV than with any change in CVV, suggesting that thinning may be driven primarily by stromal contraction rather than vascular lumen collapse. The choroid contains NVSMCs within the stromal compartment whose contraction can thin the choroid independently of luminal blood flow [31]; parasympathetic terminals synapsing on NVSMCs release nitric oxide, which acts as a smooth muscle relaxant and may modulate choroidal thickness by regulating NVSMC tone [31]. Prior studies have shown that the regional distribution of accommodation-induced choroidal thinning corresponds closely to the known distribution of NVSMCs, further implicating these cells in choroidal thickness regulation [32]. Upon cessation of near work, the reduction in pterygopalatine parasympathetic input may decrease nitric oxide release onto NVSMCs, allowing stromal contraction and the consequent reductions in CSV and CT.
This study has several limitations. First, dynamic IOP monitoring was not performed, as noncontact tonometry caused participant anxiety and disrupted the OCTA procedure; thus, short-term IOP fluctuations influencing structural and perfusion changes cannot be fully excluded. Second, the durations of both the near-work task and the rest period were relatively short, and residual differences in accommodative response may have influenced vascular outcomes; future studies should extend the experimental duration and incorporate objective real-time accommodative measurement. In addition, eye closure was selected as the sole rest modality. This represents a controlled “physiological extreme” condition characterized by the complete absence of photic input, which fully suppresses light-driven tonic inner retinal neuronal activity and thereby isolates neurovascular coupling mechanisms from the confounding influence of ongoing visual stimulation. Although eye closure differs from typical everyday rest conditions such as distance viewing, it provides a clean experimental contrast to the visual-demand state induced by near work. Consequently, the vascular changes observed during the rest phase cannot be attributed solely to recovery from near work and may equally reflect the ocular physiological response to the absence of visual stimulation. Whether eye closure and distance viewing exert differential effects on ocular vascular recovery remains to be determined, and we plan to explore this comparison in future work. Third, physiological variables such as mood, heart rate, blood pressure, and hydration status were not systematically recorded, and individual variability in these factors may have interfered with the observed changes. Finally, given the inherent limitations of OCTA-based segmentation, choroidal structural alterations may not be fully captured by CSV and CVV measurements, and more advanced high-resolution imaging modalities are needed to characterize fine-scale hemodynamic and microarchitectural changes within the choroidal vasculature.
In conclusion, this study demonstrated the acute effects of near work on retinal and choroidal perfusion and thickness, and confirmed distinct response patterns and recovery rates across different vascular and structural layers. VD and VDI of the NFLVP in the temporal 6–9 mm sector increased during near work and remained significantly elevated above baseline in the rest period, with SVC VD and VDI in the same sector likewise remaining above baseline during rest; in contrast, VD, SVD, and VLD of the SVC in the superior 3–6 mm sector fell below baseline levels during rest. CT and CSV declined significantly relative to pre-rest values at 20 min of rest. These findings characterize the acute hemodynamic responses of the retina and choroid to near work and eye-closure rest. Whether repeated exposure to such transient changes contributes to the chronic vascular alterations observed in myopic eyes remains speculative and cannot be inferred from the present short-term, cross-sectional design; longitudinal studies incorporating refractive and structural outcomes are needed to address this question.
Acknowledgements
None.
Author contributions
Fangyuan Zhou and Tsering Lhamo contributed equally to this work. Fangyuan Zhou and Tsering Lhamo were responsible for study conception and design. Data collection was performed by Fangyuan Zhou, Tsering Lhamo, Yilin Yuan, Tianshu Yang, Feiyang Tan, and Lin Tian. Fangyuan Zhou and Tsering Lhamo conducted the data analysis and interpretation.Fangyuan Zhou drafted the initial manuscript. Dihao Hua, Changzheng Chen, and Yishuang Xu provided critical revisions and overall supervision of the study. All authors approved the final version of the manuscript.
Funding
This study was supported by the National Natural Science Foundation of China (No. 42301486 and No. 42201457).
Data availability
The data that support the findings of this study are available from the corresponding author, YX, upon reasonable request.
Declarations
Ethics approval and consent to participate
Ethics approval for this study was obtained from the Clinical Research Ethics Committee, Renmin Hospital of Wuhan University (WDRY2024-K187). Written informed consent was obtained from all participants prior to enrollment in the study.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Fangyuan Zhou and Tsering Lhamo contributed equally to this work.
Contributor Information
Dihao Hua, Email: 277058240@qq.com.
Changzheng Chen, Email: chenchangzheng@whu.edu.cn.
Yishuang Xu, Email: 540282252@qq.com.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data that support the findings of this study are available from the corresponding author, YX, upon reasonable request.