Postural changes in retinal vascular parameters and risk of diabetic retinopathy progression in type 2 diabetes mellitus: a pilot study

Figshare · 2026-01-01

Abstract Background To investigate whether postural changes in retinal vascular parameters, measured using smartphone-based imaging, differ between healthy individuals and patients with diabetes mellitus (DM), and whether these changes independently predict diabetic retinopathy (DR) progression over a 5-year period. Methods Retinal images were captured using a smartphone with a clip-on adapter lens in sitting and supine positions. Vascular parameters (caliber, fractal dimension, tortuosity, branching) were quantified using the Singapore I Vessel Assessment software. Cross-sectional analyses compared postural-induced vascular responses between 38 healthy controls and 49 DM participants. DM participants were followed for 5 years, with DR progression defined as ≥ 2-step increase in severity on the Early Treatment Diabetic Retinopathy Study scale. Cox proportional hazards models evaluated associations between baseline postural changes and DR progression. Results Healthy controls exhibited significant arteriolar and venular constriction upon moving from sitting to supine (P < 0.05). In contrast, participants with DM showed diminished or paradoxical responses that did not reach statistical significance. Significant linear trends were observed for arteriolar caliber, fractal dimension, and simple tortuosity across healthy controls, DM with and without DR (all P-trend < 0.05). Greater arteriolar tortuosity was associated with a 2.41-fold higher risk of DR progression (HR = 2.41, 95% CI: 1.37–4.23; P = 0.002), while wider venular branching angles correlated with a 45% lower risk (HR = 0.55, 95% CI: 0.35–0.87; P = 0.011). Adding these parameters improved predictive discrimination beyond established factors (arteriolar tortuosity: C-statistic 0.630–0.740; venular branching angle: 0.630–0.683; P < 0.05). Conclusions Smartphone-based imaging of retinal vascular responses to postural changes provides additional prognostic value for DR progression, potentially enhancing early risk stratification and proactive management.

Postural changes in retinal vascular parameters and risk of diabetic retinopathy progression in type 2 diabetes mellitus: a pilot study

Eye and Vision · 2026-01-06

BACKGROUND: To investigate whether postural changes in retinal vascular parameters, measured using smartphone-based imaging, differ between healthy individuals and patients with diabetes mellitus (DM), and whether these changes independently predict diabetic retinopathy (DR) progression over a 5-year period. METHODS: Retinal images were captured using a smartphone with a clip-on adapter lens in sitting and supine positions. Vascular parameters (caliber, fractal dimension, tortuosity, branching) were quantified using the Singapore I Vessel Assessment software. Cross-sectional analyses compared postural-induced vascular responses between 38 healthy controls and 49 DM participants. DM participants were followed for 5 years, with DR progression defined as ≥ 2-step increase in severity on the Early Treatment Diabetic Retinopathy Study scale. Cox proportional hazards models evaluated associations between baseline postural changes and DR progression. RESULTS: Healthy controls exhibited significant arteriolar and venular constriction upon moving from sitting to supine (P < 0.05). In contrast, participants with DM showed diminished or paradoxical responses that did not reach statistical significance. Significant linear trends were observed for arteriolar caliber, fractal dimension, and simple tortuosity across healthy controls, DM with and without DR (all P-trend < 0.05). Greater arteriolar tortuosity was associated with a 2.41-fold higher risk of DR progression (HR = 2.41, 95% CI: 1.37-4.23; P = 0.002), while wider venular branching angles correlated with a 45% lower risk (HR = 0.55, 95% CI: 0.35-0.87; P = 0.011). Adding these parameters improved predictive discrimination beyond established factors (arteriolar tortuosity: C-statistic 0.630-0.740; venular branching angle: 0.630-0.683; P < 0.05). CONCLUSIONS: Smartphone-based imaging of retinal vascular responses to postural changes provides additional prognostic value for DR progression, potentially enhancing early risk stratification and proactive management.

Postural changes in retinal vascular parameters and risk of diabetic retinopathy progression in type 2 diabetes mellitus: a pilot study

Figshare · 2026-01-01

Abstract Background To investigate whether postural changes in retinal vascular parameters, measured using smartphone-based imaging, differ between healthy individuals and patients with diabetes mellitus (DM), and whether these changes independently predict diabetic retinopathy (DR) progression over a 5-year period. Methods Retinal images were captured using a smartphone with a clip-on adapter lens in sitting and supine positions. Vascular parameters (caliber, fractal dimension, tortuosity, branching) were quantified using the Singapore I Vessel Assessment software. Cross-sectional analyses compared postural-induced vascular responses between 38 healthy controls and 49 DM participants. DM participants were followed for 5 years, with DR progression defined as ≥ 2-step increase in severity on the Early Treatment Diabetic Retinopathy Study scale. Cox proportional hazards models evaluated associations between baseline postural changes and DR progression. Results Healthy controls exhibited significant arteriolar and venular constriction upon moving from sitting to supine (P &lt; 0.05). In contrast, participants with DM showed diminished or paradoxical responses that did not reach statistical significance. Significant linear trends were observed for arteriolar caliber, fractal dimension, and simple tortuosity across healthy controls, DM with and without DR (all P-trend &lt; 0.05). Greater arteriolar tortuosity was associated with a 2.41-fold higher risk of DR progression (HR = 2.41, 95% CI: 1.37–4.23; P = 0.002), while wider venular branching angles correlated with a 45% lower risk (HR = 0.55, 95% CI: 0.35–0.87; P = 0.011). Adding these parameters improved predictive discrimination beyond established factors (arteriolar tortuosity: C-statistic 0.630–0.740; venular branching angle: 0.630–0.683; P &lt; 0.05). Conclusions Smartphone-based imaging of retinal vascular responses to postural changes provides additional prognostic value for DR progression, potentially enhancing early risk stratification and proactive management.

Additional file 1 of Postural changes in retinal vascular parameters and risk of diabetic retinopathy progression in type 2 diabetes mellitus: a pilot study

Figshare · 2026-01-01

Additional file 1.

Additional file 1 of Postural changes in retinal vascular parameters and risk of diabetic retinopathy progression in type 2 diabetes mellitus: a pilot study

Open MIND · 2026-01-01

Additional file 1.

Relative Stability of Regional Facial and Ocular Temperature Measurements in Healthy Individuals

Translational Vision Science & Technology · 2022-12-29 · 9 citations

Purpose: Non-contact measurement of facial temperature using infrared thermography has been used for mass screening of body temperature during a pandemic. We investigated the relative stability of temperature measurement in different facial regions of healthy individuals. Methods: Twenty healthy subjects underwent two experiments. In the first experiment, subjects washed their faces with a 20°C wet towel for 1 minute. Temperature changes compared to baseline in the forehead, cornea, inner canthus, and outer canthus were determined using an infrared camera for 10 minutes. In the second experiment, lubricating eye drops at 20°C were instilled over one eye. Temperature changes in the same regions of interest were monitored for 5 minutes. Results: Baseline temperatures before face washing in the forehead and cornea, inner canthus, and outer canthus of the right eye were 33.4°C ± 0.8°C (mean ± SD), 33.3°C ± 0.8°C, 34.3°C ± 0.7°C, and 32.8°C ± 0.7°C, respectively. Reductions in temperature due to face washing were most significant for the forehead and least significant for the cornea. One minute after face washing, the corresponding changes were -2.8°C ± 0.6°C, -0.3°C ± 0.6°C, -0.6°C ± 0.7°C, and -0.9°C ± 0.7°C for the forehead, cornea, inner canthus, and outer canthus, respectively. After administering the eye drops, no significant temperature changes were observed. Conclusions: When facial temperature was exogenously cooled, the cornea had the most stable temperature readings. Translational Relevance: When using infrared thermography to screen facial temperature, the measurement of corneal temperature is probably a better representative if the stability of temperature readings is critical.

The Relationship Between Plasma Tetrahydrocannabinol Levels and Intraocular Pressure in Healthy Adult Subjects

Frontiers in Medicine · 2022-01-17 · 5 citations

Background Δ9-tetrahydrocannabinol (THC) has been shown to decreased intraocular pressure (IOP). This project aims to define the relationship between plasma THC levels and IOP in healthy adult subjects. Methods Eleven healthy subjects received a single dose of inhaled cannabis that was self-administered in negative pressure rooms. Measurements of IOP and plasma THC levels were taken at baseline and every 30 min for 1 h and afterwards every hour for 4 h. IOP reduction and percent change in IOP over time were calculated. Linear regression models were used to measure the relationship between IOP and plasma THC levels. Two line linear regression models with F-tests were used to detect change points in the regression. Then, Pearson correlations were computed based on the change point. Results Twenty-two eyes met inclusion criteria. The average peak percentage decrease in IOP was 16% at 60 min. Percent IOP reduction as well as total IOP reduction demonstrated a negative correlation with THC plasma levels showing r-values of −0.81 and −0.70, respectively. F -tests revealed a change point in the regression for plasma levels &amp;gt;20 ng/ml. For levels &amp;gt;20 ng/ml, the correlation coefficients changed significantly with r -values of 0.21 and 0.29 ( p &amp;lt; 0.01). Conclusion Plasma THC levels are significantly correlated with IOP reduction up to plasma levels of 20 ng/ml. Plasma levels &amp;gt;20 ng/ml were not correlated with further decrease in IOP. More research is needed to determine the efficacy of THC in reducing IOP for eyes with ocular hypertension and glaucoma.

Intraocular pressure and choroidal thickness respond differently to lower body negative pressure during spaceflight

Journal of Applied Physiology · 2021 · 45 citations

• Medicine
• Anesthesia
• Ophthalmology

Spaceflight induces a chronic headward fluid shift that is believed to underlie ocular changes observed in astronauts. The present study demonstrates, for the first time, that reversing this headward fluid shift via application of lower body negative pressure (LBNP) during spaceflight may alter the ocular venous system, as evidenced by a decrease in intraocular pressure. This finding indicates that LBNP has the potential to be an effective countermeasure against the headward fluid shift during spaceflight, which may then be beneficial in preventing or reversing associated ocular changes.

Correlation Between Office-Hour and Peak Nocturnal Intraocular Pressure in Patients Treated with Prostaglandin Analogs

American Journal of Ophthalmology · 2020 · 6 citations

• Medicine
• Ophthalmology
• Anesthesia

Smartphone-based Retinal Imaging to Characterize Early Functional Retinal Vascular Changes in Diabetic Retinopathy

2019-07-22