Choroidal Thickness in Diabetes and Diabetic Retinopathy: A Swept Source OCT Study

Prospective and dichotomous study of biomarkers with swept-source OCT and OCT-angiography in naive patients with diabetic macular edema

BACKGROUND

We used state-of-the-art high-resolution retinal imaging to explore the treatment (loading dose of aflibercept) of diabetic macular edema (DME) among treatment-naive patients. Swept-source (SS) OCT and OCT-Angiography (SS-OCTA) were performed, and a dichotomous analysis was conducted to compare responders and treatment-resistant patients (responsive and resistant). Furthermore, treatment responses were evaluated based on the subdivision of choroidal thickness.

MATERIALS AND METHODS

This prospective, noncomparative, interventional case series study examined the following biomarkers: best-corrected visual acuity (BCVA), central macular thickness (CMT), central choroidal thickness (CCT), avascular area of the superficial plexus (AASP), avascular area of the deep plexus (AADP), and vessel density (VD). Data from the baseline and 4-month examinations were compared.

RESULTS

Twenty-eight eyes from 25 patients were included. Significant improvements were observed in BCVA (0.7250 ± 0.23 to 0.3957 ± 0.21; p < 0.000), CMT µm (339.04 ± 66.19 to 265.21 ± 55.75; p < 0.000), CCT µm (221.71 ± 69.69 to 209.07 ± 70.92; p < 0.000), VD (17.90 ± 7.82 to 15.35 ± 5.80; p < 0.038), AASP µm2 (235,374 ± 91,299 to 157,326 ± 77,815; p < 0.000) and AADP µm2 (996,335 ± 1,000,047 to 362,161 ± 277,225; p < 0.000). Dichotomous analysis revealed that 15 patients were responsive (53.57%), and 13 resistant (46.43%). There were no significant differences between any of the pretreatment biomarkers. In the subdivision of choroidal thickness, which ranged from 211 to 270 µm (group 3), we found greater reductions in the CCT, AADP and CD. The choroidal thickness ranged from 181 to 210 µm (group 2): BCVA and AASP exhibited the greatest reductions.

CONCLUSION

BCVA, CMT, CCT, AASP, AADP and VD were improved after treatment. The pretreatment biomarkers did not predict treatment response between the responsive and resistant. Regarding choroidal stratification, values within the normal range of CCT showed the greatest reductions, indicating that these values may be more responsive to treatment. Notably, this is the first study to analyze biomarkers provided by SS OCT and OCTA, stratify the choroid, and perform a dichotomous analysis.

Müller cells trophism and pathology as the next therapeutic targets for retinal diseases

Müller cells are a crucial retinal cell type involved in multiple regulatory processes and functions that are essential for retinal health and functionality. Acting as structural and functional support for retinal neurons and photoreceptors, Müller cells produce growth factors, regulate ion and fluid homeostasis, and facilitate neuronal signaling. They play a pivotal role in retinal morphogenesis and cell differentiation, significantly contributing to macular development. Due to their radial morphology and unique cytoskeletal organization, Müller cells act as optical fibers, efficiently channeling photons directly to the photoreceptors. In response to retinal damage, Müller cells undergo specific gene expression and functional changes that serve as a first line of defense for neurons, but can also lead to unwarranted cell dysfunction, contributing to cell death and neurodegeneration. In some species, Müller cells can reactivate their developmental program, promoting retinal regeneration and plasticity-a remarkable ability that holds promising therapeutic potential if harnessed in mammals. The crucial and multifaceted roles of Müller cells-that we propose to collectively call "Müller cells trophism"-highlight the necessity of maintaining their functionality. Dysfunction of Müller cells, termed "Müller cells pathology," has been associated with a plethora of retinal diseases, including age-related macular degeneration, diabetic retinopathy, vitreomacular disorders, macular telangiectasia, and inherited retinal dystrophies. In this review, we outline how even subtle disruptions in Müller cells trophism can drive the pathological cascade of Müller cells pathology, emphasizing the need for targeted therapies to preserve retinal health and prevent disease progression.

Impact of diabetes and diabetic retinopathy on neovascular exudative age-related macular degeneration

BACKGROUND

To evaluate the functional and morphological changes in patients with nAMD undergoing anti-VEGF therapy, focusing on the impact of concomitant diabetes with or without diabetic retinopathy.

METHODS

This retrospective cohort study included 1096 eyes from 916 patients with nAMD treated at the retina department of the University of Bari between August 2017 and May 2023. Patients were divided into two groups: 892 eyes without diabetes and 204 eyes with diabetes. Best-corrected visual acuity (BCVA), central retinal thickness (CRT) and presence of intraretinal fluid (IRF), subretinal fluid (SRF), subretinal hyperreflective material (SHRM) and atrophy were assessed at baseline, post-loading phase and at 12-month follow-up.

RESULTS

At baseline, no significant differences were observed between groups. Post-loading phase, both groups showed significant improvements in BCVA and reductions in CRT. However, SRF persistence was notably more frequent in the diabetic group (64.2% vs. 27.2%, p < 0.001). At 12 months, SRF was present in 53.7% of the diabetic group compared to 34.9% of the non-diabetic group (p < 0.001). Diabetic patients with moderate diabetic retinopathy (DR) exhibited significantly higher SRF persistence compared to those with mild DR or no DR.

CONCLUSIONS

While anti-VEGF therapy improves visual and anatomical outcomes in both diabetic and non-diabetic patients with nAMD, diabetic patients, particularly those with more severe DR, experience a higher rate of persistence of SRF. This suggests a less than optimal anatomic treatment response and the potential need for more tailored management strategies in this patient population.

PRECIS

This retrospective cohort study investigated the impact of diabetes mellitus and diabetic retinopathy on neovascular age-related macular degeneration treatment outcomes. The study analysed 1096 eyes from 916 patients undergoing anti-VEGF therapy over 12 months.

Relationship between choroidal structure and myocardial collateral flow regulation in acute and chronic coronary heart disease

PURPOSE

This study aimed to evaluate the relationship between coronary collateral filling, collateral size, and choroidal parameters in patients with acute and chronic coronary heart disease (CHD).

METHODS

Thirty-eight patients with acute CHD and 38 with chronic CHD who underwent diagnostic angiography in a cardiology clinic were included in this observational cross-sectional study. The control group comprised 32 healthy participants, and we examined both eyes of all participants. Diagnostic coronary angiograms were used to score the coronary collaterals, and choroidal parameters were measured in patients with CHD.

RESULTS

Choroidal vascular index (CVI) and subfoveal choroidal thickness (SFCT) were significantly lower in the chronic CHD group than in the acute CHD and control groups (p < 0.05). In the multinominal logistic regression analysis, collateral size had a significant association with both CVI (OR, 0.751; 95% CI, 0.596-0.947), and SFCT (OR, 0.986; 95% CI, 0.976-0.996) in patients with chronic CHD (p < 0.05). However, in the acute CHD group, no significant relationship was observed among choroidal parameters, collateral size, and filling.

CONCLUSION

Patients with chronic CHD had the lowest mean CVI and SFCT among the three groups, and this may be helpful in indicating chronic myocardial ischaemia. Moreover, an association was observed between larger collateral size and reduced CVI and SFCT in patients with chronic CHD, which may potentially be triggered by decreased angiogenic factors.

Glabridin and gymnemic acid alleviates choroid structural change and choriocapillaris impairment in diabetic rat's eyes

BACKGROUND

Small blood vessels in the eyes are more susceptible to injury, which can lead to complications. However, since diabetic retinopathy is often a serious clinical condition, most of this study focuses on the vascular system of the choroid. As part of this study, we looked at how gymnemic acid (from Gymnema sylvestre) and glabridin (from Glycyrrhiza glabra, or licorice) might help diabetic rats' choroid structural change and blood vessels.

AIM

To explore the effects of glabridin and gymnemic acid on the structural changes of the choroidal layer and choriocapillaris as well as the expression of vascular endothelial growth factor (VEGF) and cluster of differentiation (CD) 31 in diabetic rat's eye.

METHODS

The male Wistar rats were separated into five groups: The control group (control), the diabetic group (DM), the diabetic rats treated with glabridin 40 mg/kg body weight (DM + GB), the diabetic rats treated with gymnemic acid 400 mg/kg body weight (DM + GM), and the diabetic rats treated with glyburide 4 mg/kg body weight (DM + GR).

RESULTS

There was an increase in the thickness of both the choroid layer and the wall of the arteries in the DM. A decrease in vascularity and choroidal impairment was found in DM rats. After eight weeks of experimentation, the choroidal thickness increased, and the walls of choroid arteries. The choroidal thickness in the DM + GB was 15.69 ± 1.54 μm, DM + GM was 14.84 ± 1.31, and DM + GR groups was 16.45 ± 1.15 when compared with DM group (27.22 ± 2.05), the walls thickness of choroid arteries in the DM + GB was 10.23 ± 1.11, DM + GM was 10.41 ± 1.44, and DM + GR was 9.80 ± 1.78 when compared with DM group (16.35 ± 5.01), The expression of VEGF and CD31 was lower compared to the DM group.

CONCLUSION

In diabetic choroidopathy, hyperglycemia and inflammation cause damage to the neurovascular unit and blood-retinal barrier. Anti-VEGF treatments can slow or reverse the progression of the disease. According to current research findings, glabridin and gymnemic acid can reduce damage to the choroid, which is a factor that can sometimes result in vision loss.

Three-Dimensional Choroidal Vessels Assessment in Diabetic Retinopathy

Purpose

To evaluate choroidal vasculature in eyes with diabetic retinopathy (DR) using a novel three-dimensional algorithm.

Methods

Patients with DR and healthy controls underwent clinical examinations and swept-source optical coherence tomography (PlexElite-9000). The choroidal layer was segmented using the ResUNet model. Phansalkar thresholding was used to binarize the choroidal vasculature. The macular area was divided into 5 sectors by a custom grid, and the 15 largest vessels in each sector were measured for mean choroidal vessel diameter (MChVD). Volumetric choroidal thickness (ChT) and the choroidal vascularity index (CVI) were calculated. A linear mixed model was used for analysis.

Results

This retrospective cross-sectional study analyzed 73 eyes of 45 patients with DR (36 proliferative vs. 37 nonproliferative DR, and 42 with diabetic macular edema [DME] vs. 31 without DME), and 27 eyes of 21 age-match controls. The average MChVD was decreased in DR compared with healthy (200.472 ± 28.246 µm vs. 240.264 ± 22.350 µm; P < 0.001), as well as lower sectoral MChVD (P < 0.001); however, there was no difference in average ChT between the groups (P > 0.05). The global CVI was reduced in DR, especially in temporal and central sectors (P < 0.05). Compared with nonproliferative, proliferative DR exhibited decreased ChT (temporal, P < 0.05; other sectors, P > 0.05), CVI (P > 0.05), and MChVD (P > 0.05). DME eyes demonstrated lower but not statistically significant MChVD (196.449 ± 27.221 µm vs. 205.922 ± 29.134 µm; P > 0.05) and significantly reduced average CVI (0.365 ± 0.032 vs. 0.389 ± 0.040; P = 0.008) compared with non-DME eyes.

Conclusions

DR and DME eyes showed reduced MChVD and CVI, likely owing to microvascular changes leading to ischemia. These findings highlight the need for new choroidal biomarkers to better understand DR's pathogenic mechanisms.

Association between the onset of diabetic retinopathy and thickness changes in the retina and choroid of children with type 1 diabetes: A three-year longitudinal study

PURPOSE

To explore the longitudinal changes in retinal and choroidal thickness and their relation with the onset of type 1 diabetes mellitus (T1DM) in children.

METHODS

Thirty-eight children with T1DM and 71 healthy controls were included in this 3-year longitudinal study. Ophthalmic and systemic examinations were conducted on each participant. Retinal and choroidal thickness were measured by optical coherence tomography. Baseline values and changes in retinal and choroidal thickness were compared with DR onset, diabetics without DR and healthy controls. Logistic regression was used to explore the association with DR development.

RESULTS

Six children developed DR during the follow-up period (15.79%) and five of them developed microaneurysms in the parapapillary temporal quadrant. During follow-up, greater retinal thickening occurred in subjects with DR compared with diabetic participants without DR (p = 0.03) and healthy controls (p = 0.02) in the parapapillary outer temporal section. Compared with the control group, greater retinal thickening was observed in DR subjects in the averaged parapapillary outer ring (p = 0.01), the macular inner temporal section (p = 0.03) and several macular sections (all p < 0.05). Additionally, greater retinal thickening was observed in several parapapillary regions in non-DR T1DM participants compared with healthy controls (all p < 0.05). The thickness change in the outer temporal parapapillary section was independently associated with DR onset (OR = 1.33, 95% CI 1.01-1.73, p = 0.04).

CONCLUSION

Children with T1DM showed a significant or a trend of increasing retinal and choroidal thickness compared with normal controls over a 3-year period. The change of retinal thickness in the parapapillary outer temporal section was associated with the development of DR in children with T1DM, suggesting that it could serve as a biomarker for predicting and screening DR in these individuals.

Retinal and Choroidal Phenotypes Across Novel Subtypes of Type 2 Diabetes Mellitus

PURPOSE

To investigate longitudinal changes in choroidal thickness (CT) and ganglion cell-inner plexiform layer thickness (GC-IPLT) across distinct phenotypes of type 2 diabetes mellitus (T2DM) patients.

DESIGN

Prospective cohort study.

METHODS

T2DM patients were categorized into 5 groups (SAID, SIDD, SIRD, MOD, and MARD) using K-means clustering based on β-cell function and insulin resistance. Swept-source optical coherence tomography measured baseline and 4-year follow-up CT and GC-IPLT. Linear mixed-effects models assessed absolute and relative changes in CT and GC-IPLT across subtypes.

RESULTS

Over a median 4.11-year follow-up, CT and GC-IPLT decreased significantly across all groups. Choroidal thinning rates were most pronounced in SIDD (-6.5 ± 0.53 µm/year and -3.5 ± 0.24%/year) and SAID (-6.27 ± 0.8 µm/year and -3.19 ± 0.37%/year), while MARD showed the slowest thinning rates (-3.63 ± 0.34 µm/year and -1.98 ± 0.25%/year). SIRD exhibited the greatest GC-IPLT loss (-0.66 ± 0.05 µm/year and -0.91 ± 0.07%/year), with the least in SIDD (-0.36 ± 0.05 µm/year and -0.49 ± 0.07%/year), all statistically significant (all P < 0.001). Adjusted for confounding variables, SIDD and SAID groups showed faster CT thinning than MARD [-2.57 µm/year (95% CI: -4.16 to -0.97; P = 0.002) and -2.89 µm/year (95% CI: -4.12 to -1.66; P < 0.001), respectively]. GC-IPLT thinning was notably accelerated in SIRD versus MARD, but slowed in SIDD relative to MARD [differences of -0.16 µm/year (95% CI: -0.3 to -0.03; P = 0.015) and 0.15 µm/year (95% CI: 0.03 to 0.27; P = 0.015), respectively].

CONCLUSIONS

Microvascular damage in the choroid is associated with SIDD patients, whereas early signs of retinal neurodegeneration are evident in SIRD patients. All these changes may precede the onset of DR.

Association of hypertension defined by the 2017 ACC/AHA guideline and choroidal thickness changes in type 2 diabetes: a 2-year longitudinal study

PURPOSE

This prospective cohort study investigated the longitudinal relationship between hypertension (HTN), defined by the 2017 ACC/AHA guidelines, and changes in choroidal thickness (CT) in patients with type 2 diabetes.

METHODS

Patients aged 30-80 years from the Guangzhou Diabetic Eye Study were categorized into non-HTN, stage 1-HTN, and stage 2-HTN groups based on BP criteria. Macular and parapapillary CT were measured using swept-source optical coherence tomography (SS-OCT). Mixed linear regression models analysed CT decline rates over a median 2.1-year follow-up, adjusting for confounders.

RESULTS

803 diabetes patients were included. Both stage 1-HTN and stage 2-HTN groups showed significantly thinner macular and parapapillary CT compared to non-HTN (all P < 0.05). Stage 2-HTN correlated with reduced macular CT thinning (coef = -11.29 μm/year; 95% CI, -22.36 to -0.22; P = 0.046) after adjustment, but not in the parapapillary area (coef = -4.07 μm/year; 95% CI, -12.89 to 4.74; P = 0.365). Subgroup analyses indicated faster macular CT decline in stage 2-HTN among those <65 years old (coef = -20.31 μm/year; 95% CI, -35.67 to -4.95; P = 0.10), males (coef = -14.1 μm/year; 95% CI, -32.54 to -4.33; P = 0.004), BMI ≥ 25 kg/m2 (coef = -10.24 μm/year; 95% CI, -26.86 to -6.38; P = 0.007), HbA1c > 6.5% (coef = -8.91 μm/year; 95% CI, -13.49 to -4.68; P = 0.001), and diabetes duration <10 years (coef = -12.78 μm/year; 95% CI, -27.48 to -1.91; P = 0.008).

CONCLUSION

Stage 2-HTN is associated with accelerated macular CT loss in diabetic patients, suggesting macular CT measurements could potentially serve as early indicators of systemic hypertension. Further research is needed to establish precise CT cutoff values for clinical use in detecting and monitoring hypertension-related ocular changes.

Comparison of Choroidal Vascularity Index, Retinal, and Optic Nerve Changes in Diabetes Mellitus Patients Without Diabetic Retinopathy

Objectives

To report changes in the choroid, optic nerve, and macula in diabetes mellitus patients without diabetic retinopathy, and to compare these findings with age and sex-matched healthy volunteers. Furthermore, the duration of the disease was recorded and the impact on these parameters was aimed to be analyzed.

Methods

In this study, 60 right eyes of diabetes mellitus (DM) patients without diabetic retinopathy who applied to our department for routine examination were enrolled. To evaluate the peripapillary retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL), Swept-Source Optical Coherence Tomography imaging was performed. In addition, images were recorded and processed by the image-j program and the 'choroidal vascularity index' (CVI) was calculated. The measurements were compared with 60 right eyes of age-sex-matched healthy volunteers. Furthermore, the patient group was divided into 2 subgroups according to disease duration and the measurements were compared with each other as well.

Results

Both RNFL and GCL thickness values were observed to be thinner in DM patients group compared to the control group. CVI was found to be lower in DM group compared to the control group. In addition, the duration of the disease was significantly associated with the RNFL and GCL thinning and lower CVI.

Conclusion

DM can lead to a decrease in RNLF and GCL thickness and also a decrease in CVI which can impair visual acuity even in the absence of diabetic retinopathy. Therefore, monitoring changes in the optic nerve, retina, and choroid layer is crucial in these patients.

The protective role of gamma zone peripapillary atrophy in diabetic retinopathy: insights from deep learning and SS-OCT angiography

Purpose

To explore the relationship between peripapillary atrophy (PPA) and diabetic retinopathy (DR), and to uncover potential mechanisms using swept-source optical coherence tomography (SS-OCT) angiography.

Methods

This cross-sectional study included 845 patients with type 2 diabetes (T2DM), who underwent detailed systemic and ophthalmic evaluations. A state-of-the-art deep learning method was employed to precisely identify the parapapillary beta and gamma zones. Based on PPA characteristics, eyes were categorized into four groups: without beta or gamma zone (Group A), isolated beta zone (Group B), isolated gamma zone (Group C), and with both beta and gamma zone (Group D). Digital fundus photography was utilized to diagnose and stage DR severity, while SS-OCT angiography quantified retinal and choroidal vasculature.

Results

Participants had a mean age of 66 ± 8.8 years, with 437 (51.7%) male. Beta and gamma PPA zones were observed in 574 (67.9%) and 256 (30.3%) eyes, respectively. Beta zone PPA was associated with older age, whereas gamma zone PPA was correlated with longer axial length (AL), lower vessel density, and reduced choroidal thickness. Adjusted analyses revealed that eyes with isolated (Group C) or concurrent (Group D) gamma zone PPA conferred significantly lower DR grade, independent of known risk factors including systemic diabetes risk factors and AL.

Conclusion

This study finds that gamma zone PPA is linked to a reduced risk of developing DR. These results imply that the gamma zone may reflect progressive myopia-associated thinning and microvascular depletion in posterior ocular tissues, potentially contributing to structural resilience against DR. This novel insight offers a promising avenue for understanding the interplay between PPA and DR.

Non-linear relationship between age and subfoveal choroidal thickness in Chinese patients with proliferative diabetic retinopathy

BACKGROUND

No study has investigated the change regularity between age and subfoveal choroidal thickness (SFCT) in proliferative diabetic retinopathy (PDR).

AIM

To investigate the relationship between the SFCT and age in Chinese patients with PDR.

METHODS

This was a cross-sectional retrospective study. The participants were hospitalized individuals with type 2 diabetes who underwent vitrectomy for PDR. Con-tralateral eyes that met the criteria were included in the study. All necessary laboratory tests were performed at the time of admission. Central macular thickness (CMT) and SFCT were two quantitative assessments made using enhanced depth imaging optical coherence tomography. CMT was measured automatically and SFCT was measured manually with digital calipers provided by the Heidelberg Eye Explorer software.

RESULTS

The final analysis included a total of 234 individuals with PDR. The average age was 55.60 years old ± 10.03 years old, and 57.69% of the population was male. Univariate analysis revealed a significant negative connection between age and SFCT in patients with PDR [β = -2.44, 95% confidence interval (95%CI): -3.46 to -1.42; P < 0.0001]. In the fully adjusted model, the correlation between SFCT and age remained steady (β = -1.68, 95%CI: -2.97 to -0.39; P = 0.0117). Spline smoothing showed that the relationship between SFCT and age in patients with PDR was non-linear, with an inflection point at 54 years of age.

CONCLUSION

Our findings suggest that age is a key determinant of choroidal thickness. The non-linear link between SFCT and age in PDR patients should be taken into account.

Blood Glucose Levels Moderate the Associations Between IGF-1 Levels and Choroidal Metrics in Patients With Diabetes With Acromegaly Without Diabetic Retinopathy

Purpose

To examine the effects of serum growth hormone (GH) and insulin-like growth factor-1 (IGF-1) on choroidal structures with different blood glucose levels in patients with diabetes mellitus (DM) with acromegaly without diabetic retinopathy.

Methods

Eighty-eight eyes of 44 patients with acromegaly were divided into a nondiabetic group (23 patients, 46 eyes) and a diabetic group (21 patients, 42 eyes). Forty-four age- and sex-matched healthy controls and 21 patients with type 2 DM without diabetic retinopathy were also included. Linear regression models with a simple slope analysis were used to identify the correlation and interaction between endocrine parameters and choroidal thickness (ChT), total choroidal area (TCA), luminal area (LA), stromal area (SA), and choroidal vascular index (CVI).

Results

Our study revealed significant increases in the ChT, LA, SA, and TCA in patients with acromegaly compared with healthy controls, with no difference in the CVI. Comparatively, patients with DM with acromegaly had greater ChT than matched patients with type 2 DM, with no significant differences in other choroidal parameters. The enhancement of SA, LA and TCA caused by an acromegalic status disappeared in patients with diabetic status, whereas ChT and CVI were not affected by the interaction. In the diabetic acromegaly, higher IGF-1 (P = 0.006) and GH levels (P = 0.049), longer DM duration (P = 0.007), lower blood glucose (P = 0.001), and the interaction between GH and blood glucose were associated independently with thicker ChT. Higher GH levels (P = 0.016, 0.004 and 0.007), longer DM duration (P = 0.022, 0.013 and 0.013), lower blood glucose (P = 0.034, 0.011 and 0.01), and the interaction of IGF-1 and blood glucose were associated independently with larger SA, LA, and TCA. As blood glucose levels increased, the positive correlation between serum GH level and ChT diminished, and became insignificant when blood glucose was more than 7.35 mM/L. The associations between serum IGF-1 levels and LA, SA, and TCA became increasingly negative, with LA, becoming significantly and negatively associated to the GH levels only when blood glucose levels were more than 8.59 mM/L.

Conclusions

Acromegaly-related choroidal enhancements diminish in the presence of DM. In diabetic acromegaly, blood glucose levels are linked negatively with changes in choroidal metrics and their association with GH and IGF-1.

Translational Relevance

We revealed the potential beneficial impacts of IGF-1 and GH on structural measures of the choroid in patients with DM at relatively well-controlled blood glucose level, which could provide a potential treatment target for diabetic retinopathy.

A Pilot Study to Evaluate the Usefulness of Optical Coherence Tomography for Staging Iris Pigmented Lesions in Cats

This study investigated the utility of optical coherence tomography (OCT) for staging iris pigmented lesions in cats. Eighteen cats that underwent OCT examination for unilateral iris pigmented lesion were included. The cats were either suspected of melanosis due to clinical features (n = 8) or had been definitively diagnosed through histopathology with iris melanosis (n = 3), early feline diffuse iris melanoma (FDIM) (n = 4), or mid-stage or advanced FDIM (n = 3). From OCT images, mean iris thickness (MIT) was measured, and the ratio of pigmented lesion to normal iris (PN) was calculated. OCT images depicted the entire iris layer in all eyes with suspected melanosis, iris melanosis, and early FDIM, but observing the entire lesion in mid-stage/advanced FDIM was challenging. No significant difference in MIT was observed among the groups. Conversely, PN ratio was significantly higher (p < 0.05) in early FDIM (1.29 ± 0.16) than in suspected melanosis (1.02 ± 0.10) or iris melanosis (0.99 ± 0.09). Furthermore, OCT imaging revealed hyperreflective lines in 75% of eyes with suspected melanosis and in all the eyes with iris melanosis, corresponding to the pigmented lesions. Our results demonstrate that OCT is capable of detecting subtle differences in iris thickness and features in early-stage FDIM, indicating its potential utility in distinguishing between iris melanosis and early FDIM. Further study is warranted to verify the reliability of such OCT findings.

Subfoveal choroidal thickness changes in patients with pseudoexfoliation syndrome (PEX) compared to healthy controls: A systematic review and meta-analysis

PURPOSE

To investigate changes in choroidal thickness in patients diagnosed with pseudoexfoliation syndrome (PEX) compared to healthy controls, using optical coherence tomography (OCT).

METHODS

PubMed and Scopus databases were systematically searched for published articles comparing choroidal thickness between patients with PEX and healthy controls. Standardized Mean Difference (SMD) with 95 % confidence interval (CI) was computed to compare continuous variables. Revman 5.4 was used for the analysis. Subgroup analyses were performed according to OCT devices used.

RESULTS

12 studies were included in our analysis. Subfoveal choroidal thickness was decreased in patients with PEX compared to healthy controls. Subgroup analysis confirmed this finding in studies that used Heidelberg or Optovue OCT Devices.

CONCLUSION

Our meta-analysis showed that choroidal thickness was decreased in patients with PEX compared to controls. Increased heterogeneity and small case-control studies are the main limitations of the meta-analysis. Further studies are needed to evaluate the clinical significance of reduced subfoveal choroidal thickness in PEX.

Assessing acute nicotine impact on choroidal thickness: a randomized, double-blinded study comparing smoking cessation aids, including nicotine gum and electronic cigarettes

PURPOSE

To explore whether differences in choroidal thickness arise from nicotine consumption in healthy young individuals, specifically comparing the effects of nicotine gum to electronic cigarette (vaping), while maintaining a consistent 4 mg nicotine dosage.

METHODS

In a randomized double-blinded prospective cross-sectional study, 20 healthy participants (mean age ± standard deviation: 23 ± 2.36 years) were randomly assigned to either the nicotine gum or vaping group. Choroidal thickness (ChT) measurements were conducted using optical coherence tomography (OCT) (Topcon 3D OCT-1 Maestro System) at baseline, 30, and 60 min after ingesting 4 mg of nicotine, with ChT measurements taken from five different horizontal areas.

RESULTS

Neither the nicotine delivery method (gum or vaping) demonstrated a statistically significant impact on ChT mean scores among subjects in the five measured areas at baseline, 30, and 60 min (p > 0.05). However, significant differences were observed in ChT mean scores within subjects across the five areas (F (1.83, 72) = 36.43, p < 0.001), regardless of other study factors such as group, time, and visit (p > 0.05). A statistically significant interaction was identified between the factors of area and time concerning participants' ChT mean scores when stratified by the type of smoking (tobacco, vaping, and dual) (p = 0.003).

CONCLUSION

The results of this study revealed that nicotine, up to particular concentration of 4 mg, does not have a statistically significant vasoconstrictive effect on choroidal thickness, regardless of the delivery method, within the examined group. These findings offer valuable insights into the relationship between nicotine intake and choroidal dynamics in young adults.

Distribution and determinants of choroidal vascularity index in healthy eyes from deep-learning choroidal analysis: a population-based SS-OCT study

AIMS

To quantify the profiles of choroidal vascularity index (CVI) using fully artificial intelligence (AI)-based algorithm applied to swept-source optical coherence tomography (SS-OCT) images and evaluate the determinants of CVI in a population-based study.

METHODS

This cross-sectional study included adults aged ≥35 years residing in the Yuexiu District of Guangzhou, China, a follow-up population-based study. All participants (n=646) underwent comprehensive ophthalmic examinations, including SS-OCT for quantifying choroidal parameters. The CVI and subfoveal choroidal thickness (SFCT) were measured by a novel AI-based system.

RESULTS

A total of 556 participants were included, with a mean age of 56.4±9.9 years and 44.96% women. The average CVI and SFCT of the overall population were 69.7% (95% CI 69.2 to 70.3) and 263.0 µm (95% CI 257.2 to 268.8), respectively. After adjusting for other factors, older age and longer AL were significantly associated with a lower CVI. The CVI decreased by -0.13% (-0.19 to -0.06, p<0.001) with each 1-year increase in age, -2.10% (-3.29 to -0.92, p=0.001) with each 1 mm increase in AL. Furthermore, significantly positive correlation between CVI and SFCT has been observed, with coefficient of 0.059 (0.052 to 0.065, p<0.001).

CONCLUSION

Using new AI-based choroidal segmentation software, we provided a fast, reliable and objective CVI profile for large-scale samples. Older age and longer AL were independent correlates of choroidal thinning and CVI decline. These factors should be considered when interpreting SS-OCT-based choroidal measurements.

Regional choroidal thickness estimation from color fundus images based on convolutional neural networks

Purpose

This study aims to estimate the regional choroidal thickness from color fundus images from convolutional neural networks in different network structures and task learning models.

Method

1276 color fundus photos and their corresponding choroidal thickness values from healthy subjects were obtained from the Topcon DRI Triton optical coherence tomography machine. Initially, ten commonly used convolutional neural networks were deployed to identify the most accurate model, which was subsequently selected for further training. This selected model was then employed in combination with single-, multiple-, and auxiliary-task training models to predict the average and sub-region choroidal thickness in both ETDRS (Early Treatment Diabetic Retinopathy Study) grids and 100-grid subregions. The values of mean absolute error and coefficient of determination (R2) were involved to evaluate the models' performance.

Results

Efficientnet-b0 network outperformed other networks with the lowest mean absolute error value (25.61 μm) and highest R2 (0.7817) in average choroidal thickness. Incorporating diopter spherical, anterior chamber depth, and lens thickness as auxiliary tasks improved predicted accuracy (p-value = 6.39 × 10 - 44 , 2.72 × 10 - 38 , 1.15 × 10 - 36 respectively). For ETDRS regional choroidal thickness estimation, multi-task model achieved better results than single task model (lowest mean absolute error = 31.10 μm vs. 33.20 μm). The multi-task training also can simultaneously predict the choroidal thickness of 100 grids with a minimum mean absolute error of 33.86 μm.

Conclusions

Efficientnet-b0, in combination with multi-task and auxiliary task models, achieve high accuracy in estimating average and regional macular choroidal thickness directly from color fundus photographs.

Quantitative assessment of OCT and OCTA parameters in diabetic retinopathy with and without macular edema: single-center cross-sectional analysis

Aim

The retinal and choroidal parameters were analyzed to understand the impairment of microcirculation of both retina and choroid in patients with diabetic retinopathy (DR).

Methods

Fifty-five treatment-naive non-proliferative diabetic retinopathy (NPDR) patients (75 eyes) with type 2 diabetes mellitus (T2DM), including 28 patients (36 eyes) with diabetic macular edema (DME) and 27 patients (39 eyes) without DME, and 25 healthy subjects (47 eyes) were enrolled in this study. The following parameters of DR patients with and without DME were evaluated: the foveal avascular zone area (FAZ-a), FAZ perimeter (FAZ-p), FAZ circularity index (FAZ-CI), total subfoveal choroidal area (TCA), luminal area (LA), stromal area (SA), choroidal vascularity index (CVI), choriocapillaris flow area percentage, superficial capillary plexus (SCP), and deep capillary plexus (DCP).

Results

SCP, DCP, and the percentage of choriocapillaris flow area were significantly different between DR patients with and without DME. The DR patients presented lower LA, CVI, and FAZ-CI compared to those of healthy controls (all p < 0.05). The percentage of choriocapillaris flow area in DR patients with and without DME was significantly lower than that in healthy controls (p < 0.05). SCP and DCP were significantly correlated with FAZ-a and FAZ-p but presented insignificant associations with FAZ-CI.

Conclusions

Optical coherence tomography (OCT) and OCT angiography (OCTA) parameters, such as LA, CVI, FAZ-CI, and the percentage of choriocapillaris flow area, were reduced compared to those in controls, indicating that the microcirculations of the retina and choroid in the macular area were impaired in DR patients with DME and without DME.

Choroidal Changes in Patients with Diabetic Retinopathy: A Retrospective Study

This study aimed to investigate the characteristic choroidal changes in patients with diabetic retinopathy and identify factors affecting choroidal thickness (CTh), choroidal vascular index (CVI), and choriocapillaris flow. We retrospectively analyzed 79 eyes of 48 patients with diabetes between August 2021 and February 2022. We collected laboratory data, including HbA1c, serum creatinine, blood urea nitrogen, triglyceride, total cholesterol, high-density lipoprotein, and low-density lipoprotein (LDL) levels. Optical coherence tomography images of the foveal avascular zone, retinal vascular density, choroidal flow, retinal thickness, CTh, and CVI were analyzed. Possible determining factors affecting CTh, CVI, and choriocapillaris flow were analyzed using nonparametric multivariate analysis. LDL (p < 0.001) positively correlated with CTh, whereas CVI (p = 0.007) was negatively correlated with CTh in diabetic patients with diabetes. We also identified a negative correlation between choriocapillaris flow and deep parafoveal retinal vessel density in patients with low-grade diabetic retinopathy (DR), which diminished in those with more advanced DR. Our study provides further information on the changes in choroidal structure and blood flow in patients with diabetes.

Vascular changes of the choroid and their correlations with visual acuity in diabetic retinopathy

Objective

To investigate changes in the choroidal vasculature and their correlations with visual acuity in diabetic retinopathy (DR).

Methods

The cohort was composed of 225 eyes from 225 subjects, including 60 eyes from 60 subjects with healthy control, 55 eyes from 55 subjects without DR, 46 eyes from 46 subjects with nonproliferative diabetic retinopathy (NPDR), 21 eyes from 21 subjects with proliferative diabetic retinopathy (PDR), and 43 eyes from 43 subjects with clinically significant macular edema (CSME). Swept-source optical coherence tomography (SS-OCT) was used to image the eyes with a 12-mm radial line scan protocol. The parameters for 6-mm diameters of region centered on the macular fovea were analyzed. Initially, a custom deep learning algorithm based on a modified residual U-Net architecture was utilized for choroidal boundary segmentation. Subsequently, the SS-OCT image was binarized and the Niblack-based automatic local threshold algorithm was employed to calibrate subfoveal choroidal thickness (SFCT), luminal area (LA), and stromal area (SA) by determining the distance between the two boundaries. Finally, the ratio of LA and total choroidal area (SA + LA) was defined as the choroidal vascularity index (CVI). The choroidal parameters in five groups were compared, and correlations of the choroidal parameters with age, gender, duration of diabetes mellitus (DM), glycated hemoglobin (HbA1c), fasting blood sugar, SFCT and best-corrected visual acuity (BCVA) were analyzed.

Results

The CVI, SFCT, LA, and SA values of patients with DR were found to be significantly lower compared to both healthy patients and patients without DR (P < 0.05). The SFCT was significantly higher in NPDR group compared to the No DR group (P < 0.001). Additionally, the SFCT was lower in the PDR group compared to the NPDR group (P = 0.014). Furthermore, there was a gradual decrease in CVI with progression of diabetic retinopathy, reaching its lowest value in the PDR group. However, the CVI of the CSME group exhibited a marginally closer proximity to that of the NPDR group. The multivariate regression analysis revealed a positive correlation between CVI and the duration of DM as well as LA (P < 0.05). The results of both univariate and multivariate regression analyses demonstrated a significant positive correlation between CVI and BCVA (P = 0.003).

Conclusion

Choroidal vascular alterations, especially decreased CVI, occurred in patients with DR. The CVI decreased with duration of DM and was correlated with visual impairment, indicating that the CVI might be a reliable imaging biomarker to monitor the progression of DR.

Early choroidal and retinal changes detected by swept-source oct in type 2 diabetes and their association with diabetic kidney disease: a longitudinal prospective study

BACKGROUND

To evaluate structural changes in retina and choroid in patients with type 2 diabetes (T2D) and their association with diabetic kidney disease (DKD).

METHODS

T2D patients with mild or no diabetic retinopathy (DR) were followed for 3 years using structural SS-OCT and OCT angiography (OCT-A) taken every 6 months. Parameters were compared longitudinally and according to the DKD status on baseline.

RESULTS

One hundred and sixty eyes from 80 patients were followed for 3 years, 72 with no DKD (nDKD) at baseline and 88 with DKD. Trend analysis of T2D showed significant thinning in GCL + and circumpapillary retinal fiber neural layer (cRFNL), choroid, and decreased vascular density (VD) in superficial plexus and central choriocapillaris with foveal avascular zone (FAZ) enlargement. Patients with no DKD on baseline presented more significant declines in retinal center and choroidal thickness, increased FAZ and loss of nasal and temporal choriocapillaris volume. In addition, the nDKD group had worse glycemic control and renal parameters at the end of the study.

CONCLUSION

Our data suggests the potential existence of early and progressive neurovascular damage in the retina and choroid of patients with Type 2 Diabetes (T2D) who have either no or mild Diabetic Retinopathy (DR). The progression of neurovascular damage appears to be correlated with parameters related to glycemic control and renal damage.

Comparative study of the vascular structures of the retina and choroid in Chinese Han and Uygur populations with proliferative diabetic retinopathy: An OCTA study

BACKGROUND

To compare the vascular structures of the retina and choroid in Chinese Han and Uygur populations with proliferative diabetic retinopathy (PDR) using swept-source OCTA (SS-OCTA).

METHODS

Fifty-three eyes of 53 healthy volunteers (25 from Hans and 28 from Uygurs) and 40 eyes of 40 PDR patients (20 from Hans and 20 from Uygurs) were included. Retinal and choroidal parameters, including thickness, vessel flow density (VFD), foveal avascular zone (FAZ) area, choroidal vascularity volume and index (CVV and CVI) were evaluated.

RESULTS

Compared with the respective controls, superficial capillary plexus (SCP)-VFD and deep capillary plexus (DCP)-VFD, the areas of FAZ in SCP and DCP were significantly decreased in both Han and Uygur PDR patients. choroidal parameters analysis found that Uygur controls had substantially higher choroidal thickness (CT) than Han controls (p = 0.020) and PDR eyes showed significantly decreased CT. Both races with PDR exhibited significantly reduced choriocapillaris layer-VFD, large and medium choroidal vessel (LMCV) layer-VFD, CVV and CVI, however, Uygur PDR patients had significant lower LMCV layer-VFD, CVV and CVI compared to Han PDR patients. Diabetes duration was the most significant factor affecting CVV and CVI.

CONCLUSION

Both Han and Uygur PDR patients had significantly lower CT and decreased vessel densities compared to controls, but the Uygur PDR patients had more severe choroidal damage than Han PDR patients, which is most likely related to worse visual prognosis. These findings indicate that more frequent screenings and prompt therapy are urgent for Uygur PDR patients.

Associations between retinal microvascular flow, geometry, and progression of diabetic retinopathy in type 2 diabetes: a 2-year longitudinal study

PURPOSE

To determine the association between retinal blood vessel flow and geometric parameters and the risk of diabetic retinopathy (DR) progression through a 2-year prospective cohort study.

METHODS

Patients with type 2 diabetes mellitus (T2DM) were recruited from a diabetic registry between November 2017 and March 2019. All participants underwent standardized examinations at the baseline and 2-year follow-up visit, and the presence and severity of DR were assessed based on standard seven-field color fundus photographs. They also underwent swept-source optical coherence tomography angiography (OCTA) imaging to obtain measurements of foveal avascular zone area, blood vessel density (VD), fractal dimension (FD), blood vessel tortuosity (BVT) in the superficial capillary plexus (SCP) and deep capillary plexus (DCP).

RESULTS

A total of 233 eyes of 125 patients were included, and 40 eyes (17.17%) experienced DR progression within 2 years. DR progression was significantly associated with lower baseline VD (odds ratio [OR] 2.323 per SD decrease; 95% confidence interval [CI] 1.456-3.708; P < 0.001), lower FD (OR, 2.484 per SD decrease; 95% CI 1.268-4.867; P = 0.008), and higher BVT (OR, 2.076 per SD increase; 95% CI 1.382-3.121; P < 0.001) of the DCP after adjusting for confounding factors. The addition of OCTA metrics improved the predictive ability of the original model for DR progression (area under the curve [AUC] from 0.725 to 0.805; P = 0.022).

CONCLUSIONS

OCTA-derived VD, FD and BVT in the DCP were independent predictors of DR progression and showed additive value when added to established risk models predicting DR progression.

SB431542 partially inhibits high glucose-induced EMT by restoring mitochondrial homeostasis in RPE cells

BACKGROUND

The epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells participated in the development of retinal fibrosis. SB431542 is a small molecule inhibitor with inhibitory effects on the ALK4, ALK5 and ALK7. Our study aimed to explore the effect of SB431542 on the EMT of RPE cells and to provide new ideas for the treatment of retinal fibrosis.

METHODS

We performed fundus fluorescein angiography, optical coherence tomography and hematoxylin-eosin staining in vivo to observe the effect of SB431542 on choroidal neovascularization (CNV)-induced retinopathy. The proliferation, migration, cytoskeleton, adhesion, reactive oxygen species (ROS), mitochondrial morphology and membrane potential of RPE cells were observed in vitro through fluorescein diacetate staining, Cell Counting Kit-8 experiment, wound healing assay, phalloidin staining, immunofluorescence, MitoSOX, DCFH-DA, MitoTracker and JC-10 staining. Western blot, reverse transcription quantitative and immunofluorescence were used to detect the expression of EMT-related markers, pERK1/2, pGSK3β and β-catenin.

RESULTS

SB431542 significantly alleviated retinopathy in the CNV model. The proliferation, migration and adhesion in RPE cells decreased to a certain extent in SB431542 treatment. SB431542 partially normalized the structure of RPE cells. The expression levels of E-cadherin increased, while the expression levels of laminin and N-cadherin decreased with SB431542 treatment. SB431542 reduced the production of total ROS, mitochondrial SOX and recovered the mitochondrial membrane potential to a certain degree. In addition, our study showed that SB431542 downregulated the phosphorylation of ERK1/2, GSK3β and the expression of β-catenin.

CONCLUSION

SB431542 improved EMT in RPE cells by maintaining mitochondrial homeostasis via the ERK1/2 and GSK3β/β-catenin pathways. Video Abstract SB431542 inhibits EMT in RPE cells under high glucose conditions.

Changes in the choroid detected by ultrawide-field optical coherence tomography angiography in type 2 diabetes mellitus patients without diabetic retinopathy

AIM

The study objective was to investigate the choroidal changes in type 2 diabetes mellitus (T2DM) patients without diabetic retinopathy (DR).

METHODS

This was a cross-sectional study. Controls without diabetes and T2DM patients without DR (NDR) were included. Ultrawide-field (24 × 20 mm2) optical coherence tomography angiography (OCTA) was performed to analyse choroidal thickness and vessel density. All OCTA images were divided into 3 × 3 grids. The grid centre was considered the central area, while the rest was defined as the peripheral area.

RESULTS

No differences between groups were observed in the flow density of the choriocapillaris (CC), choroidal thickness (ChT) and choroidal vascular index (CVI) of the large and medium choroidal vessel (LMCV) in the central area. In the eight peripheral areas, the mean flow density of the CC did not differ between the groups, while the mean CVI and ChT were decreased in the NDR group (P< 0.05). In each peripheral area, the mean CVI and ChT were decreased in the NDR group (P< 0.05, except in the infratemporal area and nasal area for ChT and in the infratemporal area for CVI). In the correlation analysis, both mean peripheral CVI and ChT correlated with age and the duration of diabetes.

CONCLUSION

Early choroidal lesions tended to be peripheral in the LMCV in patients with diabetes without DR and correlated with age and the duration of diabetes.

Choroidal thickness measurements in young Saudi adult population: a cross-sectional study

AIM

To determine the choroidal thickness (CT) in young healthy Saudi adults using spectral-domain optical coherence tomography (SD-OCT) with an automated CT segmentation software.

METHODS

Fifty-eight young adults (total of 116 eyes), 39 males and 19 females participated in this study between the ages of 18 and 38y (mean 22.65±3.9y). All participants underwent ophthalmic screening examination, including the SD-OCT for measurements of CT in each quadrant egmented into five eccentric regions starting from the foveal region up to 4.5 mm towards the periphery.

RESULTS

The choroid was thickest in the foveal region (central 1 mm, 300±60 µm) and began to progressively thinner beyond the parafovea (1.5-2.5 mm, 284±67 µm) towards the peripheral region (3.5-4.5 mm from the fovea, 254±83 µm). The superior choroid showed the thickest profile (309±57 µm), while the nasal choroid exhibited the thinnest (229±76 µm). The rate of the thinning with increasing eccentricity was more predominant in the nasal choroid, which thinned from the foveal region (294±58 µm) to the peripheral region (158±55 µm). The superior and inferior choroid did not show a statistically significant thinning with eccentricity (all P>0.05). There was no statistically significant difference in the CT between gender, age, and laterality of the eyes (all P>0.05). A significant association of myopia with thinner subfoveal choroid was observed (Pearson's, r=0.37), and regression analysis showed that a 10.3 µm choroidal thinning for each diopter increase of myopia.

CONCLUSION

CT profile depends on eccentric and the quadrant. The CT profile across the measured area in the young Saudi adult population is comparable to other previous reports. Refractive error is critical for CT evaluation.

Evaluation of the Relationship Between Diabetic Macular Edema and Renal Function in a Latino Population

INTRODUCTION

Diabetic macular edema (DME) is one of the leading causes of vision impairment. The relationship between DME and estimated glomerular filtration rate (eGFR) has not been clearly evaluated in Hispanic or Latino populations. The objective of this study was to evaluate the eGFR in a Latino population with DME.

METHODS

A cross-sectional, observational, and descriptive study was carried out on the basis of a multicenter phase III clinical trial.

RESULTS

A total of 82 subjects diagnosed with DME (36 women and 46 men) were included in the study. The mean age was 61.93 ± 6.71 years. Mean values of the blood chemistry parameters glycated hemoglobin and eGFR were 7.20 ± 0.95% and 74.42 ± 26.82 mL/min/1.73 m2, respectively. The time elapsed since diagnosis of diabetes mellitus was 15.30 ± 7.35 years, while the duration of DME was 1.41 ± 1.75 years. Mean values for central macular thickness (CMT) and total macular volume (TMV) were 440.99 ± 132.22 µm and 11.97 ± 2.11 mm3, respectively. DME duration had a negative correlation with TMV (Rho - 0.26, p < 0.05) and a positive correlation with mean arterial pressure (Rho 0.26, p < 0.05). CMT was correlated with TMV (Rho 0.43, p < 0.0001) and visual acuity (Rho 0.26, p < 0.05). No significant correlations were observed between eGFR and CMT, TMV, or any demographic variable (p > 0.05). Chronic kidney disease (CKD) was associated with hypertension (OR 9.32, p = 0.035), elevated intraocular pressure (IOP) (OR 0.03, p = 0.011), and advanced age (OR 0.45, p = 0.011). CMT was significantly associated with TMV (β = 27.69, p < 0.0001).

CONCLUSIONS

We did not find a correlation between eGFR and DME. Our findings suggest that the presence of hypertension is associated with a decrease in the GFR < 60 mL/min/1.73 m2, and CKD may be associated with advanced age and elevated IOP which may increase the risk for the development of glaucoma.

TRIAL REGISTRATION

NCT05217680 (clinicaltrials.gov).

Impact of obesity on peripapillary choroidal thickness, macular choroidal thickness, and lamina cribrosa morphology

BACKGROUND

Obesity is known to be a significant risk factor for many ocular diseases. In order to understand the mechanism of obesity-related ocular diseases, we examined the lamina cribrosa morphology, peripapillary choroidal thickness (PPCT), and macular choroidal thickness (MCT) in obese women using optical coherence tomography (OCT).

METHODS

This comparative cross-sectional study included the right eyes of 72 obese women and 63 healthy women classified based on body mass index (BMI). Each participant underwent a thorough ophthalmological examination and enhanced depth (EDI) OCT imaging, including measurements of PPCT from a total of 12 regions, MCT from a total of 7 regions, Bruch's membrane opening (BMO), lamina cribrosa thickness (LCT), lamina cribrosa depth (LCD), intraocular pressure (IOP), and central corneal thickness (CCT).

RESULTS

The mean age and BMI of the obese group were 32.36±7.38 years and 35.11±4.39 kg/m², while those of the control group were 31.64±7.78 years and 20.88±1.72 kg/m² (p = 0.658, and p<0.001, respectively). PPCT N1000, PPCT N1500, PPCT S1500, and PPCT T1500 were statistically significantly thinner in the obese group than the control group (p values were 0.039, 0.012, 0.027, and 0.036, respectively). IOP and CCT were significantly higher in the obese group than the control group (p = 0.016, and p = 0.019, respectively). There was no statistically significant difference between the two groups in terms of MCT, BMO, LCT, and LCD.

CONCLUSION

We discovered thinning in the PPCT, which indicates microvascular abnormalities in the optic disc head. Microvascular alteration in the peripapillary region may be a potential initial event in the pathogenesis of several obesity-related ocular diseases, especially glaucoma.

Multiple instance learning based classification of diabetic retinopathy in weakly-labeled widefield OCTA en face images

Diabetic retinopathy (DR), a pathologic change of the human retinal vasculature, is the leading cause of blindness in working-age adults with diabetes mellitus. Optical coherence tomography angiography (OCTA), a functional extension of optical coherence tomography, has shown potential as a tool for early diagnosis of DR through its ability to visualize the retinal vasculature in all spatial dimensions. Previously introduced deep learning-based classifiers were able to support the detection of DR in OCTA images, but require expert labeling at the pixel level, a labor-intensive and expensive process. We present a multiple instance learning-based network, MIL-ResNet,14 that is capable of detecting biomarkers in an OCTA dataset with high accuracy, without the need for annotations other than the information whether a scan is from a diabetic patient or not. The dataset we used for this study was acquired with a diagnostic ultra-widefield swept-source OCT device with a MHz A-scan rate. We were able to show that our proposed method outperforms previous state-of-the-art networks for this classification task, ResNet14 and VGG16. In addition, our network pays special attention to clinically relevant biomarkers and is robust against adversarial attacks. Therefore, we believe that it could serve as a powerful diagnostic decision support tool for clinical ophthalmic screening.

Influence of Serum Uric Acid on Macular Choroidal Thickness and Ganglion Cell Inner Plexiform Layer Thickness

Purpose

The purpose of this study was to determine the influence of serum uric acid (UA) on macular choroidal and ganglion cell inner plexiform layer (GC-IPL) thickness.

Methods

This cross-sectional study enrolled adult individuals in communities in Guangzhou, China. All participants underwent a comprehensive ophthalmologic examination. They were divided into four groups according to UA quartiles. The choroidal and GC-IPL thickness was measured by swept-source optical coherence tomography (SS-OCT).

Results

A total of 719 subjects (1389 eyes) were included in the study. The average UA was 348.50 ± 86.16 mmol/L. The average choroidal and GC-IPL thickness decreased with UA quartiles (P < 0.001). Multivariate linear regression analyses showed that UA was negatively associated with average choroidal (β = -0.073, 95% confidence interval [CI] = -0.117 to -0.028, P = 0.001) and GC-IPL thickness (β = -0.006, 95% CI = -0.009 to -0.002, P = 0.001). After adjusting for confounding factors, the average choroidal thickness was decreased in quartile 4 as compared with quartile 1 by -14.737 µm (95% CI = -24.460 to -5.015, P = 0.003). The average GC-IPL thickness was decreased in quartile 4 versus quartile 1 by -1.028 (95% CI = -1.873 to -0.290, P = 0.007).

Conclusions

Higher UA levels were independently associated with macular choroid and GC-IPL thinning. These contribute to a better understanding of ocular pathological mechanisms.

Translational Relevance

The associated UA with choroidal and GC-IPL thickness helps to understand the ocular pathological and retinal neurodegenerative mechanism.

Axial Shortening in Myopic Children after Repeated Low-Level Red-Light Therapy: Post Hoc Analysis of a Randomized Trial

INTRODUCTION

Axial length (AL) elongation in myopia is considered irreversible. We aimed to systemically report unexpected AL shortening observed in a randomized clinical trial (RCT) after repeated low-level red-light (RLRL) therapy.

METHODS

This is a post hoc analysis of a multicenter, single-masked RCT. Two hundred sixty-four myopic children aged 8-13 years allocated to RLRL treatment (intervention group) or a single vision spectacle (SVS, control group) were included. AL was measured using an IOL-master 500 at baseline, 1-, 3-, 6-, and 12-month follow-up visits. AL shortening was defined as AL reduction from baseline to follow-up visits at three cutoffs: > 0.05 mm, > 0.10 mm, and > 0.20 mm. Frequency of AL shortening at different cutoffs was calculated. Analysis was done with intent to treat (ITT).

RESULTS

At 12-months follow up, frequency of AL shortening > 0.05 mm was 26/119 (21.85%) and 2/145 (1.38%) for the RLRL group versus the control group, respectively. The frequency was 18/119 (15.13%) versus 0/145 (0%) for AL shortening > 0.10 mm, and 7/119 (5.88%) versus 0/145 (0%), for AL shortening > 0.20 mm, respectively (p < 0.001). Mean AL shortening after 12 months (SD) was -0.156 (0.086) mm in the RLRL group and -0.06 mm in the control group. Age was significantly associated with AL shortening in the multivariable analysis. For the RLRL group that exhibited AL shortening (n = 56), choroidal thickness (ChT) thickening (0.056 mm) could only explain 28.3% of AL shortening (-0.20 mm).

CONCLUSION

Nearly a quarter of children had > 0.05 mm AL shortening following 12 months of RLRL therapy, whereas AL shortening rarely occurred among controls.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT04073238).

Association between Aqueous Humor Cytokines and Structural Characteristics Based on Optical Coherence Tomography in Patients with Diabetic Macular Edema

Purpose

To investigate the relationship between aqueous humor cytokines and structural characteristics based on optical coherence tomography (OCT) in patients with diabetic macular edema (DME).

Methods

Forty eyes of 28 patients with DME diagnosed in the Affiliated Eye Hospital of Wenzhou Medical University at Hangzhou were included. All patients collected aqueous humor during anti-VEGF treatment, and the IL-6, IL-8, IL-10, VEGF, VCAM-1, ICAM-1, TGF-β1, FGF, and MCP-1 concentrations were detected. OCT examination was performed before anti-VEGF treatment and 1 month after anti-VEGF operation. Central macular thickness (CMT), macular volume (MV), choroidal thickness (CT), and the number of hyperreflective foci (HRF) were obtained for analysis. Each eye was determined whether there is subretinal effusion (SRD), cystoid macular edema (CME), and diffuse retinal thickening (DRT).

Results

The levels of IL-6 and FGF in DME patients with SRD were significantly higher than those without SRD (all P < 0.05). The level of VEGF in DME patients with CME was significantly higher than that in DME patients without CME (P = 0.005); IL-6, TGF-β1, and MCP-1 were significantly higher in DME patients with DRT than that without DRT (all P < 0.05). There was no significant correlation between aqueous humor cytokines and retinal thickness and retinal volume. However, the thinner the CT, the higher the level of aqueous humor cytokines IL-6 (r = -0.313, P = 0.049) and FGF (r = -0.361, P = 0.022). A multivariate linear regression analysis showed that IL-6 was significantly correlated with CT (P = 0.002) and SRD (P = 0.017), FGF was also significantly correlated with CT (P = 0.002) and SRD (P = 0.005), and TGF-β1 was correlated with triglycerides (P = 0.030) and HRF (P = 0.021).

Conclusion

DME patients with significant macular cystoid edema changes may be related to high VEGF concentrations and thin CT; meanwhile, the presence of SRD or a high number of HRF on OCT macular scans in DME patients may indicate high levels of intraocular inflammatory factors. Thus, OCT morphology characteristics to some extent reflect intraocular inflammatory factors and VEGF levels and may guide treatment alternatives.

Rates of Choroidal and Neurodegenerative Changes Over Time in Diabetic Patients Without Retinopathy: A 3-Year Prospective Study

PURPOSE

To evaluate the longitudinal changes of retinal neurodegeneration and choroidal thickness in diabetic patients with and without diabetic retinopathy (DR).

DESIGN

Prospective observational cohort study.

METHODS

This prospective observational cohort study recruited type 2 diabetic patients from a community registry in Guangzhou. All participants underwent annual ocular examinations via swept-source optical coherence tomography that obtained choroid thickness (CT), retinal thickness (RT), and ganglion cell-inner plexiform layer (GC-IPL) thickness. The changes in GC-IPL, CT, and RT between patients who developed incident DR (IDR) or remained non-DR (NDR) were compared during a 3-year follow-up.

RESULTS

Among 924 patients, 159 (17.2%) patients developed IDR within the 3-year follow-up. A reduction in GC-IPL, RT, and CT was observed in NDR and IDR; however, CT thinning in patients with IDR was significantly accelerated, with an average CT reduction of -6.98 (95% CI: -8.26, -5.71) μm/y in patients with IDR and -3.98 (95% CI: -4.60, -3.36) μm/y in NDR patients (P < .001). Reductions in average GC-IPL thickness over 3 years were -0.97 (95% CI: -1.24, -0.70) μm/y in patients with IDR and -0.76 (95% CI: -0.82, -0.70) μm/y in NDR patients (P = .025). After adjusting for confounding factors, the average CT and GC-IPL thinning were significantly faster in patients with IDR compared with those who remained NDR by 2.09 μm/y (95% CI: 1.01, 3.16; P = .004) and -0.29 μm/y (95% CI: -0.49, -0.09; P = .004), respectively. The RT in the IDR group increased, whereas the RT in the NDR group decreased over time, with the adjusted difference of 2.09 μm/y (95% CI: 1.01, 3.16; P < .001) for central field RT.

CONCLUSIONS

The rate of retinal neurodegeneration and CT thinning were significantly different between the eyes that developed IDR and remained NDR during the 3-year follow-up, but both groups observed thickness reduction. This indicates that GC-IPL and CTs may decrease before the clinical manifestations of DR.

Hertel Exophthalmometry Values in a Greek Adult Outpatient Clinic-Based Population: Association With Demographic Factors and Systemic Disease

PURPOSE

To investigate correlations of exophthalmometry values (EVs) with age, gender, and the presence of diabetes mellitus, arterial hypertension, and dyslipidemia.

METHODS

In a cross-sectional, clinic-based study, consecutive adult Greek patients presenting for evaluation at the outpatient general clinic on a scheduled appointment basis at a tertiary care referral center were submitted to Hertel exophthalmometry in both eyes by the same observer. Subjects with signs of history or orbital pathology, including thyroid-associated ophthalmopathy, were excluded. Demographics, as well as a detailed systemic history report, were recorded. Mixed effect linear regression analysis was performed to account for the correlation between the eyes of the same participant.

RESULTS

A total of 800 eyes (400 subjects) were included, 194 males and 206 females, with a mean age of 67.82 ± 12 years (range: 18-92 years). The mean exophthalmometry value was 15.7 ± 2.6 mm (range: 11-21 mm). Every one year of increase in age is associated with a decrease in EVs by 0.03 mm (95% CI -0.04, -0.02/p-value<0.001). Female gender was associated with lower EVs by 0.33mm (95% CI-0.56, -0.1/p-value=0.005). Patients with diabetes mellitus had higher EVs by 0.47 mm (95% CI 0.25, 0.70/p-value<0.001) compared to patients without diabetes, and patients with arterial hypertension had lower EVs by 0.26 mm (95% CI -0.5, -0.02/p-value=0.034) compared to patients without hypertension. No association was found between dyslipidemia and systemic history of thyroid dysfunction.  Conclusions: A negative correlation of EVs was noted with increasing age, female gender, as well as history of arterial hypertension and a positive correlation with diabetes mellitus.

OCT and OCT Angiography Update: Clinical Application to Age-Related Macular Degeneration, Central Serous Chorioretinopathy, Macular Telangiectasia, and Diabetic Retinopathy

Similar to ultrasound adapting soundwaves to depict the inner structures and tissues, optical coherence tomography (OCT) utilizes low coherence light waves to assess characteristics in the eye. Compared to the previous gold standard diagnostic imaging fluorescein angiography, OCT is a noninvasive imaging modality that generates images of ocular tissues at a rapid speed. Two commonly used iterations of OCT include spectral-domain (SD) and swept-source (SS). Each comes with different wavelengths and tissue penetration capacities. OCT angiography (OCTA) is a functional extension of the OCT. It generates a large number of pixels to capture the tissue and underlying blood flow. This allows OCTA to measure ischemia and demarcation of the vasculature in a wide range of conditions. This review focused on the study of four commonly encountered diseases involving the retina including age-related macular degeneration (AMD), diabetic retinopathy (DR), central serous chorioretinopathy (CSC), and macular telangiectasia (MacTel). Modern imaging techniques including SD-OCT, TD-OCT, SS-OCT, and OCTA assist with understanding the disease pathogenesis and natural history of disease progression, in addition to routine diagnosis and management in the clinical setting. Finally, this review compares each imaging technique's limitations and potential refinements.

Influence of Intravitreal Therapy on Choroidal Thickness in Patients with Diabetic Macular Edema

OBJECTIVE

This study aimed to analyze the variation in subfoveal choroidal thickness (SFCT) and its relationship with the variation in central macular thickness (CME) in response to intravitreal therapy with an antiangiogenic (anti-VEGF) drug or corticosteroid in type 2 diabetic patients with diabetic macular edema (DME).

MATERIAL AND METHODS

This retrospective study included 70 eyes of 35 patients: 26 eyes received 4-5 intravitreal injections of aflibercept, 26 eyes were treated with a single intravitreal implant injection of dexamethasone, and 18 eyes without DME did not receive intravitreal therapy. SPECTRALIS® optical coherence tomography (OCT) (Heidelberg Engineering, Heidelberg, Germany) was used to measure the SFCT and CME before and at the end of the follow-up period.

RESULTS

The mean reductions in CME were 18.8 +/- 14.7% (aflibercept) and 29.7 +/- 16.9% (dexamethasone). The mean reductions in SFCT were 13.8 +/- 13.1% (aflibercept) and 19.5 +/- 9.6% (dexamethasone). The lowering effects of both parameters were significantly greater in the group treated with the dexamethasone implant (p = 0.022 and p = 0.046 for CMT and SFCT, respectively). Both therapies significantly decreased both CME and SFCT, independent of factors such as age, sex, previous intravitreal therapy, antidiabetic treatment, and the time of diabetes progression. There were no changes in the mean values of CME and SFCT in the untreated eyes.

CONCLUSIONS

SFCT significantly decreased in response to intravitreal therapy with anti-VEGF or corticosteroids, irrespective of age, sex, previous intravitreal therapy, antidiabetic treatment, and the time of diabetes progression. There was a correlation between the changes in CME and SFCT after intravitreal therapy with aflibercept or dexamethasone implantation. SFCT was not a good predictor of the CME response but could be used to monitor the response to treatment. Local intravitreal therapy only affected the treated eye.

The role of retinal Müller cells in diabetic retinopathy and related therapeutic advances

Diabetic retinopathy (DR) is a significant complication of diabetes. During the pathogenesis of retinal microangiopathy and neuronopathy, activated retinal Müller cells (RMCs) undergo morphological and structural changes such as increased expression of glial fibrillary acidic protein, disturbance of potassium and water transport regulation, and onset of production of a large number of inflammatory and vascular growth factors as well as chemokines. Evidently, activated RMCs are necessary for the pathogenesis of DR; therefore, exploring the role of RMCs in DR may provide a new target for the treatment thereof. This article reviews the mechanism of RMCs involvement in DR and the progress in related treatments.

Choroidal Thickness in Different Patterns of Diabetic Macular Edema

This observational study investigated the changes in choroidal thickness (ChT) in different patterns of diabetic macular edema (DME) based on image processing using enhanced-depth imaging spectral-domain optical coherence tomography (EDI-SD-OCT). Participants with ocular conditions affecting the fundus view, including retinal diseases, were excluded. After observing the patient’s medical record, multicolor fundus photos, thickness maps, and subtypes of DME were diagnosed according to the criteria reported by the Early Treatment Diabetic Retinopathy Study (ETDRS). Edema was classified as focal or diffuse and was subdivided into cystic macular edema (CME), CME with subretinal fluid (CME+), and spongy macular edema (SME). Image processing was performed on the B-scan images from SD-OCT to segment the choroid layer and obtain the choroid thickness. A total of 159 eyes of 81 patients (46 males and 35 females; 57.53 ± 9.78 years of age), and 57 eyes of 30 healthy individuals (age 57.34 ± 8.76 years) were enrolled in this study. Out of 159 eyes, 76 had focal macular edema (FME), 13 exhibited SME, and 51 presented CME. Among those with cystic macular edema, 19 eyes showed subretinal fluid (CME+). The average choroidal thickness in FME, diffuse SME, CME, and CME+ was 216.95 ± 52.94 µm, 243.00 ± 46.34 µm, 221.38 ± 60.78 µm, and 249.63 ± 53.90 µm, respectively. The average choroidal thickness in age-matched controls was 213.88 ± 45.60 µm. Choroidal thickness increases with the severity of edema; choroidal thickness was higher in diffuse macular edema than in FME. However, choroidal thickness increased in cystic macular edema with subretinal fluid (CME+).

Oct biomarkers of treatment-naive diabetic macular edema in patients with non-proliferative and proliferative diabetic retinopathy

PURPOSE

To evaluate and compare the retinal and choroidal spectral-domain optic coherence tomography (SD-OCT) findings of treatment-naïve diabetic macular edema (DME) secondary to non-proliferative and proliferative diabetic retinopathy (NPDR-PDR).

MATERIAL AND METHODS

A hundred and thirty-eight eyes of 138 patients with DME were evaluated. Best-corrected visual acuity was recorded, biomicroscopic anterior and posterior segment examination, SD-OCT imaging, and fundus fluorescein angiography (FFA) were performed. Demographic features, OCT characteristics, FFA, and visual acuity measurements were evaluated and compared between the two groups.

RESULTS

Sixteen eyes were excluded from the study due to the lack of FFA images. Data of 122 eyes were analyzed for the study. Sixty-five eyes with NPDR (Group 1) and 57 eyes with PDR (Group 2) were enrolled in the study. There was no significant difference in central macular thicknesses (CMT) between the two groups. The eyes with DME + PDR showed a higher rate of the diffuse type of macular edema with more para and peri-foveal extension accompanied by larger cysts than the eyes with DME + NPDR. Disorganization of retinal inner layers, disrupted ellipsoid zone, and the epiretinal membrane were more prominent in the eyes with PDR. Also, there were more prominent macular ischemia on FFA and worse initial visual acuity measurements in the eyes with PDR than those with NPDR. Choroidal thickness (CT) was significantly reduced in the PDR group.

CONCLUSION

SD-OCT features of treatment-naïve DME in patients with NPDR and PDR presented some differences. These variations may be related to diabetic retinopathy severity and may provide information about prognosis.

Choroidal and Retinal Thicknesses in Type 2 Diabetes Mellitus with Moderate Diabetic Retinopathy Measured by Swept Source OCT

Background: To study choroidal thickness (CT) in type 2 diabetes mellitus (DM2) patients with moderate diabetic retinopathy (DR) and to correlate with changes in retinal thickness (RT) with swept-source OCT (SS-OCT) compared to healthy subjects. Methods: Fifty-four DM2 patients with moderate DR without diabetic macular edema (DME) and 73 age-matched healthy subjects were evaluated using SS-OCT to measure changes in total RT and CT in the nine areas of the Early Treatment Diabetic Retinopathy Study (ETDRS) macular grid. Results: The mean age was 64.06 ± 11.98 years and 60.79 ± 8.62 years in the diabetic and control groups, respectively. Total RT showed statistically significant differences in the temporal inner area, with higher values in the DM2 group (p = 0.010). CT did not show differences between the groups. There was a significant negative correlation between RT and age in all of the outer ETDRS areas and a positive significant correlation in the central area for the DM2 group. There was also a negative significant correlation between CT and age in all of the ETDRS areas except for the inferior inner area. In the DM2 group, a negative correlation was observed between RT and CT in the central area (p = 0.039) and in both horizontal parafoveal areas (temporal inner, p = 0.028; nasal inner, p= 0.003). Conclusion: DM2 patients with moderate DR have no changes with regard to CT. Both CT and RT decreased with age in DM2, showing a negative correlation between these factors in the central and horizontal parafoveal areas of the ETDRS grid.

Choroidal Assessment in Patients with Type 2 Diabetes Mellitus and Non-Proliferative Diabetic Retinopathy by Swept-Source Ocular Coherence Tomography and Image Binarization

Background and Objectives: The aim of this study was to evaluate choroidal structure and vascularity indices in patients with non-proliferative diabetic retinopathy (NPDR). Materials and Methods: Sixty-three eyes from sixty-three patients were evaluated: 21 from healthy subjects, 20 with diabetes mellitus (DM) and no diabetic retinopathy (DR), and 22 with DM and non-proliferative diabetic retinopathy without diabetic macular edema (DME). Each patient underwent ocular examination, macular swept-source ocular coherence tomography (SS-OCT) imaging, glycemic control, and systemic high blood pressure (HBP) evaluation. Subfoveal choroidal thickness (SF-CT) was manually assessed on a line scan. Line scan OCT images were exported to ImageJ program. The areas under a 1.5, 3 and 6 mm horizontal line centered on the fovea were assessed by converting the OCT images to binary images, and total choroidal area (TCA), luminal area (LA), stromal area (SA), LA:SA ratio, and choroidal vascularity index (CVI) were evaluated. SF-CT and choroidal parameters were compared between groups, and correlations with ocular and systemic factors were analyzed. Results: SF-CT, TCA, LA, and SA were similar between groups. CVIs were significantly different between groups for all three studied areas (CVI-1.5: 66.21% vs. 66.06% vs. 63.74%, p = 0.003; CVI-3: 65.88% vs. 66.46% vs. 63.79%, p = 0.008; CVI-6: 64.79% vs. 65.40% vs. 63.61%, p = 0.032). NPDR patients had significantly lower CVIs compared to DM patients (p < 0.05). No association of choroidal parameters with glycemic control, DM duration and HBP was found significant (p < 0.05). Conclusions: Choroidal assessment by SS-OCT and image binarization in healthy subjects, subjects with DM without DR, and subjects with DM and NPDR indicated that CVI changes were identifiable and significant in early DR. The lack of association with ocular and systemic factors suggest that CVIs are reliable assessment parameters of choroidal vascular structure.

The Role of Intravitreal Corticosteroids in the Treatment of DME: Predictive OCT Biomarkers

This work aims to summarize predictive biomarkers to guide treatment choice in DME. Intravitreal anti-VEGF is considered the gold standard treatment for centers involving DME, while intravitreal steroid treatment has been established as a second-line treatment in DME. However, more than 1/3 of the patients do not adequately respond to anti-VEGF treatment despite up to 4-weekly injections. Not surprisingly, insufficient response to anti-VEGF therapy has been linked to low-normal VEGF levels in the serum and aqueous humor. These patients may well benefit from an early switch to intravitreal steroid treatment. In these patients, morphological biomarkers visible in OCT may predict treatment response and guide treatment decisions. Namely, the presence of a large amount of retinal and choroidal hyperreflective foci, disruption of the outer retinal layers and other signs of chronicity such as intraretinal cysts extending into the outer retina and a lower choroidal vascular index are all signs suggestive of a favorable treatment response of steroids compared to anti-VEGF. This paper summarizes predictive biomarkers in DME in order to assist individual treatment decisions in DME. These markers will help to identify DME patients who may benefit from primary dexamethasone treatment or an early switch.

Correlation between Choroidal Vascularity Index and Outer Retina in Patients with Diabetic Retinopathy

The choroid supplies blood to the outer retina. We quantified outer retinal and choroidal parameters to understand better the pathogenesis of diabetic retinopathy (DR) and diabetic macular edema (DME). The retrospective cross-sectional single-center study included 210 eyes from 139 diabetic patients and 76 eyes from 52 healthy controls. Spectral-domain optical coherence tomography (OCT) was carried out with a Spectralis HRA + OCT imaging device. The outer retinal layer (ORL), outer nuclear layer (ONL), and choroidal thicknesses were assessed along with the choroidal vascularity index (CVI). The presence of DR, whether with DME or without, was associated with choroidal thinning (p < 0.001). Compared with the controls, patients with DR without DME presented with lower ORL and ONL thickness (p < 0.001), whereas those with DR and DME had higher values of both parameters (p < 0.001). Significant correlations between outer retinal and choroidal parameters were found only in patients with DR without DME (ORL with choroidal thickness: p = 0.003, rho = 0.34; ORL with CVI: p < 0.001, rho = 0.49, ONL with CVI: p < 0.027, rho = 0.25). No correlations between choroidal and outer retinal parameters were observed in the controls and patients with DR and concomitant DME. Aside from diabetic choroidopathy, other pathogenic mechanisms seem to predominate in the latter group.

Differential Effect of Generalized and Abdominal Obesity on the Development and Progression of Diabetic Retinopathy in Chinese Adults With Type 2 Diabetes

Background

The relationship between obesity and diabetic retinopathy (DR) remains controversial. The aim of this study was to assess the association of generalized obesity [assessed by body mass index (BMI)] and abdominal obesity [assessed by waist to hip ratio (WHR)] with incident DR, and vision-threatening DR (VTDR), and DR progression among Chinese adults with type 2 diabetic mellitus (T2DM).

Method

This prospective cohort study was conducted at the Zhongshan Ophthalmic Center, from November 2017 to December 2020. DR was assessed based on the 7-filed fundus photographs using the modified Airlie House Classification. Multivariable logistic regression models were used to evaluate the associations of BMI and WHR with the development and progression of DR after adjusting for age, sex, traditional risk factors, and mutually for BMI and WHR.

Results

Among the 1,370 eligible participants, 1,195 (87.2%) had no sign of any DR and 175 (12.8%) had DR at baseline examination. During the 2 years follow-up visit, 342 (28.6%) participants had incident DR, 11 (0.8%) participants developed VTDR, 15 (8.6%) demonstrated DR progression. After adjusting for confounders, the BMI was negatively associated with incident DR [relative risk (RR) =0.31; 95% confidence interval (CI), 0.26-0.38; P < 0.001] and incident VTDR (RR = 0.22; 95%CI, 0.11-0.43; P < 0.001), while WHR was positively associated with incident DR (RR = 1.47; 95% CI, 1.27-1.71; P < 0.001). BMI and WHR level were not significantly associated with 2-year DR progression in multivariate models (all P > 0.05).

Conclusions

This study provides longitudinal evidence that generalized obesity confer a protective effect on DR, while abdominal obesity increased the risk of DR onset in Chinese patients, indicating that abdominal obesity is a more clinically relevant risk marker of DR than generalized obesity.

Alterations in the Choroidal Sublayers in Relationship to Severity and Progression of Diabetic Retinopathy: A Swept-Source OCT Study

Purpose

To examine the association of baseline choroidal sublayers metrics with the risk of diabetic retinopathy (DR) progression over 2 years, with adjustment for confounding factors that affect choroidal measurements.

Design

Prospective, observational cohort study.

Participants

One hundred three eyes from 62 patients with diabetes mellitus (DM).

Methods

Patients were followed up at 6-month intervals for at least 2 years. Choroidal metrics including choroidal area, choroidal thickness (CT), and choroidal vascularity index were measured for both (1) the choriocapillaris plus Sattler's layer and (2) the Haller's layer within the subfoveal and parafoveal region. Cox proportional models were constructed to estimate the relationship between baseline choroidal metrics and DR progression, adjusted for intereye correlation, established risk factors (i.e., duration of DM, glycated hemoglobin [HbA1c] level, body mass index [BMI], use of insulin, and mean arterial blood pressure [MABP]) and confounding factors of choroidal measurements (i.e., age and axial length). Additional predictive value of choroidal metrics was assessed using the C-statistic.

Main Outcome Measures

Hazard ratios (HRs) calculated by Cox proportional hazards model to demonstrate the associations between baseline choroidal metrics and DR progression.

Results

After adjusting for age, axial length, and intereye correlation, choroidal metrics in Haller's layer at baseline that were associated with a higher risk of DR progression included increases in subfoveal choroidal area (HR, 2.033; 95% confidence interval [CI], 1.179-3.505; P = 0.011), subfoveal plus parafoveal choroidal area (HR, 1.909; 95% CI, 1.096-3.326; P = 0.022), subfoveal CT (HR, 2.032; 95% CI, 1.181-3.498; P = 0.010), and subfoveal plus parafoveal CT (HR, 1.908; 95% CI, 1.097-3.319; P = 0.022). These associations remained statistically significant after additionally adjusting for duration of DM, HbA1c level, BMI, use of insulin, and MABP. Addition of these choroidal metrics significantly improved the discrimination for DR progression when compared with established risk factors alone (e.g., duration of DM and HbA1c; increase in C-statistic ranged from 8.08% to 9.67% [P < 0.05]).

Conclusions

Eyes with a larger choroidal area and CT in Haller's layer at baseline were associated with a higher risk of DR progression over 2 years.

Macular Choroidal Thickness and the Risk of Referable Diabetic Retinopathy in Type 2 Diabetes: A 2-Year Longitudinal Study

Purpose

The purpose of this study was to evaluate the associations between choroidal thickness (CT) and the 2-year incidence of referable diabetic retinopathy (RDR).

Methods

This was a prospective cohort study. Patients with type 2 diabetes in Guangzhou, China, aged 30 to 80 years underwent comprehensive examinations, including standard 7-field fundus photography. Macular CT was measured using a commercial swept-source optical coherence tomography (SS-OCT) device (DRI OCT Triton; Topcon, Tokyo, Japan). The relative risk (RR) with 95% confidence intervals (CIs) was used to quantify the association between CT and new-onset RDR. The prognostic value of CT was assessed using the area under the receiver operating characteristic curve (AUC), net reclassification improvement (NRI), and integrated discrimination improvement (IDI).

Results

A total of 1345 patients with diabetes were included in the study, and 120 (8.92%) of them had newly developed RDR at the 2-year follow-up. After adjusting for other factors, the increased RDR risk was associated with greater HbA1c (RR = 1.35, 95% CI = 1.17-1.55, P < 0.001), higher systolic blood pressure (SBP; RR = 1.02, 95% CI = 1.01-1.03, P = 0.005), lower triglyceride (TG) level (RR = 0.81, 95% CI = 0.69-0.96, P = 0.015), presence of diabetic retinopathy (DR; RR = 8.16, 95% CI = 4.47-14.89, P < 0.001), and thinner average CT (RR = 0.903, 95% CI = 0.871-0.935, P < 0.001). The addition of average CT improved NRI (0.464 ± 0.096, P < 0.001) and IDI (0.0321 ± 0.0068, P < 0.001) for risk of RDR, and it also improved the AUC from 0.708 (95% CI = 0.659-0.757) to 0.761 (95% CI = 0.719-0.804).

Conclusions

CT thinning measured by SS-OCT is an early imaging biomarker for the development of RDR, suggesting that alterations in CT play an essential role in DR occurrence.

Retinal and Choroidal Vascular Perfusion and Thickness Measurement in Diabetic Retinopathy Patients by the Swept-Source Optical Coherence Tomography Angiography

Purpose

To observe the changes in retinal and choroidal microstructures in patients with different stages of diabetic retinopathy (DR) and to evaluate the vascular perfusion of retina and choroid retinal thickness, retinal and choroidal vessel density by the swept-source optical coherence tomography angiography (SS-OCTA).

Methods

Subjects were divided into three groups: healthy control group (30 cases, 51 eyes), non-proliferative diabetic retinopathy (NPDR, 42 cases, 71 eyes) and proliferative diabetic retinopathy (PDR, 31 cases, 53 eyes). The area of the foveal avascular zone (FAZ), retinal and choroidal vascular perfusion, and the deep vascular complexes, including the intermediate capillary plexus (ICP) and deep capillary plexus (DCP) within the radius of 3, 6, 9, and 12 mm around the fovea were measured by SS-OCTA.

Results

Compared with the healthy control group, DR patients presented significantly increased fovea avascular area, while vessel density (VD) in the ICP and DCP, vascular perfusion rate, and the retinal thickness were considerably decreased. There were significant differences in the retinal thickness, ICP, and DCP vessel densities between the control and NPDR groups, or control and PDR groups, or PDR and NPDR groups. The deep vascular perfusion rate also significantly differed between the control and PDR groups, but there was no significant difference between the PDR and NPDR groups. The choroidal perfusion exhibited significant differences across different areas and amongst the three groups. Furthermore, the choroidal thickness showed a significant difference between the PDR and NPDR groups.

Conclusion

Our results showed significant differences in the area of the avascular fovea and the VD of deep vascular complexes between DR patients and healthy control subjects. Moreover, there were significant differences in retinal VD, especially in the deep-retinalregions, choroidal perfusion, and the volume of large vessel choroid in DR patients with different degrees of disease severity. Notably, SS-OCTA provided in-depth information for detecting the potential VD damage in DR patients caused by a multitudeof factors.