ObjectiveTo study a deep learning-based dual-modality fundus camera which was used to study retinal blood oxygen saturation and vascular morphology changes in eyes with branch retinal vein occlusion (BRVO). MethodsA prospective study. From May to October 2020, 31 patients (31 eyes) of BRVO (BRVO group) and 20 healthy volunteers (20 eyes) with matched gender and age (control group) were included in the study. Among 31 patients (31 eyes) in BRVO group, 20 patients (20 eyes) received one intravitreal injection of anti-vascular endothelial growth factor drugs before, and 11 patients (11 eyes) did not receive any treatment. They were divided into treatment group and untreated group accordingly. Retinal images were collected with a dual-modality fundus camera; arterial and vein segments were segmented in the macular region of interest (MROI) using deep learning; the optical density ratio was used to calculate retinal blood oxygen saturation (SO2) on the affected and non-involved sides of the eyes in the control group and patients in the BRVO group, and calculated the diameter, curvature, fractal dimension and density of arteriovenous in MROI. Quantitative data were compared between groups using one-way analysis of variance. ResultsThere was a statistically significant difference in arterial SO2 (SO2-A) in the MROI between the affected eyes, the fellow eyes in the BRVO group and the control group (F=4.925, P<0.001), but there was no difference in the venous SO2 (SO2-V) (F=0.607, P=0.178). Compared with the control group, the SO2-A in the MROI of the affected side and the non-involved side of the untreated group was increased, and the difference was statistically significant (F=4.925, P=0.012); there was no significant difference in SO2-V (F=0.607, P=0.550). There was no significant difference in SO2-A and SO2-V in the MROI between the affected side, the non-involved side in the treatment group and the control group (F=0.159, 1.701; P=0.854, 0.197). There was no significant difference in SO2-A and SO2-V in MROI between the affected side of the treatment group, the untreated group and the control group (F=2.553, 0.265; P=0.088, 0.546). The ophthalmic artery diameter, arterial curvature, arterial fractal dimension, vein fractal dimension, arterial density, and vein density were compared in the untreated group, the treatment group, and the control group, and the differences were statistically significant (F=3.527, 3.322, 7.251, 26.128, 4.782, 5.612; P=0.047, 0.044, 0.002, <0.001, 0.013, 0.006); there was no significant difference in vein diameter and vein curvature (F=2.132, 1.199; P=0.143, 0.321). ConclusionArterial SO2 in BRVO patients is higher than that in healthy eyes, it decreases after anti-anti-vascular endothelial growth factor drugs treatment, SO2-V is unchanged.
Objective To observe the change of retinal artery angle in eyes with idiopathic epiretinal membrane (ERM) and to analyze the relationship between retinal artery angle, ERM classification based on optical coherence tomography (OCT), and visual acuity. MethodsA retrospective cross-sectional clinical study. A total of 187 eyes in 187 patients diagnosed with monocular idiopathic ERM (IERM group) in Department of Ophthalmology of Zhejiang Provincial People's Hospital and the Affiliated Eye Hospital of Wenzhou Medical University at Hangzhou from November 2018 to January 2023 were included in the study. The contralateral healthy eyes were included as the control group. All patients underwent best corrected visual acuity (BCVA), fundus photography, spectral-domain OCT, OCT angiography (OCTA) and axial length (AL) measurement. BCVA examination was performed using the standard logarithmic visual acuity chart, which was converted to the logarithm of the minimum angle of resolution (logMAR) visual acuity. The foveal avascular zone (FAZ) area was measured by OCTA. The central macular thickness (CMT) was measured by spectral domain OCTaccording to the grading criteria of ectopic inner foveal layer (EIFL) was divided into stages 1 to 4 with 42, 45, 62, and 38 eyes, and the IERM group was subdivided into stage 1, stage 2, stage 3, and stage 4 groups accordingly. Image J was used to measure the retinal artery angle and the 1/2 retinal artery angle on fundus images. Multiple linear regression analysis was used to analyze the correlation between BCVA and artery angle, 1/2 artery Angle, CMT, FAZ area and AL. ResultsCompared with the control group, eyes in IERM group had worse BCVA (t=9.727), thicker CMT (t=12.452), smaller FAZ area (t=－14.329), smaller artery angle (t=－9.165) and smaller 1/2 artery angle (t=－9.549). The differences were statistically significant (P＜0.001). With the increase of IERM stage, the artery angle and 1/2 artery angle decreased significantly (F=21.763, 12.515; P＜0.001). There was no significant difference in artery angle and 1/2 artery angle between stage 1 group and stage 2 group, and 1/2 arterial angle between stage 2 group and stage 3 group (P＞0.05). There were significant differences in artery angle and 1/2 artery angle between the other groups (P＜0.05). There were significant differences in CMT and logMAR BCVA among different classification subgroups in IERM groups (P＜0.05). There was no significant difference in FAZ area between grade 3 group and grade 4 group (P＞0.05). There were significant differences in FAZ area between the other groups (P＜0.05). Correlation analysis showed that decreased artery angle (P=0.013) and increased CMT (P＜0.001) were associated with decreased BCVA. ConclusionsCompared with healthy eyes, the artery angle decreases significantly with the increase of ERM stage. Decreased retinal artery angle is associated with decreased visual acuity in IERM eyes.