Branch retinal vein occlusion following cataract surgery

Cataract Surgery and Incidence of Retinal Vascular Occlusion: Population-Based Cohort Study Using a Target Trial Emulation Framework

BACKGROUND

Previous studies suggested an association between cataract surgery and retinal vascular occlusion. However, the association may be attributable to detection bias because postoperative monitoring may be more frequent for those who receive cataract surgery than for those who do not.

DESIGN

Population-based cohort study using target trial emulation framework.

METHODS

We included patients with cataract aged 50 years and older receiving cataract surgery or nonsurgical interventions identified from the Taiwan National Health Insurance Research Database between 2003 and 2018, matched by propensity score. The primary outcome was retinal vascular occlusion. Cox proportional hazards models were used to compare surgery and control groups. Additional analyses were restricted to patients who had undergone fundoscopic examination within 6 months prior to cataract surgery to address the issue of detection bias.

RESULTS

We included 577,129 cataract surgery and control pairs. We found the hazard ratio (HR) for retinal vascular occlusion after cataract surgery was 1.23 (95% confidence interval (CI): 1.17-1.29), compared with the control group. Secondary outcome analyses yielded similar results for retinal artery occlusion (HR: 1.13, 95% CI: 1.02-1.26) and retinal vein occlusion (HR: 1.26, 95% CI: 1.20-1.33). However, no risk of retinal vascular occlusion was observed among patients who had received fundoscopic examinations (HR: 1.06, 95% CI: 0.98-1.15) at baseline.

CONCLUSIONS

Our study underscored the importance of conducting complete baseline fundoscopic examinations before cataract surgery to clarify whether postoperative conditions are due to patients' underlying diseases or unintended complications of cataract surgery.

Evaluation of retinal and choroidal microvascular alteration after ICL V4c implantation based on OCTA

BACKGROUND

To evaluate the changes of retinal and choroidal microvascular including the superficial retinal capillary plexus (SCP), deep retinal capillary plexus (DCP), choriocapillaris (CC), and central retinal thickness (CRT) in high myopic eyes after the implantable collamer lens with a central hole (ICL V4c) implantation using optical coherence tomography angiography (OCTA).

METHODS

This retrospective study included 30 eyes of 30 patients (14 males and 16 females) who underwent ICL V4c implantation in Tianjin Aier Eye Hospital from October 2022 to May 2023. Uncorrected distant visual acuity (UDVA), best corrected distance visual acuity (BDVA), intraocular pressure (IOP), spherical equivalent (SE), axial length (AL), and optical coherence tomography angiography (OCTA) were measured and assessed before surgery, and 1 week, 1 month, and 3 months after surgery. OCTA was used to image and measure several key indicators: the foveal avascular zone (FAZ), vascular density (VD) of the SCP and DCP, blood flow density (BD) of the CC, and CRT. All measurement data were obtained utilizing the instrument's proprietary software, ensuring accuracy and consistency.

RESULTS

UDVA were significant improvements at the 1 week, 1 month, and 3 months after ICL V4c implantation surgery. BDVA, FAZ, and CRT maintained stable, however, IOP was higher at 1 week and 3 months post-operation compared to 1-month post-operation. The statistically significant difference was identified within the S3, S7, and S9 of SCP at each time point before and after the surgery (P1 = 0.004; P2 = 0.014; P3 = 0.037). However, paired analyses showed that there was a significant decrease in VD of S3 at 1 week after ICL V4c implantation surgery (P < 0.05), which then returned to preoperative levels by 1 month (P > 0.05), and the increase in VD of the S7 region at 1 month after ICL V4c implantation, which is significant compared to 1 week post-surgery, but not compared to preoperative levels. An overall comparison of the BD of the CC (2 mm) at each time point showed a statistically significant difference (P = 0.029).

CONCLUSION

ICL V4c implantation offers a safe and efficient therapy to the high myopic patients. However, the retinal and choroidal microvascular changes need to be paid attention to in post-ICL implantation patients.

Automatic Diagnosis of Different Types of Retinal Vein Occlusion Based on Fundus Images

Retinal vein occlusion (RVO) is the second common cause of blindness following diabetic retinopathy. The manual screening of fundus images to detect RVO is time consuming. Deep-learning techniques have been used for screening RVO due to their outstanding performance in many applications. However, unlike other images, medical images have smaller lesions, which require a more elaborate approach. To provide patients with an accurate diagnosis, followed by timely and effective treatment, we developed an intelligent method for automatic RVO screening on fundus images. Swin Transformer learns the hierarchy of low-to high-level features like the convolutional neural network. However, Swin Transformer extracts features from fundus images through attention modules, which pay more attention to the interrelationship between the features and each other. The model is more universal, does not rely entirely on the data itself, and focuses not only on local information but has a diffusion mechanism from local to global. To suppress overfitting, we adopt a regularization strategy, label smoothing, which uses one-hot to add noise to reduce the weight of the categories of true sample labels when calculating the loss function. The choice of different models using a 5-fold cross-validation on our own datasets indicates that Swin Transformer performs better. The accuracy of classifying all datasets is 98.75 ± 0.000, and the accuracy of identifying MRVO, CRVO, BRVO, and normal, using the method proposed in the paper, is 94.49 ± 0.094, 99.98 ± 0.015, 98.88 ± 0.08, and 99.42 ± 0.012, respectively. The method will be useful to diagnose RVO and help decide grade through fundus images, which has the potency to provide patients with further diagnosis and treatment.

Cataract Surgery Is Not Associated with Decreased Risk of Retinal Vein Occlusion

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