Leakage Index Associated With Macular Edema Severity

Leakage index was found to have an association with macular edema severity in patients who had nonischemic branch retinal vein occlusion (BRVO), according to a study published in Photodiagnosis and Photodynamic Therapy.

RVO is the second most prevalent retinal disease after diabetic retinopathy, with BRVO being the most frequent type. BRVO often leads to macular edema (ME), which can lead to vision loss. Vascular leakage is a feature of retinal vascular disease that appears on fundus fluorescence angiography (FFA) and could be important to guiding disease treatment. This study aimed to evaluate the association between ME and leakage index in patients with nonischemic BRVO.

The study included untreated patients with nonischemic BRVO who had visited the Eye Center at Renmin Hospital of Wuhan University in China between January 2020 and March 2023. The cross-sectional study featured participants who were aged 18 years and older, had symptoms for less than 6 months, and had completed both ultra-wide field fluorescein angiography (UWFFA) and macular optical coherence tomography. Patients were excluded if they had any concomitant ocular conditions, such as diabetic retinopathy, high myopia, or macular disease; had a history of ocular surgery; had significant optical media opacity; or there was significant obscuration of the image.

UWFFA images were acquired from all participants and were imported into the Fiji software for analysis. Leakage index was “defined as proportion of leakage area to the total retinal area on late UWFFA images.”

There were 45 eyes from 45 patients that were included in this study. The patients had a mean (range) age of 57 (29-75) years, and 19 were men; 32 eyes had major BRVO, and 13 eyes had macular BRVO. The mean (range) duration of symptoms was 4 (0-26) weeks.

The mean (SD) central macular thickness (CMT) of the patients in the study was 552.800 (183.335) μm. The mean leakage index for the panretina was 5.532% (7.667%), 23.127% (26.073%) for the perimacular area, 8.303% (16.807%) for the near-peripheral area, 1.588% (6.204%) for the mid-peripheral area, and 0.408% (2.215%) for the far-peripheral area. The CMT correlated to the leakage index in all groups according to the Spearman correlation analysis.

The macular BRVO group was found to have a lower mean CMT and leakage index in all regions when compared with the major BRVO group. Perimacular leakage index was the only area that correlated to CMT in patients with major BRVO. The macular BRVO group did not have a correlation with CMT in any leakage index.

There were some limitations to this study. The study had a small sample size and there was no longitudinal follow-up of changes in leakage index after treatment. Some patients had superficial retinal hemorrhages that could have affected the calculation of leakage index. Darker images could have affected the partial assessment of leakage. A semi-automated approach was used to assess the leakage index.

The researchers concluded that “the leakage index may have the potential ability to monitor BRVO progression and offer guidance for effective treatment strategies.”

Reference

Sun G, Wang X, Yi Z, He L, Zheng H, Chen C. Distribution of leakage index using ultra-widefield fluorescein angiography in patients with non-ischemic branch retinal vein occlusion and its association with macular edema. Photodiagnosis Photodyn Ther. 2023;43:103731. doi:10.1016/j.pdpdt.2023.103731